Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2

* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2: (64 commits)
  ocfs2/net: Add debug interface to o2net
  ocfs2: Only build ocfs2/dlm with the o2cb stack module
  ocfs2/cluster: Get rid of arguments to the timeout routines
  ocfs2: Put tree in MAINTAINERS
  ocfs2: Use BUG_ON
  ocfs2: Convert ocfs2 over to unlocked_ioctl
  ocfs2: Improve rename locking
  fs/ocfs2/aops.c: test for IS_ERR rather than 0
  ocfs2: Add inode stealing for ocfs2_reserve_new_inode
  ocfs2: Add ac_alloc_slot in ocfs2_alloc_context
  ocfs2: Add a new parameter for ocfs2_reserve_suballoc_bits
  ocfs2: Enable cross extent block merge.
  ocfs2: Add support for cross extent block
  ocfs2: Move /sys/o2cb to /sys/fs/o2cb
  sysfs: Allow removal of symlinks in the sysfs root
  ocfs2:  Reconnect after idle time out.
  ocfs2/dlm: Cleanup lockres print
  ocfs2/dlm: Fix lockname in lockres print function
  ocfs2/dlm: Move dlm_print_one_mle() from dlmmaster.c to dlmdebug.c
  ocfs2/dlm: Dumps the purgelist into a debugfs file
  ...

47 files changed, 5800 insertions, 1042 deletions

diff --git a/Documentation/ABI/obsolete/o2cb b/Documentation/ABI/obsolete/o2cb
new file mode 100644
index 000000000000..9c49d8e6c0cc
--- /dev/null
+++ b/Documentation/ABI/obsolete/o2cb
@@ -0,0 +1,11 @@
+What:           /sys/o2cb symlink
+Date:           Dec 2005
+KernelVersion:  2.6.16
+Contact:        ocfs2-devel@oss.oracle.com
+Description:    This is a symlink: /sys/o2cb to /sys/fs/o2cb. The symlink will
+                be removed when new versions of ocfs2-tools which know to look
+                in /sys/fs/o2cb are sufficiently prevalent. Don't code new
+                software to look here, it should try /sys/fs/o2cb instead.
+                See Documentation/ABI/stable/o2cb for more information on usage.
+Users:          ocfs2-tools. It's sufficient to mail proposed changes to
+                ocfs2-devel@oss.oracle.com.
diff --git a/Documentation/ABI/stable/o2cb b/Documentation/ABI/stable/o2cb
new file mode 100644
index 000000000000..5eb1545e0b8d
--- /dev/null
+++ b/Documentation/ABI/stable/o2cb
@@ -0,0 +1,10 @@
+What:           /sys/fs/o2cb/ (was /sys/o2cb)
+Date:           Dec 2005
+KernelVersion:  2.6.16
+Contact:        ocfs2-devel@oss.oracle.com
+Description:    Ocfs2-tools looks at 'interface-revision' for versioning
+                information. Each logmask/ file controls a set of debug prints
+                and can be written into with the strings "allow", "deny", or
+                "off". Reading the file returns the current state.
+Users:          ocfs2-tools. It's sufficient to mail proposed changes to
+                ocfs2-devel@oss.oracle.com.
diff --git a/Documentation/ABI/testing/sysfs-ocfs2 b/Documentation/ABI/testing/sysfs-ocfs2
new file mode 100644
index 000000000000..b7cc516a8a8a
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-ocfs2
@@ -0,0 +1,89 @@
+What:           /sys/fs/ocfs2/
+Date:           April 2008
+Contact:        ocfs2-devel@oss.oracle.com
+Description:
+                The /sys/fs/ocfs2 directory contains knobs used by the
+                ocfs2-tools to interact with the filesystem.
+
+What:           /sys/fs/ocfs2/max_locking_protocol
+Date:           April 2008
+Contact:        ocfs2-devel@oss.oracle.com
+Description:
+                The /sys/fs/ocfs2/max_locking_protocol file displays version
+                of ocfs2 locking supported by the filesystem.  This version
+                covers how ocfs2 uses distributed locking between cluster
+                nodes.
+
+                The protocol version has a major and minor number.  Two
+                cluster nodes can interoperate if they have an identical
+                major number and an overlapping minor number - thus,
+                a node with version 1.10 can interoperate with a node
+                sporting version 1.8, as long as both use the 1.8 protocol.
+
+                Reading from this file returns a single line, the major
+                number and minor number joined by a period, eg "1.10".
+
+                This file is read-only.  The value is compiled into the
+                driver.
+
+What:           /sys/fs/ocfs2/loaded_cluster_plugins
+Date:           April 2008
+Contact:        ocfs2-devel@oss.oracle.com
+Description:
+                The /sys/fs/ocfs2/loaded_cluster_plugins file describes
+                the available plugins to support ocfs2 cluster operation.
+                A cluster plugin is required to use ocfs2 in a cluster.
+                There are currently two available plugins:
+
+                * 'o2cb' - The classic o2cb cluster stack that ocfs2 has
+                        used since its inception.
+                * 'user' - A plugin supporting userspace cluster software
+                        in conjunction with fs/dlm.
+
+                Reading from this file returns the names of all loaded
+                plugins, one per line.
+
+                This file is read-only.  Its contents may change as
+                plugins are loaded or removed.
+
+What:           /sys/fs/ocfs2/active_cluster_plugin
+Date:           April 2008
+Contact:        ocfs2-devel@oss.oracle.com
+Description:
+                The /sys/fs/ocfs2/active_cluster_plugin displays which
+                cluster plugin is currently in use by the filesystem.
+                The active plugin will appear in the loaded_cluster_plugins
+                file as well.  Only one plugin can be used at a time.
+
+                Reading from this file returns the name of the active plugin
+                on a single line.
+
+                This file is read-only.  Which plugin is active depends on
+                the cluster stack in use.  The contents may change
+                when all filesystems are unmounted and the cluster stack
+                is changed.
+
+What:           /sys/fs/ocfs2/cluster_stack
+Date:           April 2008
+Contact:        ocfs2-devel@oss.oracle.com
+Description:
+                The /sys/fs/ocfs2/cluster_stack file contains the name
+                of current ocfs2 cluster stack.  This value is set by
+                userspace tools when bringing the cluster stack online.
+
+                Cluster stack names are 4 characters in length.
+
+                When the 'o2cb' cluster stack is used, the 'o2cb' cluster
+                plugin is active.  All other cluster stacks use the 'user'
+                cluster plugin.
+
+                Reading from this file returns the name of the current
+                cluster stack on a single line.
+
+                Writing a new stack name to this file changes the current
+                cluster stack unless there are mounted ocfs2 filesystems.
+                If there are mounted filesystems, attempts to change the
+                stack return an error.
+
+Users:
+        ocfs2-tools <ocfs2-tools-devel@oss.oracle.com>
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 164c89394cff..4b70622a8a91 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -318,3 +318,13 @@ Why:	Not used in-tree. The current out-of-tree users used it to
         code / infrastructure should be in the kernel and not in some
         out-of-tree driver.
 Who:    Thomas Gleixner <tglx@linutronix.de>
+
+---------------------------
+
+What:   /sys/o2cb symlink
+When:   January 2010
+Why:    /sys/fs/o2cb is the proper location for this information - /sys/o2cb
+        exists as a symlink for backwards compatibility for old versions of
+        ocfs2-tools. 2 years should be sufficient time to phase in new versions
+        which know to look in /sys/fs/o2cb.
+Who:    ocfs2-devel@oss.oracle.com
diff --git a/MAINTAINERS b/MAINTAINERS
index 3eceebb48c92..974ee8ddb12c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2952,6 +2952,7 @@ P:	Joel Becker
 M:      joel.becker@oracle.com
 L:      ocfs2-devel@oss.oracle.com
 W:      http://oss.oracle.com/projects/ocfs2/
+T:      git git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2.git
 S:      Supported
 
 OMNIKEY CARDMAN 4000 DRIVER
diff --git a/fs/Kconfig b/fs/Kconfig
index c509123bea49..028ae38ecc52 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -444,6 +444,32 @@ config OCFS2_FS
           For more information on OCFS2, see the file
           <file:Documentation/filesystems/ocfs2.txt>.
 
+config OCFS2_FS_O2CB
+        tristate "O2CB Kernelspace Clustering"
+        depends on OCFS2_FS
+        default y
+        help
+          OCFS2 includes a simple kernelspace clustering package, the OCFS2
+          Cluster Base.  It only requires a very small userspace component
+          to configure it. This comes with the standard ocfs2-tools package.
+          O2CB is limited to maintaining a cluster for OCFS2 file systems.
+          It cannot manage any other cluster applications.
+
+          It is always safe to say Y here, as the clustering method is
+          run-time selectable.
+
+config OCFS2_FS_USERSPACE_CLUSTER
+        tristate "OCFS2 Userspace Clustering"
+        depends on OCFS2_FS && DLM
+        default y
+        help
+          This option will allow OCFS2 to use userspace clustering services
+          in conjunction with the DLM in fs/dlm.  If you are using a
+          userspace cluster manager, say Y here.
+
+          It is safe to say Y, as the clustering method is run-time
+          selectable.
+
 config OCFS2_DEBUG_MASKLOG
         bool "OCFS2 logging support"
         depends on OCFS2_FS
diff --git a/fs/ocfs2/Makefile b/fs/ocfs2/Makefile
index 4d4ce48bb42c..f6956de56fdb 100644
--- a/fs/ocfs2/Makefile
+++ b/fs/ocfs2/Makefile
@@ -2,7 +2,12 @@ EXTRA_CFLAGS += -Ifs/ocfs2
 
 EXTRA_CFLAGS += -DCATCH_BH_JBD_RACES
 
-obj-$(CONFIG_OCFS2_FS) += ocfs2.o
+obj-$(CONFIG_OCFS2_FS) +=       \
+        ocfs2.o                 \
+        ocfs2_stackglue.o
+
+obj-$(CONFIG_OCFS2_FS_O2CB) += ocfs2_stack_o2cb.o
+obj-$(CONFIG_OCFS2_FS_USERSPACE_CLUSTER) += ocfs2_stack_user.o
 
 ocfs2-objs := \
         alloc.o                 \
@@ -31,5 +36,10 @@ ocfs2-objs := \
         uptodate.o              \
         ver.o
 
+ocfs2_stackglue-objs := stackglue.o
+ocfs2_stack_o2cb-objs := stack_o2cb.o
+ocfs2_stack_user-objs := stack_user.o
+
+# cluster/ is always needed when OCFS2_FS for masklog support
 obj-$(CONFIG_OCFS2_FS) += cluster/
-obj-$(CONFIG_OCFS2_FS) += dlm/
+obj-$(CONFIG_OCFS2_FS_O2CB) += dlm/
diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index 447206eb5c2e..41f84c92094f 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -1029,8 +1029,7 @@ static void ocfs2_rotate_leaf(struct ocfs2_extent_list *el,
         BUG_ON(!next_free);
 
         /* The tree code before us didn't allow enough room in the leaf. */
-        if (el->l_next_free_rec == el->l_count && !has_empty)
-                BUG();
+        BUG_ON(el->l_next_free_rec == el->l_count && !has_empty);
 
         /*
          * The easiest way to approach this is to just remove the
@@ -1450,6 +1449,8 @@ static void ocfs2_adjust_root_records(struct ocfs2_extent_list *root_el,
  *   - When our insert into the right path leaf is at the leftmost edge
  *     and requires an update of the path immediately to it's left. This
  *     can occur at the end of some types of rotation and appending inserts.
+ *   - When we've adjusted the last extent record in the left path leaf and the
+ *     1st extent record in the right path leaf during cross extent block merge.
  */
 static void ocfs2_complete_edge_insert(struct inode *inode, handle_t *handle,
                                        struct ocfs2_path *left_path,
@@ -2712,24 +2713,147 @@ static void ocfs2_cleanup_merge(struct ocfs2_extent_list *el,
         }
 }
 
+static int ocfs2_get_right_path(struct inode *inode,
+                                struct ocfs2_path *left_path,
+                                struct ocfs2_path **ret_right_path)
+{
+        int ret;
+        u32 right_cpos;
+        struct ocfs2_path *right_path = NULL;
+        struct ocfs2_extent_list *left_el;
+
+        *ret_right_path = NULL;
+
+        /* This function shouldn't be called for non-trees. */
+        BUG_ON(left_path->p_tree_depth == 0);
+
+        left_el = path_leaf_el(left_path);
+        BUG_ON(left_el->l_next_free_rec != left_el->l_count);
+
+        ret = ocfs2_find_cpos_for_right_leaf(inode->i_sb, left_path,
+                                             &right_cpos);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        /* This function shouldn't be called for the rightmost leaf. */
+        BUG_ON(right_cpos == 0);
+
+        right_path = ocfs2_new_path(path_root_bh(left_path),
+                                    path_root_el(left_path));
+        if (!right_path) {
+                ret = -ENOMEM;
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = ocfs2_find_path(inode, right_path, right_cpos);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        *ret_right_path = right_path;
+out:
+        if (ret)
+                ocfs2_free_path(right_path);
+        return ret;
+}
+
 /*
  * Remove split_rec clusters from the record at index and merge them
- * onto the beginning of the record at index + 1.
+ * onto the beginning of the record "next" to it.
+ * For index < l_count - 1, the next means the extent rec at index + 1.
+ * For index == l_count - 1, the "next" means the 1st extent rec of the
+ * next extent block.
  */
-static int ocfs2_merge_rec_right(struct inode *inode, struct buffer_head *bh,
-                                handle_t *handle,
-                                struct ocfs2_extent_rec *split_rec,
-                                struct ocfs2_extent_list *el, int index)
+static int ocfs2_merge_rec_right(struct inode *inode,
+                                 struct ocfs2_path *left_path,
+                                 handle_t *handle,
+                                 struct ocfs2_extent_rec *split_rec,
+                                 int index)
 {
-        int ret;
+        int ret, next_free, i;
         unsigned int split_clusters = le16_to_cpu(split_rec->e_leaf_clusters);
         struct ocfs2_extent_rec *left_rec;
         struct ocfs2_extent_rec *right_rec;
+        struct ocfs2_extent_list *right_el;
+        struct ocfs2_path *right_path = NULL;
+        int subtree_index = 0;
+        struct ocfs2_extent_list *el = path_leaf_el(left_path);
+        struct buffer_head *bh = path_leaf_bh(left_path);
+        struct buffer_head *root_bh = NULL;
 
         BUG_ON(index >= le16_to_cpu(el->l_next_free_rec));
-
         left_rec = &el->l_recs[index];
-        right_rec = &el->l_recs[index + 1];
+
+        if (index == le16_to_cpu(el->l_next_free_rec - 1) &&
+            le16_to_cpu(el->l_next_free_rec) == le16_to_cpu(el->l_count)) {
+                /* we meet with a cross extent block merge. */
+                ret = ocfs2_get_right_path(inode, left_path, &right_path);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                right_el = path_leaf_el(right_path);
+                next_free = le16_to_cpu(right_el->l_next_free_rec);
+                BUG_ON(next_free <= 0);
+                right_rec = &right_el->l_recs[0];
+                if (ocfs2_is_empty_extent(right_rec)) {
+                        BUG_ON(le16_to_cpu(next_free) <= 1);
+                        right_rec = &right_el->l_recs[1];
+                }
+
+                BUG_ON(le32_to_cpu(left_rec->e_cpos) +
+                       le16_to_cpu(left_rec->e_leaf_clusters) !=
+                       le32_to_cpu(right_rec->e_cpos));
+
+                subtree_index = ocfs2_find_subtree_root(inode,
+                                                        left_path, right_path);
+
+                ret = ocfs2_extend_rotate_transaction(handle, subtree_index,
+                                                      handle->h_buffer_credits,
+                                                      right_path);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                root_bh = left_path->p_node[subtree_index].bh;
+                BUG_ON(root_bh != right_path->p_node[subtree_index].bh);
+
+                ret = ocfs2_journal_access(handle, inode, root_bh,
+                                           OCFS2_JOURNAL_ACCESS_WRITE);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                for (i = subtree_index + 1;
+                     i < path_num_items(right_path); i++) {
+                        ret = ocfs2_journal_access(handle, inode,
+                                                   right_path->p_node[i].bh,
+                                                   OCFS2_JOURNAL_ACCESS_WRITE);
+                        if (ret) {
+                                mlog_errno(ret);
+                                goto out;
+                        }
+
+                        ret = ocfs2_journal_access(handle, inode,
+                                                   left_path->p_node[i].bh,
+                                                   OCFS2_JOURNAL_ACCESS_WRITE);
+                        if (ret) {
+                                mlog_errno(ret);
+                                goto out;
+                        }
+                }
+
+        } else {
+                BUG_ON(index == le16_to_cpu(el->l_next_free_rec) - 1);
+                right_rec = &el->l_recs[index + 1];
+        }
 
         ret = ocfs2_journal_access(handle, inode, bh,
                                    OCFS2_JOURNAL_ACCESS_WRITE);
@@ -2751,30 +2875,156 @@ static int ocfs2_merge_rec_right(struct inode *inode, struct buffer_head *bh,
         if (ret)
                 mlog_errno(ret);
 
+        if (right_path) {
+                ret = ocfs2_journal_dirty(handle, path_leaf_bh(right_path));
+                if (ret)
+                        mlog_errno(ret);
+
+                ocfs2_complete_edge_insert(inode, handle, left_path,
+                                           right_path, subtree_index);
+        }
+out:
+        if (right_path)
+                ocfs2_free_path(right_path);
+        return ret;
+}
+
+static int ocfs2_get_left_path(struct inode *inode,
+                               struct ocfs2_path *right_path,
+                               struct ocfs2_path **ret_left_path)
+{
+        int ret;
+        u32 left_cpos;
+        struct ocfs2_path *left_path = NULL;
+
+        *ret_left_path = NULL;
+
+        /* This function shouldn't be called for non-trees. */
+        BUG_ON(right_path->p_tree_depth == 0);
+
+        ret = ocfs2_find_cpos_for_left_leaf(inode->i_sb,
+                                            right_path, &left_cpos);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        /* This function shouldn't be called for the leftmost leaf. */
+        BUG_ON(left_cpos == 0);
+
+        left_path = ocfs2_new_path(path_root_bh(right_path),
+                                   path_root_el(right_path));
+        if (!left_path) {
+                ret = -ENOMEM;
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = ocfs2_find_path(inode, left_path, left_cpos);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        *ret_left_path = left_path;
 out:
+        if (ret)
+                ocfs2_free_path(left_path);
         return ret;
 }
 
 /*
  * Remove split_rec clusters from the record at index and merge them
- * onto the tail of the record at index - 1.
+ * onto the tail of the record "before" it.
+ * For index > 0, the "before" means the extent rec at index - 1.
+ *
+ * For index == 0, the "before" means the last record of the previous
+ * extent block. And there is also a situation that we may need to
+ * remove the rightmost leaf extent block in the right_path and change
+ * the right path to indicate the new rightmost path.
  */
-static int ocfs2_merge_rec_left(struct inode *inode, struct buffer_head *bh,
+static int ocfs2_merge_rec_left(struct inode *inode,
+                                struct ocfs2_path *right_path,
                                 handle_t *handle,
                                 struct ocfs2_extent_rec *split_rec,
-                                struct ocfs2_extent_list *el, int index)
+                                struct ocfs2_cached_dealloc_ctxt *dealloc,
+                                int index)
 {
-        int ret, has_empty_extent = 0;
+        int ret, i, subtree_index = 0, has_empty_extent = 0;
         unsigned int split_clusters = le16_to_cpu(split_rec->e_leaf_clusters);
         struct ocfs2_extent_rec *left_rec;
         struct ocfs2_extent_rec *right_rec;
+        struct ocfs2_extent_list *el = path_leaf_el(right_path);
+        struct buffer_head *bh = path_leaf_bh(right_path);
+        struct buffer_head *root_bh = NULL;
+        struct ocfs2_path *left_path = NULL;
+        struct ocfs2_extent_list *left_el;
 
-        BUG_ON(index <= 0);
+        BUG_ON(index < 0);
 
-        left_rec = &el->l_recs[index - 1];
         right_rec = &el->l_recs[index];
-        if (ocfs2_is_empty_extent(&el->l_recs[0]))
-                has_empty_extent = 1;
+        if (index == 0) {
+                /* we meet with a cross extent block merge. */
+                ret = ocfs2_get_left_path(inode, right_path, &left_path);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                left_el = path_leaf_el(left_path);
+                BUG_ON(le16_to_cpu(left_el->l_next_free_rec) !=
+                       le16_to_cpu(left_el->l_count));
+
+                left_rec = &left_el->l_recs[
+                                le16_to_cpu(left_el->l_next_free_rec) - 1];
+                BUG_ON(le32_to_cpu(left_rec->e_cpos) +
+                       le16_to_cpu(left_rec->e_leaf_clusters) !=
+                       le32_to_cpu(split_rec->e_cpos));
+
+                subtree_index = ocfs2_find_subtree_root(inode,
+                                                        left_path, right_path);
+
+                ret = ocfs2_extend_rotate_transaction(handle, subtree_index,
+                                                      handle->h_buffer_credits,
+                                                      left_path);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                root_bh = left_path->p_node[subtree_index].bh;
+                BUG_ON(root_bh != right_path->p_node[subtree_index].bh);
+
+                ret = ocfs2_journal_access(handle, inode, root_bh,
+                                           OCFS2_JOURNAL_ACCESS_WRITE);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                for (i = subtree_index + 1;
+                     i < path_num_items(right_path); i++) {
+                        ret = ocfs2_journal_access(handle, inode,
+                                                   right_path->p_node[i].bh,
+                                                   OCFS2_JOURNAL_ACCESS_WRITE);
+                        if (ret) {
+                                mlog_errno(ret);
+                                goto out;
+                        }
+
+                        ret = ocfs2_journal_access(handle, inode,
+                                                   left_path->p_node[i].bh,
+                                                   OCFS2_JOURNAL_ACCESS_WRITE);
+                        if (ret) {
+                                mlog_errno(ret);
+                                goto out;
+                        }
+                }
+        } else {
+                left_rec = &el->l_recs[index - 1];
+                if (ocfs2_is_empty_extent(&el->l_recs[0]))
+                        has_empty_extent = 1;
+        }
 
         ret = ocfs2_journal_access(handle, inode, bh,
                                    OCFS2_JOURNAL_ACCESS_WRITE);
@@ -2790,9 +3040,8 @@ static int ocfs2_merge_rec_left(struct inode *inode, struct buffer_head *bh,
                 *left_rec = *split_rec;
 
                 has_empty_extent = 0;
-        } else {
+        } else
                 le16_add_cpu(&left_rec->e_leaf_clusters, split_clusters);
-        }
 
         le32_add_cpu(&right_rec->e_cpos, split_clusters);
         le64_add_cpu(&right_rec->e_blkno,
@@ -2805,13 +3054,44 @@ static int ocfs2_merge_rec_left(struct inode *inode, struct buffer_head *bh,
         if (ret)
                 mlog_errno(ret);
 
+        if (left_path) {
+                ret = ocfs2_journal_dirty(handle, path_leaf_bh(left_path));
+                if (ret)
+                        mlog_errno(ret);
+
+                /*
+                 * In the situation that the right_rec is empty and the extent
+                 * block is empty also,  ocfs2_complete_edge_insert can't handle
+                 * it and we need to delete the right extent block.
+                 */
+                if (le16_to_cpu(right_rec->e_leaf_clusters) == 0 &&
+                    le16_to_cpu(el->l_next_free_rec) == 1) {
+
+                        ret = ocfs2_remove_rightmost_path(inode, handle,
+                                                          right_path, dealloc);
+                        if (ret) {
+                                mlog_errno(ret);
+                                goto out;
+                        }
+
+                        /* Now the rightmost extent block has been deleted.
+                         * So we use the new rightmost path.
+                         */
+                        ocfs2_mv_path(right_path, left_path);
+                        left_path = NULL;
+                } else
+                        ocfs2_complete_edge_insert(inode, handle, left_path,
+                                                   right_path, subtree_index);
+        }
 out:
+        if (left_path)
+                ocfs2_free_path(left_path);
         return ret;
 }
 
 static int ocfs2_try_to_merge_extent(struct inode *inode,
                                      handle_t *handle,
-                                     struct ocfs2_path *left_path,
+                                     struct ocfs2_path *path,
                                      int split_index,
                                      struct ocfs2_extent_rec *split_rec,
                                      struct ocfs2_cached_dealloc_ctxt *dealloc,
@@ -2819,7 +3099,7 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
 
 {
         int ret = 0;
-        struct ocfs2_extent_list *el = path_leaf_el(left_path);
+        struct ocfs2_extent_list *el = path_leaf_el(path);
         struct ocfs2_extent_rec *rec = &el->l_recs[split_index];
 
         BUG_ON(ctxt->c_contig_type == CONTIG_NONE);
@@ -2832,7 +3112,7 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
                  * extents - having more than one in a leaf is
                  * illegal.
                  */
-                ret = ocfs2_rotate_tree_left(inode, handle, left_path,
+                ret = ocfs2_rotate_tree_left(inode, handle, path,
                                              dealloc);
                 if (ret) {
                         mlog_errno(ret);
@@ -2847,7 +3127,6 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
                  * Left-right contig implies this.
                  */
                 BUG_ON(!ctxt->c_split_covers_rec);
-                BUG_ON(split_index == 0);
 
                 /*
                  * Since the leftright insert always covers the entire
@@ -2858,9 +3137,14 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
                  * Since the adding of an empty extent shifts
                  * everything back to the right, there's no need to
                  * update split_index here.
+                 *
+                 * When the split_index is zero, we need to merge it to the
+                 * prevoius extent block. It is more efficient and easier
+                 * if we do merge_right first and merge_left later.
                  */
-                ret = ocfs2_merge_rec_left(inode, path_leaf_bh(left_path),
-                                           handle, split_rec, el, split_index);
+                ret = ocfs2_merge_rec_right(inode, path,
+                                            handle, split_rec,
+                                            split_index);
                 if (ret) {
                         mlog_errno(ret);
                         goto out;
@@ -2871,32 +3155,30 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
                  */
                 BUG_ON(!ocfs2_is_empty_extent(&el->l_recs[0]));
 
-                /*
-                 * The left merge left us with an empty extent, remove
-                 * it.
-                 */
-                ret = ocfs2_rotate_tree_left(inode, handle, left_path, dealloc);
+                /* The merge left us with an empty extent, remove it. */
+                ret = ocfs2_rotate_tree_left(inode, handle, path, dealloc);
                 if (ret) {
                         mlog_errno(ret);
                         goto out;
                 }
-                split_index--;
+
                 rec = &el->l_recs[split_index];
 
                 /*
                  * Note that we don't pass split_rec here on purpose -
-                 * we've merged it into the left side.
+                 * we've merged it into the rec already.
                  */
-                ret = ocfs2_merge_rec_right(inode, path_leaf_bh(left_path),
-                                            handle, rec, el, split_index);
+                ret = ocfs2_merge_rec_left(inode, path,
+                                           handle, rec,
+                                           dealloc,
+                                           split_index);
+
                 if (ret) {
                         mlog_errno(ret);
                         goto out;
                 }
 
-                BUG_ON(!ocfs2_is_empty_extent(&el->l_recs[0]));
-
-                ret = ocfs2_rotate_tree_left(inode, handle, left_path,
+                ret = ocfs2_rotate_tree_left(inode, handle, path,
                                              dealloc);
                 /*
                  * Error from this last rotate is not critical, so
@@ -2915,8 +3197,9 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
                  */
                 if (ctxt->c_contig_type == CONTIG_RIGHT) {
                         ret = ocfs2_merge_rec_left(inode,
-                                                   path_leaf_bh(left_path),
-                                                   handle, split_rec, el,
+                                                   path,
+                                                   handle, split_rec,
+                                                   dealloc,
                                                    split_index);
                         if (ret) {
                                 mlog_errno(ret);
@@ -2924,8 +3207,8 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
                         }
                 } else {
                         ret = ocfs2_merge_rec_right(inode,
-                                                    path_leaf_bh(left_path),
-                                                    handle, split_rec, el,
+                                                    path,
+                                                    handle, split_rec,
                                                     split_index);
                         if (ret) {
                                 mlog_errno(ret);
@@ -2938,7 +3221,7 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
                          * The merge may have left an empty extent in
                          * our leaf. Try to rotate it away.
                          */
-                        ret = ocfs2_rotate_tree_left(inode, handle, left_path,
+                        ret = ocfs2_rotate_tree_left(inode, handle, path,
                                                      dealloc);
                         if (ret)
                                 mlog_errno(ret);
@@ -3498,20 +3781,57 @@ out:
 }
 
 static enum ocfs2_contig_type
-ocfs2_figure_merge_contig_type(struct inode *inode,
+ocfs2_figure_merge_contig_type(struct inode *inode, struct ocfs2_path *path,
                                struct ocfs2_extent_list *el, int index,
                                struct ocfs2_extent_rec *split_rec)
 {
-        struct ocfs2_extent_rec *rec;
+        int status;
         enum ocfs2_contig_type ret = CONTIG_NONE;
+        u32 left_cpos, right_cpos;
+        struct ocfs2_extent_rec *rec = NULL;
+        struct ocfs2_extent_list *new_el;
+        struct ocfs2_path *left_path = NULL, *right_path = NULL;
+        struct buffer_head *bh;
+        struct ocfs2_extent_block *eb;
+
+        if (index > 0) {
+                rec = &el->l_recs[index - 1];
+        } else if (path->p_tree_depth > 0) {
+                status = ocfs2_find_cpos_for_left_leaf(inode->i_sb,
+                                                       path, &left_cpos);
+                if (status)
+                        goto out;
+
+                if (left_cpos != 0) {
+                        left_path = ocfs2_new_path(path_root_bh(path),
+                                                   path_root_el(path));
+                        if (!left_path)
+                                goto out;
+
+                        status = ocfs2_find_path(inode, left_path, left_cpos);
+                        if (status)
+                                goto out;
+
+                        new_el = path_leaf_el(left_path);
+
+                        if (le16_to_cpu(new_el->l_next_free_rec) !=
+                            le16_to_cpu(new_el->l_count)) {
+                                bh = path_leaf_bh(left_path);
+                                eb = (struct ocfs2_extent_block *)bh->b_data;
+                                OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb,
+                                                                 eb);
+                                goto out;
+                        }
+                        rec = &new_el->l_recs[
+                                le16_to_cpu(new_el->l_next_free_rec) - 1];
+                }
+        }
 
         /*
          * We're careful to check for an empty extent record here -
          * the merge code will know what to do if it sees one.
          */
-
-        if (index > 0) {
-                rec = &el->l_recs[index - 1];
+        if (rec) {
                 if (index == 1 && ocfs2_is_empty_extent(rec)) {
                         if (split_rec->e_cpos == el->l_recs[index].e_cpos)
                                 ret = CONTIG_RIGHT;
@@ -3520,10 +3840,45 @@ ocfs2_figure_merge_contig_type(struct inode *inode,
                 }
         }
 
-        if (index < (le16_to_cpu(el->l_next_free_rec) - 1)) {
+        rec = NULL;
+        if (index < (le16_to_cpu(el->l_next_free_rec) - 1))
+                rec = &el->l_recs[index + 1];
+        else if (le16_to_cpu(el->l_next_free_rec) == le16_to_cpu(el->l_count) &&
+                 path->p_tree_depth > 0) {
+                status = ocfs2_find_cpos_for_right_leaf(inode->i_sb,
+                                                        path, &right_cpos);
+                if (status)
+                        goto out;
+
+                if (right_cpos == 0)
+                        goto out;
+
+                right_path = ocfs2_new_path(path_root_bh(path),
+                                            path_root_el(path));
+                if (!right_path)
+                        goto out;
+
+                status = ocfs2_find_path(inode, right_path, right_cpos);
+                if (status)
+                        goto out;
+
+                new_el = path_leaf_el(right_path);
+                rec = &new_el->l_recs[0];
+                if (ocfs2_is_empty_extent(rec)) {
+                        if (le16_to_cpu(new_el->l_next_free_rec) <= 1) {
+                                bh = path_leaf_bh(right_path);
+                                eb = (struct ocfs2_extent_block *)bh->b_data;
+                                OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb,
+                                                                 eb);
+                                goto out;
+                        }
+                        rec = &new_el->l_recs[1];
+                }
+        }
+
+        if (rec) {
                 enum ocfs2_contig_type contig_type;
 
-                rec = &el->l_recs[index + 1];
                 contig_type = ocfs2_extent_contig(inode, rec, split_rec);
 
                 if (contig_type == CONTIG_LEFT && ret == CONTIG_RIGHT)
@@ -3532,6 +3887,12 @@ ocfs2_figure_merge_contig_type(struct inode *inode,
                         ret = contig_type;
         }
 
+out:
+        if (left_path)
+                ocfs2_free_path(left_path);
+        if (right_path)
+                ocfs2_free_path(right_path);
+
         return ret;
 }
 
@@ -3994,7 +4355,7 @@ static int __ocfs2_mark_extent_written(struct inode *inode,
                 goto out;
         }
 
-        ctxt.c_contig_type = ocfs2_figure_merge_contig_type(inode, el,
+        ctxt.c_contig_type = ocfs2_figure_merge_contig_type(inode, path, el,
                                                             split_index,
                                                             split_rec);
 
@@ -4788,6 +5149,8 @@ static void ocfs2_truncate_log_worker(struct work_struct *work)
         status = ocfs2_flush_truncate_log(osb);
         if (status < 0)
                 mlog_errno(status);
+        else
+                ocfs2_init_inode_steal_slot(osb);
 
         mlog_exit(status);
 }
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 90383ed61005..17964c0505a9 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -467,11 +467,11 @@ handle_t *ocfs2_start_walk_page_trans(struct inode *inode,
                                                          unsigned to)
 {
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
-        handle_t *handle = NULL;
+        handle_t *handle;
         int ret = 0;
 
         handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
-        if (!handle) {
+        if (IS_ERR(handle)) {
                 ret = -ENOMEM;
                 mlog_errno(ret);
                 goto out;
@@ -487,7 +487,7 @@ handle_t *ocfs2_start_walk_page_trans(struct inode *inode,
         }
 out:
         if (ret) {
-                if (handle)
+                if (!IS_ERR(handle))
                         ocfs2_commit_trans(osb, handle);
                 handle = ERR_PTR(ret);
         }
diff --git a/fs/ocfs2/cluster/Makefile b/fs/ocfs2/cluster/Makefile
index cdd162f13650..bc8c5e7d8608 100644
--- a/fs/ocfs2/cluster/Makefile
+++ b/fs/ocfs2/cluster/Makefile
@@ -1,4 +1,4 @@
 obj-$(CONFIG_OCFS2_FS) += ocfs2_nodemanager.o
 
 ocfs2_nodemanager-objs := heartbeat.o masklog.o sys.o nodemanager.o \
-        quorum.o tcp.o ver.o
+        quorum.o tcp.o netdebug.o ver.o
diff --git a/fs/ocfs2/cluster/netdebug.c b/fs/ocfs2/cluster/netdebug.c
new file mode 100644
index 000000000000..7bf3c0ea7bd9
--- /dev/null
+++ b/fs/ocfs2/cluster/netdebug.c
@@ -0,0 +1,441 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * netdebug.c
+ *
+ * debug functionality for o2net
+ *
+ * Copyright (C) 2005, 2008 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ */
+
+#ifdef CONFIG_DEBUG_FS
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/idr.h>
+#include <linux/kref.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+
+#include <linux/uaccess.h>
+
+#include "tcp.h"
+#include "nodemanager.h"
+#define MLOG_MASK_PREFIX ML_TCP
+#include "masklog.h"
+
+#include "tcp_internal.h"
+
+#define O2NET_DEBUG_DIR         "o2net"
+#define SC_DEBUG_NAME           "sock_containers"
+#define NST_DEBUG_NAME          "send_tracking"
+
+static struct dentry *o2net_dentry;
+static struct dentry *sc_dentry;
+static struct dentry *nst_dentry;
+
+static DEFINE_SPINLOCK(o2net_debug_lock);
+
+static LIST_HEAD(sock_containers);
+static LIST_HEAD(send_tracking);
+
+void o2net_debug_add_nst(struct o2net_send_tracking *nst)
+{
+        spin_lock(&o2net_debug_lock);
+        list_add(&nst->st_net_debug_item, &send_tracking);
+        spin_unlock(&o2net_debug_lock);
+}
+
+void o2net_debug_del_nst(struct o2net_send_tracking *nst)
+{
+        spin_lock(&o2net_debug_lock);
+        if (!list_empty(&nst->st_net_debug_item))
+                list_del_init(&nst->st_net_debug_item);
+        spin_unlock(&o2net_debug_lock);
+}
+
+static struct o2net_send_tracking
+                        *next_nst(struct o2net_send_tracking *nst_start)
+{
+        struct o2net_send_tracking *nst, *ret = NULL;
+
+        assert_spin_locked(&o2net_debug_lock);
+
+        list_for_each_entry(nst, &nst_start->st_net_debug_item,
+                            st_net_debug_item) {
+                /* discover the head of the list */
+                if (&nst->st_net_debug_item == &send_tracking)
+                        break;
+
+                /* use st_task to detect real nsts in the list */
+                if (nst->st_task != NULL) {
+                        ret = nst;
+                        break;
+                }
+        }
+
+        return ret;
+}
+
+static void *nst_seq_start(struct seq_file *seq, loff_t *pos)
+{
+        struct o2net_send_tracking *nst, *dummy_nst = seq->private;
+
+        spin_lock(&o2net_debug_lock);
+        nst = next_nst(dummy_nst);
+        spin_unlock(&o2net_debug_lock);
+
+        return nst;
+}
+
+static void *nst_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+        struct o2net_send_tracking *nst, *dummy_nst = seq->private;
+
+        spin_lock(&o2net_debug_lock);
+        nst = next_nst(dummy_nst);
+        list_del_init(&dummy_nst->st_net_debug_item);
+        if (nst)
+                list_add(&dummy_nst->st_net_debug_item,
+                         &nst->st_net_debug_item);
+        spin_unlock(&o2net_debug_lock);
+
+        return nst; /* unused, just needs to be null when done */
+}
+
+static int nst_seq_show(struct seq_file *seq, void *v)
+{
+        struct o2net_send_tracking *nst, *dummy_nst = seq->private;
+
+        spin_lock(&o2net_debug_lock);
+        nst = next_nst(dummy_nst);
+
+        if (nst != NULL) {
+                /* get_task_comm isn't exported.  oh well. */
+                seq_printf(seq, "%p:\n"
+                           "  pid:          %lu\n"
+                           "  tgid:         %lu\n"
+                           "  process name: %s\n"
+                           "  node:         %u\n"
+                           "  sc:           %p\n"
+                           "  message id:   %d\n"
+                           "  message type: %u\n"
+                           "  message key:  0x%08x\n"
+                           "  sock acquiry: %lu.%lu\n"
+                           "  send start:   %lu.%lu\n"
+                           "  wait start:   %lu.%lu\n",
+                           nst, (unsigned long)nst->st_task->pid,
+                           (unsigned long)nst->st_task->tgid,
+                           nst->st_task->comm, nst->st_node,
+                           nst->st_sc, nst->st_id, nst->st_msg_type,
+                           nst->st_msg_key,
+                           nst->st_sock_time.tv_sec, nst->st_sock_time.tv_usec,
+                           nst->st_send_time.tv_sec, nst->st_send_time.tv_usec,
+                           nst->st_status_time.tv_sec,
+                           nst->st_status_time.tv_usec);
+        }
+
+        spin_unlock(&o2net_debug_lock);
+
+        return 0;
+}
+
+static void nst_seq_stop(struct seq_file *seq, void *v)
+{
+}
+
+static struct seq_operations nst_seq_ops = {
+        .start = nst_seq_start,
+        .next = nst_seq_next,
+        .stop = nst_seq_stop,
+        .show = nst_seq_show,
+};
+
+static int nst_fop_open(struct inode *inode, struct file *file)
+{
+        struct o2net_send_tracking *dummy_nst;
+        struct seq_file *seq;
+        int ret;
+
+        dummy_nst = kmalloc(sizeof(struct o2net_send_tracking), GFP_KERNEL);
+        if (dummy_nst == NULL) {
+                ret = -ENOMEM;
+                goto out;
+        }
+        dummy_nst->st_task = NULL;
+
+        ret = seq_open(file, &nst_seq_ops);
+        if (ret)
+                goto out;
+
+        seq = file->private_data;
+        seq->private = dummy_nst;
+        o2net_debug_add_nst(dummy_nst);
+
+        dummy_nst = NULL;
+
+out:
+        kfree(dummy_nst);
+        return ret;
+}
+
+static int nst_fop_release(struct inode *inode, struct file *file)
+{
+        struct seq_file *seq = file->private_data;
+        struct o2net_send_tracking *dummy_nst = seq->private;
+
+        o2net_debug_del_nst(dummy_nst);
+        return seq_release_private(inode, file);
+}
+
+static struct file_operations nst_seq_fops = {
+        .open = nst_fop_open,
+        .read = seq_read,
+        .llseek = seq_lseek,
+        .release = nst_fop_release,
+};
+
+void o2net_debug_add_sc(struct o2net_sock_container *sc)
+{
+        spin_lock(&o2net_debug_lock);
+        list_add(&sc->sc_net_debug_item, &sock_containers);
+        spin_unlock(&o2net_debug_lock);
+}
+
+void o2net_debug_del_sc(struct o2net_sock_container *sc)
+{
+        spin_lock(&o2net_debug_lock);
+        list_del_init(&sc->sc_net_debug_item);
+        spin_unlock(&o2net_debug_lock);
+}
+
+static struct o2net_sock_container
+                        *next_sc(struct o2net_sock_container *sc_start)
+{
+        struct o2net_sock_container *sc, *ret = NULL;
+
+        assert_spin_locked(&o2net_debug_lock);
+
+        list_for_each_entry(sc, &sc_start->sc_net_debug_item,
+                            sc_net_debug_item) {
+                /* discover the head of the list miscast as a sc */
+                if (&sc->sc_net_debug_item == &sock_containers)
+                        break;
+
+                /* use sc_page to detect real scs in the list */
+                if (sc->sc_page != NULL) {
+                        ret = sc;
+                        break;
+                }
+        }
+
+        return ret;
+}
+
+static void *sc_seq_start(struct seq_file *seq, loff_t *pos)
+{
+        struct o2net_sock_container *sc, *dummy_sc = seq->private;
+
+        spin_lock(&o2net_debug_lock);
+        sc = next_sc(dummy_sc);
+        spin_unlock(&o2net_debug_lock);
+
+        return sc;
+}
+
+static void *sc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+        struct o2net_sock_container *sc, *dummy_sc = seq->private;
+
+        spin_lock(&o2net_debug_lock);
+        sc = next_sc(dummy_sc);
+        list_del_init(&dummy_sc->sc_net_debug_item);
+        if (sc)
+                list_add(&dummy_sc->sc_net_debug_item, &sc->sc_net_debug_item);
+        spin_unlock(&o2net_debug_lock);
+
+        return sc; /* unused, just needs to be null when done */
+}
+
+#define TV_SEC_USEC(TV) TV.tv_sec, TV.tv_usec
+
+static int sc_seq_show(struct seq_file *seq, void *v)
+{
+        struct o2net_sock_container *sc, *dummy_sc = seq->private;
+
+        spin_lock(&o2net_debug_lock);
+        sc = next_sc(dummy_sc);
+
+        if (sc != NULL) {
+                struct inet_sock *inet = NULL;
+
+                __be32 saddr = 0, daddr = 0;
+                __be16 sport = 0, dport = 0;
+
+                if (sc->sc_sock) {
+                        inet = inet_sk(sc->sc_sock->sk);
+                        /* the stack's structs aren't sparse endian clean */
+                        saddr = (__force __be32)inet->saddr;
+                        daddr = (__force __be32)inet->daddr;
+                        sport = (__force __be16)inet->sport;
+                        dport = (__force __be16)inet->dport;
+                }
+
+                /* XXX sigh, inet-> doesn't have sparse annotation so any
+                 * use of it here generates a warning with -Wbitwise */
+                seq_printf(seq, "%p:\n"
+                           "  krefs:           %d\n"
+                           "  sock:            %u.%u.%u.%u:%u -> "
+                                              "%u.%u.%u.%u:%u\n"
+                           "  remote node:     %s\n"
+                           "  page off:        %zu\n"
+                           "  handshake ok:    %u\n"
+                           "  timer:           %lu.%lu\n"
+                           "  data ready:      %lu.%lu\n"
+                           "  advance start:   %lu.%lu\n"
+                           "  advance stop:    %lu.%lu\n"
+                           "  func start:      %lu.%lu\n"
+                           "  func stop:       %lu.%lu\n"
+                           "  func key:        %u\n"
+                           "  func type:       %u\n",
+                           sc,
+                           atomic_read(&sc->sc_kref.refcount),
+                           NIPQUAD(saddr), inet ? ntohs(sport) : 0,
+                           NIPQUAD(daddr), inet ? ntohs(dport) : 0,
+                           sc->sc_node->nd_name,
+                           sc->sc_page_off,
+                           sc->sc_handshake_ok,
+                           TV_SEC_USEC(sc->sc_tv_timer),
+                           TV_SEC_USEC(sc->sc_tv_data_ready),
+                           TV_SEC_USEC(sc->sc_tv_advance_start),
+                           TV_SEC_USEC(sc->sc_tv_advance_stop),
+                           TV_SEC_USEC(sc->sc_tv_func_start),
+                           TV_SEC_USEC(sc->sc_tv_func_stop),
+                           sc->sc_msg_key,
+                           sc->sc_msg_type);
+        }
+
+
+        spin_unlock(&o2net_debug_lock);
+
+        return 0;
+}
+
+static void sc_seq_stop(struct seq_file *seq, void *v)
+{
+}
+
+static struct seq_operations sc_seq_ops = {
+        .start = sc_seq_start,
+        .next = sc_seq_next,
+        .stop = sc_seq_stop,
+        .show = sc_seq_show,
+};
+
+static int sc_fop_open(struct inode *inode, struct file *file)
+{
+        struct o2net_sock_container *dummy_sc;
+        struct seq_file *seq;
+        int ret;
+
+        dummy_sc = kmalloc(sizeof(struct o2net_sock_container), GFP_KERNEL);
+        if (dummy_sc == NULL) {
+                ret = -ENOMEM;
+                goto out;
+        }
+        dummy_sc->sc_page = NULL;
+
+        ret = seq_open(file, &sc_seq_ops);
+        if (ret)
+                goto out;
+
+        seq = file->private_data;
+        seq->private = dummy_sc;
+        o2net_debug_add_sc(dummy_sc);
+
+        dummy_sc = NULL;
+
+out:
+        kfree(dummy_sc);
+        return ret;
+}
+
+static int sc_fop_release(struct inode *inode, struct file *file)
+{
+        struct seq_file *seq = file->private_data;
+        struct o2net_sock_container *dummy_sc = seq->private;
+
+        o2net_debug_del_sc(dummy_sc);
+        return seq_release_private(inode, file);
+}
+
+static struct file_operations sc_seq_fops = {
+        .open = sc_fop_open,
+        .read = seq_read,
+        .llseek = seq_lseek,
+        .release = sc_fop_release,
+};
+
+int o2net_debugfs_init(void)
+{
+        o2net_dentry = debugfs_create_dir(O2NET_DEBUG_DIR, NULL);
+        if (!o2net_dentry) {
+                mlog_errno(-ENOMEM);
+                goto bail;
+        }
+
+        nst_dentry = debugfs_create_file(NST_DEBUG_NAME, S_IFREG|S_IRUSR,
+                                         o2net_dentry, NULL,
+                                         &nst_seq_fops);
+        if (!nst_dentry) {
+                mlog_errno(-ENOMEM);
+                goto bail;
+        }
+
+        sc_dentry = debugfs_create_file(SC_DEBUG_NAME, S_IFREG|S_IRUSR,
+                                        o2net_dentry, NULL,
+                                        &sc_seq_fops);
+        if (!sc_dentry) {
+                mlog_errno(-ENOMEM);
+                goto bail;
+        }
+
+        return 0;
+bail:
+        if (sc_dentry)
+                debugfs_remove(sc_dentry);
+        if (nst_dentry)
+                debugfs_remove(nst_dentry);
+        if (o2net_dentry)
+                debugfs_remove(o2net_dentry);
+        return -ENOMEM;
+}
+
+void o2net_debugfs_exit(void)
+{
+        if (sc_dentry)
+                debugfs_remove(sc_dentry);
+        if (nst_dentry)
+                debugfs_remove(nst_dentry);
+        if (o2net_dentry)
+                debugfs_remove(o2net_dentry);
+}
+
+#endif  /* CONFIG_DEBUG_FS */
diff --git a/fs/ocfs2/cluster/nodemanager.c b/fs/ocfs2/cluster/nodemanager.c
index 709fba25bf7e..cf9401e8cd0b 100644
--- a/fs/ocfs2/cluster/nodemanager.c
+++ b/fs/ocfs2/cluster/nodemanager.c
@@ -959,7 +959,10 @@ static int __init init_o2nm(void)
         cluster_print_version();
 
         o2hb_init();
-        o2net_init();
+
+        ret = o2net_init();
+        if (ret)
+                goto out;
 
         ocfs2_table_header = register_sysctl_table(ocfs2_root_table);
         if (!ocfs2_table_header) {
diff --git a/fs/ocfs2/cluster/sys.c b/fs/ocfs2/cluster/sys.c
index 0c095ce7723d..98429fd68499 100644
--- a/fs/ocfs2/cluster/sys.c
+++ b/fs/ocfs2/cluster/sys.c
@@ -57,6 +57,7 @@ static struct kset *o2cb_kset;
 void o2cb_sys_shutdown(void)
 {
         mlog_sys_shutdown();
+        sysfs_remove_link(NULL, "o2cb");
         kset_unregister(o2cb_kset);
 }
 
@@ -68,6 +69,14 @@ int o2cb_sys_init(void)
         if (!o2cb_kset)
                 return -ENOMEM;
 
+        /*
+         * Create this symlink for backwards compatibility with old
+         * versions of ocfs2-tools which look for things in /sys/o2cb.
+         */
+        ret = sysfs_create_link(NULL, &o2cb_kset->kobj, "o2cb");
+        if (ret)
+                goto error;
+
         ret = sysfs_create_group(&o2cb_kset->kobj, &o2cb_attr_group);
         if (ret)
                 goto error;
diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
index b8057c51b205..1e44ad14881a 100644
--- a/fs/ocfs2/cluster/tcp.c
+++ b/fs/ocfs2/cluster/tcp.c
@@ -142,23 +142,65 @@ static void o2net_idle_timer(unsigned long data);
 static void o2net_sc_postpone_idle(struct o2net_sock_container *sc);
 static void o2net_sc_reset_idle_timer(struct o2net_sock_container *sc);
 
-/*
- * FIXME: These should use to_o2nm_cluster_from_node(), but we end up
- * losing our parent link to the cluster during shutdown. This can be
- * solved by adding a pre-removal callback to configfs, or passing
- * around the cluster with the node. -jeffm
- */
-static inline int o2net_reconnect_delay(struct o2nm_node *node)
+static void o2net_init_nst(struct o2net_send_tracking *nst, u32 msgtype,
+                           u32 msgkey, struct task_struct *task, u8 node)
+{
+#ifdef CONFIG_DEBUG_FS
+        INIT_LIST_HEAD(&nst->st_net_debug_item);
+        nst->st_task = task;
+        nst->st_msg_type = msgtype;
+        nst->st_msg_key = msgkey;
+        nst->st_node = node;
+#endif
+}
+
+static void o2net_set_nst_sock_time(struct o2net_send_tracking *nst)
+{
+#ifdef CONFIG_DEBUG_FS
+        do_gettimeofday(&nst->st_sock_time);
+#endif
+}
+
+static void o2net_set_nst_send_time(struct o2net_send_tracking *nst)
+{
+#ifdef CONFIG_DEBUG_FS
+        do_gettimeofday(&nst->st_send_time);
+#endif
+}
+
+static void o2net_set_nst_status_time(struct o2net_send_tracking *nst)
+{
+#ifdef CONFIG_DEBUG_FS
+        do_gettimeofday(&nst->st_status_time);
+#endif
+}
+
+static void o2net_set_nst_sock_container(struct o2net_send_tracking *nst,
+                                         struct o2net_sock_container *sc)
+{
+#ifdef CONFIG_DEBUG_FS
+        nst->st_sc = sc;
+#endif
+}
+
+static void o2net_set_nst_msg_id(struct o2net_send_tracking *nst, u32 msg_id)
+{
+#ifdef CONFIG_DEBUG_FS
+        nst->st_id = msg_id;
+#endif
+}
+
+static inline int o2net_reconnect_delay(void)
 {
         return o2nm_single_cluster->cl_reconnect_delay_ms;
 }
 
-static inline int o2net_keepalive_delay(struct o2nm_node *node)
+static inline int o2net_keepalive_delay(void)
 {
         return o2nm_single_cluster->cl_keepalive_delay_ms;
 }
 
-static inline int o2net_idle_timeout(struct o2nm_node *node)
+static inline int o2net_idle_timeout(void)
 {
         return o2nm_single_cluster->cl_idle_timeout_ms;
 }
@@ -296,6 +338,7 @@ static void sc_kref_release(struct kref *kref)
         o2nm_node_put(sc->sc_node);
         sc->sc_node = NULL;
 
+        o2net_debug_del_sc(sc);
         kfree(sc);
 }
 
@@ -336,6 +379,7 @@ static struct o2net_sock_container *sc_alloc(struct o2nm_node *node)
 
         ret = sc;
         sc->sc_page = page;
+        o2net_debug_add_sc(sc);
         sc = NULL;
         page = NULL;
 
@@ -399,8 +443,6 @@ static void o2net_set_nn_state(struct o2net_node *nn,
         mlog_bug_on_msg(err && valid, "err %d valid %u\n", err, valid);
         mlog_bug_on_msg(valid && !sc, "valid %u sc %p\n", valid, sc);
 
-        /* we won't reconnect after our valid conn goes away for
-         * this hb iteration.. here so it shows up in the logs */
         if (was_valid && !valid && err == 0)
                 err = -ENOTCONN;
 
@@ -430,11 +472,6 @@ static void o2net_set_nn_state(struct o2net_node *nn,
 
         if (!was_valid && valid) {
                 o2quo_conn_up(o2net_num_from_nn(nn));
-                /* this is a bit of a hack.  we only try reconnecting
-                 * when heartbeating starts until we get a connection.
-                 * if that connection then dies we don't try reconnecting.
-                 * the only way to start connecting again is to down
-                 * heartbeat and bring it back up. */
                 cancel_delayed_work(&nn->nn_connect_expired);
                 printk(KERN_INFO "o2net: %s " SC_NODEF_FMT "\n",
                        o2nm_this_node() > sc->sc_node->nd_num ?
@@ -451,12 +488,24 @@ static void o2net_set_nn_state(struct o2net_node *nn,
                 /* delay if we're withing a RECONNECT_DELAY of the
                  * last attempt */
                 delay = (nn->nn_last_connect_attempt +
-                         msecs_to_jiffies(o2net_reconnect_delay(NULL)))
+                         msecs_to_jiffies(o2net_reconnect_delay()))
                         - jiffies;
-                if (delay > msecs_to_jiffies(o2net_reconnect_delay(NULL)))
+                if (delay > msecs_to_jiffies(o2net_reconnect_delay()))
                         delay = 0;
                 mlog(ML_CONN, "queueing conn attempt in %lu jiffies\n", delay);
                 queue_delayed_work(o2net_wq, &nn->nn_connect_work, delay);
+
+                /*
+                 * Delay the expired work after idle timeout.
+                 *
+                 * We might have lots of failed connection attempts that run
+                 * through here but we only cancel the connect_expired work when
+                 * a connection attempt succeeds.  So only the first enqueue of
+                 * the connect_expired work will do anything.  The rest will see
+                 * that it's already queued and do nothing.
+                 */
+                delay += msecs_to_jiffies(o2net_idle_timeout());
+                queue_delayed_work(o2net_wq, &nn->nn_connect_expired, delay);
         }
 
         /* keep track of the nn's sc ref for the caller */
@@ -914,6 +963,9 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
         struct o2net_status_wait nsw = {
                 .ns_node_item = LIST_HEAD_INIT(nsw.ns_node_item),
         };
+        struct o2net_send_tracking nst;
+
+        o2net_init_nst(&nst, msg_type, key, current, target_node);
 
         if (o2net_wq == NULL) {
                 mlog(0, "attempt to tx without o2netd running\n");
@@ -939,6 +991,10 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
                 goto out;
         }
 
+        o2net_debug_add_nst(&nst);
+
+        o2net_set_nst_sock_time(&nst);
+
         ret = wait_event_interruptible(nn->nn_sc_wq,
                                        o2net_tx_can_proceed(nn, &sc, &error));
         if (!ret && error)
@@ -946,6 +1002,8 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
         if (ret)
                 goto out;
 
+        o2net_set_nst_sock_container(&nst, sc);
+
         veclen = caller_veclen + 1;
         vec = kmalloc(sizeof(struct kvec) * veclen, GFP_ATOMIC);
         if (vec == NULL) {
@@ -972,6 +1030,9 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
                 goto out;
 
         msg->msg_num = cpu_to_be32(nsw.ns_id);
+        o2net_set_nst_msg_id(&nst, nsw.ns_id);
+
+        o2net_set_nst_send_time(&nst);
 
         /* finally, convert the message header to network byte-order
          * and send */
@@ -986,6 +1047,7 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
         }
 
         /* wait on other node's handler */
+        o2net_set_nst_status_time(&nst);
         wait_event(nsw.ns_wq, o2net_nsw_completed(nn, &nsw));
 
         /* Note that we avoid overwriting the callers status return
@@ -998,6 +1060,7 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
         mlog(0, "woken, returning system status %d, user status %d\n",
              ret, nsw.ns_status);
 out:
+        o2net_debug_del_nst(&nst); /* must be before dropping sc and node */
         if (sc)
                 sc_put(sc);
         if (vec)
@@ -1154,23 +1217,23 @@ static int o2net_check_handshake(struct o2net_sock_container *sc)
          * but isn't. This can ultimately cause corruption.
          */
         if (be32_to_cpu(hand->o2net_idle_timeout_ms) !=
-                                o2net_idle_timeout(sc->sc_node)) {
+                                o2net_idle_timeout()) {
                 mlog(ML_NOTICE, SC_NODEF_FMT " uses a network idle timeout of "
                      "%u ms, but we use %u ms locally.  disconnecting\n",
                      SC_NODEF_ARGS(sc),
                      be32_to_cpu(hand->o2net_idle_timeout_ms),
-                     o2net_idle_timeout(sc->sc_node));
+                     o2net_idle_timeout());
                 o2net_ensure_shutdown(nn, sc, -ENOTCONN);
                 return -1;
         }
 
         if (be32_to_cpu(hand->o2net_keepalive_delay_ms) !=
-                        o2net_keepalive_delay(sc->sc_node)) {
+                        o2net_keepalive_delay()) {
                 mlog(ML_NOTICE, SC_NODEF_FMT " uses a keepalive delay of "
                      "%u ms, but we use %u ms locally.  disconnecting\n",
                      SC_NODEF_ARGS(sc),
                      be32_to_cpu(hand->o2net_keepalive_delay_ms),
-                     o2net_keepalive_delay(sc->sc_node));
+                     o2net_keepalive_delay());
                 o2net_ensure_shutdown(nn, sc, -ENOTCONN);
                 return -1;
         }
@@ -1193,6 +1256,7 @@ static int o2net_check_handshake(struct o2net_sock_container *sc)
          * shut down already */
         if (nn->nn_sc == sc) {
                 o2net_sc_reset_idle_timer(sc);
+                atomic_set(&nn->nn_timeout, 0);
                 o2net_set_nn_state(nn, sc, 1, 0);
         }
         spin_unlock(&nn->nn_lock);
@@ -1347,12 +1411,11 @@ static void o2net_initialize_handshake(void)
 {
         o2net_hand->o2hb_heartbeat_timeout_ms = cpu_to_be32(
                 O2HB_MAX_WRITE_TIMEOUT_MS);
-        o2net_hand->o2net_idle_timeout_ms = cpu_to_be32(
-                o2net_idle_timeout(NULL));
+        o2net_hand->o2net_idle_timeout_ms = cpu_to_be32(o2net_idle_timeout());
         o2net_hand->o2net_keepalive_delay_ms = cpu_to_be32(
-                o2net_keepalive_delay(NULL));
+                o2net_keepalive_delay());
         o2net_hand->o2net_reconnect_delay_ms = cpu_to_be32(
-                o2net_reconnect_delay(NULL));
+                o2net_reconnect_delay());
 }
 
 /* ------------------------------------------------------------ */
@@ -1391,14 +1454,15 @@ static void o2net_sc_send_keep_req(struct work_struct *work)
 static void o2net_idle_timer(unsigned long data)
 {
         struct o2net_sock_container *sc = (struct o2net_sock_container *)data;
+        struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);
         struct timeval now;
 
         do_gettimeofday(&now);
 
         printk(KERN_INFO "o2net: connection to " SC_NODEF_FMT " has been idle for %u.%u "
              "seconds, shutting it down.\n", SC_NODEF_ARGS(sc),
-                     o2net_idle_timeout(sc->sc_node) / 1000,
-                     o2net_idle_timeout(sc->sc_node) % 1000);
+                     o2net_idle_timeout() / 1000,
+                     o2net_idle_timeout() % 1000);
         mlog(ML_NOTICE, "here are some times that might help debug the "
              "situation: (tmr %ld.%ld now %ld.%ld dr %ld.%ld adv "
              "%ld.%ld:%ld.%ld func (%08x:%u) %ld.%ld:%ld.%ld)\n",
@@ -1413,6 +1477,12 @@ static void o2net_idle_timer(unsigned long data)
              sc->sc_tv_func_start.tv_sec, (long) sc->sc_tv_func_start.tv_usec,
              sc->sc_tv_func_stop.tv_sec, (long) sc->sc_tv_func_stop.tv_usec);
 
+        /*
+         * Initialize the nn_timeout so that the next connection attempt
+         * will continue in o2net_start_connect.
+         */
+        atomic_set(&nn->nn_timeout, 1);
+
         o2net_sc_queue_work(sc, &sc->sc_shutdown_work);
 }
 
@@ -1420,10 +1490,10 @@ static void o2net_sc_reset_idle_timer(struct o2net_sock_container *sc)
 {
         o2net_sc_cancel_delayed_work(sc, &sc->sc_keepalive_work);
         o2net_sc_queue_delayed_work(sc, &sc->sc_keepalive_work,
-                      msecs_to_jiffies(o2net_keepalive_delay(sc->sc_node)));
+                      msecs_to_jiffies(o2net_keepalive_delay()));
         do_gettimeofday(&sc->sc_tv_timer);
         mod_timer(&sc->sc_idle_timeout,
-               jiffies + msecs_to_jiffies(o2net_idle_timeout(sc->sc_node)));
+               jiffies + msecs_to_jiffies(o2net_idle_timeout()));
 }
 
 static void o2net_sc_postpone_idle(struct o2net_sock_container *sc)
@@ -1447,6 +1517,7 @@ static void o2net_start_connect(struct work_struct *work)
         struct socket *sock = NULL;
         struct sockaddr_in myaddr = {0, }, remoteaddr = {0, };
         int ret = 0, stop;
+        unsigned int timeout;
 
         /* if we're greater we initiate tx, otherwise we accept */
         if (o2nm_this_node() <= o2net_num_from_nn(nn))
@@ -1466,8 +1537,17 @@ static void o2net_start_connect(struct work_struct *work)
         }
 
         spin_lock(&nn->nn_lock);
-        /* see if we already have one pending or have given up */
-        stop = (nn->nn_sc || nn->nn_persistent_error);
+        /*
+         * see if we already have one pending or have given up.
+         * For nn_timeout, it is set when we close the connection
+         * because of the idle time out. So it means that we have
+         * at least connected to that node successfully once,
+         * now try to connect to it again.
+         */
+        timeout = atomic_read(&nn->nn_timeout);
+        stop = (nn->nn_sc ||
+                (nn->nn_persistent_error &&
+                (nn->nn_persistent_error != -ENOTCONN || timeout == 0)));
         spin_unlock(&nn->nn_lock);
         if (stop)
                 goto out;
@@ -1555,8 +1635,8 @@ static void o2net_connect_expired(struct work_struct *work)
                 mlog(ML_ERROR, "no connection established with node %u after "
                      "%u.%u seconds, giving up and returning errors.\n",
                      o2net_num_from_nn(nn),
-                     o2net_idle_timeout(NULL) / 1000,
-                     o2net_idle_timeout(NULL) % 1000);
+                     o2net_idle_timeout() / 1000,
+                     o2net_idle_timeout() % 1000);
 
                 o2net_set_nn_state(nn, NULL, 0, -ENOTCONN);
         }
@@ -1579,6 +1659,7 @@ void o2net_disconnect_node(struct o2nm_node *node)
 
         /* don't reconnect until it's heartbeating again */
         spin_lock(&nn->nn_lock);
+        atomic_set(&nn->nn_timeout, 0);
         o2net_set_nn_state(nn, NULL, 0, -ENOTCONN);
         spin_unlock(&nn->nn_lock);
 
@@ -1610,20 +1691,15 @@ static void o2net_hb_node_up_cb(struct o2nm_node *node, int node_num,
 
         /* ensure an immediate connect attempt */
         nn->nn_last_connect_attempt = jiffies -
-                (msecs_to_jiffies(o2net_reconnect_delay(node)) + 1);
+                (msecs_to_jiffies(o2net_reconnect_delay()) + 1);
 
         if (node_num != o2nm_this_node()) {
-                /* heartbeat doesn't work unless a local node number is
-                 * configured and doing so brings up the o2net_wq, so we can
-                 * use it.. */
-                queue_delayed_work(o2net_wq, &nn->nn_connect_expired,
-                                   msecs_to_jiffies(o2net_idle_timeout(node)));
-
                 /* believe it or not, accept and node hearbeating testing
                  * can succeed for this node before we got here.. so
                  * only use set_nn_state to clear the persistent error
                  * if that hasn't already happened */
                 spin_lock(&nn->nn_lock);
+                atomic_set(&nn->nn_timeout, 0);
                 if (nn->nn_persistent_error)
                         o2net_set_nn_state(nn, NULL, 0, 0);
                 spin_unlock(&nn->nn_lock);
@@ -1747,6 +1823,7 @@ static int o2net_accept_one(struct socket *sock)
         new_sock = NULL;
 
         spin_lock(&nn->nn_lock);
+        atomic_set(&nn->nn_timeout, 0);
         o2net_set_nn_state(nn, sc, 0, 0);
         spin_unlock(&nn->nn_lock);
 
@@ -1922,6 +1999,9 @@ int o2net_init(void)
 
         o2quo_init();
 
+        if (o2net_debugfs_init())
+                return -ENOMEM;
+
         o2net_hand = kzalloc(sizeof(struct o2net_handshake), GFP_KERNEL);
         o2net_keep_req = kzalloc(sizeof(struct o2net_msg), GFP_KERNEL);
         o2net_keep_resp = kzalloc(sizeof(struct o2net_msg), GFP_KERNEL);
@@ -1941,6 +2021,7 @@ int o2net_init(void)
         for (i = 0; i < ARRAY_SIZE(o2net_nodes); i++) {
                 struct o2net_node *nn = o2net_nn_from_num(i);
 
+                atomic_set(&nn->nn_timeout, 0);
                 spin_lock_init(&nn->nn_lock);
                 INIT_DELAYED_WORK(&nn->nn_connect_work, o2net_start_connect);
                 INIT_DELAYED_WORK(&nn->nn_connect_expired,
@@ -1962,4 +2043,5 @@ void o2net_exit(void)
         kfree(o2net_hand);
         kfree(o2net_keep_req);
         kfree(o2net_keep_resp);
+        o2net_debugfs_exit();
 }
diff --git a/fs/ocfs2/cluster/tcp.h b/fs/ocfs2/cluster/tcp.h
index f36f66aab3dd..a705d5d19036 100644
--- a/fs/ocfs2/cluster/tcp.h
+++ b/fs/ocfs2/cluster/tcp.h
@@ -117,4 +117,36 @@ int o2net_num_connected_peers(void);
 int o2net_init(void);
 void o2net_exit(void);
 
+struct o2net_send_tracking;
+struct o2net_sock_container;
+
+#ifdef CONFIG_DEBUG_FS
+int o2net_debugfs_init(void);
+void o2net_debugfs_exit(void);
+void o2net_debug_add_nst(struct o2net_send_tracking *nst);
+void o2net_debug_del_nst(struct o2net_send_tracking *nst);
+void o2net_debug_add_sc(struct o2net_sock_container *sc);
+void o2net_debug_del_sc(struct o2net_sock_container *sc);
+#else
+static int o2net_debugfs_init(void)
+{
+        return 0;
+}
+static void o2net_debugfs_exit(void)
+{
+}
+static void o2net_debug_add_nst(struct o2net_send_tracking *nst)
+{
+}
+static void o2net_debug_del_nst(struct o2net_send_tracking *nst)
+{
+}
+static void o2net_debug_add_sc(struct o2net_sock_container *sc)
+{
+}
+static void o2net_debug_del_sc(struct o2net_sock_container *sc)
+{
+}
+#endif  /* CONFIG_DEBUG_FS */
+
 #endif /* O2CLUSTER_TCP_H */
diff --git a/fs/ocfs2/cluster/tcp_internal.h b/fs/ocfs2/cluster/tcp_internal.h
index d25b9af28500..8d58cfe410b1 100644
--- a/fs/ocfs2/cluster/tcp_internal.h
+++ b/fs/ocfs2/cluster/tcp_internal.h
@@ -95,6 +95,8 @@ struct o2net_node {
         unsigned                        nn_sc_valid:1;
         /* if this is set tx just returns it */
         int                             nn_persistent_error;
+        /* It is only set to 1 after the idle time out. */
+        atomic_t                        nn_timeout;
 
         /* threads waiting for an sc to arrive wait on the wq for generation
          * to increase.  it is increased when a connecting socket succeeds
@@ -164,7 +166,9 @@ struct o2net_sock_container {
         /* original handlers for the sockets */
         void                    (*sc_state_change)(struct sock *sk);
         void                    (*sc_data_ready)(struct sock *sk, int bytes);
-
+#ifdef CONFIG_DEBUG_FS
+        struct list_head        sc_net_debug_item;
+#endif
         struct timeval          sc_tv_timer;
         struct timeval          sc_tv_data_ready;
         struct timeval          sc_tv_advance_start;
@@ -206,4 +210,24 @@ struct o2net_status_wait {
         struct list_head        ns_node_item;
 };
 
+#ifdef CONFIG_DEBUG_FS
+/* just for state dumps */
+struct o2net_send_tracking {
+        struct list_head                st_net_debug_item;
+        struct task_struct              *st_task;
+        struct o2net_sock_container     *st_sc;
+        u32                             st_id;
+        u32                             st_msg_type;
+        u32                             st_msg_key;
+        u8                              st_node;
+        struct timeval                  st_sock_time;
+        struct timeval                  st_send_time;
+        struct timeval                  st_status_time;
+};
+#else
+struct o2net_send_tracking {
+        u32     dummy;
+};
+#endif  /* CONFIG_DEBUG_FS */
+
 #endif /* O2CLUSTER_TCP_INTERNAL_H */
diff --git a/fs/ocfs2/dlm/Makefile b/fs/ocfs2/dlm/Makefile
index ce3f7c29d270..190361375700 100644
--- a/fs/ocfs2/dlm/Makefile
+++ b/fs/ocfs2/dlm/Makefile
@@ -1,6 +1,6 @@
 EXTRA_CFLAGS += -Ifs/ocfs2
 
-obj-$(CONFIG_OCFS2_FS) += ocfs2_dlm.o ocfs2_dlmfs.o
+obj-$(CONFIG_OCFS2_FS_O2CB) += ocfs2_dlm.o ocfs2_dlmfs.o
 
 ocfs2_dlm-objs := dlmdomain.o dlmdebug.o dlmthread.o dlmrecovery.o \
         dlmmaster.o dlmast.o dlmconvert.o dlmlock.o dlmunlock.o dlmver.o
diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h
index dc8ea666efdb..d5a86fb81a49 100644
--- a/fs/ocfs2/dlm/dlmcommon.h
+++ b/fs/ocfs2/dlm/dlmcommon.h
@@ -49,6 +49,41 @@
 /* Intended to make it easier for us to switch out hash functions */
 #define dlm_lockid_hash(_n, _l) full_name_hash(_n, _l)
 
+enum dlm_mle_type {
+        DLM_MLE_BLOCK,
+        DLM_MLE_MASTER,
+        DLM_MLE_MIGRATION
+};
+
+struct dlm_lock_name {
+        u8 len;
+        u8 name[DLM_LOCKID_NAME_MAX];
+};
+
+struct dlm_master_list_entry {
+        struct list_head list;
+        struct list_head hb_events;
+        struct dlm_ctxt *dlm;
+        spinlock_t spinlock;
+        wait_queue_head_t wq;
+        atomic_t woken;
+        struct kref mle_refs;
+        int inuse;
+        unsigned long maybe_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+        unsigned long vote_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+        unsigned long response_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+        unsigned long node_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+        u8 master;
+        u8 new_master;
+        enum dlm_mle_type type;
+        struct o2hb_callback_func mle_hb_up;
+        struct o2hb_callback_func mle_hb_down;
+        union {
+                struct dlm_lock_resource *res;
+                struct dlm_lock_name name;
+        } u;
+};
+
 enum dlm_ast_type {
         DLM_AST = 0,
         DLM_BAST,
@@ -101,6 +136,7 @@ struct dlm_ctxt
         struct list_head purge_list;
         struct list_head pending_asts;
         struct list_head pending_basts;
+        struct list_head tracking_list;
         unsigned int purge_count;
         spinlock_t spinlock;
         spinlock_t ast_lock;
@@ -122,6 +158,9 @@ struct dlm_ctxt
         atomic_t remote_resources;
         atomic_t unknown_resources;
 
+        struct dlm_debug_ctxt *dlm_debug_ctxt;
+        struct dentry *dlm_debugfs_subroot;
+
         /* NOTE: Next three are protected by dlm_domain_lock */
         struct kref dlm_refs;
         enum dlm_ctxt_state dlm_state;
@@ -270,6 +309,9 @@ struct dlm_lock_resource
         struct list_head dirty;
         struct list_head recovering; // dlm_recovery_ctxt.resources list
 
+        /* Added during init and removed during release */
+        struct list_head tracking;      /* dlm->tracking_list */
+
         /* unused lock resources have their last_used stamped and are
          * put on a list for the dlm thread to run. */
         unsigned long    last_used;
@@ -963,9 +1005,16 @@ static inline void __dlm_wait_on_lockres(struct dlm_lock_resource *res)
                                           DLM_LOCK_RES_MIGRATING));
 }
 
+/* create/destroy slab caches */
+int dlm_init_master_caches(void);
+void dlm_destroy_master_caches(void);
+
+int dlm_init_lock_cache(void);
+void dlm_destroy_lock_cache(void);
 
 int dlm_init_mle_cache(void);
 void dlm_destroy_mle_cache(void);
+
 void dlm_hb_event_notify_attached(struct dlm_ctxt *dlm, int idx, int node_up);
 int dlm_drop_lockres_ref(struct dlm_ctxt *dlm,
                          struct dlm_lock_resource *res);
diff --git a/fs/ocfs2/dlm/dlmdebug.c b/fs/ocfs2/dlm/dlmdebug.c
index 64239b37e5d4..5f6d858770a2 100644
--- a/fs/ocfs2/dlm/dlmdebug.c
+++ b/fs/ocfs2/dlm/dlmdebug.c
@@ -5,7 +5,7 @@
  *
  * debug functionality for the dlm
  *
- * Copyright (C) 2004 Oracle.  All rights reserved.
+ * Copyright (C) 2004, 2008 Oracle.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public
@@ -30,6 +30,7 @@
 #include <linux/utsname.h>
 #include <linux/sysctl.h>
 #include <linux/spinlock.h>
+#include <linux/debugfs.h>
 
 #include "cluster/heartbeat.h"
 #include "cluster/nodemanager.h"
@@ -37,17 +38,16 @@
 
 #include "dlmapi.h"
 #include "dlmcommon.h"
-
 #include "dlmdomain.h"
+#include "dlmdebug.h"
 
 #define MLOG_MASK_PREFIX ML_DLM
 #include "cluster/masklog.h"
 
+int stringify_lockname(const char *lockname, int locklen, char *buf, int len);
+
 void dlm_print_one_lock_resource(struct dlm_lock_resource *res)
 {
-        mlog(ML_NOTICE, "lockres: %.*s, owner=%u, state=%u\n",
-               res->lockname.len, res->lockname.name,
-               res->owner, res->state);
         spin_lock(&res->spinlock);
         __dlm_print_one_lock_resource(res);
         spin_unlock(&res->spinlock);
@@ -58,7 +58,7 @@ static void dlm_print_lockres_refmap(struct dlm_lock_resource *res)
         int bit;
         assert_spin_locked(&res->spinlock);
 
-        mlog(ML_NOTICE, "  refmap nodes: [ ");
+        printk("  refmap nodes: [ ");
         bit = 0;
         while (1) {
                 bit = find_next_bit(res->refmap, O2NM_MAX_NODES, bit);
@@ -70,63 +70,66 @@ static void dlm_print_lockres_refmap(struct dlm_lock_resource *res)
         printk("], inflight=%u\n", res->inflight_locks);
 }
 
+static void __dlm_print_lock(struct dlm_lock *lock)
+{
+        spin_lock(&lock->spinlock);
+
+        printk("    type=%d, conv=%d, node=%u, cookie=%u:%llu, "
+               "ref=%u, ast=(empty=%c,pend=%c), bast=(empty=%c,pend=%c), "
+               "pending=(conv=%c,lock=%c,cancel=%c,unlock=%c)\n",
+               lock->ml.type, lock->ml.convert_type, lock->ml.node,
+               dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+               dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+               atomic_read(&lock->lock_refs.refcount),
+               (list_empty(&lock->ast_list) ? 'y' : 'n'),
+               (lock->ast_pending ? 'y' : 'n'),
+               (list_empty(&lock->bast_list) ? 'y' : 'n'),
+               (lock->bast_pending ? 'y' : 'n'),
+               (lock->convert_pending ? 'y' : 'n'),
+               (lock->lock_pending ? 'y' : 'n'),
+               (lock->cancel_pending ? 'y' : 'n'),
+               (lock->unlock_pending ? 'y' : 'n'));
+
+        spin_unlock(&lock->spinlock);
+}
+
 void __dlm_print_one_lock_resource(struct dlm_lock_resource *res)
 {
         struct list_head *iter2;
         struct dlm_lock *lock;
+        char buf[DLM_LOCKID_NAME_MAX];
 
         assert_spin_locked(&res->spinlock);
 
-        mlog(ML_NOTICE, "lockres: %.*s, owner=%u, state=%u\n",
-               res->lockname.len, res->lockname.name,
-               res->owner, res->state);
-        mlog(ML_NOTICE, "  last used: %lu, on purge list: %s\n",
-             res->last_used, list_empty(&res->purge) ? "no" : "yes");
+        stringify_lockname(res->lockname.name, res->lockname.len,
+                           buf, sizeof(buf) - 1);
+        printk("lockres: %s, owner=%u, state=%u\n",
+               buf, res->owner, res->state);
+        printk("  last used: %lu, refcnt: %u, on purge list: %s\n",
+               res->last_used, atomic_read(&res->refs.refcount),
+               list_empty(&res->purge) ? "no" : "yes");
+        printk("  on dirty list: %s, on reco list: %s, "
+               "migrating pending: %s\n",
+               list_empty(&res->dirty) ? "no" : "yes",
+               list_empty(&res->recovering) ? "no" : "yes",
+               res->migration_pending ? "yes" : "no");
+        printk("  inflight locks: %d, asts reserved: %d\n",
+               res->inflight_locks, atomic_read(&res->asts_reserved));
         dlm_print_lockres_refmap(res);
-        mlog(ML_NOTICE, "  granted queue: \n");
+        printk("  granted queue:\n");
         list_for_each(iter2, &res->granted) {
                 lock = list_entry(iter2, struct dlm_lock, list);
-                spin_lock(&lock->spinlock);
-                mlog(ML_NOTICE, "    type=%d, conv=%d, node=%u, "
-                       "cookie=%u:%llu, ast=(empty=%c,pend=%c), bast=(empty=%c,pend=%c)\n", 
-                       lock->ml.type, lock->ml.convert_type, lock->ml.node, 
-                     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
-                     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
-                       list_empty(&lock->ast_list) ? 'y' : 'n',
-                       lock->ast_pending ? 'y' : 'n',
-                       list_empty(&lock->bast_list) ? 'y' : 'n',
-                       lock->bast_pending ? 'y' : 'n');
-                spin_unlock(&lock->spinlock);
+                __dlm_print_lock(lock);
         }
-        mlog(ML_NOTICE, "  converting queue: \n");
+        printk("  converting queue:\n");
         list_for_each(iter2, &res->converting) {
                 lock = list_entry(iter2, struct dlm_lock, list);
-                spin_lock(&lock->spinlock);
-                mlog(ML_NOTICE, "    type=%d, conv=%d, node=%u, "
-                       "cookie=%u:%llu, ast=(empty=%c,pend=%c), bast=(empty=%c,pend=%c)\n", 
-                       lock->ml.type, lock->ml.convert_type, lock->ml.node, 
-                     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
-                     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
-                       list_empty(&lock->ast_list) ? 'y' : 'n',
-                       lock->ast_pending ? 'y' : 'n',
-                       list_empty(&lock->bast_list) ? 'y' : 'n',
-                       lock->bast_pending ? 'y' : 'n');
-                spin_unlock(&lock->spinlock);
+                __dlm_print_lock(lock);
         }
-        mlog(ML_NOTICE, "  blocked queue: \n");
+        printk("  blocked queue:\n");
         list_for_each(iter2, &res->blocked) {
                 lock = list_entry(iter2, struct dlm_lock, list);
-                spin_lock(&lock->spinlock);
-                mlog(ML_NOTICE, "    type=%d, conv=%d, node=%u, "
-                       "cookie=%u:%llu, ast=(empty=%c,pend=%c), bast=(empty=%c,pend=%c)\n", 
-                       lock->ml.type, lock->ml.convert_type, lock->ml.node, 
-                     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
-                     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
-                       list_empty(&lock->ast_list) ? 'y' : 'n',
-                       lock->ast_pending ? 'y' : 'n',
-                       list_empty(&lock->bast_list) ? 'y' : 'n',
-                       lock->bast_pending ? 'y' : 'n');
-                spin_unlock(&lock->spinlock);
+                __dlm_print_lock(lock);
         }
 }
 
@@ -136,31 +139,6 @@ void dlm_print_one_lock(struct dlm_lock *lockid)
 }
 EXPORT_SYMBOL_GPL(dlm_print_one_lock);
 
-#if 0
-void dlm_dump_lock_resources(struct dlm_ctxt *dlm)
-{
-        struct dlm_lock_resource *res;
-        struct hlist_node *iter;
-        struct hlist_head *bucket;
-        int i;
-
-        mlog(ML_NOTICE, "struct dlm_ctxt: %s, node=%u, key=%u\n",
-                  dlm->name, dlm->node_num, dlm->key);
-        if (!dlm || !dlm->name) {
-                mlog(ML_ERROR, "dlm=%p\n", dlm);
-                return;
-        }
-
-        spin_lock(&dlm->spinlock);
-        for (i=0; i<DLM_HASH_BUCKETS; i++) {
-                bucket = dlm_lockres_hash(dlm, i);
-                hlist_for_each_entry(res, iter, bucket, hash_node)
-                        dlm_print_one_lock_resource(res);
-        }
-        spin_unlock(&dlm->spinlock);
-}
-#endif  /*  0  */
-
 static const char *dlm_errnames[] = {
         [DLM_NORMAL] =                  "DLM_NORMAL",
         [DLM_GRANTED] =                 "DLM_GRANTED",
@@ -266,3 +244,792 @@ const char *dlm_errname(enum dlm_status err)
         return dlm_errnames[err];
 }
 EXPORT_SYMBOL_GPL(dlm_errname);
+
+/* NOTE: This function converts a lockname into a string. It uses knowledge
+ * of the format of the lockname that should be outside the purview of the dlm.
+ * We are adding only to make dlm debugging slightly easier.
+ *
+ * For more on lockname formats, please refer to dlmglue.c and ocfs2_lockid.h.
+ */
+int stringify_lockname(const char *lockname, int locklen, char *buf, int len)
+{
+        int out = 0;
+        __be64 inode_blkno_be;
+
+#define OCFS2_DENTRY_LOCK_INO_START     18
+        if (*lockname == 'N') {
+                memcpy((__be64 *)&inode_blkno_be,
+                       (char *)&lockname[OCFS2_DENTRY_LOCK_INO_START],
+                       sizeof(__be64));
+                out += snprintf(buf + out, len - out, "%.*s%08x",
+                                OCFS2_DENTRY_LOCK_INO_START - 1, lockname,
+                                (unsigned int)be64_to_cpu(inode_blkno_be));
+        } else
+                out += snprintf(buf + out, len - out, "%.*s",
+                                locklen, lockname);
+        return out;
+}
+
+static int stringify_nodemap(unsigned long *nodemap, int maxnodes,
+                             char *buf, int len)
+{
+        int out = 0;
+        int i = -1;
+
+        while ((i = find_next_bit(nodemap, maxnodes, i + 1)) < maxnodes)
+                out += snprintf(buf + out, len - out, "%d ", i);
+
+        return out;
+}
+
+static int dump_mle(struct dlm_master_list_entry *mle, char *buf, int len)
+{
+        int out = 0;
+        unsigned int namelen;
+        const char *name;
+        char *mle_type;
+
+        if (mle->type != DLM_MLE_MASTER) {
+                namelen = mle->u.name.len;
+                name = mle->u.name.name;
+        } else {
+                namelen = mle->u.res->lockname.len;
+                name = mle->u.res->lockname.name;
+        }
+
+        if (mle->type == DLM_MLE_BLOCK)
+                mle_type = "BLK";
+        else if (mle->type == DLM_MLE_MASTER)
+                mle_type = "MAS";
+        else
+                mle_type = "MIG";
+
+        out += stringify_lockname(name, namelen, buf + out, len - out);
+        out += snprintf(buf + out, len - out,
+                        "\t%3s\tmas=%3u\tnew=%3u\tevt=%1d\tuse=%1d\tref=%3d\n",
+                        mle_type, mle->master, mle->new_master,
+                        !list_empty(&mle->hb_events),
+                        !!mle->inuse,
+                        atomic_read(&mle->mle_refs.refcount));
+
+        out += snprintf(buf + out, len - out, "Maybe=");
+        out += stringify_nodemap(mle->maybe_map, O2NM_MAX_NODES,
+                                 buf + out, len - out);
+        out += snprintf(buf + out, len - out, "\n");
+
+        out += snprintf(buf + out, len - out, "Vote=");
+        out += stringify_nodemap(mle->vote_map, O2NM_MAX_NODES,
+                                 buf + out, len - out);
+        out += snprintf(buf + out, len - out, "\n");
+
+        out += snprintf(buf + out, len - out, "Response=");
+        out += stringify_nodemap(mle->response_map, O2NM_MAX_NODES,
+                                 buf + out, len - out);
+        out += snprintf(buf + out, len - out, "\n");
+
+        out += snprintf(buf + out, len - out, "Node=");
+        out += stringify_nodemap(mle->node_map, O2NM_MAX_NODES,
+                                 buf + out, len - out);
+        out += snprintf(buf + out, len - out, "\n");
+
+        out += snprintf(buf + out, len - out, "\n");
+
+        return out;
+}
+
+void dlm_print_one_mle(struct dlm_master_list_entry *mle)
+{
+        char *buf;
+
+        buf = (char *) get_zeroed_page(GFP_NOFS);
+        if (buf) {
+                dump_mle(mle, buf, PAGE_SIZE - 1);
+                free_page((unsigned long)buf);
+        }
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+static struct dentry *dlm_debugfs_root = NULL;
+
+#define DLM_DEBUGFS_DIR                         "o2dlm"
+#define DLM_DEBUGFS_DLM_STATE                   "dlm_state"
+#define DLM_DEBUGFS_LOCKING_STATE               "locking_state"
+#define DLM_DEBUGFS_MLE_STATE                   "mle_state"
+#define DLM_DEBUGFS_PURGE_LIST                  "purge_list"
+
+/* begin - utils funcs */
+static void dlm_debug_free(struct kref *kref)
+{
+        struct dlm_debug_ctxt *dc;
+
+        dc = container_of(kref, struct dlm_debug_ctxt, debug_refcnt);
+
+        kfree(dc);
+}
+
+void dlm_debug_put(struct dlm_debug_ctxt *dc)
+{
+        if (dc)
+                kref_put(&dc->debug_refcnt, dlm_debug_free);
+}
+
+static void dlm_debug_get(struct dlm_debug_ctxt *dc)
+{
+        kref_get(&dc->debug_refcnt);
+}
+
+static struct debug_buffer *debug_buffer_allocate(void)
+{
+        struct debug_buffer *db = NULL;
+
+        db = kzalloc(sizeof(struct debug_buffer), GFP_KERNEL);
+        if (!db)
+                goto bail;
+
+        db->len = PAGE_SIZE;
+        db->buf = kmalloc(db->len, GFP_KERNEL);
+        if (!db->buf)
+                goto bail;
+
+        return db;
+bail:
+        kfree(db);
+        return NULL;
+}
+
+static ssize_t debug_buffer_read(struct file *file, char __user *buf,
+                                 size_t nbytes, loff_t *ppos)
+{
+        struct debug_buffer *db = file->private_data;
+
+        return simple_read_from_buffer(buf, nbytes, ppos, db->buf, db->len);
+}
+
+static loff_t debug_buffer_llseek(struct file *file, loff_t off, int whence)
+{
+        struct debug_buffer *db = file->private_data;
+        loff_t new = -1;
+
+        switch (whence) {
+        case 0:
+                new = off;
+                break;
+        case 1:
+                new = file->f_pos + off;
+                break;
+        }
+
+        if (new < 0 || new > db->len)
+                return -EINVAL;
+
+        return (file->f_pos = new);
+}
+
+static int debug_buffer_release(struct inode *inode, struct file *file)
+{
+        struct debug_buffer *db = (struct debug_buffer *)file->private_data;
+
+        if (db)
+                kfree(db->buf);
+        kfree(db);
+
+        return 0;
+}
+/* end - util funcs */
+
+/* begin - purge list funcs */
+static int debug_purgelist_print(struct dlm_ctxt *dlm, struct debug_buffer *db)
+{
+        struct dlm_lock_resource *res;
+        int out = 0;
+        unsigned long total = 0;
+
+        out += snprintf(db->buf + out, db->len - out,
+                        "Dumping Purgelist for Domain: %s\n", dlm->name);
+
+        spin_lock(&dlm->spinlock);
+        list_for_each_entry(res, &dlm->purge_list, purge) {
+                ++total;
+                if (db->len - out < 100)
+                        continue;
+                spin_lock(&res->spinlock);
+                out += stringify_lockname(res->lockname.name,
+                                          res->lockname.len,
+                                          db->buf + out, db->len - out);
+                out += snprintf(db->buf + out, db->len - out, "\t%ld\n",
+                                (jiffies - res->last_used)/HZ);
+                spin_unlock(&res->spinlock);
+        }
+        spin_unlock(&dlm->spinlock);
+
+        out += snprintf(db->buf + out, db->len - out,
+                        "Total on list: %ld\n", total);
+
+        return out;
+}
+
+static int debug_purgelist_open(struct inode *inode, struct file *file)
+{
+        struct dlm_ctxt *dlm = inode->i_private;
+        struct debug_buffer *db;
+
+        db = debug_buffer_allocate();
+        if (!db)
+                goto bail;
+
+        db->len = debug_purgelist_print(dlm, db);
+
+        file->private_data = db;
+
+        return 0;
+bail:
+        return -ENOMEM;
+}
+
+static struct file_operations debug_purgelist_fops = {
+        .open =         debug_purgelist_open,
+        .release =      debug_buffer_release,
+        .read =         debug_buffer_read,
+        .llseek =       debug_buffer_llseek,
+};
+/* end - purge list funcs */
+
+/* begin - debug mle funcs */
+static int debug_mle_print(struct dlm_ctxt *dlm, struct debug_buffer *db)
+{
+        struct dlm_master_list_entry *mle;
+        int out = 0;
+        unsigned long total = 0;
+
+        out += snprintf(db->buf + out, db->len - out,
+                        "Dumping MLEs for Domain: %s\n", dlm->name);
+
+        spin_lock(&dlm->master_lock);
+        list_for_each_entry(mle, &dlm->master_list, list) {
+                ++total;
+                if (db->len - out < 200)
+                        continue;
+                out += dump_mle(mle, db->buf + out, db->len - out);
+        }
+        spin_unlock(&dlm->master_lock);
+
+        out += snprintf(db->buf + out, db->len - out,
+                        "Total on list: %ld\n", total);
+        return out;
+}
+
+static int debug_mle_open(struct inode *inode, struct file *file)
+{
+        struct dlm_ctxt *dlm = inode->i_private;
+        struct debug_buffer *db;
+
+        db = debug_buffer_allocate();
+        if (!db)
+                goto bail;
+
+        db->len = debug_mle_print(dlm, db);
+
+        file->private_data = db;
+
+        return 0;
+bail:
+        return -ENOMEM;
+}
+
+static struct file_operations debug_mle_fops = {
+        .open =         debug_mle_open,
+        .release =      debug_buffer_release,
+        .read =         debug_buffer_read,
+        .llseek =       debug_buffer_llseek,
+};
+
+/* end - debug mle funcs */
+
+/* begin - debug lockres funcs */
+static int dump_lock(struct dlm_lock *lock, int list_type, char *buf, int len)
+{
+        int out;
+
+#define DEBUG_LOCK_VERSION      1
+        spin_lock(&lock->spinlock);
+        out = snprintf(buf, len, "LOCK:%d,%d,%d,%d,%d,%d:%lld,%d,%d,%d,%d,%d,"
+                       "%d,%d,%d,%d\n",
+                       DEBUG_LOCK_VERSION,
+                       list_type, lock->ml.type, lock->ml.convert_type,
+                       lock->ml.node,
+                       dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+                       dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+                       !list_empty(&lock->ast_list),
+                       !list_empty(&lock->bast_list),
+                       lock->ast_pending, lock->bast_pending,
+                       lock->convert_pending, lock->lock_pending,
+                       lock->cancel_pending, lock->unlock_pending,
+                       atomic_read(&lock->lock_refs.refcount));
+        spin_unlock(&lock->spinlock);
+
+        return out;
+}
+
+static int dump_lockres(struct dlm_lock_resource *res, char *buf, int len)
+{
+        struct dlm_lock *lock;
+        int i;
+        int out = 0;
+
+        out += snprintf(buf + out, len - out, "NAME:");
+        out += stringify_lockname(res->lockname.name, res->lockname.len,
+                                  buf + out, len - out);
+        out += snprintf(buf + out, len - out, "\n");
+
+#define DEBUG_LRES_VERSION      1
+        out += snprintf(buf + out, len - out,
+                        "LRES:%d,%d,%d,%ld,%d,%d,%d,%d,%d,%d,%d\n",
+                        DEBUG_LRES_VERSION,
+                        res->owner, res->state, res->last_used,
+                        !list_empty(&res->purge),
+                        !list_empty(&res->dirty),
+                        !list_empty(&res->recovering),
+                        res->inflight_locks, res->migration_pending,
+                        atomic_read(&res->asts_reserved),
+                        atomic_read(&res->refs.refcount));
+
+        /* refmap */
+        out += snprintf(buf + out, len - out, "RMAP:");
+        out += stringify_nodemap(res->refmap, O2NM_MAX_NODES,
+                                 buf + out, len - out);
+        out += snprintf(buf + out, len - out, "\n");
+
+        /* lvb */
+        out += snprintf(buf + out, len - out, "LVBX:");
+        for (i = 0; i < DLM_LVB_LEN; i++)
+                out += snprintf(buf + out, len - out,
+                                        "%02x", (unsigned char)res->lvb[i]);
+        out += snprintf(buf + out, len - out, "\n");
+
+        /* granted */
+        list_for_each_entry(lock, &res->granted, list)
+                out += dump_lock(lock, 0, buf + out, len - out);
+
+        /* converting */
+        list_for_each_entry(lock, &res->converting, list)
+                out += dump_lock(lock, 1, buf + out, len - out);
+
+        /* blocked */
+        list_for_each_entry(lock, &res->blocked, list)
+                out += dump_lock(lock, 2, buf + out, len - out);
+
+        out += snprintf(buf + out, len - out, "\n");
+
+        return out;
+}
+
+static void *lockres_seq_start(struct seq_file *m, loff_t *pos)
+{
+        struct debug_lockres *dl = m->private;
+        struct dlm_ctxt *dlm = dl->dl_ctxt;
+        struct dlm_lock_resource *res = NULL;
+
+        spin_lock(&dlm->spinlock);
+
+        if (dl->dl_res) {
+                list_for_each_entry(res, &dl->dl_res->tracking, tracking) {
+                        if (dl->dl_res) {
+                                dlm_lockres_put(dl->dl_res);
+                                dl->dl_res = NULL;
+                        }
+                        if (&res->tracking == &dlm->tracking_list) {
+                                mlog(0, "End of list found, %p\n", res);
+                                dl = NULL;
+                                break;
+                        }
+                        dlm_lockres_get(res);
+                        dl->dl_res = res;
+                        break;
+                }
+        } else {
+                if (!list_empty(&dlm->tracking_list)) {
+                        list_for_each_entry(res, &dlm->tracking_list, tracking)
+                                break;
+                        dlm_lockres_get(res);
+                        dl->dl_res = res;
+                } else
+                        dl = NULL;
+        }
+
+        if (dl) {
+                spin_lock(&dl->dl_res->spinlock);
+                dump_lockres(dl->dl_res, dl->dl_buf, dl->dl_len - 1);
+                spin_unlock(&dl->dl_res->spinlock);
+        }
+
+        spin_unlock(&dlm->spinlock);
+
+        return dl;
+}
+
+static void lockres_seq_stop(struct seq_file *m, void *v)
+{
+}
+
+static void *lockres_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+        return NULL;
+}
+
+static int lockres_seq_show(struct seq_file *s, void *v)
+{
+        struct debug_lockres *dl = (struct debug_lockres *)v;
+
+        seq_printf(s, "%s", dl->dl_buf);
+
+        return 0;
+}
+
+static struct seq_operations debug_lockres_ops = {
+        .start =        lockres_seq_start,
+        .stop =         lockres_seq_stop,
+        .next =         lockres_seq_next,
+        .show =         lockres_seq_show,
+};
+
+static int debug_lockres_open(struct inode *inode, struct file *file)
+{
+        struct dlm_ctxt *dlm = inode->i_private;
+        int ret = -ENOMEM;
+        struct seq_file *seq;
+        struct debug_lockres *dl = NULL;
+
+        dl = kzalloc(sizeof(struct debug_lockres), GFP_KERNEL);
+        if (!dl) {
+                mlog_errno(ret);
+                goto bail;
+        }
+
+        dl->dl_len = PAGE_SIZE;
+        dl->dl_buf = kmalloc(dl->dl_len, GFP_KERNEL);
+        if (!dl->dl_buf) {
+                mlog_errno(ret);
+                goto bail;
+        }
+
+        ret = seq_open(file, &debug_lockres_ops);
+        if (ret) {
+                mlog_errno(ret);
+                goto bail;
+        }
+
+        seq = (struct seq_file *) file->private_data;
+        seq->private = dl;
+
+        dlm_grab(dlm);
+        dl->dl_ctxt = dlm;
+
+        return 0;
+bail:
+        if (dl)
+                kfree(dl->dl_buf);
+        kfree(dl);
+        return ret;
+}
+
+static int debug_lockres_release(struct inode *inode, struct file *file)
+{
+        struct seq_file *seq = (struct seq_file *)file->private_data;
+        struct debug_lockres *dl = (struct debug_lockres *)seq->private;
+
+        if (dl->dl_res)
+                dlm_lockres_put(dl->dl_res);
+        dlm_put(dl->dl_ctxt);
+        kfree(dl->dl_buf);
+        return seq_release_private(inode, file);
+}
+
+static struct file_operations debug_lockres_fops = {
+        .open =         debug_lockres_open,
+        .release =      debug_lockres_release,
+        .read =         seq_read,
+        .llseek =       seq_lseek,
+};
+/* end - debug lockres funcs */
+
+/* begin - debug state funcs */
+static int debug_state_print(struct dlm_ctxt *dlm, struct debug_buffer *db)
+{
+        int out = 0;
+        struct dlm_reco_node_data *node;
+        char *state;
+        int lres, rres, ures, tres;
+
+        lres = atomic_read(&dlm->local_resources);
+        rres = atomic_read(&dlm->remote_resources);
+        ures = atomic_read(&dlm->unknown_resources);
+        tres = lres + rres + ures;
+
+        spin_lock(&dlm->spinlock);
+
+        switch (dlm->dlm_state) {
+        case DLM_CTXT_NEW:
+                state = "NEW"; break;
+        case DLM_CTXT_JOINED:
+                state = "JOINED"; break;
+        case DLM_CTXT_IN_SHUTDOWN:
+                state = "SHUTDOWN"; break;
+        case DLM_CTXT_LEAVING:
+                state = "LEAVING"; break;
+        default:
+                state = "UNKNOWN"; break;
+        }
+
+        /* Domain: xxxxxxxxxx  Key: 0xdfbac769 */
+        out += snprintf(db->buf + out, db->len - out,
+                        "Domain: %s  Key: 0x%08x\n", dlm->name, dlm->key);
+
+        /* Thread Pid: xxx  Node: xxx  State: xxxxx */
+        out += snprintf(db->buf + out, db->len - out,
+                        "Thread Pid: %d  Node: %d  State: %s\n",
+                        dlm->dlm_thread_task->pid, dlm->node_num, state);
+
+        /* Number of Joins: xxx  Joining Node: xxx */
+        out += snprintf(db->buf + out, db->len - out,
+                        "Number of Joins: %d  Joining Node: %d\n",
+                        dlm->num_joins, dlm->joining_node);
+
+        /* Domain Map: xx xx xx */
+        out += snprintf(db->buf + out, db->len - out, "Domain Map: ");
+        out += stringify_nodemap(dlm->domain_map, O2NM_MAX_NODES,
+                                 db->buf + out, db->len - out);
+        out += snprintf(db->buf + out, db->len - out, "\n");
+
+        /* Live Map: xx xx xx */
+        out += snprintf(db->buf + out, db->len - out, "Live Map: ");
+        out += stringify_nodemap(dlm->live_nodes_map, O2NM_MAX_NODES,
+                                 db->buf + out, db->len - out);
+        out += snprintf(db->buf + out, db->len - out, "\n");
+
+        /* Mastered Resources Total: xxx  Locally: xxx  Remotely: ... */
+        out += snprintf(db->buf + out, db->len - out,
+                        "Mastered Resources Total: %d  Locally: %d  "
+                        "Remotely: %d  Unknown: %d\n",
+                        tres, lres, rres, ures);
+
+        /* Lists: Dirty=Empty  Purge=InUse  PendingASTs=Empty  ... */
+        out += snprintf(db->buf + out, db->len - out,
+                        "Lists: Dirty=%s  Purge=%s  PendingASTs=%s  "
+                        "PendingBASTs=%s  Master=%s\n",
+                        (list_empty(&dlm->dirty_list) ? "Empty" : "InUse"),
+                        (list_empty(&dlm->purge_list) ? "Empty" : "InUse"),
+                        (list_empty(&dlm->pending_asts) ? "Empty" : "InUse"),
+                        (list_empty(&dlm->pending_basts) ? "Empty" : "InUse"),
+                        (list_empty(&dlm->master_list) ? "Empty" : "InUse"));
+
+        /* Purge Count: xxx  Refs: xxx */
+        out += snprintf(db->buf + out, db->len - out,
+                        "Purge Count: %d  Refs: %d\n", dlm->purge_count,
+                        atomic_read(&dlm->dlm_refs.refcount));
+
+        /* Dead Node: xxx */
+        out += snprintf(db->buf + out, db->len - out,
+                        "Dead Node: %d\n", dlm->reco.dead_node);
+
+        /* What about DLM_RECO_STATE_FINALIZE? */
+        if (dlm->reco.state == DLM_RECO_STATE_ACTIVE)
+                state = "ACTIVE";
+        else
+                state = "INACTIVE";
+
+        /* Recovery Pid: xxxx  Master: xxx  State: xxxx */
+        out += snprintf(db->buf + out, db->len - out,
+                        "Recovery Pid: %d  Master: %d  State: %s\n",
+                        dlm->dlm_reco_thread_task->pid,
+                        dlm->reco.new_master, state);
+
+        /* Recovery Map: xx xx */
+        out += snprintf(db->buf + out, db->len - out, "Recovery Map: ");
+        out += stringify_nodemap(dlm->recovery_map, O2NM_MAX_NODES,
+                                 db->buf + out, db->len - out);
+        out += snprintf(db->buf + out, db->len - out, "\n");
+
+        /* Recovery Node State: */
+        out += snprintf(db->buf + out, db->len - out, "Recovery Node State:\n");
+        list_for_each_entry(node, &dlm->reco.node_data, list) {
+                switch (node->state) {
+                case DLM_RECO_NODE_DATA_INIT:
+                        state = "INIT";
+                        break;
+                case DLM_RECO_NODE_DATA_REQUESTING:
+                        state = "REQUESTING";
+                        break;
+                case DLM_RECO_NODE_DATA_DEAD:
+                        state = "DEAD";
+                        break;
+                case DLM_RECO_NODE_DATA_RECEIVING:
+                        state = "RECEIVING";
+                        break;
+                case DLM_RECO_NODE_DATA_REQUESTED:
+                        state = "REQUESTED";
+                        break;
+                case DLM_RECO_NODE_DATA_DONE:
+                        state = "DONE";
+                        break;
+                case DLM_RECO_NODE_DATA_FINALIZE_SENT:
+                        state = "FINALIZE-SENT";
+                        break;
+                default:
+                        state = "BAD";
+                        break;
+                }
+                out += snprintf(db->buf + out, db->len - out, "\t%u - %s\n",
+                                node->node_num, state);
+        }
+
+        spin_unlock(&dlm->spinlock);
+
+        return out;
+}
+
+static int debug_state_open(struct inode *inode, struct file *file)
+{
+        struct dlm_ctxt *dlm = inode->i_private;
+        struct debug_buffer *db = NULL;
+
+        db = debug_buffer_allocate();
+        if (!db)
+                goto bail;
+
+        db->len = debug_state_print(dlm, db);
+
+        file->private_data = db;
+
+        return 0;
+bail:
+        return -ENOMEM;
+}
+
+static struct file_operations debug_state_fops = {
+        .open =         debug_state_open,
+        .release =      debug_buffer_release,
+        .read =         debug_buffer_read,
+        .llseek =       debug_buffer_llseek,
+};
+/* end  - debug state funcs */
+
+/* files in subroot */
+int dlm_debug_init(struct dlm_ctxt *dlm)
+{
+        struct dlm_debug_ctxt *dc = dlm->dlm_debug_ctxt;
+
+        /* for dumping dlm_ctxt */
+        dc->debug_state_dentry = debugfs_create_file(DLM_DEBUGFS_DLM_STATE,
+                                                     S_IFREG|S_IRUSR,
+                                                     dlm->dlm_debugfs_subroot,
+                                                     dlm, &debug_state_fops);
+        if (!dc->debug_state_dentry) {
+                mlog_errno(-ENOMEM);
+                goto bail;
+        }
+
+        /* for dumping lockres */
+        dc->debug_lockres_dentry =
+                        debugfs_create_file(DLM_DEBUGFS_LOCKING_STATE,
+                                            S_IFREG|S_IRUSR,
+                                            dlm->dlm_debugfs_subroot,
+                                            dlm, &debug_lockres_fops);
+        if (!dc->debug_lockres_dentry) {
+                mlog_errno(-ENOMEM);
+                goto bail;
+        }
+
+        /* for dumping mles */
+        dc->debug_mle_dentry = debugfs_create_file(DLM_DEBUGFS_MLE_STATE,
+                                                   S_IFREG|S_IRUSR,
+                                                   dlm->dlm_debugfs_subroot,
+                                                   dlm, &debug_mle_fops);
+        if (!dc->debug_mle_dentry) {
+                mlog_errno(-ENOMEM);
+                goto bail;
+        }
+
+        /* for dumping lockres on the purge list */
+        dc->debug_purgelist_dentry =
+                        debugfs_create_file(DLM_DEBUGFS_PURGE_LIST,
+                                            S_IFREG|S_IRUSR,
+                                            dlm->dlm_debugfs_subroot,
+                                            dlm, &debug_purgelist_fops);
+        if (!dc->debug_purgelist_dentry) {
+                mlog_errno(-ENOMEM);
+                goto bail;
+        }
+
+        dlm_debug_get(dc);
+        return 0;
+
+bail:
+        dlm_debug_shutdown(dlm);
+        return -ENOMEM;
+}
+
+void dlm_debug_shutdown(struct dlm_ctxt *dlm)
+{
+        struct dlm_debug_ctxt *dc = dlm->dlm_debug_ctxt;
+
+        if (dc) {
+                if (dc->debug_purgelist_dentry)
+                        debugfs_remove(dc->debug_purgelist_dentry);
+                if (dc->debug_mle_dentry)
+                        debugfs_remove(dc->debug_mle_dentry);
+                if (dc->debug_lockres_dentry)
+                        debugfs_remove(dc->debug_lockres_dentry);
+                if (dc->debug_state_dentry)
+                        debugfs_remove(dc->debug_state_dentry);
+                dlm_debug_put(dc);
+        }
+}
+
+/* subroot - domain dir */
+int dlm_create_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+        dlm->dlm_debugfs_subroot = debugfs_create_dir(dlm->name,
+                                                      dlm_debugfs_root);
+        if (!dlm->dlm_debugfs_subroot) {
+                mlog_errno(-ENOMEM);
+                goto bail;
+        }
+
+        dlm->dlm_debug_ctxt = kzalloc(sizeof(struct dlm_debug_ctxt),
+                                      GFP_KERNEL);
+        if (!dlm->dlm_debug_ctxt) {
+                mlog_errno(-ENOMEM);
+                goto bail;
+        }
+        kref_init(&dlm->dlm_debug_ctxt->debug_refcnt);
+
+        return 0;
+bail:
+        dlm_destroy_debugfs_subroot(dlm);
+        return -ENOMEM;
+}
+
+void dlm_destroy_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+        if (dlm->dlm_debugfs_subroot)
+                debugfs_remove(dlm->dlm_debugfs_subroot);
+}
+
+/* debugfs root */
+int dlm_create_debugfs_root(void)
+{
+        dlm_debugfs_root = debugfs_create_dir(DLM_DEBUGFS_DIR, NULL);
+        if (!dlm_debugfs_root) {
+                mlog_errno(-ENOMEM);
+                return -ENOMEM;
+        }
+        return 0;
+}
+
+void dlm_destroy_debugfs_root(void)
+{
+        if (dlm_debugfs_root)
+                debugfs_remove(dlm_debugfs_root);
+}
+#endif  /* CONFIG_DEBUG_FS */
diff --git a/fs/ocfs2/dlm/dlmdebug.h b/fs/ocfs2/dlm/dlmdebug.h
new file mode 100644
index 000000000000..d34a62a3a625
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmdebug.h
@@ -0,0 +1,86 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * dlmdebug.h
+ *
+ * Copyright (C) 2008 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ */
+
+#ifndef DLMDEBUG_H
+#define DLMDEBUG_H
+
+void dlm_print_one_mle(struct dlm_master_list_entry *mle);
+
+#ifdef CONFIG_DEBUG_FS
+
+struct dlm_debug_ctxt {
+        struct kref debug_refcnt;
+        struct dentry *debug_state_dentry;
+        struct dentry *debug_lockres_dentry;
+        struct dentry *debug_mle_dentry;
+        struct dentry *debug_purgelist_dentry;
+};
+
+struct debug_buffer {
+        int len;
+        char *buf;
+};
+
+struct debug_lockres {
+        int dl_len;
+        char *dl_buf;
+        struct dlm_ctxt *dl_ctxt;
+        struct dlm_lock_resource *dl_res;
+};
+
+int dlm_debug_init(struct dlm_ctxt *dlm);
+void dlm_debug_shutdown(struct dlm_ctxt *dlm);
+
+int dlm_create_debugfs_subroot(struct dlm_ctxt *dlm);
+void dlm_destroy_debugfs_subroot(struct dlm_ctxt *dlm);
+
+int dlm_create_debugfs_root(void);
+void dlm_destroy_debugfs_root(void);
+
+#else
+
+static int dlm_debug_init(struct dlm_ctxt *dlm)
+{
+        return 0;
+}
+static void dlm_debug_shutdown(struct dlm_ctxt *dlm)
+{
+}
+static int dlm_create_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+        return 0;
+}
+static void dlm_destroy_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+}
+static int dlm_create_debugfs_root(void)
+{
+        return 0;
+}
+static void dlm_destroy_debugfs_root(void)
+{
+}
+
+#endif  /* CONFIG_DEBUG_FS */
+#endif  /* DLMDEBUG_H */
diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
index 0879d86113e3..63f8125824e8 100644
--- a/fs/ocfs2/dlm/dlmdomain.c
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -33,6 +33,7 @@
 #include <linux/spinlock.h>
 #include <linux/delay.h>
 #include <linux/err.h>
+#include <linux/debugfs.h>
 
 #include "cluster/heartbeat.h"
 #include "cluster/nodemanager.h"
@@ -40,8 +41,8 @@
 
 #include "dlmapi.h"
 #include "dlmcommon.h"
-
 #include "dlmdomain.h"
+#include "dlmdebug.h"
 
 #include "dlmver.h"
 
@@ -298,6 +299,8 @@ static int dlm_wait_on_domain_helper(const char *domain)
 
 static void dlm_free_ctxt_mem(struct dlm_ctxt *dlm)
 {
+        dlm_destroy_debugfs_subroot(dlm);
+
         if (dlm->lockres_hash)
                 dlm_free_pagevec((void **)dlm->lockres_hash, DLM_HASH_PAGES);
 
@@ -395,6 +398,7 @@ static void dlm_destroy_dlm_worker(struct dlm_ctxt *dlm)
 static void dlm_complete_dlm_shutdown(struct dlm_ctxt *dlm)
 {
         dlm_unregister_domain_handlers(dlm);
+        dlm_debug_shutdown(dlm);
         dlm_complete_thread(dlm);
         dlm_complete_recovery_thread(dlm);
         dlm_destroy_dlm_worker(dlm);
@@ -644,6 +648,7 @@ int dlm_shutting_down(struct dlm_ctxt *dlm)
 void dlm_unregister_domain(struct dlm_ctxt *dlm)
 {
         int leave = 0;
+        struct dlm_lock_resource *res;
 
         spin_lock(&dlm_domain_lock);
         BUG_ON(dlm->dlm_state != DLM_CTXT_JOINED);
@@ -673,6 +678,15 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm)
                         msleep(500);
                         mlog(0, "%s: more migration to do\n", dlm->name);
                 }
+
+                /* This list should be empty. If not, print remaining lockres */
+                if (!list_empty(&dlm->tracking_list)) {
+                        mlog(ML_ERROR, "Following lockres' are still on the "
+                             "tracking list:\n");
+                        list_for_each_entry(res, &dlm->tracking_list, tracking)
+                                dlm_print_one_lock_resource(res);
+                }
+
                 dlm_mark_domain_leaving(dlm);
                 dlm_leave_domain(dlm);
                 dlm_complete_dlm_shutdown(dlm);
@@ -1405,6 +1419,12 @@ static int dlm_join_domain(struct dlm_ctxt *dlm)
                 goto bail;
         }
 
+        status = dlm_debug_init(dlm);
+        if (status < 0) {
+                mlog_errno(status);
+                goto bail;
+        }
+
         status = dlm_launch_thread(dlm);
         if (status < 0) {
                 mlog_errno(status);
@@ -1472,6 +1492,7 @@ bail:
 
         if (status) {
                 dlm_unregister_domain_handlers(dlm);
+                dlm_debug_shutdown(dlm);
                 dlm_complete_thread(dlm);
                 dlm_complete_recovery_thread(dlm);
                 dlm_destroy_dlm_worker(dlm);
@@ -1484,6 +1505,7 @@ static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
                                 u32 key)
 {
         int i;
+        int ret;
         struct dlm_ctxt *dlm = NULL;
 
         dlm = kzalloc(sizeof(*dlm), GFP_KERNEL);
@@ -1516,6 +1538,15 @@ static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
         dlm->key = key;
         dlm->node_num = o2nm_this_node();
 
+        ret = dlm_create_debugfs_subroot(dlm);
+        if (ret < 0) {
+                dlm_free_pagevec((void **)dlm->lockres_hash, DLM_HASH_PAGES);
+                kfree(dlm->name);
+                kfree(dlm);
+                dlm = NULL;
+                goto leave;
+        }
+
         spin_lock_init(&dlm->spinlock);
         spin_lock_init(&dlm->master_lock);
         spin_lock_init(&dlm->ast_lock);
@@ -1526,6 +1557,7 @@ static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
         INIT_LIST_HEAD(&dlm->reco.node_data);
         INIT_LIST_HEAD(&dlm->purge_list);
         INIT_LIST_HEAD(&dlm->dlm_domain_handlers);
+        INIT_LIST_HEAD(&dlm->tracking_list);
         dlm->reco.state = 0;
 
         INIT_LIST_HEAD(&dlm->pending_asts);
@@ -1816,21 +1848,49 @@ static int __init dlm_init(void)
         dlm_print_version();
 
         status = dlm_init_mle_cache();
-        if (status)
-                return -1;
+        if (status) {
+                mlog(ML_ERROR, "Could not create o2dlm_mle slabcache\n");
+                goto error;
+        }
+
+        status = dlm_init_master_caches();
+        if (status) {
+                mlog(ML_ERROR, "Could not create o2dlm_lockres and "
+                     "o2dlm_lockname slabcaches\n");
+                goto error;
+        }
+
+        status = dlm_init_lock_cache();
+        if (status) {
+                mlog(ML_ERROR, "Count not create o2dlm_lock slabcache\n");
+                goto error;
+        }
 
         status = dlm_register_net_handlers();
         if (status) {
-                dlm_destroy_mle_cache();
-                return -1;
+                mlog(ML_ERROR, "Unable to register network handlers\n");
+                goto error;
         }
 
+        status = dlm_create_debugfs_root();
+        if (status)
+                goto error;
+
         return 0;
+error:
+        dlm_unregister_net_handlers();
+        dlm_destroy_lock_cache();
+        dlm_destroy_master_caches();
+        dlm_destroy_mle_cache();
+        return -1;
 }
 
 static void __exit dlm_exit (void)
 {
+        dlm_destroy_debugfs_root();
         dlm_unregister_net_handlers();
+        dlm_destroy_lock_cache();
+        dlm_destroy_master_caches();
         dlm_destroy_mle_cache();
 }
 
diff --git a/fs/ocfs2/dlm/dlmlock.c b/fs/ocfs2/dlm/dlmlock.c
index 52578d907d9a..83a9f2972ac8 100644
--- a/fs/ocfs2/dlm/dlmlock.c
+++ b/fs/ocfs2/dlm/dlmlock.c
@@ -53,6 +53,8 @@
 #define MLOG_MASK_PREFIX ML_DLM
 #include "cluster/masklog.h"
 
+static struct kmem_cache *dlm_lock_cache = NULL;
+
 static DEFINE_SPINLOCK(dlm_cookie_lock);
 static u64 dlm_next_cookie = 1;
 
@@ -64,6 +66,22 @@ static void dlm_init_lock(struct dlm_lock *newlock, int type,
 static void dlm_lock_release(struct kref *kref);
 static void dlm_lock_detach_lockres(struct dlm_lock *lock);
 
+int dlm_init_lock_cache(void)
+{
+        dlm_lock_cache = kmem_cache_create("o2dlm_lock",
+                                           sizeof(struct dlm_lock),
+                                           0, SLAB_HWCACHE_ALIGN, NULL);
+        if (dlm_lock_cache == NULL)
+                return -ENOMEM;
+        return 0;
+}
+
+void dlm_destroy_lock_cache(void)
+{
+        if (dlm_lock_cache)
+                kmem_cache_destroy(dlm_lock_cache);
+}
+
 /* Tell us whether we can grant a new lock request.
  * locking:
  *   caller needs:  res->spinlock
@@ -353,7 +371,7 @@ static void dlm_lock_release(struct kref *kref)
                 mlog(0, "freeing kernel-allocated lksb\n");
                 kfree(lock->lksb);
         }
-        kfree(lock);
+        kmem_cache_free(dlm_lock_cache, lock);
 }
 
 /* associate a lock with it's lockres, getting a ref on the lockres */
@@ -412,7 +430,7 @@ struct dlm_lock * dlm_new_lock(int type, u8 node, u64 cookie,
         struct dlm_lock *lock;
         int kernel_allocated = 0;
 
-        lock = kzalloc(sizeof(*lock), GFP_NOFS);
+        lock = (struct dlm_lock *) kmem_cache_zalloc(dlm_lock_cache, GFP_NOFS);
         if (!lock)
                 return NULL;
 
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index ea6b89577860..efc015c6128a 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -48,47 +48,11 @@
 #include "dlmapi.h"
 #include "dlmcommon.h"
 #include "dlmdomain.h"
+#include "dlmdebug.h"
 
 #define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_MASTER)
 #include "cluster/masklog.h"
 
-enum dlm_mle_type {
-        DLM_MLE_BLOCK,
-        DLM_MLE_MASTER,
-        DLM_MLE_MIGRATION
-};
-
-struct dlm_lock_name
-{
-        u8 len;
-        u8 name[DLM_LOCKID_NAME_MAX];
-};
-
-struct dlm_master_list_entry
-{
-        struct list_head list;
-        struct list_head hb_events;
-        struct dlm_ctxt *dlm;
-        spinlock_t spinlock;
-        wait_queue_head_t wq;
-        atomic_t woken;
-        struct kref mle_refs;
-        int inuse;
-        unsigned long maybe_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
-        unsigned long vote_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
-        unsigned long response_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
-        unsigned long node_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
-        u8 master;
-        u8 new_master;
-        enum dlm_mle_type type;
-        struct o2hb_callback_func mle_hb_up;
-        struct o2hb_callback_func mle_hb_down;
-        union {
-                struct dlm_lock_resource *res;
-                struct dlm_lock_name name;
-        } u;
-};
-
 static void dlm_mle_node_down(struct dlm_ctxt *dlm,
                               struct dlm_master_list_entry *mle,
                               struct o2nm_node *node,
@@ -128,98 +92,10 @@ static inline int dlm_mle_equal(struct dlm_ctxt *dlm,
         return 1;
 }
 
-#define dlm_print_nodemap(m)  _dlm_print_nodemap(m,#m)
-static void _dlm_print_nodemap(unsigned long *map, const char *mapname)
-{
-        int i;
-        printk("%s=[ ", mapname);
-        for (i=0; i<O2NM_MAX_NODES; i++)
-                if (test_bit(i, map))
-                        printk("%d ", i);
-        printk("]");
-}
-
-static void dlm_print_one_mle(struct dlm_master_list_entry *mle)
-{
-        int refs;
-        char *type;
-        char attached;
-        u8 master;
-        unsigned int namelen;
-        const char *name;
-        struct kref *k;
-        unsigned long *maybe = mle->maybe_map,
-                      *vote = mle->vote_map,
-                      *resp = mle->response_map,
-                      *node = mle->node_map;
-
-        k = &mle->mle_refs;
-        if (mle->type == DLM_MLE_BLOCK)
-                type = "BLK";
-        else if (mle->type == DLM_MLE_MASTER)
-                type = "MAS";
-        else
-                type = "MIG";
-        refs = atomic_read(&k->refcount);
-        master = mle->master;
-        attached = (list_empty(&mle->hb_events) ? 'N' : 'Y');
-
-        if (mle->type != DLM_MLE_MASTER) {
-                namelen = mle->u.name.len;
-                name = mle->u.name.name;
-        } else {
-                namelen = mle->u.res->lockname.len;
-                name = mle->u.res->lockname.name;
-        }
-
-        mlog(ML_NOTICE, "%.*s: %3s refs=%3d mas=%3u new=%3u evt=%c inuse=%d ",
-                  namelen, name, type, refs, master, mle->new_master, attached,
-                  mle->inuse);
-        dlm_print_nodemap(maybe);
-        printk(", ");
-        dlm_print_nodemap(vote);
-        printk(", ");
-        dlm_print_nodemap(resp);
-        printk(", ");
-        dlm_print_nodemap(node);
-        printk(", ");
-        printk("\n");
-}
-
-#if 0
-/* Code here is included but defined out as it aids debugging */
-
-static void dlm_dump_mles(struct dlm_ctxt *dlm)
-{
-        struct dlm_master_list_entry *mle;
-        
-        mlog(ML_NOTICE, "dumping all mles for domain %s:\n", dlm->name);
-        spin_lock(&dlm->master_lock);
-        list_for_each_entry(mle, &dlm->master_list, list)
-                dlm_print_one_mle(mle);
-        spin_unlock(&dlm->master_lock);
-}
-
-int dlm_dump_all_mles(const char __user *data, unsigned int len)
-{
-        struct dlm_ctxt *dlm;
-
-        spin_lock(&dlm_domain_lock);
-        list_for_each_entry(dlm, &dlm_domains, list) {
-                mlog(ML_NOTICE, "found dlm: %p, name=%s\n", dlm, dlm->name);
-                dlm_dump_mles(dlm);
-        }
-        spin_unlock(&dlm_domain_lock);
-        return len;
-}
-EXPORT_SYMBOL_GPL(dlm_dump_all_mles);
-
-#endif  /*  0  */
-
-
+static struct kmem_cache *dlm_lockres_cache = NULL;
+static struct kmem_cache *dlm_lockname_cache = NULL;
 static struct kmem_cache *dlm_mle_cache = NULL;
 
-
 static void dlm_mle_release(struct kref *kref);
 static void dlm_init_mle(struct dlm_master_list_entry *mle,
                         enum dlm_mle_type type,
@@ -507,7 +383,7 @@ static void dlm_mle_node_up(struct dlm_ctxt *dlm,
 
 int dlm_init_mle_cache(void)
 {
-        dlm_mle_cache = kmem_cache_create("dlm_mle_cache",
+        dlm_mle_cache = kmem_cache_create("o2dlm_mle",
                                           sizeof(struct dlm_master_list_entry),
                                           0, SLAB_HWCACHE_ALIGN,
                                           NULL);
@@ -560,6 +436,35 @@ static void dlm_mle_release(struct kref *kref)
  * LOCK RESOURCE FUNCTIONS
  */
 
+int dlm_init_master_caches(void)
+{
+        dlm_lockres_cache = kmem_cache_create("o2dlm_lockres",
+                                              sizeof(struct dlm_lock_resource),
+                                              0, SLAB_HWCACHE_ALIGN, NULL);
+        if (!dlm_lockres_cache)
+                goto bail;
+
+        dlm_lockname_cache = kmem_cache_create("o2dlm_lockname",
+                                               DLM_LOCKID_NAME_MAX, 0,
+                                               SLAB_HWCACHE_ALIGN, NULL);
+        if (!dlm_lockname_cache)
+                goto bail;
+
+        return 0;
+bail:
+        dlm_destroy_master_caches();
+        return -ENOMEM;
+}
+
+void dlm_destroy_master_caches(void)
+{
+        if (dlm_lockname_cache)
+                kmem_cache_destroy(dlm_lockname_cache);
+
+        if (dlm_lockres_cache)
+                kmem_cache_destroy(dlm_lockres_cache);
+}
+
 static void dlm_set_lockres_owner(struct dlm_ctxt *dlm,
                                   struct dlm_lock_resource *res,
                                   u8 owner)
@@ -610,6 +515,14 @@ static void dlm_lockres_release(struct kref *kref)
         mlog(0, "destroying lockres %.*s\n", res->lockname.len,
              res->lockname.name);
 
+        if (!list_empty(&res->tracking))
+                list_del_init(&res->tracking);
+        else {
+                mlog(ML_ERROR, "Resource %.*s not on the Tracking list\n",
+                     res->lockname.len, res->lockname.name);
+                dlm_print_one_lock_resource(res);
+        }
+
         if (!hlist_unhashed(&res->hash_node) ||
             !list_empty(&res->granted) ||
             !list_empty(&res->converting) ||
@@ -642,9 +555,9 @@ static void dlm_lockres_release(struct kref *kref)
         BUG_ON(!list_empty(&res->recovering));
         BUG_ON(!list_empty(&res->purge));
 
-        kfree(res->lockname.name);
+        kmem_cache_free(dlm_lockname_cache, (void *)res->lockname.name);
 
-        kfree(res);
+        kmem_cache_free(dlm_lockres_cache, res);
 }
 
 void dlm_lockres_put(struct dlm_lock_resource *res)
@@ -677,6 +590,7 @@ static void dlm_init_lockres(struct dlm_ctxt *dlm,
         INIT_LIST_HEAD(&res->dirty);
         INIT_LIST_HEAD(&res->recovering);
         INIT_LIST_HEAD(&res->purge);
+        INIT_LIST_HEAD(&res->tracking);
         atomic_set(&res->asts_reserved, 0);
         res->migration_pending = 0;
         res->inflight_locks = 0;
@@ -692,6 +606,8 @@ static void dlm_init_lockres(struct dlm_ctxt *dlm,
 
         res->last_used = 0;
 
+        list_add_tail(&res->tracking, &dlm->tracking_list);
+
         memset(res->lvb, 0, DLM_LVB_LEN);
         memset(res->refmap, 0, sizeof(res->refmap));
 }
@@ -700,20 +616,28 @@ struct dlm_lock_resource *dlm_new_lockres(struct dlm_ctxt *dlm,
                                    const char *name,
                                    unsigned int namelen)
 {
-        struct dlm_lock_resource *res;
+        struct dlm_lock_resource *res = NULL;
 
-        res = kmalloc(sizeof(struct dlm_lock_resource), GFP_NOFS);
+        res = (struct dlm_lock_resource *)
+                                kmem_cache_zalloc(dlm_lockres_cache, GFP_NOFS);
         if (!res)
-                return NULL;
+                goto error;
 
-        res->lockname.name = kmalloc(namelen, GFP_NOFS);
-        if (!res->lockname.name) {
-                kfree(res);
-                return NULL;
-        }
+        res->lockname.name = (char *)
+                                kmem_cache_zalloc(dlm_lockname_cache, GFP_NOFS);
+        if (!res->lockname.name)
+                goto error;
 
         dlm_init_lockres(dlm, res, name, namelen);
         return res;
+
+error:
+        if (res && res->lockname.name)
+                kmem_cache_free(dlm_lockname_cache, (void *)res->lockname.name);
+
+        if (res)
+                kmem_cache_free(dlm_lockres_cache, res);
+        return NULL;
 }
 
 void __dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 1f1873bf41fb..394d25a131a5 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -27,18 +27,11 @@
 #include <linux/slab.h>
 #include <linux/highmem.h>
 #include <linux/mm.h>
-#include <linux/crc32.h>
 #include <linux/kthread.h>
 #include <linux/pagemap.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
 
-#include <cluster/heartbeat.h>
-#include <cluster/nodemanager.h>
-#include <cluster/tcp.h>
-
-#include <dlm/dlmapi.h>
-
 #define MLOG_MASK_PREFIX ML_DLM_GLUE
 #include <cluster/masklog.h>
 
@@ -53,6 +46,7 @@
 #include "heartbeat.h"
 #include "inode.h"
 #include "journal.h"
+#include "stackglue.h"
 #include "slot_map.h"
 #include "super.h"
 #include "uptodate.h"
@@ -113,7 +107,8 @@ static void ocfs2_dump_meta_lvb_info(u64 level,
                                      unsigned int line,
                                      struct ocfs2_lock_res *lockres)
 {
-        struct ocfs2_meta_lvb *lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
+        struct ocfs2_meta_lvb *lvb =
+                (struct ocfs2_meta_lvb *)ocfs2_dlm_lvb(&lockres->l_lksb);
 
         mlog(level, "LVB information for %s (called from %s:%u):\n",
              lockres->l_name, function, line);
@@ -259,31 +254,6 @@ static struct ocfs2_lock_res_ops ocfs2_flock_lops = {
         .flags          = 0,
 };
 
-/*
- * This is the filesystem locking protocol version.
- *
- * Whenever the filesystem does new things with locks (adds or removes a
- * lock, orders them differently, does different things underneath a lock),
- * the version must be changed.  The protocol is negotiated when joining
- * the dlm domain.  A node may join the domain if its major version is
- * identical to all other nodes and its minor version is greater than
- * or equal to all other nodes.  When its minor version is greater than
- * the other nodes, it will run at the minor version specified by the
- * other nodes.
- *
- * If a locking change is made that will not be compatible with older
- * versions, the major number must be increased and the minor version set
- * to zero.  If a change merely adds a behavior that can be disabled when
- * speaking to older versions, the minor version must be increased.  If a
- * change adds a fully backwards compatible change (eg, LVB changes that
- * are just ignored by older versions), the version does not need to be
- * updated.
- */
-const struct dlm_protocol_version ocfs2_locking_protocol = {
-        .pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
-        .pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
-};
-
 static inline int ocfs2_is_inode_lock(struct ocfs2_lock_res *lockres)
 {
         return lockres->l_type == OCFS2_LOCK_TYPE_META ||
@@ -316,7 +286,7 @@ static inline struct ocfs2_super *ocfs2_get_lockres_osb(struct ocfs2_lock_res *l
 static int ocfs2_lock_create(struct ocfs2_super *osb,
                              struct ocfs2_lock_res *lockres,
                              int level,
-                             int dlm_flags);
+                             u32 dlm_flags);
 static inline int ocfs2_may_continue_on_blocked_lock(struct ocfs2_lock_res *lockres,
                                                      int wanted);
 static void ocfs2_cluster_unlock(struct ocfs2_super *osb,
@@ -330,10 +300,9 @@ static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
                                         struct ocfs2_lock_res *lockres);
 static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
                                                 int convert);
-#define ocfs2_log_dlm_error(_func, _stat, _lockres) do {        \
-        mlog(ML_ERROR, "Dlm error \"%s\" while calling %s on "  \
-                "resource %s: %s\n", dlm_errname(_stat), _func, \
-                _lockres->l_name, dlm_errmsg(_stat));           \
+#define ocfs2_log_dlm_error(_func, _err, _lockres) do {                 \
+        mlog(ML_ERROR, "DLM error %d while calling %s on resource %s\n", \
+             _err, _func, _lockres->l_name);                            \
 } while (0)
 static int ocfs2_downconvert_thread(void *arg);
 static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
@@ -342,12 +311,13 @@ static int ocfs2_inode_lock_update(struct inode *inode,
                                   struct buffer_head **bh);
 static void ocfs2_drop_osb_locks(struct ocfs2_super *osb);
 static inline int ocfs2_highest_compat_lock_level(int level);
-static void ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
-                                      int new_level);
+static unsigned int ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
+                                              int new_level);
 static int ocfs2_downconvert_lock(struct ocfs2_super *osb,
                                   struct ocfs2_lock_res *lockres,
                                   int new_level,
-                                  int lvb);
+                                  int lvb,
+                                  unsigned int generation);
 static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb,
                                         struct ocfs2_lock_res *lockres);
 static int ocfs2_cancel_convert(struct ocfs2_super *osb,
@@ -406,9 +376,9 @@ static void ocfs2_lock_res_init_common(struct ocfs2_super *osb,
         res->l_ops           = ops;
         res->l_priv          = priv;
 
-        res->l_level         = LKM_IVMODE;
-        res->l_requested     = LKM_IVMODE;
-        res->l_blocking      = LKM_IVMODE;
+        res->l_level         = DLM_LOCK_IV;
+        res->l_requested     = DLM_LOCK_IV;
+        res->l_blocking      = DLM_LOCK_IV;
         res->l_action        = OCFS2_AST_INVALID;
         res->l_unlock_action = OCFS2_UNLOCK_INVALID;
 
@@ -604,10 +574,10 @@ static inline void ocfs2_inc_holders(struct ocfs2_lock_res *lockres,
         BUG_ON(!lockres);
 
         switch(level) {
-        case LKM_EXMODE:
+        case DLM_LOCK_EX:
                 lockres->l_ex_holders++;
                 break;
-        case LKM_PRMODE:
+        case DLM_LOCK_PR:
                 lockres->l_ro_holders++;
                 break;
         default:
@@ -625,11 +595,11 @@ static inline void ocfs2_dec_holders(struct ocfs2_lock_res *lockres,
         BUG_ON(!lockres);
 
         switch(level) {
-        case LKM_EXMODE:
+        case DLM_LOCK_EX:
                 BUG_ON(!lockres->l_ex_holders);
                 lockres->l_ex_holders--;
                 break;
-        case LKM_PRMODE:
+        case DLM_LOCK_PR:
                 BUG_ON(!lockres->l_ro_holders);
                 lockres->l_ro_holders--;
                 break;
@@ -644,12 +614,12 @@ static inline void ocfs2_dec_holders(struct ocfs2_lock_res *lockres,
  * lock types are added. */
 static inline int ocfs2_highest_compat_lock_level(int level)
 {
-        int new_level = LKM_EXMODE;
+        int new_level = DLM_LOCK_EX;
 
-        if (level == LKM_EXMODE)
-                new_level = LKM_NLMODE;
-        else if (level == LKM_PRMODE)
-                new_level = LKM_PRMODE;
+        if (level == DLM_LOCK_EX)
+                new_level = DLM_LOCK_NL;
+        else if (level == DLM_LOCK_PR)
+                new_level = DLM_LOCK_PR;
         return new_level;
 }
 
@@ -688,12 +658,12 @@ static inline void ocfs2_generic_handle_downconvert_action(struct ocfs2_lock_res
         BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
         BUG_ON(!(lockres->l_flags & OCFS2_LOCK_ATTACHED));
         BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BLOCKED));
-        BUG_ON(lockres->l_blocking <= LKM_NLMODE);
+        BUG_ON(lockres->l_blocking <= DLM_LOCK_NL);
 
         lockres->l_level = lockres->l_requested;
         if (lockres->l_level <=
             ocfs2_highest_compat_lock_level(lockres->l_blocking)) {
-                lockres->l_blocking = LKM_NLMODE;
+                lockres->l_blocking = DLM_LOCK_NL;
                 lockres_clear_flags(lockres, OCFS2_LOCK_BLOCKED);
         }
         lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
@@ -712,7 +682,7 @@ static inline void ocfs2_generic_handle_convert_action(struct ocfs2_lock_res *lo
          * information is already up to data. Convert from NL to
          * *anything* however should mark ourselves as needing an
          * update */
-        if (lockres->l_level == LKM_NLMODE &&
+        if (lockres->l_level == DLM_LOCK_NL &&
             lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)
                 lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
 
@@ -729,7 +699,7 @@ static inline void ocfs2_generic_handle_attach_action(struct ocfs2_lock_res *loc
         BUG_ON((!(lockres->l_flags & OCFS2_LOCK_BUSY)));
         BUG_ON(lockres->l_flags & OCFS2_LOCK_ATTACHED);
 
-        if (lockres->l_requested > LKM_NLMODE &&
+        if (lockres->l_requested > DLM_LOCK_NL &&
             !(lockres->l_flags & OCFS2_LOCK_LOCAL) &&
             lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)
                 lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
@@ -767,6 +737,113 @@ static int ocfs2_generic_handle_bast(struct ocfs2_lock_res *lockres,
         return needs_downconvert;
 }
 
+/*
+ * OCFS2_LOCK_PENDING and l_pending_gen.
+ *
+ * Why does OCFS2_LOCK_PENDING exist?  To close a race between setting
+ * OCFS2_LOCK_BUSY and calling ocfs2_dlm_lock().  See ocfs2_unblock_lock()
+ * for more details on the race.
+ *
+ * OCFS2_LOCK_PENDING closes the race quite nicely.  However, it introduces
+ * a race on itself.  In o2dlm, we can get the ast before ocfs2_dlm_lock()
+ * returns.  The ast clears OCFS2_LOCK_BUSY, and must therefore clear
+ * OCFS2_LOCK_PENDING at the same time.  When ocfs2_dlm_lock() returns,
+ * the caller is going to try to clear PENDING again.  If nothing else is
+ * happening, __lockres_clear_pending() sees PENDING is unset and does
+ * nothing.
+ *
+ * But what if another path (eg downconvert thread) has just started a
+ * new locking action?  The other path has re-set PENDING.  Our path
+ * cannot clear PENDING, because that will re-open the original race
+ * window.
+ *
+ * [Example]
+ *
+ * ocfs2_meta_lock()
+ *  ocfs2_cluster_lock()
+ *   set BUSY
+ *   set PENDING
+ *   drop l_lock
+ *   ocfs2_dlm_lock()
+ *    ocfs2_locking_ast()               ocfs2_downconvert_thread()
+ *     clear PENDING                     ocfs2_unblock_lock()
+ *                                        take_l_lock
+ *                                        !BUSY
+ *                                        ocfs2_prepare_downconvert()
+ *                                         set BUSY
+ *                                         set PENDING
+ *                                        drop l_lock
+ *   take l_lock
+ *   clear PENDING
+ *   drop l_lock
+ *                      <window>
+ *                                        ocfs2_dlm_lock()
+ *
+ * So as you can see, we now have a window where l_lock is not held,
+ * PENDING is not set, and ocfs2_dlm_lock() has not been called.
+ *
+ * The core problem is that ocfs2_cluster_lock() has cleared the PENDING
+ * set by ocfs2_prepare_downconvert().  That wasn't nice.
+ *
+ * To solve this we introduce l_pending_gen.  A call to
+ * lockres_clear_pending() will only do so when it is passed a generation
+ * number that matches the lockres.  lockres_set_pending() will return the
+ * current generation number.  When ocfs2_cluster_lock() goes to clear
+ * PENDING, it passes the generation it got from set_pending().  In our
+ * example above, the generation numbers will *not* match.  Thus,
+ * ocfs2_cluster_lock() will not clear the PENDING set by
+ * ocfs2_prepare_downconvert().
+ */
+
+/* Unlocked version for ocfs2_locking_ast() */
+static void __lockres_clear_pending(struct ocfs2_lock_res *lockres,
+                                    unsigned int generation,
+                                    struct ocfs2_super *osb)
+{
+        assert_spin_locked(&lockres->l_lock);
+
+        /*
+         * The ast and locking functions can race us here.  The winner
+         * will clear pending, the loser will not.
+         */
+        if (!(lockres->l_flags & OCFS2_LOCK_PENDING) ||
+            (lockres->l_pending_gen != generation))
+                return;
+
+        lockres_clear_flags(lockres, OCFS2_LOCK_PENDING);
+        lockres->l_pending_gen++;
+
+        /*
+         * The downconvert thread may have skipped us because we
+         * were PENDING.  Wake it up.
+         */
+        if (lockres->l_flags & OCFS2_LOCK_BLOCKED)
+                ocfs2_wake_downconvert_thread(osb);
+}
+
+/* Locked version for callers of ocfs2_dlm_lock() */
+static void lockres_clear_pending(struct ocfs2_lock_res *lockres,
+                                  unsigned int generation,
+                                  struct ocfs2_super *osb)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&lockres->l_lock, flags);
+        __lockres_clear_pending(lockres, generation, osb);
+        spin_unlock_irqrestore(&lockres->l_lock, flags);
+}
+
+static unsigned int lockres_set_pending(struct ocfs2_lock_res *lockres)
+{
+        assert_spin_locked(&lockres->l_lock);
+        BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
+
+        lockres_or_flags(lockres, OCFS2_LOCK_PENDING);
+
+        return lockres->l_pending_gen;
+}
+
+
 static void ocfs2_blocking_ast(void *opaque, int level)
 {
         struct ocfs2_lock_res *lockres = opaque;
@@ -774,7 +851,7 @@ static void ocfs2_blocking_ast(void *opaque, int level)
         int needs_downconvert;
         unsigned long flags;
 
-        BUG_ON(level <= LKM_NLMODE);
+        BUG_ON(level <= DLM_LOCK_NL);
 
         mlog(0, "BAST fired for lockres %s, blocking %d, level %d type %s\n",
              lockres->l_name, level, lockres->l_level,
@@ -801,14 +878,22 @@ static void ocfs2_blocking_ast(void *opaque, int level)
 static void ocfs2_locking_ast(void *opaque)
 {
         struct ocfs2_lock_res *lockres = opaque;
-        struct dlm_lockstatus *lksb = &lockres->l_lksb;
+        struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);
         unsigned long flags;
+        int status;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
 
-        if (lksb->status != DLM_NORMAL) {
-                mlog(ML_ERROR, "lockres %s: lksb status value of %u!\n",
-                     lockres->l_name, lksb->status);
+        status = ocfs2_dlm_lock_status(&lockres->l_lksb);
+
+        if (status == -EAGAIN) {
+                lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
+                goto out;
+        }
+
+        if (status) {
+                mlog(ML_ERROR, "lockres %s: lksb status value of %d!\n",
+                     lockres->l_name, status);
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
                 return;
         }
@@ -831,11 +916,23 @@ static void ocfs2_locking_ast(void *opaque)
                      lockres->l_unlock_action);
                 BUG();
         }
-
+out:
         /* set it to something invalid so if we get called again we
          * can catch it. */
         lockres->l_action = OCFS2_AST_INVALID;
 
+        /* Did we try to cancel this lock?  Clear that state */
+        if (lockres->l_unlock_action == OCFS2_UNLOCK_CANCEL_CONVERT)
+                lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
+
+        /*
+         * We may have beaten the locking functions here.  We certainly
+         * know that dlm_lock() has been called :-)
+         * Because we can't have two lock calls in flight at once, we
+         * can use lockres->l_pending_gen.
+         */
+        __lockres_clear_pending(lockres, lockres->l_pending_gen,  osb);
+
         wake_up(&lockres->l_event);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 }
@@ -865,15 +962,15 @@ static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
 static int ocfs2_lock_create(struct ocfs2_super *osb,
                              struct ocfs2_lock_res *lockres,
                              int level,
-                             int dlm_flags)
+                             u32 dlm_flags)
 {
         int ret = 0;
-        enum dlm_status status = DLM_NORMAL;
         unsigned long flags;
+        unsigned int gen;
 
         mlog_entry_void();
 
-        mlog(0, "lock %s, level = %d, flags = %d\n", lockres->l_name, level,
+        mlog(0, "lock %s, level = %d, flags = %u\n", lockres->l_name, level,
              dlm_flags);
 
         spin_lock_irqsave(&lockres->l_lock, flags);
@@ -886,24 +983,23 @@ static int ocfs2_lock_create(struct ocfs2_super *osb,
         lockres->l_action = OCFS2_AST_ATTACH;
         lockres->l_requested = level;
         lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+        gen = lockres_set_pending(lockres);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
-        status = dlmlock(osb->dlm,
-                         level,
-                         &lockres->l_lksb,
-                         dlm_flags,
-                         lockres->l_name,
-                         OCFS2_LOCK_ID_MAX_LEN - 1,
-                         ocfs2_locking_ast,
-                         lockres,
-                         ocfs2_blocking_ast);
-        if (status != DLM_NORMAL) {
-                ocfs2_log_dlm_error("dlmlock", status, lockres);
-                ret = -EINVAL;
+        ret = ocfs2_dlm_lock(osb->cconn,
+                             level,
+                             &lockres->l_lksb,
+                             dlm_flags,
+                             lockres->l_name,
+                             OCFS2_LOCK_ID_MAX_LEN - 1,
+                             lockres);
+        lockres_clear_pending(lockres, gen, osb);
+        if (ret) {
+                ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
                 ocfs2_recover_from_dlm_error(lockres, 1);
         }
 
-        mlog(0, "lock %s, successfull return from dlmlock\n", lockres->l_name);
+        mlog(0, "lock %s, return from ocfs2_dlm_lock\n", lockres->l_name);
 
 bail:
         mlog_exit(ret);
@@ -1016,21 +1112,22 @@ static int ocfs2_wait_for_mask_interruptible(struct ocfs2_mask_waiter *mw,
 static int ocfs2_cluster_lock(struct ocfs2_super *osb,
                               struct ocfs2_lock_res *lockres,
                               int level,
-                              int lkm_flags,
+                              u32 lkm_flags,
                               int arg_flags)
 {
         struct ocfs2_mask_waiter mw;
-        enum dlm_status status;
         int wait, catch_signals = !(osb->s_mount_opt & OCFS2_MOUNT_NOINTR);
         int ret = 0; /* gcc doesn't realize wait = 1 guarantees ret is set */
         unsigned long flags;
+        unsigned int gen;
+        int noqueue_attempted = 0;
 
         mlog_entry_void();
 
         ocfs2_init_mask_waiter(&mw);
 
         if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
-                lkm_flags |= LKM_VALBLK;
+                lkm_flags |= DLM_LKF_VALBLK;
 
 again:
         wait = 0;
@@ -1068,52 +1165,56 @@ again:
         }
 
         if (level > lockres->l_level) {
+                if (noqueue_attempted > 0) {
+                        ret = -EAGAIN;
+                        goto unlock;
+                }
+                if (lkm_flags & DLM_LKF_NOQUEUE)
+                        noqueue_attempted = 1;
+
                 if (lockres->l_action != OCFS2_AST_INVALID)
                         mlog(ML_ERROR, "lockres %s has action %u pending\n",
                              lockres->l_name, lockres->l_action);
 
                 if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) {
                         lockres->l_action = OCFS2_AST_ATTACH;
-                        lkm_flags &= ~LKM_CONVERT;
+                        lkm_flags &= ~DLM_LKF_CONVERT;
                 } else {
                         lockres->l_action = OCFS2_AST_CONVERT;
-                        lkm_flags |= LKM_CONVERT;
+                        lkm_flags |= DLM_LKF_CONVERT;
                 }
 
                 lockres->l_requested = level;
                 lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+                gen = lockres_set_pending(lockres);
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
 
-                BUG_ON(level == LKM_IVMODE);
-                BUG_ON(level == LKM_NLMODE);
+                BUG_ON(level == DLM_LOCK_IV);
+                BUG_ON(level == DLM_LOCK_NL);
 
                 mlog(0, "lock %s, convert from %d to level = %d\n",
                      lockres->l_name, lockres->l_level, level);
 
                 /* call dlm_lock to upgrade lock now */
-                status = dlmlock(osb->dlm,
-                                 level,
-                                 &lockres->l_lksb,
-                                 lkm_flags,
-                                 lockres->l_name,
-                                 OCFS2_LOCK_ID_MAX_LEN - 1,
-                                 ocfs2_locking_ast,
-                                 lockres,
-                                 ocfs2_blocking_ast);
-                if (status != DLM_NORMAL) {
-                        if ((lkm_flags & LKM_NOQUEUE) &&
-                            (status == DLM_NOTQUEUED))
-                                ret = -EAGAIN;
-                        else {
-                                ocfs2_log_dlm_error("dlmlock", status,
-                                                    lockres);
-                                ret = -EINVAL;
+                ret = ocfs2_dlm_lock(osb->cconn,
+                                     level,
+                                     &lockres->l_lksb,
+                                     lkm_flags,
+                                     lockres->l_name,
+                                     OCFS2_LOCK_ID_MAX_LEN - 1,
+                                     lockres);
+                lockres_clear_pending(lockres, gen, osb);
+                if (ret) {
+                        if (!(lkm_flags & DLM_LKF_NOQUEUE) ||
+                            (ret != -EAGAIN)) {
+                                ocfs2_log_dlm_error("ocfs2_dlm_lock",
+                                                    ret, lockres);
                         }
                         ocfs2_recover_from_dlm_error(lockres, 1);
                         goto out;
                 }
 
-                mlog(0, "lock %s, successfull return from dlmlock\n",
+                mlog(0, "lock %s, successfull return from ocfs2_dlm_lock\n",
                      lockres->l_name);
 
                 /* At this point we've gone inside the dlm and need to
@@ -1177,9 +1278,9 @@ static int ocfs2_create_new_lock(struct ocfs2_super *osb,
                                  int ex,
                                  int local)
 {
-        int level =  ex ? LKM_EXMODE : LKM_PRMODE;
+        int level =  ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         unsigned long flags;
-        int lkm_flags = local ? LKM_LOCAL : 0;
+        u32 lkm_flags = local ? DLM_LKF_LOCAL : 0;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
         BUG_ON(lockres->l_flags & OCFS2_LOCK_ATTACHED);
@@ -1222,7 +1323,7 @@ int ocfs2_create_new_inode_locks(struct inode *inode)
         }
 
         /*
-         * We don't want to use LKM_LOCAL on a meta data lock as they
+         * We don't want to use DLM_LKF_LOCAL on a meta data lock as they
          * don't use a generation in their lock names.
          */
         ret = ocfs2_create_new_lock(osb, &OCFS2_I(inode)->ip_inode_lockres, 1, 0);
@@ -1261,7 +1362,7 @@ int ocfs2_rw_lock(struct inode *inode, int write)
 
         lockres = &OCFS2_I(inode)->ip_rw_lockres;
 
-        level = write ? LKM_EXMODE : LKM_PRMODE;
+        level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
 
         status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres, level, 0,
                                     0);
@@ -1274,7 +1375,7 @@ int ocfs2_rw_lock(struct inode *inode, int write)
 
 void ocfs2_rw_unlock(struct inode *inode, int write)
 {
-        int level = write ? LKM_EXMODE : LKM_PRMODE;
+        int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_rw_lockres;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
@@ -1312,7 +1413,7 @@ int ocfs2_open_lock(struct inode *inode)
         lockres = &OCFS2_I(inode)->ip_open_lockres;
 
         status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres,
-                                    LKM_PRMODE, 0, 0);
+                                    DLM_LOCK_PR, 0, 0);
         if (status < 0)
                 mlog_errno(status);
 
@@ -1340,16 +1441,16 @@ int ocfs2_try_open_lock(struct inode *inode, int write)
 
         lockres = &OCFS2_I(inode)->ip_open_lockres;
 
-        level = write ? LKM_EXMODE : LKM_PRMODE;
+        level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
 
         /*
          * The file system may already holding a PRMODE/EXMODE open lock.
-         * Since we pass LKM_NOQUEUE, the request won't block waiting on
+         * Since we pass DLM_LKF_NOQUEUE, the request won't block waiting on
          * other nodes and the -EAGAIN will indicate to the caller that
          * this inode is still in use.
          */
         status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres,
-                                    level, LKM_NOQUEUE, 0);
+                                    level, DLM_LKF_NOQUEUE, 0);
 
 out:
         mlog_exit(status);
@@ -1374,10 +1475,10 @@ void ocfs2_open_unlock(struct inode *inode)
 
         if(lockres->l_ro_holders)
                 ocfs2_cluster_unlock(OCFS2_SB(inode->i_sb), lockres,
-                                     LKM_PRMODE);
+                                     DLM_LOCK_PR);
         if(lockres->l_ex_holders)
                 ocfs2_cluster_unlock(OCFS2_SB(inode->i_sb), lockres,
-                                     LKM_EXMODE);
+                                     DLM_LOCK_EX);
 
 out:
         mlog_exit_void();
@@ -1464,7 +1565,7 @@ int ocfs2_file_lock(struct file *file, int ex, int trylock)
         ocfs2_init_mask_waiter(&mw);
 
         if ((lockres->l_flags & OCFS2_LOCK_BUSY) ||
-            (lockres->l_level > LKM_NLMODE)) {
+            (lockres->l_level > DLM_LOCK_NL)) {
                 mlog(ML_ERROR,
                      "File lock \"%s\" has busy or locked state: flags: 0x%lx, "
                      "level: %u\n", lockres->l_name, lockres->l_flags,
@@ -1503,14 +1604,12 @@ int ocfs2_file_lock(struct file *file, int ex, int trylock)
         lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
-        ret = dlmlock(osb->dlm, level, &lockres->l_lksb, lkm_flags,
-                      lockres->l_name, OCFS2_LOCK_ID_MAX_LEN - 1,
-                      ocfs2_locking_ast, lockres, ocfs2_blocking_ast);
-        if (ret != DLM_NORMAL) {
-                if (trylock && ret == DLM_NOTQUEUED)
-                        ret = -EAGAIN;
-                else {
-                        ocfs2_log_dlm_error("dlmlock", ret, lockres);
+        ret = ocfs2_dlm_lock(osb->cconn, level, &lockres->l_lksb, lkm_flags,
+                             lockres->l_name, OCFS2_LOCK_ID_MAX_LEN - 1,
+                             lockres);
+        if (ret) {
+                if (!trylock || (ret != -EAGAIN)) {
+                        ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
                         ret = -EINVAL;
                 }
 
@@ -1537,6 +1636,10 @@ int ocfs2_file_lock(struct file *file, int ex, int trylock)
                  * to just bubble sucess back up to the user.
                  */
                 ret = ocfs2_flock_handle_signal(lockres, level);
+        } else if (!ret && (level > lockres->l_level)) {
+                /* Trylock failed asynchronously */
+                BUG_ON(!trylock);
+                ret = -EAGAIN;
         }
 
 out:
@@ -1549,6 +1652,7 @@ out:
 void ocfs2_file_unlock(struct file *file)
 {
         int ret;
+        unsigned int gen;
         unsigned long flags;
         struct ocfs2_file_private *fp = file->private_data;
         struct ocfs2_lock_res *lockres = &fp->fp_flock;
@@ -1572,13 +1676,13 @@ void ocfs2_file_unlock(struct file *file)
          * Fake a blocking ast for the downconvert code.
          */
         lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);
-        lockres->l_blocking = LKM_EXMODE;
+        lockres->l_blocking = DLM_LOCK_EX;
 
-        ocfs2_prepare_downconvert(lockres, LKM_NLMODE);
+        gen = ocfs2_prepare_downconvert(lockres, LKM_NLMODE);
         lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
-        ret = ocfs2_downconvert_lock(osb, lockres, LKM_NLMODE, 0);
+        ret = ocfs2_downconvert_lock(osb, lockres, LKM_NLMODE, 0, gen);
         if (ret) {
                 mlog_errno(ret);
                 return;
@@ -1601,11 +1705,11 @@ static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
          * condition. */
         if (lockres->l_flags & OCFS2_LOCK_BLOCKED) {
                 switch(lockres->l_blocking) {
-                case LKM_EXMODE:
+                case DLM_LOCK_EX:
                         if (!lockres->l_ex_holders && !lockres->l_ro_holders)
                                 kick = 1;
                         break;
-                case LKM_PRMODE:
+                case DLM_LOCK_PR:
                         if (!lockres->l_ex_holders)
                                 kick = 1;
                         break;
@@ -1648,7 +1752,7 @@ static void __ocfs2_stuff_meta_lvb(struct inode *inode)
 
         mlog_entry_void();
 
-        lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
+        lvb = (struct ocfs2_meta_lvb *)ocfs2_dlm_lvb(&lockres->l_lksb);
 
         /*
          * Invalidate the LVB of a deleted inode - this way other
@@ -1700,7 +1804,7 @@ static void ocfs2_refresh_inode_from_lvb(struct inode *inode)
 
         mlog_meta_lvb(0, lockres);
 
-        lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
+        lvb = (struct ocfs2_meta_lvb *)ocfs2_dlm_lvb(&lockres->l_lksb);
 
         /* We're safe here without the lockres lock... */
         spin_lock(&oi->ip_lock);
@@ -1735,7 +1839,8 @@ static void ocfs2_refresh_inode_from_lvb(struct inode *inode)
 static inline int ocfs2_meta_lvb_is_trustable(struct inode *inode,
                                               struct ocfs2_lock_res *lockres)
 {
-        struct ocfs2_meta_lvb *lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
+        struct ocfs2_meta_lvb *lvb =
+                (struct ocfs2_meta_lvb *)ocfs2_dlm_lvb(&lockres->l_lksb);
 
         if (lvb->lvb_version == OCFS2_LVB_VERSION
             && be32_to_cpu(lvb->lvb_igeneration) == inode->i_generation)
@@ -1923,7 +2028,8 @@ int ocfs2_inode_lock_full(struct inode *inode,
                          int ex,
                          int arg_flags)
 {
-        int status, level, dlm_flags, acquired;
+        int status, level, acquired;
+        u32 dlm_flags;
         struct ocfs2_lock_res *lockres = NULL;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
         struct buffer_head *local_bh = NULL;
@@ -1950,14 +2056,13 @@ int ocfs2_inode_lock_full(struct inode *inode,
                 goto local;
 
         if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
-                wait_event(osb->recovery_event,
-                           ocfs2_node_map_is_empty(osb, &osb->recovery_map));
+                ocfs2_wait_for_recovery(osb);
 
         lockres = &OCFS2_I(inode)->ip_inode_lockres;
-        level = ex ? LKM_EXMODE : LKM_PRMODE;
+        level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         dlm_flags = 0;
         if (arg_flags & OCFS2_META_LOCK_NOQUEUE)
-                dlm_flags |= LKM_NOQUEUE;
+                dlm_flags |= DLM_LKF_NOQUEUE;
 
         status = ocfs2_cluster_lock(osb, lockres, level, dlm_flags, arg_flags);
         if (status < 0) {
@@ -1974,8 +2079,7 @@ int ocfs2_inode_lock_full(struct inode *inode,
          * committed to owning this lock so we don't allow signals to
          * abort the operation. */
         if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
-                wait_event(osb->recovery_event,
-                           ocfs2_node_map_is_empty(osb, &osb->recovery_map));
+                ocfs2_wait_for_recovery(osb);
 
 local:
         /*
@@ -2109,7 +2213,7 @@ int ocfs2_inode_lock_atime(struct inode *inode,
 void ocfs2_inode_unlock(struct inode *inode,
                        int ex)
 {
-        int level = ex ? LKM_EXMODE : LKM_PRMODE;
+        int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_inode_lockres;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
@@ -2130,10 +2234,8 @@ int ocfs2_super_lock(struct ocfs2_super *osb,
                      int ex)
 {
         int status = 0;
-        int level = ex ? LKM_EXMODE : LKM_PRMODE;
+        int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_lock_res *lockres = &osb->osb_super_lockres;
-        struct buffer_head *bh;
-        struct ocfs2_slot_info *si = osb->slot_info;
 
         mlog_entry_void();
 
@@ -2159,11 +2261,7 @@ int ocfs2_super_lock(struct ocfs2_super *osb,
                 goto bail;
         }
         if (status) {
-                bh = si->si_bh;
-                status = ocfs2_read_block(osb, bh->b_blocknr, &bh, 0,
-                                          si->si_inode);
-                if (status == 0)
-                        ocfs2_update_slot_info(si);
+                status = ocfs2_refresh_slot_info(osb);
 
                 ocfs2_complete_lock_res_refresh(lockres, status);
 
@@ -2178,7 +2276,7 @@ bail:
 void ocfs2_super_unlock(struct ocfs2_super *osb,
                         int ex)
 {
-        int level = ex ? LKM_EXMODE : LKM_PRMODE;
+        int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_lock_res *lockres = &osb->osb_super_lockres;
 
         if (!ocfs2_mount_local(osb))
@@ -2196,7 +2294,7 @@ int ocfs2_rename_lock(struct ocfs2_super *osb)
         if (ocfs2_mount_local(osb))
                 return 0;
 
-        status = ocfs2_cluster_lock(osb, lockres, LKM_EXMODE, 0, 0);
+        status = ocfs2_cluster_lock(osb, lockres, DLM_LOCK_EX, 0, 0);
         if (status < 0)
                 mlog_errno(status);
 
@@ -2208,13 +2306,13 @@ void ocfs2_rename_unlock(struct ocfs2_super *osb)
         struct ocfs2_lock_res *lockres = &osb->osb_rename_lockres;
 
         if (!ocfs2_mount_local(osb))
-                ocfs2_cluster_unlock(osb, lockres, LKM_EXMODE);
+                ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_EX);
 }
 
 int ocfs2_dentry_lock(struct dentry *dentry, int ex)
 {
         int ret;
-        int level = ex ? LKM_EXMODE : LKM_PRMODE;
+        int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
         struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
 
@@ -2235,7 +2333,7 @@ int ocfs2_dentry_lock(struct dentry *dentry, int ex)
 
 void ocfs2_dentry_unlock(struct dentry *dentry, int ex)
 {
-        int level = ex ? LKM_EXMODE : LKM_PRMODE;
+        int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
         struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
         struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
 
@@ -2400,7 +2498,7 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
                    lockres->l_blocking);
 
         /* Dump the raw LVB */
-        lvb = lockres->l_lksb.lvb;
+        lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
         for(i = 0; i < DLM_LVB_LEN; i++)
                 seq_printf(m, "0x%x\t", lvb[i]);
 
@@ -2504,13 +2602,14 @@ static void ocfs2_dlm_shutdown_debug(struct ocfs2_super *osb)
 int ocfs2_dlm_init(struct ocfs2_super *osb)
 {
         int status = 0;
-        u32 dlm_key;
-        struct dlm_ctxt *dlm = NULL;
+        struct ocfs2_cluster_connection *conn = NULL;
 
         mlog_entry_void();
 
-        if (ocfs2_mount_local(osb))
+        if (ocfs2_mount_local(osb)) {
+                osb->node_num = 0;
                 goto local;
+        }
 
         status = ocfs2_dlm_init_debug(osb);
         if (status < 0) {
@@ -2527,26 +2626,31 @@ int ocfs2_dlm_init(struct ocfs2_super *osb)
                 goto bail;
         }
 
-        /* used by the dlm code to make message headers unique, each
-         * node in this domain must agree on this. */
-        dlm_key = crc32_le(0, osb->uuid_str, strlen(osb->uuid_str));
-
         /* for now, uuid == domain */
-        dlm = dlm_register_domain(osb->uuid_str, dlm_key,
-                                  &osb->osb_locking_proto);
-        if (IS_ERR(dlm)) {
-                status = PTR_ERR(dlm);
+        status = ocfs2_cluster_connect(osb->osb_cluster_stack,
+                                       osb->uuid_str,
+                                       strlen(osb->uuid_str),
+                                       ocfs2_do_node_down, osb,
+                                       &conn);
+        if (status) {
                 mlog_errno(status);
                 goto bail;
         }
 
-        dlm_register_eviction_cb(dlm, &osb->osb_eviction_cb);
+        status = ocfs2_cluster_this_node(&osb->node_num);
+        if (status < 0) {
+                mlog_errno(status);
+                mlog(ML_ERROR,
+                     "could not find this host's node number\n");
+                ocfs2_cluster_disconnect(conn, 0);
+                goto bail;
+        }
 
 local:
         ocfs2_super_lock_res_init(&osb->osb_super_lockres, osb);
         ocfs2_rename_lock_res_init(&osb->osb_rename_lockres, osb);
 
-        osb->dlm = dlm;
+        osb->cconn = conn;
 
         status = 0;
 bail:
@@ -2560,14 +2664,19 @@ bail:
         return status;
 }
 
-void ocfs2_dlm_shutdown(struct ocfs2_super *osb)
+void ocfs2_dlm_shutdown(struct ocfs2_super *osb,
+                        int hangup_pending)
 {
         mlog_entry_void();
 
-        dlm_unregister_eviction_cb(&osb->osb_eviction_cb);
-
         ocfs2_drop_osb_locks(osb);
 
+        /*
+         * Now that we have dropped all locks and ocfs2_dismount_volume()
+         * has disabled recovery, the DLM won't be talking to us.  It's
+         * safe to tear things down before disconnecting the cluster.
+         */
+
         if (osb->dc_task) {
                 kthread_stop(osb->dc_task);
                 osb->dc_task = NULL;
@@ -2576,15 +2685,15 @@ void ocfs2_dlm_shutdown(struct ocfs2_super *osb)
         ocfs2_lock_res_free(&osb->osb_super_lockres);
         ocfs2_lock_res_free(&osb->osb_rename_lockres);
 
-        dlm_unregister_domain(osb->dlm);
-        osb->dlm = NULL;
+        ocfs2_cluster_disconnect(osb->cconn, hangup_pending);
+        osb->cconn = NULL;
 
         ocfs2_dlm_shutdown_debug(osb);
 
         mlog_exit_void();
 }
 
-static void ocfs2_unlock_ast(void *opaque, enum dlm_status status)
+static void ocfs2_unlock_ast(void *opaque, int error)
 {
         struct ocfs2_lock_res *lockres = opaque;
         unsigned long flags;
@@ -2595,24 +2704,9 @@ static void ocfs2_unlock_ast(void *opaque, enum dlm_status status)
              lockres->l_unlock_action);
 
         spin_lock_irqsave(&lockres->l_lock, flags);
-        /* We tried to cancel a convert request, but it was already
-         * granted. All we want to do here is clear our unlock
-         * state. The wake_up call done at the bottom is redundant
-         * (ocfs2_prepare_cancel_convert doesn't sleep on this) but doesn't
-         * hurt anything anyway */
-        if (status == DLM_CANCELGRANT &&
-            lockres->l_unlock_action == OCFS2_UNLOCK_CANCEL_CONVERT) {
-                mlog(0, "Got cancelgrant for %s\n", lockres->l_name);
-
-                /* We don't clear the busy flag in this case as it
-                 * should have been cleared by the ast which the dlm
-                 * has called. */
-                goto complete_unlock;
-        }
-
-        if (status != DLM_NORMAL) {
-                mlog(ML_ERROR, "Dlm passes status %d for lock %s, "
-                     "unlock_action %d\n", status, lockres->l_name,
+        if (error) {
+                mlog(ML_ERROR, "Dlm passes error %d for lock %s, "
+                     "unlock_action %d\n", error, lockres->l_name,
                      lockres->l_unlock_action);
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
                 return;
@@ -2624,14 +2718,13 @@ static void ocfs2_unlock_ast(void *opaque, enum dlm_status status)
                 lockres->l_action = OCFS2_AST_INVALID;
                 break;
         case OCFS2_UNLOCK_DROP_LOCK:
-                lockres->l_level = LKM_IVMODE;
+                lockres->l_level = DLM_LOCK_IV;
                 break;
         default:
                 BUG();
         }
 
         lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
-complete_unlock:
         lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
         spin_unlock_irqrestore(&lockres->l_lock, flags);
 
@@ -2643,16 +2736,16 @@ complete_unlock:
 static int ocfs2_drop_lock(struct ocfs2_super *osb,
                            struct ocfs2_lock_res *lockres)
 {
-        enum dlm_status status;
+        int ret;
         unsigned long flags;
-        int lkm_flags = 0;
+        u32 lkm_flags = 0;
 
         /* We didn't get anywhere near actually using this lockres. */
         if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED))
                 goto out;
 
         if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
-                lkm_flags |= LKM_VALBLK;
+                lkm_flags |= DLM_LKF_VALBLK;
 
         spin_lock_irqsave(&lockres->l_lock, flags);
 
@@ -2678,7 +2771,7 @@ static int ocfs2_drop_lock(struct ocfs2_super *osb,
 
         if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB) {
                 if (lockres->l_flags & OCFS2_LOCK_ATTACHED &&
-                    lockres->l_level == LKM_EXMODE &&
+                    lockres->l_level == DLM_LOCK_EX &&
                     !(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH))
                         lockres->l_ops->set_lvb(lockres);
         }
@@ -2707,15 +2800,15 @@ static int ocfs2_drop_lock(struct ocfs2_super *osb,
 
         mlog(0, "lock %s\n", lockres->l_name);
 
-        status = dlmunlock(osb->dlm, &lockres->l_lksb, lkm_flags,
-                           ocfs2_unlock_ast, lockres);
-        if (status != DLM_NORMAL) {
-                ocfs2_log_dlm_error("dlmunlock", status, lockres);
+        ret = ocfs2_dlm_unlock(osb->cconn, &lockres->l_lksb, lkm_flags,
+                               lockres);
+        if (ret) {
+                ocfs2_log_dlm_error("ocfs2_dlm_unlock", ret, lockres);
                 mlog(ML_ERROR, "lockres flags: %lu\n", lockres->l_flags);
-                dlm_print_one_lock(lockres->l_lksb.lockid);
+                ocfs2_dlm_dump_lksb(&lockres->l_lksb);
                 BUG();
         }
-        mlog(0, "lock %s, successfull return from dlmunlock\n",
+        mlog(0, "lock %s, successfull return from ocfs2_dlm_unlock\n",
              lockres->l_name);
 
         ocfs2_wait_on_busy_lock(lockres);
@@ -2806,15 +2899,15 @@ int ocfs2_drop_inode_locks(struct inode *inode)
         return status;
 }
 
-static void ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
-                                      int new_level)
+static unsigned int ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
+                                              int new_level)
 {
         assert_spin_locked(&lockres->l_lock);
 
-        BUG_ON(lockres->l_blocking <= LKM_NLMODE);
+        BUG_ON(lockres->l_blocking <= DLM_LOCK_NL);
 
         if (lockres->l_level <= new_level) {
-                mlog(ML_ERROR, "lockres->l_level (%u) <= new_level (%u)\n",
+                mlog(ML_ERROR, "lockres->l_level (%d) <= new_level (%d)\n",
                      lockres->l_level, new_level);
                 BUG();
         }
@@ -2825,33 +2918,33 @@ static void ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
         lockres->l_action = OCFS2_AST_DOWNCONVERT;
         lockres->l_requested = new_level;
         lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+        return lockres_set_pending(lockres);
 }
 
 static int ocfs2_downconvert_lock(struct ocfs2_super *osb,
                                   struct ocfs2_lock_res *lockres,
                                   int new_level,
-                                  int lvb)
+                                  int lvb,
+                                  unsigned int generation)
 {
-        int ret, dlm_flags = LKM_CONVERT;
-        enum dlm_status status;
+        int ret;
+        u32 dlm_flags = DLM_LKF_CONVERT;
 
         mlog_entry_void();
 
         if (lvb)
-                dlm_flags |= LKM_VALBLK;
-
-        status = dlmlock(osb->dlm,
-                         new_level,
-                         &lockres->l_lksb,
-                         dlm_flags,
-                         lockres->l_name,
-                         OCFS2_LOCK_ID_MAX_LEN - 1,
-                         ocfs2_locking_ast,
-                         lockres,
-                         ocfs2_blocking_ast);
-        if (status != DLM_NORMAL) {
-                ocfs2_log_dlm_error("dlmlock", status, lockres);
-                ret = -EINVAL;
+                dlm_flags |= DLM_LKF_VALBLK;
+
+        ret = ocfs2_dlm_lock(osb->cconn,
+                             new_level,
+                             &lockres->l_lksb,
+                             dlm_flags,
+                             lockres->l_name,
+                             OCFS2_LOCK_ID_MAX_LEN - 1,
+                             lockres);
+        lockres_clear_pending(lockres, generation, osb);
+        if (ret) {
+                ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
                 ocfs2_recover_from_dlm_error(lockres, 1);
                 goto bail;
         }
@@ -2862,7 +2955,7 @@ bail:
         return ret;
 }
 
-/* returns 1 when the caller should unlock and call dlmunlock */
+/* returns 1 when the caller should unlock and call ocfs2_dlm_unlock */
 static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb,
                                         struct ocfs2_lock_res *lockres)
 {
@@ -2898,24 +2991,18 @@ static int ocfs2_cancel_convert(struct ocfs2_super *osb,
                                 struct ocfs2_lock_res *lockres)
 {
         int ret;
-        enum dlm_status status;
 
         mlog_entry_void();
         mlog(0, "lock %s\n", lockres->l_name);
 
-        ret = 0;
-        status = dlmunlock(osb->dlm,
-                           &lockres->l_lksb,
-                           LKM_CANCEL,
-                           ocfs2_unlock_ast,
-                           lockres);
-        if (status != DLM_NORMAL) {
-                ocfs2_log_dlm_error("dlmunlock", status, lockres);
-                ret = -EINVAL;
+        ret = ocfs2_dlm_unlock(osb->cconn, &lockres->l_lksb,
+                               DLM_LKF_CANCEL, lockres);
+        if (ret) {
+                ocfs2_log_dlm_error("ocfs2_dlm_unlock", ret, lockres);
                 ocfs2_recover_from_dlm_error(lockres, 0);
         }
 
-        mlog(0, "lock %s return from dlmunlock\n", lockres->l_name);
+        mlog(0, "lock %s return from ocfs2_dlm_unlock\n", lockres->l_name);
 
         mlog_exit(ret);
         return ret;
@@ -2930,6 +3017,7 @@ static int ocfs2_unblock_lock(struct ocfs2_super *osb,
         int new_level;
         int ret = 0;
         int set_lvb = 0;
+        unsigned int gen;
 
         mlog_entry_void();
 
@@ -2939,6 +3027,32 @@ static int ocfs2_unblock_lock(struct ocfs2_super *osb,
 
 recheck:
         if (lockres->l_flags & OCFS2_LOCK_BUSY) {
+                /* XXX
+                 * This is a *big* race.  The OCFS2_LOCK_PENDING flag
+                 * exists entirely for one reason - another thread has set
+                 * OCFS2_LOCK_BUSY, but has *NOT* yet called dlm_lock().
+                 *
+                 * If we do ocfs2_cancel_convert() before the other thread
+                 * calls dlm_lock(), our cancel will do nothing.  We will
+                 * get no ast, and we will have no way of knowing the
+                 * cancel failed.  Meanwhile, the other thread will call
+                 * into dlm_lock() and wait...forever.
+                 *
+                 * Why forever?  Because another node has asked for the
+                 * lock first; that's why we're here in unblock_lock().
+                 *
+                 * The solution is OCFS2_LOCK_PENDING.  When PENDING is
+                 * set, we just requeue the unblock.  Only when the other
+                 * thread has called dlm_lock() and cleared PENDING will
+                 * we then cancel their request.
+                 *
+                 * All callers of dlm_lock() must set OCFS2_DLM_PENDING
+                 * at the same time they set OCFS2_DLM_BUSY.  They must
+                 * clear OCFS2_DLM_PENDING after dlm_lock() returns.
+                 */
+                if (lockres->l_flags & OCFS2_LOCK_PENDING)
+                        goto leave_requeue;
+
                 ctl->requeue = 1;
                 ret = ocfs2_prepare_cancel_convert(osb, lockres);
                 spin_unlock_irqrestore(&lockres->l_lock, flags);
@@ -2952,13 +3066,13 @@ recheck:
 
         /* if we're blocking an exclusive and we have *any* holders,
          * then requeue. */
-        if ((lockres->l_blocking == LKM_EXMODE)
+        if ((lockres->l_blocking == DLM_LOCK_EX)
             && (lockres->l_ex_holders || lockres->l_ro_holders))
                 goto leave_requeue;
 
         /* If it's a PR we're blocking, then only
          * requeue if we've got any EX holders */
-        if (lockres->l_blocking == LKM_PRMODE &&
+        if (lockres->l_blocking == DLM_LOCK_PR &&
             lockres->l_ex_holders)
                 goto leave_requeue;
 
@@ -3005,7 +3119,7 @@ downconvert:
         ctl->requeue = 0;
 
         if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB) {
-                if (lockres->l_level == LKM_EXMODE)
+                if (lockres->l_level == DLM_LOCK_EX)
                         set_lvb = 1;
 
                 /*
@@ -3018,9 +3132,11 @@ downconvert:
                         lockres->l_ops->set_lvb(lockres);
         }
 
-        ocfs2_prepare_downconvert(lockres, new_level);
+        gen = ocfs2_prepare_downconvert(lockres, new_level);
         spin_unlock_irqrestore(&lockres->l_lock, flags);
-        ret = ocfs2_downconvert_lock(osb, lockres, new_level, set_lvb);
+        ret = ocfs2_downconvert_lock(osb, lockres, new_level, set_lvb,
+                                     gen);
+
 leave:
         mlog_exit(ret);
         return ret;
@@ -3059,7 +3175,7 @@ static int ocfs2_data_convert_worker(struct ocfs2_lock_res *lockres,
                      (unsigned long long)OCFS2_I(inode)->ip_blkno);
         }
         sync_mapping_buffers(mapping);
-        if (blocking == LKM_EXMODE) {
+        if (blocking == DLM_LOCK_EX) {
                 truncate_inode_pages(mapping, 0);
         } else {
                 /* We only need to wait on the I/O if we're not also
@@ -3080,8 +3196,8 @@ static int ocfs2_check_meta_downconvert(struct ocfs2_lock_res *lockres,
         struct inode *inode = ocfs2_lock_res_inode(lockres);
         int checkpointed = ocfs2_inode_fully_checkpointed(inode);
 
-        BUG_ON(new_level != LKM_NLMODE && new_level != LKM_PRMODE);
-        BUG_ON(lockres->l_level != LKM_EXMODE && !checkpointed);
+        BUG_ON(new_level != DLM_LOCK_NL && new_level != DLM_LOCK_PR);
+        BUG_ON(lockres->l_level != DLM_LOCK_EX && !checkpointed);
 
         if (checkpointed)
                 return 1;
@@ -3145,7 +3261,7 @@ static int ocfs2_dentry_convert_worker(struct ocfs2_lock_res *lockres,
          * valid. The downconvert code will retain a PR for this node,
          * so there's no further work to do.
          */
-        if (blocking == LKM_PRMODE)
+        if (blocking == DLM_LOCK_PR)
                 return UNBLOCK_CONTINUE;
 
         /*
@@ -3219,6 +3335,45 @@ static int ocfs2_dentry_convert_worker(struct ocfs2_lock_res *lockres,
         return UNBLOCK_CONTINUE_POST;
 }
 
+/*
+ * This is the filesystem locking protocol.  It provides the lock handling
+ * hooks for the underlying DLM.  It has a maximum version number.
+ * The version number allows interoperability with systems running at
+ * the same major number and an equal or smaller minor number.
+ *
+ * Whenever the filesystem does new things with locks (adds or removes a
+ * lock, orders them differently, does different things underneath a lock),
+ * the version must be changed.  The protocol is negotiated when joining
+ * the dlm domain.  A node may join the domain if its major version is
+ * identical to all other nodes and its minor version is greater than
+ * or equal to all other nodes.  When its minor version is greater than
+ * the other nodes, it will run at the minor version specified by the
+ * other nodes.
+ *
+ * If a locking change is made that will not be compatible with older
+ * versions, the major number must be increased and the minor version set
+ * to zero.  If a change merely adds a behavior that can be disabled when
+ * speaking to older versions, the minor version must be increased.  If a
+ * change adds a fully backwards compatible change (eg, LVB changes that
+ * are just ignored by older versions), the version does not need to be
+ * updated.
+ */
+static struct ocfs2_locking_protocol lproto = {
+        .lp_max_version = {
+                .pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
+                .pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
+        },
+        .lp_lock_ast            = ocfs2_locking_ast,
+        .lp_blocking_ast        = ocfs2_blocking_ast,
+        .lp_unlock_ast          = ocfs2_unlock_ast,
+};
+
+void ocfs2_set_locking_protocol(void)
+{
+        ocfs2_stack_glue_set_locking_protocol(&lproto);
+}
+
+
 static void ocfs2_process_blocked_lock(struct ocfs2_super *osb,
                                        struct ocfs2_lock_res *lockres)
 {
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
index e3cf902404b4..2bb01f09c1b1 100644
--- a/fs/ocfs2/dlmglue.h
+++ b/fs/ocfs2/dlmglue.h
@@ -58,7 +58,7 @@ struct ocfs2_meta_lvb {
 #define OCFS2_LOCK_NONBLOCK             (0x04)
 
 int ocfs2_dlm_init(struct ocfs2_super *osb);
-void ocfs2_dlm_shutdown(struct ocfs2_super *osb);
+void ocfs2_dlm_shutdown(struct ocfs2_super *osb, int hangup_pending);
 void ocfs2_lock_res_init_once(struct ocfs2_lock_res *res);
 void ocfs2_inode_lock_res_init(struct ocfs2_lock_res *res,
                                enum ocfs2_lock_type type,
@@ -114,5 +114,6 @@ void ocfs2_wake_downconvert_thread(struct ocfs2_super *osb);
 struct ocfs2_dlm_debug *ocfs2_new_dlm_debug(void);
 void ocfs2_put_dlm_debug(struct ocfs2_dlm_debug *dlm_debug);
 
-extern const struct dlm_protocol_version ocfs2_locking_protocol;
+/* To set the locking protocol on module initialization */
+void ocfs2_set_locking_protocol(void);
 #endif  /* DLMGLUE_H */
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index ed5d5232e85d..9154c82d3258 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2242,7 +2242,7 @@ const struct file_operations ocfs2_fops = {
         .open           = ocfs2_file_open,
         .aio_read       = ocfs2_file_aio_read,
         .aio_write      = ocfs2_file_aio_write,
-        .ioctl          = ocfs2_ioctl,
+        .unlocked_ioctl = ocfs2_ioctl,
 #ifdef CONFIG_COMPAT
         .compat_ioctl   = ocfs2_compat_ioctl,
 #endif
@@ -2258,7 +2258,7 @@ const struct file_operations ocfs2_dops = {
         .fsync          = ocfs2_sync_file,
         .release        = ocfs2_dir_release,
         .open           = ocfs2_dir_open,
-        .ioctl          = ocfs2_ioctl,
+        .unlocked_ioctl = ocfs2_ioctl,
 #ifdef CONFIG_COMPAT
         .compat_ioctl   = ocfs2_compat_ioctl,
 #endif
diff --git a/fs/ocfs2/heartbeat.c b/fs/ocfs2/heartbeat.c
index 0758daf64da0..c6e7213db868 100644
--- a/fs/ocfs2/heartbeat.c
+++ b/fs/ocfs2/heartbeat.c
@@ -28,9 +28,6 @@
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/highmem.h>
-#include <linux/kmod.h>
-
-#include <dlm/dlmapi.h>
 
 #define MLOG_MASK_PREFIX ML_SUPER
 #include <cluster/masklog.h>
@@ -48,7 +45,6 @@ static inline void __ocfs2_node_map_set_bit(struct ocfs2_node_map *map,
                                             int bit);
 static inline void __ocfs2_node_map_clear_bit(struct ocfs2_node_map *map,
                                               int bit);
-static inline int __ocfs2_node_map_is_empty(struct ocfs2_node_map *map);
 
 /* special case -1 for now
  * TODO: should *really* make sure the calling func never passes -1!!  */
@@ -62,23 +58,23 @@ static void ocfs2_node_map_init(struct ocfs2_node_map *map)
 void ocfs2_init_node_maps(struct ocfs2_super *osb)
 {
         spin_lock_init(&osb->node_map_lock);
-        ocfs2_node_map_init(&osb->recovery_map);
         ocfs2_node_map_init(&osb->osb_recovering_orphan_dirs);
 }
 
-static void ocfs2_do_node_down(int node_num,
-                               struct ocfs2_super *osb)
+void ocfs2_do_node_down(int node_num, void *data)
 {
+        struct ocfs2_super *osb = data;
+
         BUG_ON(osb->node_num == node_num);
 
         mlog(0, "ocfs2: node down event for %d\n", node_num);
 
-        if (!osb->dlm) {
+        if (!osb->cconn) {
                 /*
-                 * No DLM means we're not even ready to participate yet.
-                 * We check the slots after the DLM comes up, so we will
-                 * notice the node death then.  We can safely ignore it
-                 * here.
+                 * No cluster connection means we're not even ready to
+                 * participate yet.  We check the slots after the cluster
+                 * comes up, so we will notice the node death then.  We
+                 * can safely ignore it here.
                  */
                 return;
         }
@@ -86,61 +82,6 @@ static void ocfs2_do_node_down(int node_num,
         ocfs2_recovery_thread(osb, node_num);
 }
 
-/* Called from the dlm when it's about to evict a node. We may also
- * get a heartbeat callback later. */
-static void ocfs2_dlm_eviction_cb(int node_num,
-                                  void *data)
-{
-        struct ocfs2_super *osb = (struct ocfs2_super *) data;
-        struct super_block *sb = osb->sb;
-
-        mlog(ML_NOTICE, "device (%u,%u): dlm has evicted node %d\n",
-             MAJOR(sb->s_dev), MINOR(sb->s_dev), node_num);
-
-        ocfs2_do_node_down(node_num, osb);
-}
-
-void ocfs2_setup_hb_callbacks(struct ocfs2_super *osb)
-{
-        /* Not exactly a heartbeat callback, but leads to essentially
-         * the same path so we set it up here. */
-        dlm_setup_eviction_cb(&osb->osb_eviction_cb,
-                              ocfs2_dlm_eviction_cb,
-                              osb);
-}
-
-void ocfs2_stop_heartbeat(struct ocfs2_super *osb)
-{
-        int ret;
-        char *argv[5], *envp[3];
-
-        if (ocfs2_mount_local(osb))
-                return;
-
-        if (!osb->uuid_str) {
-                /* This can happen if we don't get far enough in mount... */
-                mlog(0, "No UUID with which to stop heartbeat!\n\n");
-                return;
-        }
-
-        argv[0] = (char *)o2nm_get_hb_ctl_path();
-        argv[1] = "-K";
-        argv[2] = "-u";
-        argv[3] = osb->uuid_str;
-        argv[4] = NULL;
-
-        mlog(0, "Run: %s %s %s %s\n", argv[0], argv[1], argv[2], argv[3]);
-
-        /* minimal command environment taken from cpu_run_sbin_hotplug */
-        envp[0] = "HOME=/";
-        envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
-        envp[2] = NULL;
-
-        ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
-        if (ret < 0)
-                mlog_errno(ret);
-}
-
 static inline void __ocfs2_node_map_set_bit(struct ocfs2_node_map *map,
                                             int bit)
 {
@@ -192,112 +133,3 @@ int ocfs2_node_map_test_bit(struct ocfs2_super *osb,
         return ret;
 }
 
-static inline int __ocfs2_node_map_is_empty(struct ocfs2_node_map *map)
-{
-        int bit;
-        bit = find_next_bit(map->map, map->num_nodes, 0);
-        if (bit < map->num_nodes)
-                return 0;
-        return 1;
-}
-
-int ocfs2_node_map_is_empty(struct ocfs2_super *osb,
-                            struct ocfs2_node_map *map)
-{
-        int ret;
-        BUG_ON(map->num_nodes == 0);
-        spin_lock(&osb->node_map_lock);
-        ret = __ocfs2_node_map_is_empty(map);
-        spin_unlock(&osb->node_map_lock);
-        return ret;
-}
-
-#if 0
-
-static void __ocfs2_node_map_dup(struct ocfs2_node_map *target,
-                                 struct ocfs2_node_map *from)
-{
-        BUG_ON(from->num_nodes == 0);
-        ocfs2_node_map_init(target);
-        __ocfs2_node_map_set(target, from);
-}
-
-/* returns 1 if bit is the only bit set in target, 0 otherwise */
-int ocfs2_node_map_is_only(struct ocfs2_super *osb,
-                           struct ocfs2_node_map *target,
-                           int bit)
-{
-        struct ocfs2_node_map temp;
-        int ret;
-
-        spin_lock(&osb->node_map_lock);
-        __ocfs2_node_map_dup(&temp, target);
-        __ocfs2_node_map_clear_bit(&temp, bit);
-        ret = __ocfs2_node_map_is_empty(&temp);
-        spin_unlock(&osb->node_map_lock);
-
-        return ret;
-}
-
-static void __ocfs2_node_map_set(struct ocfs2_node_map *target,
-                                 struct ocfs2_node_map *from)
-{
-        int num_longs, i;
-
-        BUG_ON(target->num_nodes != from->num_nodes);
-        BUG_ON(target->num_nodes == 0);
-
-        num_longs = BITS_TO_LONGS(target->num_nodes);
-        for (i = 0; i < num_longs; i++)
-                target->map[i] = from->map[i];
-}
-
-#endif  /*  0  */
-
-/* Returns whether the recovery bit was actually set - it may not be
- * if a node is still marked as needing recovery */
-int ocfs2_recovery_map_set(struct ocfs2_super *osb,
-                           int num)
-{
-        int set = 0;
-
-        spin_lock(&osb->node_map_lock);
-
-        if (!test_bit(num, osb->recovery_map.map)) {
-            __ocfs2_node_map_set_bit(&osb->recovery_map, num);
-            set = 1;
-        }
-
-        spin_unlock(&osb->node_map_lock);
-
-        return set;
-}
-
-void ocfs2_recovery_map_clear(struct ocfs2_super *osb,
-                              int num)
-{
-        ocfs2_node_map_clear_bit(osb, &osb->recovery_map, num);
-}
-
-int ocfs2_node_map_iterate(struct ocfs2_super *osb,
-                           struct ocfs2_node_map *map,
-                           int idx)
-{
-        int i = idx;
-
-        idx = O2NM_INVALID_NODE_NUM;
-        spin_lock(&osb->node_map_lock);
-        if ((i != O2NM_INVALID_NODE_NUM) &&
-            (i >= 0) &&
-            (i < map->num_nodes)) {
-                while(i < map->num_nodes) {
-                        if (test_bit(i, map->map)) {
-                                idx = i;
-                                break;
-                        }
-                        i++;
-                }
-        }
-        spin_unlock(&osb->node_map_lock);
-        return idx;
-}
diff --git a/fs/ocfs2/heartbeat.h b/fs/ocfs2/heartbeat.h
index eac63aed7611..74b9c5dda28d 100644
--- a/fs/ocfs2/heartbeat.h
+++ b/fs/ocfs2/heartbeat.h
@@ -28,13 +28,10 @@
 
 void ocfs2_init_node_maps(struct ocfs2_super *osb);
 
-void ocfs2_setup_hb_callbacks(struct ocfs2_super *osb);
-void ocfs2_stop_heartbeat(struct ocfs2_super *osb);
+void ocfs2_do_node_down(int node_num, void *data);
 
 /* node map functions - used to keep track of mounted and in-recovery
  * nodes. */
-int ocfs2_node_map_is_empty(struct ocfs2_super *osb,
-                            struct ocfs2_node_map *map);
 void ocfs2_node_map_set_bit(struct ocfs2_super *osb,
                             struct ocfs2_node_map *map,
                             int bit);
@@ -44,17 +41,5 @@ void ocfs2_node_map_clear_bit(struct ocfs2_super *osb,
 int ocfs2_node_map_test_bit(struct ocfs2_super *osb,
                             struct ocfs2_node_map *map,
                             int bit);
-int ocfs2_node_map_iterate(struct ocfs2_super *osb,
-                           struct ocfs2_node_map *map,
-                           int idx);
-static inline int ocfs2_node_map_first_set_bit(struct ocfs2_super *osb,
-                                               struct ocfs2_node_map *map)
-{
-        return ocfs2_node_map_iterate(osb, map, 0);
-}
-int ocfs2_recovery_map_set(struct ocfs2_super *osb,
-                           int num);
-void ocfs2_recovery_map_clear(struct ocfs2_super *osb,
-                              int num);
 
 #endif /* OCFS2_HEARTBEAT_H */
diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
index 5177fba5162b..b413166dd163 100644
--- a/fs/ocfs2/ioctl.c
+++ b/fs/ocfs2/ioctl.c
@@ -7,6 +7,7 @@
 
 #include <linux/fs.h>
 #include <linux/mount.h>
+#include <linux/smp_lock.h>
 
 #define MLOG_MASK_PREFIX ML_INODE
 #include <cluster/masklog.h>
@@ -112,9 +113,9 @@ bail:
         return status;
 }
 
-int ocfs2_ioctl(struct inode * inode, struct file * filp,
-        unsigned int cmd, unsigned long arg)
+long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
+        struct inode *inode = filp->f_path.dentry->d_inode;
         unsigned int flags;
         int new_clusters;
         int status;
@@ -168,9 +169,6 @@ int ocfs2_ioctl(struct inode * inode, struct file * filp,
 #ifdef CONFIG_COMPAT
 long ocfs2_compat_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 {
-        struct inode *inode = file->f_path.dentry->d_inode;
-        int ret;
-
         switch (cmd) {
         case OCFS2_IOC32_GETFLAGS:
                 cmd = OCFS2_IOC_GETFLAGS;
@@ -190,9 +188,6 @@ long ocfs2_compat_ioctl(struct file *file, unsigned cmd, unsigned long arg)
                 return -ENOIOCTLCMD;
         }
 
-        lock_kernel();
-        ret = ocfs2_ioctl(inode, file, cmd, arg);
-        unlock_kernel();
-        return ret;
+        return ocfs2_ioctl(file, cmd, arg);
 }
 #endif
diff --git a/fs/ocfs2/ioctl.h b/fs/ocfs2/ioctl.h
index 4d6c4f430d0d..cf9a5ee30fef 100644
--- a/fs/ocfs2/ioctl.h
+++ b/fs/ocfs2/ioctl.h
@@ -10,8 +10,7 @@
 #ifndef OCFS2_IOCTL_H
 #define OCFS2_IOCTL_H
 
-int ocfs2_ioctl(struct inode * inode, struct file * filp,
-        unsigned int cmd, unsigned long arg);
+long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
 long ocfs2_compat_ioctl(struct file *file, unsigned cmd, unsigned long arg);
 
 #endif /* OCFS2_IOCTL_H */
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index f31c7e8c19c3..9698338adc39 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -64,6 +64,137 @@ static int ocfs2_recover_orphans(struct ocfs2_super *osb,
                                  int slot);
 static int ocfs2_commit_thread(void *arg);
 
+
+/*
+ * The recovery_list is a simple linked list of node numbers to recover.
+ * It is protected by the recovery_lock.
+ */
+
+struct ocfs2_recovery_map {
+        unsigned int rm_used;
+        unsigned int *rm_entries;
+};
+
+int ocfs2_recovery_init(struct ocfs2_super *osb)
+{
+        struct ocfs2_recovery_map *rm;
+
+        mutex_init(&osb->recovery_lock);
+        osb->disable_recovery = 0;
+        osb->recovery_thread_task = NULL;
+        init_waitqueue_head(&osb->recovery_event);
+
+        rm = kzalloc(sizeof(struct ocfs2_recovery_map) +
+                     osb->max_slots * sizeof(unsigned int),
+                     GFP_KERNEL);
+        if (!rm) {
+                mlog_errno(-ENOMEM);
+                return -ENOMEM;
+        }
+
+        rm->rm_entries = (unsigned int *)((char *)rm +
+                                          sizeof(struct ocfs2_recovery_map));
+        osb->recovery_map = rm;
+
+        return 0;
+}
+
+/* we can't grab the goofy sem lock from inside wait_event, so we use
+ * memory barriers to make sure that we'll see the null task before
+ * being woken up */
+static int ocfs2_recovery_thread_running(struct ocfs2_super *osb)
+{
+        mb();
+        return osb->recovery_thread_task != NULL;
+}
+
+void ocfs2_recovery_exit(struct ocfs2_super *osb)
+{
+        struct ocfs2_recovery_map *rm;
+
+        /* disable any new recovery threads and wait for any currently
+         * running ones to exit. Do this before setting the vol_state. */
+        mutex_lock(&osb->recovery_lock);
+        osb->disable_recovery = 1;
+        mutex_unlock(&osb->recovery_lock);
+        wait_event(osb->recovery_event, !ocfs2_recovery_thread_running(osb));
+
+        /* At this point, we know that no more recovery threads can be
+         * launched, so wait for any recovery completion work to
+         * complete. */
+        flush_workqueue(ocfs2_wq);
+
+        /*
+         * Now that recovery is shut down, and the osb is about to be
+         * freed,  the osb_lock is not taken here.
+         */
+        rm = osb->recovery_map;
+        /* XXX: Should we bug if there are dirty entries? */
+
+        kfree(rm);
+}
+
+static int __ocfs2_recovery_map_test(struct ocfs2_super *osb,
+                                     unsigned int node_num)
+{
+        int i;
+        struct ocfs2_recovery_map *rm = osb->recovery_map;
+
+        assert_spin_locked(&osb->osb_lock);
+
+        for (i = 0; i < rm->rm_used; i++) {
+                if (rm->rm_entries[i] == node_num)
+                        return 1;
+        }
+
+        return 0;
+}
+
+/* Behaves like test-and-set.  Returns the previous value */
+static int ocfs2_recovery_map_set(struct ocfs2_super *osb,
+                                  unsigned int node_num)
+{
+        struct ocfs2_recovery_map *rm = osb->recovery_map;
+
+        spin_lock(&osb->osb_lock);
+        if (__ocfs2_recovery_map_test(osb, node_num)) {
+                spin_unlock(&osb->osb_lock);
+                return 1;
+        }
+
+        /* XXX: Can this be exploited? Not from o2dlm... */
+        BUG_ON(rm->rm_used >= osb->max_slots);
+
+        rm->rm_entries[rm->rm_used] = node_num;
+        rm->rm_used++;
+        spin_unlock(&osb->osb_lock);
+
+        return 0;
+}
+
+static void ocfs2_recovery_map_clear(struct ocfs2_super *osb,
+                                     unsigned int node_num)
+{
+        int i;
+        struct ocfs2_recovery_map *rm = osb->recovery_map;
+
+        spin_lock(&osb->osb_lock);
+
+        for (i = 0; i < rm->rm_used; i++) {
+                if (rm->rm_entries[i] == node_num)
+                        break;
+        }
+
+        if (i < rm->rm_used) {
+                /* XXX: be careful with the pointer math */
+                memmove(&(rm->rm_entries[i]), &(rm->rm_entries[i + 1]),
+                        (rm->rm_used - i - 1) * sizeof(unsigned int));
+                rm->rm_used--;
+        }
+
+        spin_unlock(&osb->osb_lock);
+}
+
 static int ocfs2_commit_cache(struct ocfs2_super *osb)
 {
         int status = 0;
@@ -586,8 +717,7 @@ int ocfs2_journal_load(struct ocfs2_journal *journal, int local)
 
         mlog_entry_void();
 
-        if (!journal)
-                BUG();
+        BUG_ON(!journal);
 
         osb = journal->j_osb;
 
@@ -650,6 +780,23 @@ bail:
         return status;
 }
 
+static int ocfs2_recovery_completed(struct ocfs2_super *osb)
+{
+        int empty;
+        struct ocfs2_recovery_map *rm = osb->recovery_map;
+
+        spin_lock(&osb->osb_lock);
+        empty = (rm->rm_used == 0);
+        spin_unlock(&osb->osb_lock);
+
+        return empty;
+}
+
+void ocfs2_wait_for_recovery(struct ocfs2_super *osb)
+{
+        wait_event(osb->recovery_event, ocfs2_recovery_completed(osb));
+}
+
 /*
  * JBD Might read a cached version of another nodes journal file. We
  * don't want this as this file changes often and we get no
@@ -848,6 +995,7 @@ static int __ocfs2_recovery_thread(void *arg)
 {
         int status, node_num;
         struct ocfs2_super *osb = arg;
+        struct ocfs2_recovery_map *rm = osb->recovery_map;
 
         mlog_entry_void();
 
@@ -863,26 +1011,29 @@ restart:
                 goto bail;
         }
 
-        while(!ocfs2_node_map_is_empty(osb, &osb->recovery_map)) {
-                node_num = ocfs2_node_map_first_set_bit(osb,
-                                                        &osb->recovery_map);
-                if (node_num == O2NM_INVALID_NODE_NUM) {
-                        mlog(0, "Out of nodes to recover.\n");
-                        break;
-                }
+        spin_lock(&osb->osb_lock);
+        while (rm->rm_used) {
+                /* It's always safe to remove entry zero, as we won't
+                 * clear it until ocfs2_recover_node() has succeeded. */
+                node_num = rm->rm_entries[0];
+                spin_unlock(&osb->osb_lock);
 
                 status = ocfs2_recover_node(osb, node_num);
-                if (status < 0) {
+                if (!status) {
+                        ocfs2_recovery_map_clear(osb, node_num);
+                } else {
                         mlog(ML_ERROR,
                              "Error %d recovering node %d on device (%u,%u)!\n",
                              status, node_num,
                              MAJOR(osb->sb->s_dev), MINOR(osb->sb->s_dev));
                         mlog(ML_ERROR, "Volume requires unmount.\n");
-                        continue;
                 }
 
-                ocfs2_recovery_map_clear(osb, node_num);
+                spin_lock(&osb->osb_lock);
         }
+        spin_unlock(&osb->osb_lock);
+        mlog(0, "All nodes recovered\n");
+
         ocfs2_super_unlock(osb, 1);
 
         /* We always run recovery on our own orphan dir - the dead
@@ -893,8 +1044,7 @@ restart:
 
 bail:
         mutex_lock(&osb->recovery_lock);
-        if (!status &&
-            !ocfs2_node_map_is_empty(osb, &osb->recovery_map)) {
+        if (!status && !ocfs2_recovery_completed(osb)) {
                 mutex_unlock(&osb->recovery_lock);
                 goto restart;
         }
@@ -924,8 +1074,8 @@ void ocfs2_recovery_thread(struct ocfs2_super *osb, int node_num)
 
         /* People waiting on recovery will wait on
          * the recovery map to empty. */
-        if (!ocfs2_recovery_map_set(osb, node_num))
-                mlog(0, "node %d already be in recovery.\n", node_num);
+        if (ocfs2_recovery_map_set(osb, node_num))
+                mlog(0, "node %d already in recovery map.\n", node_num);
 
         mlog(0, "starting recovery thread...\n");
 
@@ -1079,7 +1229,6 @@ static int ocfs2_recover_node(struct ocfs2_super *osb,
 {
         int status = 0;
         int slot_num;
-        struct ocfs2_slot_info *si = osb->slot_info;
         struct ocfs2_dinode *la_copy = NULL;
         struct ocfs2_dinode *tl_copy = NULL;
 
@@ -1092,8 +1241,8 @@ static int ocfs2_recover_node(struct ocfs2_super *osb,
          * case we should've called ocfs2_journal_load instead. */
         BUG_ON(osb->node_num == node_num);
 
-        slot_num = ocfs2_node_num_to_slot(si, node_num);
-        if (slot_num == OCFS2_INVALID_SLOT) {
+        slot_num = ocfs2_node_num_to_slot(osb, node_num);
+        if (slot_num == -ENOENT) {
                 status = 0;
                 mlog(0, "no slot for this node, so no recovery required.\n");
                 goto done;
@@ -1123,8 +1272,7 @@ static int ocfs2_recover_node(struct ocfs2_super *osb,
 
         /* Likewise, this would be a strange but ultimately not so
          * harmful place to get an error... */
-        ocfs2_clear_slot(si, slot_num);
-        status = ocfs2_update_disk_slots(osb, si);
+        status = ocfs2_clear_slot(osb, slot_num);
         if (status < 0)
                 mlog_errno(status);
 
@@ -1184,23 +1332,24 @@ bail:
  * slot info struct has been updated from disk. */
 int ocfs2_mark_dead_nodes(struct ocfs2_super *osb)
 {
-        int status, i, node_num;
-        struct ocfs2_slot_info *si = osb->slot_info;
+        unsigned int node_num;
+        int status, i;
 
         /* This is called with the super block cluster lock, so we
          * know that the slot map can't change underneath us. */
 
-        spin_lock(&si->si_lock);
-        for(i = 0; i < si->si_num_slots; i++) {
+        spin_lock(&osb->osb_lock);
+        for (i = 0; i < osb->max_slots; i++) {
                 if (i == osb->slot_num)
                         continue;
-                if (ocfs2_is_empty_slot(si, i))
+
+                status = ocfs2_slot_to_node_num_locked(osb, i, &node_num);
+                if (status == -ENOENT)
                         continue;
 
-                node_num = si->si_global_node_nums[i];
-                if (ocfs2_node_map_test_bit(osb, &osb->recovery_map, node_num))
+                if (__ocfs2_recovery_map_test(osb, node_num))
                         continue;
-                spin_unlock(&si->si_lock);
+                spin_unlock(&osb->osb_lock);
 
                 /* Ok, we have a slot occupied by another node which
                  * is not in the recovery map. We trylock his journal
@@ -1216,9 +1365,9 @@ int ocfs2_mark_dead_nodes(struct ocfs2_super *osb)
                         goto bail;
                 }
 
-                spin_lock(&si->si_lock);
+                spin_lock(&osb->osb_lock);
         }
-        spin_unlock(&si->si_lock);
+        spin_unlock(&osb->osb_lock);
 
         status = 0;
 bail:
diff --git a/fs/ocfs2/journal.h b/fs/ocfs2/journal.h
index 220f3e818e78..db82be2532ed 100644
--- a/fs/ocfs2/journal.h
+++ b/fs/ocfs2/journal.h
@@ -134,6 +134,10 @@ static inline void ocfs2_inode_set_new(struct ocfs2_super *osb,
 
 /* Exported only for the journal struct init code in super.c. Do not call. */
 void ocfs2_complete_recovery(struct work_struct *work);
+void ocfs2_wait_for_recovery(struct ocfs2_super *osb);
+
+int ocfs2_recovery_init(struct ocfs2_super *osb);
+void ocfs2_recovery_exit(struct ocfs2_super *osb);
 
 /*
  *  Journal Control:
diff --git a/fs/ocfs2/localalloc.c b/fs/ocfs2/localalloc.c
index ab83fd562429..ce0dc147602a 100644
--- a/fs/ocfs2/localalloc.c
+++ b/fs/ocfs2/localalloc.c
@@ -447,6 +447,8 @@ out_mutex:
         iput(main_bm_inode);
 
 out:
+        if (!status)
+                ocfs2_init_inode_steal_slot(osb);
         mlog_exit(status);
         return status;
 }
@@ -523,6 +525,8 @@ int ocfs2_reserve_local_alloc_bits(struct ocfs2_super *osb,
         }
 
         ac->ac_inode = local_alloc_inode;
+        /* We should never use localalloc from another slot */
+        ac->ac_alloc_slot = osb->slot_num;
         ac->ac_which = OCFS2_AC_USE_LOCAL;
         get_bh(osb->local_alloc_bh);
         ac->ac_bh = osb->local_alloc_bh;
diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
index ae9ad9587516..d5d808fe0140 100644
--- a/fs/ocfs2/namei.c
+++ b/fs/ocfs2/namei.c
@@ -424,7 +424,7 @@ static int ocfs2_mknod_locked(struct ocfs2_super *osb,
         fe->i_fs_generation = cpu_to_le32(osb->fs_generation);
         fe->i_blkno = cpu_to_le64(fe_blkno);
         fe->i_suballoc_bit = cpu_to_le16(suballoc_bit);
-        fe->i_suballoc_slot = cpu_to_le16(osb->slot_num);
+        fe->i_suballoc_slot = cpu_to_le16(inode_ac->ac_alloc_slot);
         fe->i_uid = cpu_to_le32(current->fsuid);
         if (dir->i_mode & S_ISGID) {
                 fe->i_gid = cpu_to_le32(dir->i_gid);
@@ -997,7 +997,7 @@ static int ocfs2_rename(struct inode *old_dir,
          *
          * And that's why, just like the VFS, we need a file system
          * rename lock. */
-        if (old_dentry != new_dentry) {
+        if (old_dir != new_dir && S_ISDIR(old_inode->i_mode)) {
                 status = ocfs2_rename_lock(osb);
                 if (status < 0) {
                         mlog_errno(status);
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 6546cef212e3..31692379c170 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -36,11 +36,8 @@
 #include <linux/mutex.h>
 #include <linux/jbd.h>
 
-#include "cluster/nodemanager.h"
-#include "cluster/heartbeat.h"
-#include "cluster/tcp.h"
-
-#include "dlm/dlmapi.h"
+/* For union ocfs2_dlm_lksb */
+#include "stackglue.h"
 
 #include "ocfs2_fs.h"
 #include "ocfs2_lockid.h"
@@ -101,6 +98,9 @@ enum ocfs2_unlock_action {
                                                * dropped. */
 #define OCFS2_LOCK_QUEUED        (0x00000100) /* queued for downconvert */
 #define OCFS2_LOCK_NOCACHE       (0x00000200) /* don't use a holder count */
+#define OCFS2_LOCK_PENDING       (0x00000400) /* This lockres is pending a
+                                                 call to dlm_lock.  Only
+                                                 exists with BUSY set. */
 
 struct ocfs2_lock_res_ops;
 
@@ -120,13 +120,14 @@ struct ocfs2_lock_res {
         int                      l_level;
         unsigned int             l_ro_holders;
         unsigned int             l_ex_holders;
-        struct dlm_lockstatus    l_lksb;
+        union ocfs2_dlm_lksb     l_lksb;
 
         /* used from AST/BAST funcs. */
         enum ocfs2_ast_action    l_action;
         enum ocfs2_unlock_action l_unlock_action;
         int                      l_requested;
         int                      l_blocking;
+        unsigned int             l_pending_gen;
 
         wait_queue_head_t        l_event;
 
@@ -179,6 +180,8 @@ enum ocfs2_mount_options
 #define OCFS2_DEFAULT_ATIME_QUANTUM     60
 
 struct ocfs2_journal;
+struct ocfs2_slot_info;
+struct ocfs2_recovery_map;
 struct ocfs2_super
 {
         struct task_struct *commit_task;
@@ -190,7 +193,6 @@ struct ocfs2_super
         struct ocfs2_slot_info *slot_info;
 
         spinlock_t node_map_lock;
-        struct ocfs2_node_map recovery_map;
 
         u64 root_blkno;
         u64 system_dir_blkno;
@@ -206,25 +208,29 @@ struct ocfs2_super
         u32 s_feature_incompat;
         u32 s_feature_ro_compat;
 
-        /* Protects s_next_generaion, osb_flags. Could protect more on
-         * osb as it's very short lived. */
+        /* Protects s_next_generation, osb_flags and s_inode_steal_slot.
+         * Could protect more on osb as it's very short lived.
+         */
         spinlock_t osb_lock;
         u32 s_next_generation;
         unsigned long osb_flags;
+        s16 s_inode_steal_slot;
+        atomic_t s_num_inodes_stolen;
 
         unsigned long s_mount_opt;
         unsigned int s_atime_quantum;
 
-        u16 max_slots;
-        s16 node_num;
-        s16 slot_num;
-        s16 preferred_slot;
+        unsigned int max_slots;
+        unsigned int node_num;
+        int slot_num;
+        int preferred_slot;
         int s_sectsize_bits;
         int s_clustersize;
         int s_clustersize_bits;
 
         atomic_t vol_state;
         struct mutex recovery_lock;
+        struct ocfs2_recovery_map *recovery_map;
         struct task_struct *recovery_thread_task;
         int disable_recovery;
         wait_queue_head_t checkpoint_event;
@@ -245,12 +251,11 @@ struct ocfs2_super
         struct ocfs2_alloc_stats alloc_stats;
         char dev_str[20];               /* "major,minor" of the device */
 
-        struct dlm_ctxt *dlm;
+        char osb_cluster_stack[OCFS2_STACK_LABEL_LEN + 1];
+        struct ocfs2_cluster_connection *cconn;
         struct ocfs2_lock_res osb_super_lockres;
         struct ocfs2_lock_res osb_rename_lockres;
-        struct dlm_eviction_cb osb_eviction_cb;
         struct ocfs2_dlm_debug *osb_dlm_debug;
-        struct dlm_protocol_version osb_locking_proto;
 
         struct dentry *osb_debug_root;
 
@@ -367,11 +372,24 @@ static inline int ocfs2_is_soft_readonly(struct ocfs2_super *osb)
         return ret;
 }
 
+static inline int ocfs2_userspace_stack(struct ocfs2_super *osb)
+{
+        return (osb->s_feature_incompat &
+                OCFS2_FEATURE_INCOMPAT_USERSPACE_STACK);
+}
+
 static inline int ocfs2_mount_local(struct ocfs2_super *osb)
 {
         return (osb->s_feature_incompat & OCFS2_FEATURE_INCOMPAT_LOCAL_MOUNT);
 }
 
+static inline int ocfs2_uses_extended_slot_map(struct ocfs2_super *osb)
+{
+        return (osb->s_feature_incompat &
+                OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP);
+}
+
+
 #define OCFS2_IS_VALID_DINODE(ptr)                                      \
         (!strcmp((ptr)->i_signature, OCFS2_INODE_SIGNATURE))
 
@@ -522,6 +540,33 @@ static inline unsigned int ocfs2_pages_per_cluster(struct super_block *sb)
         return pages_per_cluster;
 }
 
+static inline void ocfs2_init_inode_steal_slot(struct ocfs2_super *osb)
+{
+        spin_lock(&osb->osb_lock);
+        osb->s_inode_steal_slot = OCFS2_INVALID_SLOT;
+        spin_unlock(&osb->osb_lock);
+        atomic_set(&osb->s_num_inodes_stolen, 0);
+}
+
+static inline void ocfs2_set_inode_steal_slot(struct ocfs2_super *osb,
+                                              s16 slot)
+{
+        spin_lock(&osb->osb_lock);
+        osb->s_inode_steal_slot = slot;
+        spin_unlock(&osb->osb_lock);
+}
+
+static inline s16 ocfs2_get_inode_steal_slot(struct ocfs2_super *osb)
+{
+        s16 slot;
+
+        spin_lock(&osb->osb_lock);
+        slot = osb->s_inode_steal_slot;
+        spin_unlock(&osb->osb_lock);
+
+        return slot;
+}
+
 #define ocfs2_set_bit ext2_set_bit
 #define ocfs2_clear_bit ext2_clear_bit
 #define ocfs2_test_bit ext2_test_bit
diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
index 3633edd3982f..52c426665154 100644
--- a/fs/ocfs2/ocfs2_fs.h
+++ b/fs/ocfs2/ocfs2_fs.h
@@ -88,7 +88,9 @@
 #define OCFS2_FEATURE_COMPAT_SUPP       OCFS2_FEATURE_COMPAT_BACKUP_SB
 #define OCFS2_FEATURE_INCOMPAT_SUPP     (OCFS2_FEATURE_INCOMPAT_LOCAL_MOUNT \
                                          | OCFS2_FEATURE_INCOMPAT_SPARSE_ALLOC \
-                                         | OCFS2_FEATURE_INCOMPAT_INLINE_DATA)
+                                         | OCFS2_FEATURE_INCOMPAT_INLINE_DATA \
+                                         | OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP \
+                                         | OCFS2_FEATURE_INCOMPAT_USERSPACE_STACK)
 #define OCFS2_FEATURE_RO_COMPAT_SUPP    OCFS2_FEATURE_RO_COMPAT_UNWRITTEN
 
 /*
@@ -125,6 +127,21 @@
 /* Support for data packed into inode blocks */
 #define OCFS2_FEATURE_INCOMPAT_INLINE_DATA      0x0040
 
+/* Support for the extended slot map */
+#define OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP 0x100
+
+
+/*
+ * Support for alternate, userspace cluster stacks.  If set, the superblock
+ * field s_cluster_info contains a tag for the alternate stack in use as
+ * well as the name of the cluster being joined.
+ * mount.ocfs2 must pass in a matching stack name.
+ *
+ * If not set, the classic stack will be used.  This is compatbile with
+ * all older versions.
+ */
+#define OCFS2_FEATURE_INCOMPAT_USERSPACE_STACK  0x0080
+
 /*
  * backup superblock flag is used to indicate that this volume
  * has backup superblocks.
@@ -267,6 +284,10 @@ struct ocfs2_new_group_input {
 #define OCFS2_VOL_UUID_LEN              16
 #define OCFS2_MAX_VOL_LABEL_LEN         64
 
+/* The alternate, userspace stack fields */
+#define OCFS2_STACK_LABEL_LEN           4
+#define OCFS2_CLUSTER_NAME_LEN          16
+
 /* Journal limits (in bytes) */
 #define OCFS2_MIN_JOURNAL_SIZE          (4 * 1024 * 1024)
 
@@ -475,6 +496,47 @@ struct ocfs2_extent_block
 };
 
 /*
+ * On disk slot map for OCFS2.  This defines the contents of the "slot_map"
+ * system file.  A slot is valid if it contains a node number >= 0.  The
+ * value -1 (0xFFFF) is OCFS2_INVALID_SLOT.  This marks a slot empty.
+ */
+struct ocfs2_slot_map {
+/*00*/  __le16 sm_slots[0];
+/*
+ * Actual on-disk size is one block.  OCFS2_MAX_SLOTS is 255,
+ * 255 * sizeof(__le16) == 512B, within the 512B block minimum blocksize.
+ */
+};
+
+struct ocfs2_extended_slot {
+/*00*/  __u8    es_valid;
+        __u8    es_reserved1[3];
+        __le32  es_node_num;
+/*10*/
+};
+
+/*
+ * The extended slot map, used when OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP
+ * is set.  It separates out the valid marker from the node number, and
+ * has room to grow.  Unlike the old slot map, this format is defined by
+ * i_size.
+ */
+struct ocfs2_slot_map_extended {
+/*00*/  struct ocfs2_extended_slot se_slots[0];
+/*
+ * Actual size is i_size of the slot_map system file.  It should
+ * match s_max_slots * sizeof(struct ocfs2_extended_slot)
+ */
+};
+
+struct ocfs2_cluster_info {
+/*00*/  __u8   ci_stack[OCFS2_STACK_LABEL_LEN];
+        __le32 ci_reserved;
+/*08*/  __u8   ci_cluster[OCFS2_CLUSTER_NAME_LEN];
+/*18*/
+};
+
+/*
  * On disk superblock for OCFS2
  * Note that it is contained inside an ocfs2_dinode, so all offsets
  * are relative to the start of ocfs2_dinode.id2.
@@ -506,7 +568,20 @@ struct ocfs2_super_block {
                                          * group header */
 /*50*/  __u8  s_label[OCFS2_MAX_VOL_LABEL_LEN]; /* Label for mounting, etc. */
 /*90*/  __u8  s_uuid[OCFS2_VOL_UUID_LEN];       /* 128-bit uuid */
-/*A0*/
+/*A0*/  struct ocfs2_cluster_info s_cluster_info; /* Selected userspace
+                                                     stack.  Only valid
+                                                     with INCOMPAT flag. */
+/*B8*/  __le64 s_reserved2[17];         /* Fill out superblock */
+/*140*/
+
+        /*
+         * NOTE: As stated above, all offsets are relative to
+         * ocfs2_dinode.id2, which is at 0xC0 in the inode.
+         * 0xC0 + 0x140 = 0x200 or 512 bytes.  A superblock must fit within
+         * our smallest blocksize, which is 512 bytes.  To ensure this,
+         * we reserve the space in s_reserved2.  Anything past s_reserved2
+         * will not be available on the smallest blocksize.
+         */
 };
 
 /*
diff --git a/fs/ocfs2/ocfs2_lockid.h b/fs/ocfs2/ocfs2_lockid.h
index 86f3e3799c2b..82c200f7a8f1 100644
--- a/fs/ocfs2/ocfs2_lockid.h
+++ b/fs/ocfs2/ocfs2_lockid.h
@@ -100,7 +100,7 @@ static char *ocfs2_lock_type_strings[] = {
 static inline const char *ocfs2_lock_type_string(enum ocfs2_lock_type type)
 {
 #ifdef __KERNEL__
-        mlog_bug_on_msg(type >= OCFS2_NUM_LOCK_TYPES, "%d\n", type);
+        BUG_ON(type >= OCFS2_NUM_LOCK_TYPES);
 #endif
         return ocfs2_lock_type_strings[type];
 }
diff --git a/fs/ocfs2/slot_map.c b/fs/ocfs2/slot_map.c
index 3a50ce555e64..bb5ff8939bf1 100644
--- a/fs/ocfs2/slot_map.c
+++ b/fs/ocfs2/slot_map.c
@@ -42,81 +42,244 @@
 
 #include "buffer_head_io.h"
 
-static s16 __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
-                                    s16 global);
-static void __ocfs2_fill_slot(struct ocfs2_slot_info *si,
-                              s16 slot_num,
-                              s16 node_num);
-
-/* post the slot information on disk into our slot_info struct. */
-void ocfs2_update_slot_info(struct ocfs2_slot_info *si)
+
+struct ocfs2_slot {
+        int sl_valid;
+        unsigned int sl_node_num;
+};
+
+struct ocfs2_slot_info {
+        int si_extended;
+        int si_slots_per_block;
+        struct inode *si_inode;
+        unsigned int si_blocks;
+        struct buffer_head **si_bh;
+        unsigned int si_num_slots;
+        struct ocfs2_slot *si_slots;
+};
+
+
+static int __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
+                                    unsigned int node_num);
+
+static void ocfs2_invalidate_slot(struct ocfs2_slot_info *si,
+                                  int slot_num)
+{
+        BUG_ON((slot_num < 0) || (slot_num >= si->si_num_slots));
+        si->si_slots[slot_num].sl_valid = 0;
+}
+
+static void ocfs2_set_slot(struct ocfs2_slot_info *si,
+                           int slot_num, unsigned int node_num)
+{
+        BUG_ON((slot_num < 0) || (slot_num >= si->si_num_slots));
+
+        si->si_slots[slot_num].sl_valid = 1;
+        si->si_slots[slot_num].sl_node_num = node_num;
+}
+
+/* This version is for the extended slot map */
+static void ocfs2_update_slot_info_extended(struct ocfs2_slot_info *si)
+{
+        int b, i, slotno;
+        struct ocfs2_slot_map_extended *se;
+
+        slotno = 0;
+        for (b = 0; b < si->si_blocks; b++) {
+                se = (struct ocfs2_slot_map_extended *)si->si_bh[b]->b_data;
+                for (i = 0;
+                     (i < si->si_slots_per_block) &&
+                     (slotno < si->si_num_slots);
+                     i++, slotno++) {
+                        if (se->se_slots[i].es_valid)
+                                ocfs2_set_slot(si, slotno,
+                                               le32_to_cpu(se->se_slots[i].es_node_num));
+                        else
+                                ocfs2_invalidate_slot(si, slotno);
+                }
+        }
+}
+
+/*
+ * Post the slot information on disk into our slot_info struct.
+ * Must be protected by osb_lock.
+ */
+static void ocfs2_update_slot_info_old(struct ocfs2_slot_info *si)
 {
         int i;
-        __le16 *disk_info;
+        struct ocfs2_slot_map *sm;
 
-        /* we don't read the slot block here as ocfs2_super_lock
-         * should've made sure we have the most recent copy. */
-        spin_lock(&si->si_lock);
-        disk_info = (__le16 *) si->si_bh->b_data;
+        sm = (struct ocfs2_slot_map *)si->si_bh[0]->b_data;
 
-        for (i = 0; i < si->si_size; i++)
-                si->si_global_node_nums[i] = le16_to_cpu(disk_info[i]);
+        for (i = 0; i < si->si_num_slots; i++) {
+                if (le16_to_cpu(sm->sm_slots[i]) == (u16)OCFS2_INVALID_SLOT)
+                        ocfs2_invalidate_slot(si, i);
+                else
+                        ocfs2_set_slot(si, i, le16_to_cpu(sm->sm_slots[i]));
+        }
+}
 
-        spin_unlock(&si->si_lock);
+static void ocfs2_update_slot_info(struct ocfs2_slot_info *si)
+{
+        /*
+         * The slot data will have been refreshed when ocfs2_super_lock
+         * was taken.
+         */
+        if (si->si_extended)
+                ocfs2_update_slot_info_extended(si);
+        else
+                ocfs2_update_slot_info_old(si);
+}
+
+int ocfs2_refresh_slot_info(struct ocfs2_super *osb)
+{
+        int ret;
+        struct ocfs2_slot_info *si = osb->slot_info;
+
+        if (si == NULL)
+                return 0;
+
+        BUG_ON(si->si_blocks == 0);
+        BUG_ON(si->si_bh == NULL);
+
+        mlog(0, "Refreshing slot map, reading %u block(s)\n",
+             si->si_blocks);
+
+        /*
+         * We pass -1 as blocknr because we expect all of si->si_bh to
+         * be !NULL.  Thus, ocfs2_read_blocks() will ignore blocknr.  If
+         * this is not true, the read of -1 (UINT64_MAX) will fail.
+         */
+        ret = ocfs2_read_blocks(osb, -1, si->si_blocks, si->si_bh, 0,
+                                si->si_inode);
+        if (ret == 0) {
+                spin_lock(&osb->osb_lock);
+                ocfs2_update_slot_info(si);
+                spin_unlock(&osb->osb_lock);
+        }
+
+        return ret;
 }
 
 /* post the our slot info stuff into it's destination bh and write it
  * out. */
-int ocfs2_update_disk_slots(struct ocfs2_super *osb,
-                            struct ocfs2_slot_info *si)
+static void ocfs2_update_disk_slot_extended(struct ocfs2_slot_info *si,
+                                            int slot_num,
+                                            struct buffer_head **bh)
 {
-        int status, i;
-        __le16 *disk_info = (__le16 *) si->si_bh->b_data;
+        int blkind = slot_num / si->si_slots_per_block;
+        int slotno = slot_num % si->si_slots_per_block;
+        struct ocfs2_slot_map_extended *se;
+
+        BUG_ON(blkind >= si->si_blocks);
+
+        se = (struct ocfs2_slot_map_extended *)si->si_bh[blkind]->b_data;
+        se->se_slots[slotno].es_valid = si->si_slots[slot_num].sl_valid;
+        if (si->si_slots[slot_num].sl_valid)
+                se->se_slots[slotno].es_node_num =
+                        cpu_to_le32(si->si_slots[slot_num].sl_node_num);
+        *bh = si->si_bh[blkind];
+}
 
-        spin_lock(&si->si_lock);
-        for (i = 0; i < si->si_size; i++)
-                disk_info[i] = cpu_to_le16(si->si_global_node_nums[i]);
-        spin_unlock(&si->si_lock);
+static void ocfs2_update_disk_slot_old(struct ocfs2_slot_info *si,
+                                       int slot_num,
+                                       struct buffer_head **bh)
+{
+        int i;
+        struct ocfs2_slot_map *sm;
+
+        sm = (struct ocfs2_slot_map *)si->si_bh[0]->b_data;
+        for (i = 0; i < si->si_num_slots; i++) {
+                if (si->si_slots[i].sl_valid)
+                        sm->sm_slots[i] =
+                                cpu_to_le16(si->si_slots[i].sl_node_num);
+                else
+                        sm->sm_slots[i] = cpu_to_le16(OCFS2_INVALID_SLOT);
+        }
+        *bh = si->si_bh[0];
+}
+
+static int ocfs2_update_disk_slot(struct ocfs2_super *osb,
+                                  struct ocfs2_slot_info *si,
+                                  int slot_num)
+{
+        int status;
+        struct buffer_head *bh;
+
+        spin_lock(&osb->osb_lock);
+        if (si->si_extended)
+                ocfs2_update_disk_slot_extended(si, slot_num, &bh);
+        else
+                ocfs2_update_disk_slot_old(si, slot_num, &bh);
+        spin_unlock(&osb->osb_lock);
 
-        status = ocfs2_write_block(osb, si->si_bh, si->si_inode);
+        status = ocfs2_write_block(osb, bh, si->si_inode);
         if (status < 0)
                 mlog_errno(status);
 
         return status;
 }
 
-/* try to find global node in the slot info. Returns
- * OCFS2_INVALID_SLOT if nothing is found. */
-static s16 __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
-                                    s16 global)
+/*
+ * Calculate how many bytes are needed by the slot map.  Returns
+ * an error if the slot map file is too small.
+ */
+static int ocfs2_slot_map_physical_size(struct ocfs2_super *osb,
+                                        struct inode *inode,
+                                        unsigned long long *bytes)
 {
-        int i;
-        s16 ret = OCFS2_INVALID_SLOT;
+        unsigned long long bytes_needed;
+
+        if (ocfs2_uses_extended_slot_map(osb)) {
+                bytes_needed = osb->max_slots *
+                        sizeof(struct ocfs2_extended_slot);
+        } else {
+                bytes_needed = osb->max_slots * sizeof(__le16);
+        }
+        if (bytes_needed > i_size_read(inode)) {
+                mlog(ML_ERROR,
+                     "Slot map file is too small!  (size %llu, needed %llu)\n",
+                     i_size_read(inode), bytes_needed);
+                return -ENOSPC;
+        }
+
+        *bytes = bytes_needed;
+        return 0;
+}
+
+/* try to find global node in the slot info. Returns -ENOENT
+ * if nothing is found. */
+static int __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
+                                    unsigned int node_num)
+{
+        int i, ret = -ENOENT;
 
         for(i = 0; i < si->si_num_slots; i++) {
-                if (global == si->si_global_node_nums[i]) {
-                        ret = (s16) i;
+                if (si->si_slots[i].sl_valid &&
+                    (node_num == si->si_slots[i].sl_node_num)) {
+                        ret = i;
                         break;
                 }
         }
+
         return ret;
 }
 
-static s16 __ocfs2_find_empty_slot(struct ocfs2_slot_info *si, s16 preferred)
+static int __ocfs2_find_empty_slot(struct ocfs2_slot_info *si,
+                                   int preferred)
 {
-        int i;
-        s16 ret = OCFS2_INVALID_SLOT;
+        int i, ret = -ENOSPC;
 
-        if (preferred >= 0 && preferred < si->si_num_slots) {
-                if (OCFS2_INVALID_SLOT == si->si_global_node_nums[preferred]) {
+        if ((preferred >= 0) && (preferred < si->si_num_slots)) {
+                if (!si->si_slots[preferred].sl_valid) {
                         ret = preferred;
                         goto out;
                 }
         }
 
         for(i = 0; i < si->si_num_slots; i++) {
-                if (OCFS2_INVALID_SLOT == si->si_global_node_nums[i]) {
-                        ret = (s16) i;
+                if (!si->si_slots[i].sl_valid) {
+                        ret = i;
                         break;
                 }
         }
@@ -124,58 +287,155 @@ out:
         return ret;
 }
 
-s16 ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
-                           s16 global)
+int ocfs2_node_num_to_slot(struct ocfs2_super *osb, unsigned int node_num)
 {
-        s16 ret;
+        int slot;
+        struct ocfs2_slot_info *si = osb->slot_info;
 
-        spin_lock(&si->si_lock);
-        ret = __ocfs2_node_num_to_slot(si, global);
-        spin_unlock(&si->si_lock);
-        return ret;
+        spin_lock(&osb->osb_lock);
+        slot = __ocfs2_node_num_to_slot(si, node_num);
+        spin_unlock(&osb->osb_lock);
+
+        return slot;
+}
+
+int ocfs2_slot_to_node_num_locked(struct ocfs2_super *osb, int slot_num,
+                                  unsigned int *node_num)
+{
+        struct ocfs2_slot_info *si = osb->slot_info;
+
+        assert_spin_locked(&osb->osb_lock);
+
+        BUG_ON(slot_num < 0);
+        BUG_ON(slot_num > osb->max_slots);
+
+        if (!si->si_slots[slot_num].sl_valid)
+                return -ENOENT;
+
+        *node_num = si->si_slots[slot_num].sl_node_num;
+        return 0;
 }
 
-static void __ocfs2_fill_slot(struct ocfs2_slot_info *si,
-                              s16 slot_num,
-                              s16 node_num)
+static void __ocfs2_free_slot_info(struct ocfs2_slot_info *si)
 {
-        BUG_ON(slot_num == OCFS2_INVALID_SLOT);
-        BUG_ON(slot_num >= si->si_num_slots);
-        BUG_ON((node_num != O2NM_INVALID_NODE_NUM) &&
-               (node_num >= O2NM_MAX_NODES));
+        unsigned int i;
+
+        if (si == NULL)
+                return;
+
+        if (si->si_inode)
+                iput(si->si_inode);
+        if (si->si_bh) {
+                for (i = 0; i < si->si_blocks; i++) {
+                        if (si->si_bh[i]) {
+                                brelse(si->si_bh[i]);
+                                si->si_bh[i] = NULL;
+                        }
+                }
+                kfree(si->si_bh);
+        }
 
-        si->si_global_node_nums[slot_num] = node_num;
+        kfree(si);
 }
 
-void ocfs2_clear_slot(struct ocfs2_slot_info *si,
-                      s16 slot_num)
+int ocfs2_clear_slot(struct ocfs2_super *osb, int slot_num)
 {
-        spin_lock(&si->si_lock);
-        __ocfs2_fill_slot(si, slot_num, OCFS2_INVALID_SLOT);
-        spin_unlock(&si->si_lock);
+        struct ocfs2_slot_info *si = osb->slot_info;
+
+        if (si == NULL)
+                return 0;
+
+        spin_lock(&osb->osb_lock);
+        ocfs2_invalidate_slot(si, slot_num);
+        spin_unlock(&osb->osb_lock);
+
+        return ocfs2_update_disk_slot(osb, osb->slot_info, slot_num);
 }
 
-int ocfs2_init_slot_info(struct ocfs2_super *osb)
+static int ocfs2_map_slot_buffers(struct ocfs2_super *osb,
+                                  struct ocfs2_slot_info *si)
 {
-        int status, i;
+        int status = 0;
         u64 blkno;
+        unsigned long long blocks, bytes;
+        unsigned int i;
+        struct buffer_head *bh;
+
+        status = ocfs2_slot_map_physical_size(osb, si->si_inode, &bytes);
+        if (status)
+                goto bail;
+
+        blocks = ocfs2_blocks_for_bytes(si->si_inode->i_sb, bytes);
+        BUG_ON(blocks > UINT_MAX);
+        si->si_blocks = blocks;
+        if (!si->si_blocks)
+                goto bail;
+
+        if (si->si_extended)
+                si->si_slots_per_block =
+                        (osb->sb->s_blocksize /
+                         sizeof(struct ocfs2_extended_slot));
+        else
+                si->si_slots_per_block = osb->sb->s_blocksize / sizeof(__le16);
+
+        /* The size checks above should ensure this */
+        BUG_ON((osb->max_slots / si->si_slots_per_block) > blocks);
+
+        mlog(0, "Slot map needs %u buffers for %llu bytes\n",
+             si->si_blocks, bytes);
+
+        si->si_bh = kzalloc(sizeof(struct buffer_head *) * si->si_blocks,
+                            GFP_KERNEL);
+        if (!si->si_bh) {
+                status = -ENOMEM;
+                mlog_errno(status);
+                goto bail;
+        }
+
+        for (i = 0; i < si->si_blocks; i++) {
+                status = ocfs2_extent_map_get_blocks(si->si_inode, i,
+                                                     &blkno, NULL, NULL);
+                if (status < 0) {
+                        mlog_errno(status);
+                        goto bail;
+                }
+
+                mlog(0, "Reading slot map block %u at %llu\n", i,
+                     (unsigned long long)blkno);
+
+                bh = NULL;  /* Acquire a fresh bh */
+                status = ocfs2_read_block(osb, blkno, &bh, 0, si->si_inode);
+                if (status < 0) {
+                        mlog_errno(status);
+                        goto bail;
+                }
+
+                si->si_bh[i] = bh;
+        }
+
+bail:
+        return status;
+}
+
+int ocfs2_init_slot_info(struct ocfs2_super *osb)
+{
+        int status;
         struct inode *inode = NULL;
-        struct buffer_head *bh = NULL;
         struct ocfs2_slot_info *si;
 
-        si = kzalloc(sizeof(struct ocfs2_slot_info), GFP_KERNEL);
+        si = kzalloc(sizeof(struct ocfs2_slot_info) +
+                     (sizeof(struct ocfs2_slot) * osb->max_slots),
+                     GFP_KERNEL);
         if (!si) {
                 status = -ENOMEM;
                 mlog_errno(status);
                 goto bail;
         }
 
-        spin_lock_init(&si->si_lock);
+        si->si_extended = ocfs2_uses_extended_slot_map(osb);
         si->si_num_slots = osb->max_slots;
-        si->si_size = OCFS2_MAX_SLOTS;
-
-        for(i = 0; i < si->si_num_slots; i++)
-                si->si_global_node_nums[i] = OCFS2_INVALID_SLOT;
+        si->si_slots = (struct ocfs2_slot *)((char *)si +
+                                             sizeof(struct ocfs2_slot_info));
 
         inode = ocfs2_get_system_file_inode(osb, SLOT_MAP_SYSTEM_INODE,
                                             OCFS2_INVALID_SLOT);
@@ -185,61 +445,53 @@ int ocfs2_init_slot_info(struct ocfs2_super *osb)
                 goto bail;
         }
 
-        status = ocfs2_extent_map_get_blocks(inode, 0ULL, &blkno, NULL, NULL);
-        if (status < 0) {
-                mlog_errno(status);
-                goto bail;
-        }
-
-        status = ocfs2_read_block(osb, blkno, &bh, 0, inode);
+        si->si_inode = inode;
+        status = ocfs2_map_slot_buffers(osb, si);
         if (status < 0) {
                 mlog_errno(status);
                 goto bail;
         }
 
-        si->si_inode = inode;
-        si->si_bh = bh;
-        osb->slot_info = si;
+        osb->slot_info = (struct ocfs2_slot_info *)si;
 bail:
         if (status < 0 && si)
-                ocfs2_free_slot_info(si);
+                __ocfs2_free_slot_info(si);
 
         return status;
 }
 
-void ocfs2_free_slot_info(struct ocfs2_slot_info *si)
+void ocfs2_free_slot_info(struct ocfs2_super *osb)
 {
-        if (si->si_inode)
-                iput(si->si_inode);
-        if (si->si_bh)
-                brelse(si->si_bh);
-        kfree(si);
+        struct ocfs2_slot_info *si = osb->slot_info;
+
+        osb->slot_info = NULL;
+        __ocfs2_free_slot_info(si);
 }
 
 int ocfs2_find_slot(struct ocfs2_super *osb)
 {
         int status;
-        s16 slot;
+        int slot;
         struct ocfs2_slot_info *si;
 
         mlog_entry_void();
 
         si = osb->slot_info;
 
+        spin_lock(&osb->osb_lock);
         ocfs2_update_slot_info(si);
 
-        spin_lock(&si->si_lock);
         /* search for ourselves first and take the slot if it already
          * exists. Perhaps we need to mark this in a variable for our
          * own journal recovery? Possibly not, though we certainly
          * need to warn to the user */
         slot = __ocfs2_node_num_to_slot(si, osb->node_num);
-        if (slot == OCFS2_INVALID_SLOT) {
+        if (slot < 0) {
                 /* if no slot yet, then just take 1st available
                  * one. */
                 slot = __ocfs2_find_empty_slot(si, osb->preferred_slot);
-                if (slot == OCFS2_INVALID_SLOT) {
-                        spin_unlock(&si->si_lock);
+                if (slot < 0) {
+                        spin_unlock(&osb->osb_lock);
                         mlog(ML_ERROR, "no free slots available!\n");
                         status = -EINVAL;
                         goto bail;
@@ -248,13 +500,13 @@ int ocfs2_find_slot(struct ocfs2_super *osb)
                 mlog(ML_NOTICE, "slot %d is already allocated to this node!\n",
                      slot);
 
-        __ocfs2_fill_slot(si, slot, osb->node_num);
+        ocfs2_set_slot(si, slot, osb->node_num);
         osb->slot_num = slot;
-        spin_unlock(&si->si_lock);
+        spin_unlock(&osb->osb_lock);
 
         mlog(0, "taking node slot %d\n", osb->slot_num);
 
-        status = ocfs2_update_disk_slots(osb, si);
+        status = ocfs2_update_disk_slot(osb, si, osb->slot_num);
         if (status < 0)
                 mlog_errno(status);
 
@@ -265,27 +517,27 @@ bail:
 
 void ocfs2_put_slot(struct ocfs2_super *osb)
 {
-        int status;
+        int status, slot_num;
         struct ocfs2_slot_info *si = osb->slot_info;
 
         if (!si)
                 return;
 
+        spin_lock(&osb->osb_lock);
         ocfs2_update_slot_info(si);
 
-        spin_lock(&si->si_lock);
-        __ocfs2_fill_slot(si, osb->slot_num, OCFS2_INVALID_SLOT);
+        slot_num = osb->slot_num;
+        ocfs2_invalidate_slot(si, osb->slot_num);
         osb->slot_num = OCFS2_INVALID_SLOT;
-        spin_unlock(&si->si_lock);
+        spin_unlock(&osb->osb_lock);
 
-        status = ocfs2_update_disk_slots(osb, si);
+        status = ocfs2_update_disk_slot(osb, si, slot_num);
         if (status < 0) {
                 mlog_errno(status);
                 goto bail;
         }
 
 bail:
-        osb->slot_info = NULL;
-        ocfs2_free_slot_info(si);
+        ocfs2_free_slot_info(osb);
 }
 
diff --git a/fs/ocfs2/slot_map.h b/fs/ocfs2/slot_map.h
index 1025872aaade..601c95fd7003 100644
--- a/fs/ocfs2/slot_map.h
+++ b/fs/ocfs2/slot_map.h
@@ -27,38 +27,18 @@
 #ifndef SLOTMAP_H
 #define SLOTMAP_H
 
-struct ocfs2_slot_info {
-        spinlock_t si_lock;
-
-        struct inode *si_inode;
-        struct buffer_head *si_bh;
-        unsigned int si_num_slots;
-        unsigned int si_size;
-        s16 si_global_node_nums[OCFS2_MAX_SLOTS];
-};
-
 int ocfs2_init_slot_info(struct ocfs2_super *osb);
-void ocfs2_free_slot_info(struct ocfs2_slot_info *si);
+void ocfs2_free_slot_info(struct ocfs2_super *osb);
 
 int ocfs2_find_slot(struct ocfs2_super *osb);
 void ocfs2_put_slot(struct ocfs2_super *osb);
 
-void ocfs2_update_slot_info(struct ocfs2_slot_info *si);
-int ocfs2_update_disk_slots(struct ocfs2_super *osb,
-                            struct ocfs2_slot_info *si);
-
-s16 ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
-                           s16 global);
-void ocfs2_clear_slot(struct ocfs2_slot_info *si,
-                      s16 slot_num);
+int ocfs2_refresh_slot_info(struct ocfs2_super *osb);
 
-static inline int ocfs2_is_empty_slot(struct ocfs2_slot_info *si,
-                                      int slot_num)
-{
-        BUG_ON(slot_num == OCFS2_INVALID_SLOT);
-        assert_spin_locked(&si->si_lock);
+int ocfs2_node_num_to_slot(struct ocfs2_super *osb, unsigned int node_num);
+int ocfs2_slot_to_node_num_locked(struct ocfs2_super *osb, int slot_num,
+                                  unsigned int *node_num);
 
-        return si->si_global_node_nums[slot_num] == OCFS2_INVALID_SLOT;
-}
+int ocfs2_clear_slot(struct ocfs2_super *osb, int slot_num);
 
 #endif
diff --git a/fs/ocfs2/stack_o2cb.c b/fs/ocfs2/stack_o2cb.c
new file mode 100644
index 000000000000..ac1d74c63bf5
--- /dev/null
+++ b/fs/ocfs2/stack_o2cb.c
@@ -0,0 +1,420 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * stack_o2cb.c
+ *
+ * Code which interfaces ocfs2 with the o2cb stack.
+ *
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/crc32.h>
+#include <linux/module.h>
+
+/* Needed for AOP_TRUNCATED_PAGE in mlog_errno() */
+#include <linux/fs.h>
+
+#include "cluster/masklog.h"
+#include "cluster/nodemanager.h"
+#include "cluster/heartbeat.h"
+
+#include "stackglue.h"
+
+struct o2dlm_private {
+        struct dlm_eviction_cb op_eviction_cb;
+};
+
+static struct ocfs2_stack_plugin o2cb_stack;
+
+/* These should be identical */
+#if (DLM_LOCK_IV != LKM_IVMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_NL != LKM_NLMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_CR != LKM_CRMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_CW != LKM_CWMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_PR != LKM_PRMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_PW != LKM_PWMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_EX != LKM_EXMODE)
+# error Lock modes do not match
+#endif
+static inline int mode_to_o2dlm(int mode)
+{
+        BUG_ON(mode > LKM_MAXMODE);
+
+        return mode;
+}
+
+#define map_flag(_generic, _o2dlm)              \
+        if (flags & (_generic)) {               \
+                flags &= ~(_generic);           \
+                o2dlm_flags |= (_o2dlm);        \
+        }
+static int flags_to_o2dlm(u32 flags)
+{
+        int o2dlm_flags = 0;
+
+        map_flag(DLM_LKF_NOQUEUE, LKM_NOQUEUE);
+        map_flag(DLM_LKF_CANCEL, LKM_CANCEL);
+        map_flag(DLM_LKF_CONVERT, LKM_CONVERT);
+        map_flag(DLM_LKF_VALBLK, LKM_VALBLK);
+        map_flag(DLM_LKF_IVVALBLK, LKM_INVVALBLK);
+        map_flag(DLM_LKF_ORPHAN, LKM_ORPHAN);
+        map_flag(DLM_LKF_FORCEUNLOCK, LKM_FORCE);
+        map_flag(DLM_LKF_TIMEOUT, LKM_TIMEOUT);
+        map_flag(DLM_LKF_LOCAL, LKM_LOCAL);
+
+        /* map_flag() should have cleared every flag passed in */
+        BUG_ON(flags != 0);
+
+        return o2dlm_flags;
+}
+#undef map_flag
+
+/*
+ * Map an o2dlm status to standard errno values.
+ *
+ * o2dlm only uses a handful of these, and returns even fewer to the
+ * caller. Still, we try to assign sane values to each error.
+ *
+ * The following value pairs have special meanings to dlmglue, thus
+ * the right hand side needs to stay unique - never duplicate the
+ * mapping elsewhere in the table!
+ *
+ * DLM_NORMAL:          0
+ * DLM_NOTQUEUED:       -EAGAIN
+ * DLM_CANCELGRANT:     -EBUSY
+ * DLM_CANCEL:          -DLM_ECANCEL
+ */
+/* Keep in sync with dlmapi.h */
+static int status_map[] = {
+        [DLM_NORMAL]                    = 0,            /* Success */
+        [DLM_GRANTED]                   = -EINVAL,
+        [DLM_DENIED]                    = -EACCES,
+        [DLM_DENIED_NOLOCKS]            = -EACCES,
+        [DLM_WORKING]                   = -EACCES,
+        [DLM_BLOCKED]                   = -EINVAL,
+        [DLM_BLOCKED_ORPHAN]            = -EINVAL,
+        [DLM_DENIED_GRACE_PERIOD]       = -EACCES,
+        [DLM_SYSERR]                    = -ENOMEM,      /* It is what it is */
+        [DLM_NOSUPPORT]                 = -EPROTO,
+        [DLM_CANCELGRANT]               = -EBUSY,       /* Cancel after grant */
+        [DLM_IVLOCKID]                  = -EINVAL,
+        [DLM_SYNC]                      = -EINVAL,
+        [DLM_BADTYPE]                   = -EINVAL,
+        [DLM_BADRESOURCE]               = -EINVAL,
+        [DLM_MAXHANDLES]                = -ENOMEM,
+        [DLM_NOCLINFO]                  = -EINVAL,
+        [DLM_NOLOCKMGR]                 = -EINVAL,
+        [DLM_NOPURGED]                  = -EINVAL,
+        [DLM_BADARGS]                   = -EINVAL,
+        [DLM_VOID]                      = -EINVAL,
+        [DLM_NOTQUEUED]                 = -EAGAIN,      /* Trylock failed */
+        [DLM_IVBUFLEN]                  = -EINVAL,
+        [DLM_CVTUNGRANT]                = -EPERM,
+        [DLM_BADPARAM]                  = -EINVAL,
+        [DLM_VALNOTVALID]               = -EINVAL,
+        [DLM_REJECTED]                  = -EPERM,
+        [DLM_ABORT]                     = -EINVAL,
+        [DLM_CANCEL]                    = -DLM_ECANCEL, /* Successful cancel */
+        [DLM_IVRESHANDLE]               = -EINVAL,
+        [DLM_DEADLOCK]                  = -EDEADLK,
+        [DLM_DENIED_NOASTS]             = -EINVAL,
+        [DLM_FORWARD]                   = -EINVAL,
+        [DLM_TIMEOUT]                   = -ETIMEDOUT,
+        [DLM_IVGROUPID]                 = -EINVAL,
+        [DLM_VERS_CONFLICT]             = -EOPNOTSUPP,
+        [DLM_BAD_DEVICE_PATH]           = -ENOENT,
+        [DLM_NO_DEVICE_PERMISSION]      = -EPERM,
+        [DLM_NO_CONTROL_DEVICE]         = -ENOENT,
+        [DLM_RECOVERING]                = -ENOTCONN,
+        [DLM_MIGRATING]                 = -ERESTART,
+        [DLM_MAXSTATS]                  = -EINVAL,
+};
+
+static int dlm_status_to_errno(enum dlm_status status)
+{
+        BUG_ON(status > (sizeof(status_map) / sizeof(status_map[0])));
+
+        return status_map[status];
+}
+
+static void o2dlm_lock_ast_wrapper(void *astarg)
+{
+        BUG_ON(o2cb_stack.sp_proto == NULL);
+
+        o2cb_stack.sp_proto->lp_lock_ast(astarg);
+}
+
+static void o2dlm_blocking_ast_wrapper(void *astarg, int level)
+{
+        BUG_ON(o2cb_stack.sp_proto == NULL);
+
+        o2cb_stack.sp_proto->lp_blocking_ast(astarg, level);
+}
+
+static void o2dlm_unlock_ast_wrapper(void *astarg, enum dlm_status status)
+{
+        int error = dlm_status_to_errno(status);
+
+        BUG_ON(o2cb_stack.sp_proto == NULL);
+
+        /*
+         * In o2dlm, you can get both the lock_ast() for the lock being
+         * granted and the unlock_ast() for the CANCEL failing.  A
+         * successful cancel sends DLM_NORMAL here.  If the
+         * lock grant happened before the cancel arrived, you get
+         * DLM_CANCELGRANT.
+         *
+         * There's no need for the double-ast.  If we see DLM_CANCELGRANT,
+         * we just ignore it.  We expect the lock_ast() to handle the
+         * granted lock.
+         */
+        if (status == DLM_CANCELGRANT)
+                return;
+
+        o2cb_stack.sp_proto->lp_unlock_ast(astarg, error);
+}
+
+static int o2cb_dlm_lock(struct ocfs2_cluster_connection *conn,
+                         int mode,
+                         union ocfs2_dlm_lksb *lksb,
+                         u32 flags,
+                         void *name,
+                         unsigned int namelen,
+                         void *astarg)
+{
+        enum dlm_status status;
+        int o2dlm_mode = mode_to_o2dlm(mode);
+        int o2dlm_flags = flags_to_o2dlm(flags);
+        int ret;
+
+        status = dlmlock(conn->cc_lockspace, o2dlm_mode, &lksb->lksb_o2dlm,
+                         o2dlm_flags, name, namelen,
+                         o2dlm_lock_ast_wrapper, astarg,
+                         o2dlm_blocking_ast_wrapper);
+        ret = dlm_status_to_errno(status);
+        return ret;
+}
+
+static int o2cb_dlm_unlock(struct ocfs2_cluster_connection *conn,
+                           union ocfs2_dlm_lksb *lksb,
+                           u32 flags,
+                           void *astarg)
+{
+        enum dlm_status status;
+        int o2dlm_flags = flags_to_o2dlm(flags);
+        int ret;
+
+        status = dlmunlock(conn->cc_lockspace, &lksb->lksb_o2dlm,
+                           o2dlm_flags, o2dlm_unlock_ast_wrapper, astarg);
+        ret = dlm_status_to_errno(status);
+        return ret;
+}
+
+static int o2cb_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
+{
+        return dlm_status_to_errno(lksb->lksb_o2dlm.status);
+}
+
+static void *o2cb_dlm_lvb(union ocfs2_dlm_lksb *lksb)
+{
+        return (void *)(lksb->lksb_o2dlm.lvb);
+}
+
+static void o2cb_dump_lksb(union ocfs2_dlm_lksb *lksb)
+{
+        dlm_print_one_lock(lksb->lksb_o2dlm.lockid);
+}
+
+/*
+ * Called from the dlm when it's about to evict a node. This is how the
+ * classic stack signals node death.
+ */
+static void o2dlm_eviction_cb(int node_num, void *data)
+{
+        struct ocfs2_cluster_connection *conn = data;
+
+        mlog(ML_NOTICE, "o2dlm has evicted node %d from group %.*s\n",
+             node_num, conn->cc_namelen, conn->cc_name);
+
+        conn->cc_recovery_handler(node_num, conn->cc_recovery_data);
+}
+
+static int o2cb_cluster_connect(struct ocfs2_cluster_connection *conn)
+{
+        int rc = 0;
+        u32 dlm_key;
+        struct dlm_ctxt *dlm;
+        struct o2dlm_private *priv;
+        struct dlm_protocol_version dlm_version;
+
+        BUG_ON(conn == NULL);
+        BUG_ON(o2cb_stack.sp_proto == NULL);
+
+        /* for now we only have one cluster/node, make sure we see it
+         * in the heartbeat universe */
+        if (!o2hb_check_local_node_heartbeating()) {
+                rc = -EINVAL;
+                goto out;
+        }
+
+        priv = kzalloc(sizeof(struct o2dlm_private), GFP_KERNEL);
+        if (!priv) {
+                rc = -ENOMEM;
+                goto out_free;
+        }
+
+        /* This just fills the structure in.  It is safe to pass conn. */
+        dlm_setup_eviction_cb(&priv->op_eviction_cb, o2dlm_eviction_cb,
+                              conn);
+
+        conn->cc_private = priv;
+
+        /* used by the dlm code to make message headers unique, each
+         * node in this domain must agree on this. */
+        dlm_key = crc32_le(0, conn->cc_name, conn->cc_namelen);
+        dlm_version.pv_major = conn->cc_version.pv_major;
+        dlm_version.pv_minor = conn->cc_version.pv_minor;
+
+        dlm = dlm_register_domain(conn->cc_name, dlm_key, &dlm_version);
+        if (IS_ERR(dlm)) {
+                rc = PTR_ERR(dlm);
+                mlog_errno(rc);
+                goto out_free;
+        }
+
+        conn->cc_version.pv_major = dlm_version.pv_major;
+        conn->cc_version.pv_minor = dlm_version.pv_minor;
+        conn->cc_lockspace = dlm;
+
+        dlm_register_eviction_cb(dlm, &priv->op_eviction_cb);
+
+out_free:
+        if (rc && conn->cc_private)
+                kfree(conn->cc_private);
+
+out:
+        return rc;
+}
+
+static int o2cb_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+                                   int hangup_pending)
+{
+        struct dlm_ctxt *dlm = conn->cc_lockspace;
+        struct o2dlm_private *priv = conn->cc_private;
+
+        dlm_unregister_eviction_cb(&priv->op_eviction_cb);
+        conn->cc_private = NULL;
+        kfree(priv);
+
+        dlm_unregister_domain(dlm);
+        conn->cc_lockspace = NULL;
+
+        return 0;
+}
+
+static void o2hb_stop(const char *group)
+{
+        int ret;
+        char *argv[5], *envp[3];
+
+        argv[0] = (char *)o2nm_get_hb_ctl_path();
+        argv[1] = "-K";
+        argv[2] = "-u";
+        argv[3] = (char *)group;
+        argv[4] = NULL;
+
+        mlog(0, "Run: %s %s %s %s\n", argv[0], argv[1], argv[2], argv[3]);
+
+        /* minimal command environment taken from cpu_run_sbin_hotplug */
+        envp[0] = "HOME=/";
+        envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+        envp[2] = NULL;
+
+        ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
+        if (ret < 0)
+                mlog_errno(ret);
+}
+
+/*
+ * Hangup is a hack for tools compatibility.  Older ocfs2-tools software
+ * expects the filesystem to call "ocfs2_hb_ctl" during unmount.  This
+ * happens regardless of whether the DLM got started, so we can't do it
+ * in ocfs2_cluster_disconnect().  We bring the o2hb_stop() function into
+ * the glue and provide a "hangup" API for super.c to call.
+ *
+ * Other stacks will eventually provide a NULL ->hangup() pointer.
+ */
+static void o2cb_cluster_hangup(const char *group, int grouplen)
+{
+        o2hb_stop(group);
+}
+
+static int o2cb_cluster_this_node(unsigned int *node)
+{
+        int node_num;
+
+        node_num = o2nm_this_node();
+        if (node_num == O2NM_INVALID_NODE_NUM)
+                return -ENOENT;
+
+        if (node_num >= O2NM_MAX_NODES)
+                return -EOVERFLOW;
+
+        *node = node_num;
+        return 0;
+}
+
+struct ocfs2_stack_operations o2cb_stack_ops = {
+        .connect        = o2cb_cluster_connect,
+        .disconnect     = o2cb_cluster_disconnect,
+        .hangup         = o2cb_cluster_hangup,
+        .this_node      = o2cb_cluster_this_node,
+        .dlm_lock       = o2cb_dlm_lock,
+        .dlm_unlock     = o2cb_dlm_unlock,
+        .lock_status    = o2cb_dlm_lock_status,
+        .lock_lvb       = o2cb_dlm_lvb,
+        .dump_lksb      = o2cb_dump_lksb,
+};
+
+static struct ocfs2_stack_plugin o2cb_stack = {
+        .sp_name        = "o2cb",
+        .sp_ops         = &o2cb_stack_ops,
+        .sp_owner       = THIS_MODULE,
+};
+
+static int __init o2cb_stack_init(void)
+{
+        return ocfs2_stack_glue_register(&o2cb_stack);
+}
+
+static void __exit o2cb_stack_exit(void)
+{
+        ocfs2_stack_glue_unregister(&o2cb_stack);
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_DESCRIPTION("ocfs2 driver for the classic o2cb stack");
+MODULE_LICENSE("GPL");
+module_init(o2cb_stack_init);
+module_exit(o2cb_stack_exit);
diff --git a/fs/ocfs2/stack_user.c b/fs/ocfs2/stack_user.c
new file mode 100644
index 000000000000..7428663f9cbb
--- /dev/null
+++ b/fs/ocfs2/stack_user.c
@@ -0,0 +1,883 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * stack_user.c
+ *
+ * Code which interfaces ocfs2 with fs/dlm and a userspace stack.
+ *
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/mutex.h>
+#include <linux/reboot.h>
+#include <asm/uaccess.h>
+
+#include "ocfs2.h"  /* For struct ocfs2_lock_res */
+#include "stackglue.h"
+
+
+/*
+ * The control protocol starts with a handshake.  Until the handshake
+ * is complete, the control device will fail all write(2)s.
+ *
+ * The handshake is simple.  First, the client reads until EOF.  Each line
+ * of output is a supported protocol tag.  All protocol tags are a single
+ * character followed by a two hex digit version number.  Currently the
+ * only things supported is T01, for "Text-base version 0x01".  Next, the
+ * client writes the version they would like to use, including the newline.
+ * Thus, the protocol tag is 'T01\n'.  If the version tag written is
+ * unknown, -EINVAL is returned.  Once the negotiation is complete, the
+ * client can start sending messages.
+ *
+ * The T01 protocol has three messages.  First is the "SETN" message.
+ * It has the following syntax:
+ *
+ *  SETN<space><8-char-hex-nodenum><newline>
+ *
+ * This is 14 characters.
+ *
+ * The "SETN" message must be the first message following the protocol.
+ * It tells ocfs2_control the local node number.
+ *
+ * Next comes the "SETV" message.  It has the following syntax:
+ *
+ *  SETV<space><2-char-hex-major><space><2-char-hex-minor><newline>
+ *
+ * This is 11 characters.
+ *
+ * The "SETV" message sets the filesystem locking protocol version as
+ * negotiated by the client.  The client negotiates based on the maximum
+ * version advertised in /sys/fs/ocfs2/max_locking_protocol.  The major
+ * number from the "SETV" message must match
+ * user_stack.sp_proto->lp_max_version.pv_major, and the minor number
+ * must be less than or equal to ...->lp_max_version.pv_minor.
+ *
+ * Once this information has been set, mounts will be allowed.  From this
+ * point on, the "DOWN" message can be sent for node down notification.
+ * It has the following syntax:
+ *
+ *  DOWN<space><32-char-cap-hex-uuid><space><8-char-hex-nodenum><newline>
+ *
+ * eg:
+ *
+ *  DOWN 632A924FDD844190BDA93C0DF6B94899 00000001\n
+ *
+ * This is 47 characters.
+ */
+
+/*
+ * Whether or not the client has done the handshake.
+ * For now, we have just one protocol version.
+ */
+#define OCFS2_CONTROL_PROTO                     "T01\n"
+#define OCFS2_CONTROL_PROTO_LEN                 4
+
+/* Handshake states */
+#define OCFS2_CONTROL_HANDSHAKE_INVALID         (0)
+#define OCFS2_CONTROL_HANDSHAKE_READ            (1)
+#define OCFS2_CONTROL_HANDSHAKE_PROTOCOL        (2)
+#define OCFS2_CONTROL_HANDSHAKE_VALID           (3)
+
+/* Messages */
+#define OCFS2_CONTROL_MESSAGE_OP_LEN            4
+#define OCFS2_CONTROL_MESSAGE_SETNODE_OP        "SETN"
+#define OCFS2_CONTROL_MESSAGE_SETNODE_TOTAL_LEN 14
+#define OCFS2_CONTROL_MESSAGE_SETVERSION_OP     "SETV"
+#define OCFS2_CONTROL_MESSAGE_SETVERSION_TOTAL_LEN      11
+#define OCFS2_CONTROL_MESSAGE_DOWN_OP           "DOWN"
+#define OCFS2_CONTROL_MESSAGE_DOWN_TOTAL_LEN    47
+#define OCFS2_TEXT_UUID_LEN                     32
+#define OCFS2_CONTROL_MESSAGE_VERNUM_LEN        2
+#define OCFS2_CONTROL_MESSAGE_NODENUM_LEN       8
+
+/*
+ * ocfs2_live_connection is refcounted because the filesystem and
+ * miscdevice sides can detach in different order.  Let's just be safe.
+ */
+struct ocfs2_live_connection {
+        struct list_head                oc_list;
+        struct ocfs2_cluster_connection *oc_conn;
+};
+
+struct ocfs2_control_private {
+        struct list_head op_list;
+        int op_state;
+        int op_this_node;
+        struct ocfs2_protocol_version op_proto;
+};
+
+/* SETN<space><8-char-hex-nodenum><newline> */
+struct ocfs2_control_message_setn {
+        char    tag[OCFS2_CONTROL_MESSAGE_OP_LEN];
+        char    space;
+        char    nodestr[OCFS2_CONTROL_MESSAGE_NODENUM_LEN];
+        char    newline;
+};
+
+/* SETV<space><2-char-hex-major><space><2-char-hex-minor><newline> */
+struct ocfs2_control_message_setv {
+        char    tag[OCFS2_CONTROL_MESSAGE_OP_LEN];
+        char    space1;
+        char    major[OCFS2_CONTROL_MESSAGE_VERNUM_LEN];
+        char    space2;
+        char    minor[OCFS2_CONTROL_MESSAGE_VERNUM_LEN];
+        char    newline;
+};
+
+/* DOWN<space><32-char-cap-hex-uuid><space><8-char-hex-nodenum><newline> */
+struct ocfs2_control_message_down {
+        char    tag[OCFS2_CONTROL_MESSAGE_OP_LEN];
+        char    space1;
+        char    uuid[OCFS2_TEXT_UUID_LEN];
+        char    space2;
+        char    nodestr[OCFS2_CONTROL_MESSAGE_NODENUM_LEN];
+        char    newline;
+};
+
+union ocfs2_control_message {
+        char                                    tag[OCFS2_CONTROL_MESSAGE_OP_LEN];
+        struct ocfs2_control_message_setn       u_setn;
+        struct ocfs2_control_message_setv       u_setv;
+        struct ocfs2_control_message_down       u_down;
+};
+
+static struct ocfs2_stack_plugin user_stack;
+
+static atomic_t ocfs2_control_opened;
+static int ocfs2_control_this_node = -1;
+static struct ocfs2_protocol_version running_proto;
+
+static LIST_HEAD(ocfs2_live_connection_list);
+static LIST_HEAD(ocfs2_control_private_list);
+static DEFINE_MUTEX(ocfs2_control_lock);
+
+static inline void ocfs2_control_set_handshake_state(struct file *file,
+                                                     int state)
+{
+        struct ocfs2_control_private *p = file->private_data;
+        p->op_state = state;
+}
+
+static inline int ocfs2_control_get_handshake_state(struct file *file)
+{
+        struct ocfs2_control_private *p = file->private_data;
+        return p->op_state;
+}
+
+static struct ocfs2_live_connection *ocfs2_connection_find(const char *name)
+{
+        size_t len = strlen(name);
+        struct ocfs2_live_connection *c;
+
+        BUG_ON(!mutex_is_locked(&ocfs2_control_lock));
+
+        list_for_each_entry(c, &ocfs2_live_connection_list, oc_list) {
+                if ((c->oc_conn->cc_namelen == len) &&
+                    !strncmp(c->oc_conn->cc_name, name, len))
+                        return c;
+        }
+
+        return c;
+}
+
+/*
+ * ocfs2_live_connection structures are created underneath the ocfs2
+ * mount path.  Since the VFS prevents multiple calls to
+ * fill_super(), we can't get dupes here.
+ */
+static int ocfs2_live_connection_new(struct ocfs2_cluster_connection *conn,
+                                     struct ocfs2_live_connection **c_ret)
+{
+        int rc = 0;
+        struct ocfs2_live_connection *c;
+
+        c = kzalloc(sizeof(struct ocfs2_live_connection), GFP_KERNEL);
+        if (!c)
+                return -ENOMEM;
+
+        mutex_lock(&ocfs2_control_lock);
+        c->oc_conn = conn;
+
+        if (atomic_read(&ocfs2_control_opened))
+                list_add(&c->oc_list, &ocfs2_live_connection_list);
+        else {
+                printk(KERN_ERR
+                       "ocfs2: Userspace control daemon is not present\n");
+                rc = -ESRCH;
+        }
+
+        mutex_unlock(&ocfs2_control_lock);
+
+        if (!rc)
+                *c_ret = c;
+        else
+                kfree(c);
+
+        return rc;
+}
+
+/*
+ * This function disconnects the cluster connection from ocfs2_control.
+ * Afterwards, userspace can't affect the cluster connection.
+ */
+static void ocfs2_live_connection_drop(struct ocfs2_live_connection *c)
+{
+        mutex_lock(&ocfs2_control_lock);
+        list_del_init(&c->oc_list);
+        c->oc_conn = NULL;
+        mutex_unlock(&ocfs2_control_lock);
+
+        kfree(c);
+}
+
+static int ocfs2_control_cfu(void *target, size_t target_len,
+                             const char __user *buf, size_t count)
+{
+        /* The T01 expects write(2) calls to have exactly one command */
+        if ((count != target_len) ||
+            (count > sizeof(union ocfs2_control_message)))
+                return -EINVAL;
+
+        if (copy_from_user(target, buf, target_len))
+                return -EFAULT;
+
+        return 0;
+}
+
+static ssize_t ocfs2_control_validate_protocol(struct file *file,
+                                               const char __user *buf,
+                                               size_t count)
+{
+        ssize_t ret;
+        char kbuf[OCFS2_CONTROL_PROTO_LEN];
+
+        ret = ocfs2_control_cfu(kbuf, OCFS2_CONTROL_PROTO_LEN,
+                                buf, count);
+        if (ret)
+                return ret;
+
+        if (strncmp(kbuf, OCFS2_CONTROL_PROTO, OCFS2_CONTROL_PROTO_LEN))
+                return -EINVAL;
+
+        ocfs2_control_set_handshake_state(file,
+                                          OCFS2_CONTROL_HANDSHAKE_PROTOCOL);
+
+        return count;
+}
+
+static void ocfs2_control_send_down(const char *uuid,
+                                    int nodenum)
+{
+        struct ocfs2_live_connection *c;
+
+        mutex_lock(&ocfs2_control_lock);
+
+        c = ocfs2_connection_find(uuid);
+        if (c) {
+                BUG_ON(c->oc_conn == NULL);
+                c->oc_conn->cc_recovery_handler(nodenum,
+                                                c->oc_conn->cc_recovery_data);
+        }
+
+        mutex_unlock(&ocfs2_control_lock);
+}
+
+/*
+ * Called whenever configuration elements are sent to /dev/ocfs2_control.
+ * If all configuration elements are present, try to set the global
+ * values.  If there is a problem, return an error.  Skip any missing
+ * elements, and only bump ocfs2_control_opened when we have all elements
+ * and are successful.
+ */
+static int ocfs2_control_install_private(struct file *file)
+{
+        int rc = 0;
+        int set_p = 1;
+        struct ocfs2_control_private *p = file->private_data;
+
+        BUG_ON(p->op_state != OCFS2_CONTROL_HANDSHAKE_PROTOCOL);
+
+        mutex_lock(&ocfs2_control_lock);
+
+        if (p->op_this_node < 0) {
+                set_p = 0;
+        } else if ((ocfs2_control_this_node >= 0) &&
+                   (ocfs2_control_this_node != p->op_this_node)) {
+                rc = -EINVAL;
+                goto out_unlock;
+        }
+
+        if (!p->op_proto.pv_major) {
+                set_p = 0;
+        } else if (!list_empty(&ocfs2_live_connection_list) &&
+                   ((running_proto.pv_major != p->op_proto.pv_major) ||
+                    (running_proto.pv_minor != p->op_proto.pv_minor))) {
+                rc = -EINVAL;
+                goto out_unlock;
+        }
+
+        if (set_p) {
+                ocfs2_control_this_node = p->op_this_node;
+                running_proto.pv_major = p->op_proto.pv_major;
+                running_proto.pv_minor = p->op_proto.pv_minor;
+        }
+
+out_unlock:
+        mutex_unlock(&ocfs2_control_lock);
+
+        if (!rc && set_p) {
+                /* We set the global values successfully */
+                atomic_inc(&ocfs2_control_opened);
+                ocfs2_control_set_handshake_state(file,
+                                        OCFS2_CONTROL_HANDSHAKE_VALID);
+        }
+
+        return rc;
+}
+
+static int ocfs2_control_get_this_node(void)
+{
+        int rc;
+
+        mutex_lock(&ocfs2_control_lock);
+        if (ocfs2_control_this_node < 0)
+                rc = -EINVAL;
+        else
+                rc = ocfs2_control_this_node;
+        mutex_unlock(&ocfs2_control_lock);
+
+        return rc;
+}
+
+static int ocfs2_control_do_setnode_msg(struct file *file,
+                                        struct ocfs2_control_message_setn *msg)
+{
+        long nodenum;
+        char *ptr = NULL;
+        struct ocfs2_control_private *p = file->private_data;
+
+        if (ocfs2_control_get_handshake_state(file) !=
+            OCFS2_CONTROL_HANDSHAKE_PROTOCOL)
+                return -EINVAL;
+
+        if (strncmp(msg->tag, OCFS2_CONTROL_MESSAGE_SETNODE_OP,
+                    OCFS2_CONTROL_MESSAGE_OP_LEN))
+                return -EINVAL;
+
+        if ((msg->space != ' ') || (msg->newline != '\n'))
+                return -EINVAL;
+        msg->space = msg->newline = '\0';
+
+        nodenum = simple_strtol(msg->nodestr, &ptr, 16);
+        if (!ptr || *ptr)
+                return -EINVAL;
+
+        if ((nodenum == LONG_MIN) || (nodenum == LONG_MAX) ||
+            (nodenum > INT_MAX) || (nodenum < 0))
+                return -ERANGE;
+        p->op_this_node = nodenum;
+
+        return ocfs2_control_install_private(file);
+}
+
+static int ocfs2_control_do_setversion_msg(struct file *file,
+                                           struct ocfs2_control_message_setv *msg)
+ {
+        long major, minor;
+        char *ptr = NULL;
+        struct ocfs2_control_private *p = file->private_data;
+        struct ocfs2_protocol_version *max =
+                &user_stack.sp_proto->lp_max_version;
+
+        if (ocfs2_control_get_handshake_state(file) !=
+            OCFS2_CONTROL_HANDSHAKE_PROTOCOL)
+                return -EINVAL;
+
+        if (strncmp(msg->tag, OCFS2_CONTROL_MESSAGE_SETVERSION_OP,
+                    OCFS2_CONTROL_MESSAGE_OP_LEN))
+                return -EINVAL;
+
+        if ((msg->space1 != ' ') || (msg->space2 != ' ') ||
+            (msg->newline != '\n'))
+                return -EINVAL;
+        msg->space1 = msg->space2 = msg->newline = '\0';
+
+        major = simple_strtol(msg->major, &ptr, 16);
+        if (!ptr || *ptr)
+                return -EINVAL;
+        minor = simple_strtol(msg->minor, &ptr, 16);
+        if (!ptr || *ptr)
+                return -EINVAL;
+
+        /*
+         * The major must be between 1 and 255, inclusive.  The minor
+         * must be between 0 and 255, inclusive.  The version passed in
+         * must be within the maximum version supported by the filesystem.
+         */
+        if ((major == LONG_MIN) || (major == LONG_MAX) ||
+            (major > (u8)-1) || (major < 1))
+                return -ERANGE;
+        if ((minor == LONG_MIN) || (minor == LONG_MAX) ||
+            (minor > (u8)-1) || (minor < 0))
+                return -ERANGE;
+        if ((major != max->pv_major) ||
+            (minor > max->pv_minor))
+                return -EINVAL;
+
+        p->op_proto.pv_major = major;
+        p->op_proto.pv_minor = minor;
+
+        return ocfs2_control_install_private(file);
+}
+
+static int ocfs2_control_do_down_msg(struct file *file,
+                                     struct ocfs2_control_message_down *msg)
+{
+        long nodenum;
+        char *p = NULL;
+
+        if (ocfs2_control_get_handshake_state(file) !=
+            OCFS2_CONTROL_HANDSHAKE_VALID)
+                return -EINVAL;
+
+        if (strncmp(msg->tag, OCFS2_CONTROL_MESSAGE_DOWN_OP,
+                    OCFS2_CONTROL_MESSAGE_OP_LEN))
+                return -EINVAL;
+
+        if ((msg->space1 != ' ') || (msg->space2 != ' ') ||
+            (msg->newline != '\n'))
+                return -EINVAL;
+        msg->space1 = msg->space2 = msg->newline = '\0';
+
+        nodenum = simple_strtol(msg->nodestr, &p, 16);
+        if (!p || *p)
+                return -EINVAL;
+
+        if ((nodenum == LONG_MIN) || (nodenum == LONG_MAX) ||
+            (nodenum > INT_MAX) || (nodenum < 0))
+                return -ERANGE;
+
+        ocfs2_control_send_down(msg->uuid, nodenum);
+
+        return 0;
+}
+
+static ssize_t ocfs2_control_message(struct file *file,
+                                     const char __user *buf,
+                                     size_t count)
+{
+        ssize_t ret;
+        union ocfs2_control_message msg;
+
+        /* Try to catch padding issues */
+        WARN_ON(offsetof(struct ocfs2_control_message_down, uuid) !=
+                (sizeof(msg.u_down.tag) + sizeof(msg.u_down.space1)));
+
+        memset(&msg, 0, sizeof(union ocfs2_control_message));
+        ret = ocfs2_control_cfu(&msg, count, buf, count);
+        if (ret)
+                goto out;
+
+        if ((count == OCFS2_CONTROL_MESSAGE_SETNODE_TOTAL_LEN) &&
+            !strncmp(msg.tag, OCFS2_CONTROL_MESSAGE_SETNODE_OP,
+                     OCFS2_CONTROL_MESSAGE_OP_LEN))
+                ret = ocfs2_control_do_setnode_msg(file, &msg.u_setn);
+        else if ((count == OCFS2_CONTROL_MESSAGE_SETVERSION_TOTAL_LEN) &&
+                 !strncmp(msg.tag, OCFS2_CONTROL_MESSAGE_SETVERSION_OP,
+                          OCFS2_CONTROL_MESSAGE_OP_LEN))
+                ret = ocfs2_control_do_setversion_msg(file, &msg.u_setv);
+        else if ((count == OCFS2_CONTROL_MESSAGE_DOWN_TOTAL_LEN) &&
+                 !strncmp(msg.tag, OCFS2_CONTROL_MESSAGE_DOWN_OP,
+                          OCFS2_CONTROL_MESSAGE_OP_LEN))
+                ret = ocfs2_control_do_down_msg(file, &msg.u_down);
+        else
+                ret = -EINVAL;
+
+out:
+        return ret ? ret : count;
+}
+
+static ssize_t ocfs2_control_write(struct file *file,
+                                   const char __user *buf,
+                                   size_t count,
+                                   loff_t *ppos)
+{
+        ssize_t ret;
+
+        switch (ocfs2_control_get_handshake_state(file)) {
+                case OCFS2_CONTROL_HANDSHAKE_INVALID:
+                        ret = -EINVAL;
+                        break;
+
+                case OCFS2_CONTROL_HANDSHAKE_READ:
+                        ret = ocfs2_control_validate_protocol(file, buf,
+                                                              count);
+                        break;
+
+                case OCFS2_CONTROL_HANDSHAKE_PROTOCOL:
+                case OCFS2_CONTROL_HANDSHAKE_VALID:
+                        ret = ocfs2_control_message(file, buf, count);
+                        break;
+
+                default:
+                        BUG();
+                        ret = -EIO;
+                        break;
+        }
+
+        return ret;
+}
+
+/*
+ * This is a naive version.  If we ever have a new protocol, we'll expand
+ * it.  Probably using seq_file.
+ */
+static ssize_t ocfs2_control_read(struct file *file,
+                                  char __user *buf,
+                                  size_t count,
+                                  loff_t *ppos)
+{
+        char *proto_string = OCFS2_CONTROL_PROTO;
+        size_t to_write = 0;
+
+        if (*ppos >= OCFS2_CONTROL_PROTO_LEN)
+                return 0;
+
+        to_write = OCFS2_CONTROL_PROTO_LEN - *ppos;
+        if (to_write > count)
+                to_write = count;
+        if (copy_to_user(buf, proto_string + *ppos, to_write))
+                return -EFAULT;
+
+        *ppos += to_write;
+
+        /* Have we read the whole protocol list? */
+        if (*ppos >= OCFS2_CONTROL_PROTO_LEN)
+                ocfs2_control_set_handshake_state(file,
+                                                  OCFS2_CONTROL_HANDSHAKE_READ);
+
+        return to_write;
+}
+
+static int ocfs2_control_release(struct inode *inode, struct file *file)
+{
+        struct ocfs2_control_private *p = file->private_data;
+
+        mutex_lock(&ocfs2_control_lock);
+
+        if (ocfs2_control_get_handshake_state(file) !=
+            OCFS2_CONTROL_HANDSHAKE_VALID)
+                goto out;
+
+        if (atomic_dec_and_test(&ocfs2_control_opened)) {
+                if (!list_empty(&ocfs2_live_connection_list)) {
+                        /* XXX: Do bad things! */
+                        printk(KERN_ERR
+                               "ocfs2: Unexpected release of ocfs2_control!\n"
+                               "       Loss of cluster connection requires "
+                               "an emergency restart!\n");
+                        emergency_restart();
+                }
+                /*
+                 * Last valid close clears the node number and resets
+                 * the locking protocol version
+                 */
+                ocfs2_control_this_node = -1;
+                running_proto.pv_major = 0;
+                running_proto.pv_major = 0;
+        }
+
+out:
+        list_del_init(&p->op_list);
+        file->private_data = NULL;
+
+        mutex_unlock(&ocfs2_control_lock);
+
+        kfree(p);
+
+        return 0;
+}
+
+static int ocfs2_control_open(struct inode *inode, struct file *file)
+{
+        struct ocfs2_control_private *p;
+
+        p = kzalloc(sizeof(struct ocfs2_control_private), GFP_KERNEL);
+        if (!p)
+                return -ENOMEM;
+        p->op_this_node = -1;
+
+        mutex_lock(&ocfs2_control_lock);
+        file->private_data = p;
+        list_add(&p->op_list, &ocfs2_control_private_list);
+        mutex_unlock(&ocfs2_control_lock);
+
+        return 0;
+}
+
+static const struct file_operations ocfs2_control_fops = {
+        .open    = ocfs2_control_open,
+        .release = ocfs2_control_release,
+        .read    = ocfs2_control_read,
+        .write   = ocfs2_control_write,
+        .owner   = THIS_MODULE,
+};
+
+struct miscdevice ocfs2_control_device = {
+        .minor          = MISC_DYNAMIC_MINOR,
+        .name           = "ocfs2_control",
+        .fops           = &ocfs2_control_fops,
+};
+
+static int ocfs2_control_init(void)
+{
+        int rc;
+
+        atomic_set(&ocfs2_control_opened, 0);
+
+        rc = misc_register(&ocfs2_control_device);
+        if (rc)
+                printk(KERN_ERR
+                       "ocfs2: Unable to register ocfs2_control device "
+                       "(errno %d)\n",
+                       -rc);
+
+        return rc;
+}
+
+static void ocfs2_control_exit(void)
+{
+        int rc;
+
+        rc = misc_deregister(&ocfs2_control_device);
+        if (rc)
+                printk(KERN_ERR
+                       "ocfs2: Unable to deregister ocfs2_control device "
+                       "(errno %d)\n",
+                       -rc);
+}
+
+static struct dlm_lksb *fsdlm_astarg_to_lksb(void *astarg)
+{
+        struct ocfs2_lock_res *res = astarg;
+        return &res->l_lksb.lksb_fsdlm;
+}
+
+static void fsdlm_lock_ast_wrapper(void *astarg)
+{
+        struct dlm_lksb *lksb = fsdlm_astarg_to_lksb(astarg);
+        int status = lksb->sb_status;
+
+        BUG_ON(user_stack.sp_proto == NULL);
+
+        /*
+         * For now we're punting on the issue of other non-standard errors
+         * where we can't tell if the unlock_ast or lock_ast should be called.
+         * The main "other error" that's possible is EINVAL which means the
+         * function was called with invalid args, which shouldn't be possible
+         * since the caller here is under our control.  Other non-standard
+         * errors probably fall into the same category, or otherwise are fatal
+         * which means we can't carry on anyway.
+         */
+
+        if (status == -DLM_EUNLOCK || status == -DLM_ECANCEL)
+                user_stack.sp_proto->lp_unlock_ast(astarg, 0);
+        else
+                user_stack.sp_proto->lp_lock_ast(astarg);
+}
+
+static void fsdlm_blocking_ast_wrapper(void *astarg, int level)
+{
+        BUG_ON(user_stack.sp_proto == NULL);
+
+        user_stack.sp_proto->lp_blocking_ast(astarg, level);
+}
+
+static int user_dlm_lock(struct ocfs2_cluster_connection *conn,
+                         int mode,
+                         union ocfs2_dlm_lksb *lksb,
+                         u32 flags,
+                         void *name,
+                         unsigned int namelen,
+                         void *astarg)
+{
+        int ret;
+
+        if (!lksb->lksb_fsdlm.sb_lvbptr)
+                lksb->lksb_fsdlm.sb_lvbptr = (char *)lksb +
+                                             sizeof(struct dlm_lksb);
+
+        ret = dlm_lock(conn->cc_lockspace, mode, &lksb->lksb_fsdlm,
+                       flags|DLM_LKF_NODLCKWT, name, namelen, 0,
+                       fsdlm_lock_ast_wrapper, astarg,
+                       fsdlm_blocking_ast_wrapper);
+        return ret;
+}
+
+static int user_dlm_unlock(struct ocfs2_cluster_connection *conn,
+                           union ocfs2_dlm_lksb *lksb,
+                           u32 flags,
+                           void *astarg)
+{
+        int ret;
+
+        ret = dlm_unlock(conn->cc_lockspace, lksb->lksb_fsdlm.sb_lkid,
+                         flags, &lksb->lksb_fsdlm, astarg);
+        return ret;
+}
+
+static int user_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
+{
+        return lksb->lksb_fsdlm.sb_status;
+}
+
+static void *user_dlm_lvb(union ocfs2_dlm_lksb *lksb)
+{
+        return (void *)(lksb->lksb_fsdlm.sb_lvbptr);
+}
+
+static void user_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
+{
+}
+
+/*
+ * Compare a requested locking protocol version against the current one.
+ *
+ * If the major numbers are different, they are incompatible.
+ * If the current minor is greater than the request, they are incompatible.
+ * If the current minor is less than or equal to the request, they are
+ * compatible, and the requester should run at the current minor version.
+ */
+static int fs_protocol_compare(struct ocfs2_protocol_version *existing,
+                               struct ocfs2_protocol_version *request)
+{
+        if (existing->pv_major != request->pv_major)
+                return 1;
+
+        if (existing->pv_minor > request->pv_minor)
+                return 1;
+
+        if (existing->pv_minor < request->pv_minor)
+                request->pv_minor = existing->pv_minor;
+
+        return 0;
+}
+
+static int user_cluster_connect(struct ocfs2_cluster_connection *conn)
+{
+        dlm_lockspace_t *fsdlm;
+        struct ocfs2_live_connection *control;
+        int rc = 0;
+
+        BUG_ON(conn == NULL);
+
+        rc = ocfs2_live_connection_new(conn, &control);
+        if (rc)
+                goto out;
+
+        /*
+         * running_proto must have been set before we allowed any mounts
+         * to proceed.
+         */
+        if (fs_protocol_compare(&running_proto, &conn->cc_version)) {
+                printk(KERN_ERR
+                       "Unable to mount with fs locking protocol version "
+                       "%u.%u because the userspace control daemon has "
+                       "negotiated %u.%u\n",
+                       conn->cc_version.pv_major, conn->cc_version.pv_minor,
+                       running_proto.pv_major, running_proto.pv_minor);
+                rc = -EPROTO;
+                ocfs2_live_connection_drop(control);
+                goto out;
+        }
+
+        rc = dlm_new_lockspace(conn->cc_name, strlen(conn->cc_name),
+                               &fsdlm, DLM_LSFL_FS, DLM_LVB_LEN);
+        if (rc) {
+                ocfs2_live_connection_drop(control);
+                goto out;
+        }
+
+        conn->cc_private = control;
+        conn->cc_lockspace = fsdlm;
+out:
+        return rc;
+}
+
+static int user_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+                                   int hangup_pending)
+{
+        dlm_release_lockspace(conn->cc_lockspace, 2);
+        conn->cc_lockspace = NULL;
+        ocfs2_live_connection_drop(conn->cc_private);
+        conn->cc_private = NULL;
+        return 0;
+}
+
+static int user_cluster_this_node(unsigned int *this_node)
+{
+        int rc;
+
+        rc = ocfs2_control_get_this_node();
+        if (rc < 0)
+                return rc;
+
+        *this_node = rc;
+        return 0;
+}
+
+static struct ocfs2_stack_operations user_stack_ops = {
+        .connect        = user_cluster_connect,
+        .disconnect     = user_cluster_disconnect,
+        .this_node      = user_cluster_this_node,
+        .dlm_lock       = user_dlm_lock,
+        .dlm_unlock     = user_dlm_unlock,
+        .lock_status    = user_dlm_lock_status,
+        .lock_lvb       = user_dlm_lvb,
+        .dump_lksb      = user_dlm_dump_lksb,
+};
+
+static struct ocfs2_stack_plugin user_stack = {
+        .sp_name        = "user",
+        .sp_ops         = &user_stack_ops,
+        .sp_owner       = THIS_MODULE,
+};
+
+
+static int __init user_stack_init(void)
+{
+        int rc;
+
+        rc = ocfs2_control_init();
+        if (!rc) {
+                rc = ocfs2_stack_glue_register(&user_stack);
+                if (rc)
+                        ocfs2_control_exit();
+        }
+
+        return rc;
+}
+
+static void __exit user_stack_exit(void)
+{
+        ocfs2_stack_glue_unregister(&user_stack);
+        ocfs2_control_exit();
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_DESCRIPTION("ocfs2 driver for userspace cluster stacks");
+MODULE_LICENSE("GPL");
+module_init(user_stack_init);
+module_exit(user_stack_exit);
diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
new file mode 100644
index 000000000000..119f60cea9cc
--- /dev/null
+++ b/fs/ocfs2/stackglue.c
@@ -0,0 +1,568 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * stackglue.c
+ *
+ * Code which implements an OCFS2 specific interface to underlying
+ * cluster stacks.
+ *
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/kmod.h>
+#include <linux/fs.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+
+#include "ocfs2_fs.h"
+
+#include "stackglue.h"
+
+#define OCFS2_STACK_PLUGIN_O2CB         "o2cb"
+#define OCFS2_STACK_PLUGIN_USER         "user"
+
+static struct ocfs2_locking_protocol *lproto;
+static DEFINE_SPINLOCK(ocfs2_stack_lock);
+static LIST_HEAD(ocfs2_stack_list);
+static char cluster_stack_name[OCFS2_STACK_LABEL_LEN + 1];
+
+/*
+ * The stack currently in use.  If not null, active_stack->sp_count > 0,
+ * the module is pinned, and the locking protocol cannot be changed.
+ */
+static struct ocfs2_stack_plugin *active_stack;
+
+static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name)
+{
+        struct ocfs2_stack_plugin *p;
+
+        assert_spin_locked(&ocfs2_stack_lock);
+
+        list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
+                if (!strcmp(p->sp_name, name))
+                        return p;
+        }
+
+        return NULL;
+}
+
+static int ocfs2_stack_driver_request(const char *stack_name,
+                                      const char *plugin_name)
+{
+        int rc;
+        struct ocfs2_stack_plugin *p;
+
+        spin_lock(&ocfs2_stack_lock);
+
+        /*
+         * If the stack passed by the filesystem isn't the selected one,
+         * we can't continue.
+         */
+        if (strcmp(stack_name, cluster_stack_name)) {
+                rc = -EBUSY;
+                goto out;
+        }
+
+        if (active_stack) {
+                /*
+                 * If the active stack isn't the one we want, it cannot
+                 * be selected right now.
+                 */
+                if (!strcmp(active_stack->sp_name, plugin_name))
+                        rc = 0;
+                else
+                        rc = -EBUSY;
+                goto out;
+        }
+
+        p = ocfs2_stack_lookup(plugin_name);
+        if (!p || !try_module_get(p->sp_owner)) {
+                rc = -ENOENT;
+                goto out;
+        }
+
+        /* Ok, the stack is pinned */
+        p->sp_count++;
+        active_stack = p;
+
+        rc = 0;
+
+out:
+        spin_unlock(&ocfs2_stack_lock);
+        return rc;
+}
+
+/*
+ * This function looks up the appropriate stack and makes it active.  If
+ * there is no stack, it tries to load it.  It will fail if the stack still
+ * cannot be found.  It will also fail if a different stack is in use.
+ */
+static int ocfs2_stack_driver_get(const char *stack_name)
+{
+        int rc;
+        char *plugin_name = OCFS2_STACK_PLUGIN_O2CB;
+
+        /*
+         * Classic stack does not pass in a stack name.  This is
+         * compatible with older tools as well.
+         */
+        if (!stack_name || !*stack_name)
+                stack_name = OCFS2_STACK_PLUGIN_O2CB;
+
+        if (strlen(stack_name) != OCFS2_STACK_LABEL_LEN) {
+                printk(KERN_ERR
+                       "ocfs2 passed an invalid cluster stack label: \"%s\"\n",
+                       stack_name);
+                return -EINVAL;
+        }
+
+        /* Anything that isn't the classic stack is a user stack */
+        if (strcmp(stack_name, OCFS2_STACK_PLUGIN_O2CB))
+                plugin_name = OCFS2_STACK_PLUGIN_USER;
+
+        rc = ocfs2_stack_driver_request(stack_name, plugin_name);
+        if (rc == -ENOENT) {
+                request_module("ocfs2_stack_%s", plugin_name);
+                rc = ocfs2_stack_driver_request(stack_name, plugin_name);
+        }
+
+        if (rc == -ENOENT) {
+                printk(KERN_ERR
+                       "ocfs2: Cluster stack driver \"%s\" cannot be found\n",
+                       plugin_name);
+        } else if (rc == -EBUSY) {
+                printk(KERN_ERR
+                       "ocfs2: A different cluster stack is in use\n");
+        }
+
+        return rc;
+}
+
+static void ocfs2_stack_driver_put(void)
+{
+        spin_lock(&ocfs2_stack_lock);
+        BUG_ON(active_stack == NULL);
+        BUG_ON(active_stack->sp_count == 0);
+
+        active_stack->sp_count--;
+        if (!active_stack->sp_count) {
+                module_put(active_stack->sp_owner);
+                active_stack = NULL;
+        }
+        spin_unlock(&ocfs2_stack_lock);
+}
+
+int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin)
+{
+        int rc;
+
+        spin_lock(&ocfs2_stack_lock);
+        if (!ocfs2_stack_lookup(plugin->sp_name)) {
+                plugin->sp_count = 0;
+                plugin->sp_proto = lproto;
+                list_add(&plugin->sp_list, &ocfs2_stack_list);
+                printk(KERN_INFO "ocfs2: Registered cluster interface %s\n",
+                       plugin->sp_name);
+                rc = 0;
+        } else {
+                printk(KERN_ERR "ocfs2: Stack \"%s\" already registered\n",
+                       plugin->sp_name);
+                rc = -EEXIST;
+        }
+        spin_unlock(&ocfs2_stack_lock);
+
+        return rc;
+}
+EXPORT_SYMBOL_GPL(ocfs2_stack_glue_register);
+
+void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin)
+{
+        struct ocfs2_stack_plugin *p;
+
+        spin_lock(&ocfs2_stack_lock);
+        p = ocfs2_stack_lookup(plugin->sp_name);
+        if (p) {
+                BUG_ON(p != plugin);
+                BUG_ON(plugin == active_stack);
+                BUG_ON(plugin->sp_count != 0);
+                list_del_init(&plugin->sp_list);
+                printk(KERN_INFO "ocfs2: Unregistered cluster interface %s\n",
+                       plugin->sp_name);
+        } else {
+                printk(KERN_ERR "Stack \"%s\" is not registered\n",
+                       plugin->sp_name);
+        }
+        spin_unlock(&ocfs2_stack_lock);
+}
+EXPORT_SYMBOL_GPL(ocfs2_stack_glue_unregister);
+
+void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto)
+{
+        struct ocfs2_stack_plugin *p;
+
+        BUG_ON(proto == NULL);
+
+        spin_lock(&ocfs2_stack_lock);
+        BUG_ON(active_stack != NULL);
+
+        lproto = proto;
+        list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
+                p->sp_proto = lproto;
+        }
+
+        spin_unlock(&ocfs2_stack_lock);
+}
+EXPORT_SYMBOL_GPL(ocfs2_stack_glue_set_locking_protocol);
+
+
+/*
+ * The ocfs2_dlm_lock() and ocfs2_dlm_unlock() functions take
+ * "struct ocfs2_lock_res *astarg" instead of "void *astarg" because the
+ * underlying stack plugins need to pilfer the lksb off of the lock_res.
+ * If some other structure needs to be passed as an astarg, the plugins
+ * will need to be given a different avenue to the lksb.
+ */
+int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
+                   int mode,
+                   union ocfs2_dlm_lksb *lksb,
+                   u32 flags,
+                   void *name,
+                   unsigned int namelen,
+                   struct ocfs2_lock_res *astarg)
+{
+        BUG_ON(lproto == NULL);
+
+        return active_stack->sp_ops->dlm_lock(conn, mode, lksb, flags,
+                                              name, namelen, astarg);
+}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_lock);
+
+int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
+                     union ocfs2_dlm_lksb *lksb,
+                     u32 flags,
+                     struct ocfs2_lock_res *astarg)
+{
+        BUG_ON(lproto == NULL);
+
+        return active_stack->sp_ops->dlm_unlock(conn, lksb, flags, astarg);
+}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_unlock);
+
+int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
+{
+        return active_stack->sp_ops->lock_status(lksb);
+}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_lock_status);
+
+/*
+ * Why don't we cast to ocfs2_meta_lvb?  The "clean" answer is that we
+ * don't cast at the glue level.  The real answer is that the header
+ * ordering is nigh impossible.
+ */
+void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb)
+{
+        return active_stack->sp_ops->lock_lvb(lksb);
+}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb);
+
+void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
+{
+        active_stack->sp_ops->dump_lksb(lksb);
+}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);
+
+int ocfs2_cluster_connect(const char *stack_name,
+                          const char *group,
+                          int grouplen,
+                          void (*recovery_handler)(int node_num,
+                                                   void *recovery_data),
+                          void *recovery_data,
+                          struct ocfs2_cluster_connection **conn)
+{
+        int rc = 0;
+        struct ocfs2_cluster_connection *new_conn;
+
+        BUG_ON(group == NULL);
+        BUG_ON(conn == NULL);
+        BUG_ON(recovery_handler == NULL);
+
+        if (grouplen > GROUP_NAME_MAX) {
+                rc = -EINVAL;
+                goto out;
+        }
+
+        new_conn = kzalloc(sizeof(struct ocfs2_cluster_connection),
+                           GFP_KERNEL);
+        if (!new_conn) {
+                rc = -ENOMEM;
+                goto out;
+        }
+
+        memcpy(new_conn->cc_name, group, grouplen);
+        new_conn->cc_namelen = grouplen;
+        new_conn->cc_recovery_handler = recovery_handler;
+        new_conn->cc_recovery_data = recovery_data;
+
+        /* Start the new connection at our maximum compatibility level */
+        new_conn->cc_version = lproto->lp_max_version;
+
+        /* This will pin the stack driver if successful */
+        rc = ocfs2_stack_driver_get(stack_name);
+        if (rc)
+                goto out_free;
+
+        rc = active_stack->sp_ops->connect(new_conn);
+        if (rc) {
+                ocfs2_stack_driver_put();
+                goto out_free;
+        }
+
+        *conn = new_conn;
+
+out_free:
+        if (rc)
+                kfree(new_conn);
+
+out:
+        return rc;
+}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);
+
+/* If hangup_pending is 0, the stack driver will be dropped */
+int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+                             int hangup_pending)
+{
+        int ret;
+
+        BUG_ON(conn == NULL);
+
+        ret = active_stack->sp_ops->disconnect(conn, hangup_pending);
+
+        /* XXX Should we free it anyway? */
+        if (!ret) {
+                kfree(conn);
+                if (!hangup_pending)
+                        ocfs2_stack_driver_put();
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_disconnect);
+
+void ocfs2_cluster_hangup(const char *group, int grouplen)
+{
+        BUG_ON(group == NULL);
+        BUG_ON(group[grouplen] != '\0');
+
+        if (active_stack->sp_ops->hangup)
+                active_stack->sp_ops->hangup(group, grouplen);
+
+        /* cluster_disconnect() was called with hangup_pending==1 */
+        ocfs2_stack_driver_put();
+}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_hangup);
+
+int ocfs2_cluster_this_node(unsigned int *node)
+{
+        return active_stack->sp_ops->this_node(node);
+}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);
+
+
+/*
+ * Sysfs bits
+ */
+
+static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
+                                               struct kobj_attribute *attr,
+                                               char *buf)
+{
+        ssize_t ret = 0;
+
+        spin_lock(&ocfs2_stack_lock);
+        if (lproto)
+                ret = snprintf(buf, PAGE_SIZE, "%u.%u\n",
+                               lproto->lp_max_version.pv_major,
+                               lproto->lp_max_version.pv_minor);
+        spin_unlock(&ocfs2_stack_lock);
+
+        return ret;
+}
+
+static struct kobj_attribute ocfs2_attr_max_locking_protocol =
+        __ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
+               ocfs2_max_locking_protocol_show, NULL);
+
+static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
+                                                 struct kobj_attribute *attr,
+                                                 char *buf)
+{
+        ssize_t ret = 0, total = 0, remain = PAGE_SIZE;
+        struct ocfs2_stack_plugin *p;
+
+        spin_lock(&ocfs2_stack_lock);
+        list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
+                ret = snprintf(buf, remain, "%s\n",
+                               p->sp_name);
+                if (ret < 0) {
+                        total = ret;
+                        break;
+                }
+                if (ret == remain) {
+                        /* snprintf() didn't fit */
+                        total = -E2BIG;
+                        break;
+                }
+                total += ret;
+                remain -= ret;
+        }
+        spin_unlock(&ocfs2_stack_lock);
+
+        return total;
+}
+
+static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
+        __ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
+               ocfs2_loaded_cluster_plugins_show, NULL);
+
+static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
+                                                struct kobj_attribute *attr,
+                                                char *buf)
+{
+        ssize_t ret = 0;
+
+        spin_lock(&ocfs2_stack_lock);
+        if (active_stack) {
+                ret = snprintf(buf, PAGE_SIZE, "%s\n",
+                               active_stack->sp_name);
+                if (ret == PAGE_SIZE)
+                        ret = -E2BIG;
+        }
+        spin_unlock(&ocfs2_stack_lock);
+
+        return ret;
+}
+
+static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
+        __ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
+               ocfs2_active_cluster_plugin_show, NULL);
+
+static ssize_t ocfs2_cluster_stack_show(struct kobject *kobj,
+                                        struct kobj_attribute *attr,
+                                        char *buf)
+{
+        ssize_t ret;
+        spin_lock(&ocfs2_stack_lock);
+        ret = snprintf(buf, PAGE_SIZE, "%s\n", cluster_stack_name);
+        spin_unlock(&ocfs2_stack_lock);
+
+        return ret;
+}
+
+static ssize_t ocfs2_cluster_stack_store(struct kobject *kobj,
+                                         struct kobj_attribute *attr,
+                                         const char *buf, size_t count)
+{
+        size_t len = count;
+        ssize_t ret;
+
+        if (len == 0)
+                return len;
+
+        if (buf[len - 1] == '\n')
+                len--;
+
+        if ((len != OCFS2_STACK_LABEL_LEN) ||
+            (strnlen(buf, len) != len))
+                return -EINVAL;
+
+        spin_lock(&ocfs2_stack_lock);
+        if (active_stack) {
+                if (!strncmp(buf, cluster_stack_name, len))
+                        ret = count;
+                else
+                        ret = -EBUSY;
+        } else {
+                memcpy(cluster_stack_name, buf, len);
+                ret = count;
+        }
+        spin_unlock(&ocfs2_stack_lock);
+
+        return ret;
+}
+
+
+static struct kobj_attribute ocfs2_attr_cluster_stack =
+        __ATTR(cluster_stack, S_IFREG | S_IRUGO | S_IWUSR,
+               ocfs2_cluster_stack_show,
+               ocfs2_cluster_stack_store);
+
+static struct attribute *ocfs2_attrs[] = {
+        &ocfs2_attr_max_locking_protocol.attr,
+        &ocfs2_attr_loaded_cluster_plugins.attr,
+        &ocfs2_attr_active_cluster_plugin.attr,
+        &ocfs2_attr_cluster_stack.attr,
+        NULL,
+};
+
+static struct attribute_group ocfs2_attr_group = {
+        .attrs = ocfs2_attrs,
+};
+
+static struct kset *ocfs2_kset;
+
+static void ocfs2_sysfs_exit(void)
+{
+        kset_unregister(ocfs2_kset);
+}
+
+static int ocfs2_sysfs_init(void)
+{
+        int ret;
+
+        ocfs2_kset = kset_create_and_add("ocfs2", NULL, fs_kobj);
+        if (!ocfs2_kset)
+                return -ENOMEM;
+
+        ret = sysfs_create_group(&ocfs2_kset->kobj, &ocfs2_attr_group);
+        if (ret)
+                goto error;
+
+        return 0;
+
+error:
+        kset_unregister(ocfs2_kset);
+        return ret;
+}
+
+static int __init ocfs2_stack_glue_init(void)
+{
+        strcpy(cluster_stack_name, OCFS2_STACK_PLUGIN_O2CB);
+
+        return ocfs2_sysfs_init();
+}
+
+static void __exit ocfs2_stack_glue_exit(void)
+{
+        lproto = NULL;
+        ocfs2_sysfs_exit();
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_DESCRIPTION("ocfs2 cluter stack glue layer");
+MODULE_LICENSE("GPL");
+module_init(ocfs2_stack_glue_init);
+module_exit(ocfs2_stack_glue_exit);
diff --git a/fs/ocfs2/stackglue.h b/fs/ocfs2/stackglue.h
new file mode 100644
index 000000000000..005e4f170e0f
--- /dev/null
+++ b/fs/ocfs2/stackglue.h
@@ -0,0 +1,261 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * stackglue.h
+ *
+ * Glue to the underlying cluster stack.
+ *
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+
+#ifndef STACKGLUE_H
+#define STACKGLUE_H
+
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/dlmconstants.h>
+
+#include "dlm/dlmapi.h"
+#include <linux/dlm.h>
+
+/*
+ * dlmconstants.h does not have a LOCAL flag.  We hope to remove it
+ * some day, but right now we need it.  Let's fake it.  This value is larger
+ * than any flag in dlmconstants.h.
+ */
+#define DLM_LKF_LOCAL           0x00100000
+
+/*
+ * This shadows DLM_LOCKSPACE_LEN in fs/dlm/dlm_internal.h.  That probably
+ * wants to be in a public header.
+ */
+#define GROUP_NAME_MAX          64
+
+
+/*
+ * ocfs2_protocol_version changes when ocfs2 does something different in
+ * its inter-node behavior.  See dlmglue.c for more information.
+ */
+struct ocfs2_protocol_version {
+        u8 pv_major;
+        u8 pv_minor;
+};
+
+/*
+ * The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
+ */
+struct ocfs2_locking_protocol {
+        struct ocfs2_protocol_version lp_max_version;
+        void (*lp_lock_ast)(void *astarg);
+        void (*lp_blocking_ast)(void *astarg, int level);
+        void (*lp_unlock_ast)(void *astarg, int error);
+};
+
+
+/*
+ * The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
+ * has a pointer to separately allocated lvb space.  This struct exists only to
+ * include in the lksb union to make space for a combined dlm_lksb and lvb.
+ */
+struct fsdlm_lksb_plus_lvb {
+        struct dlm_lksb lksb;
+        char lvb[DLM_LVB_LEN];
+};
+
+/*
+ * A union of all lock status structures.  We define it here so that the
+ * size of the union is known.  Lock status structures are embedded in
+ * ocfs2 inodes.
+ */
+union ocfs2_dlm_lksb {
+        struct dlm_lockstatus lksb_o2dlm;
+        struct dlm_lksb lksb_fsdlm;
+        struct fsdlm_lksb_plus_lvb padding;
+};
+
+/*
+ * A cluster connection.  Mostly opaque to ocfs2, the connection holds
+ * state for the underlying stack.  ocfs2 does use cc_version to determine
+ * locking compatibility.
+ */
+struct ocfs2_cluster_connection {
+        char cc_name[GROUP_NAME_MAX];
+        int cc_namelen;
+        struct ocfs2_protocol_version cc_version;
+        void (*cc_recovery_handler)(int node_num, void *recovery_data);
+        void *cc_recovery_data;
+        void *cc_lockspace;
+        void *cc_private;
+};
+
+/*
+ * Each cluster stack implements the stack operations structure.  Not used
+ * in the ocfs2 code, the stackglue code translates generic cluster calls
+ * into stack operations.
+ */
+struct ocfs2_stack_operations {
+        /*
+         * The fs code calls ocfs2_cluster_connect() to attach a new
+         * filesystem to the cluster stack.  The ->connect() op is passed
+         * an ocfs2_cluster_connection with the name and recovery field
+         * filled in.
+         *
+         * The stack must set up any notification mechanisms and create
+         * the filesystem lockspace in the DLM.  The lockspace should be
+         * stored on cc_lockspace.  Any other information can be stored on
+         * cc_private.
+         *
+         * ->connect() must not return until it is guaranteed that
+         *
+         *  - Node down notifications for the filesystem will be recieved
+         *    and passed to conn->cc_recovery_handler().
+         *  - Locking requests for the filesystem will be processed.
+         */
+        int (*connect)(struct ocfs2_cluster_connection *conn);
+
+        /*
+         * The fs code calls ocfs2_cluster_disconnect() when a filesystem
+         * no longer needs cluster services.  All DLM locks have been
+         * dropped, and recovery notification is being ignored by the
+         * fs code.  The stack must disengage from the DLM and discontinue
+         * recovery notification.
+         *
+         * Once ->disconnect() has returned, the connection structure will
+         * be freed.  Thus, a stack must not return from ->disconnect()
+         * until it will no longer reference the conn pointer.
+         *
+         * If hangup_pending is zero, ocfs2_cluster_disconnect() will also
+         * be dropping the reference on the module.
+         */
+        int (*disconnect)(struct ocfs2_cluster_connection *conn,
+                          int hangup_pending);
+
+        /*
+         * ocfs2_cluster_hangup() exists for compatibility with older
+         * ocfs2 tools.  Only the classic stack really needs it.  As such
+         * ->hangup() is not required of all stacks.  See the comment by
+         * ocfs2_cluster_hangup() for more details.
+         *
+         * Note that ocfs2_cluster_hangup() can only be called if
+         * hangup_pending was passed to ocfs2_cluster_disconnect().
+         */
+        void (*hangup)(const char *group, int grouplen);
+
+        /*
+         * ->this_node() returns the cluster's unique identifier for the
+         * local node.
+         */
+        int (*this_node)(unsigned int *node);
+
+        /*
+         * Call the underlying dlm lock function.  The ->dlm_lock()
+         * callback should convert the flags and mode as appropriate.
+         *
+         * ast and bast functions are not part of the call because the
+         * stack will likely want to wrap ast and bast calls before passing
+         * them to stack->sp_proto.
+         */
+        int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
+                        int mode,
+                        union ocfs2_dlm_lksb *lksb,
+                        u32 flags,
+                        void *name,
+                        unsigned int namelen,
+                        void *astarg);
+
+        /*
+         * Call the underlying dlm unlock function.  The ->dlm_unlock()
+         * function should convert the flags as appropriate.
+         *
+         * The unlock ast is not passed, as the stack will want to wrap
+         * it before calling stack->sp_proto->lp_unlock_ast().
+         */
+        int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
+                          union ocfs2_dlm_lksb *lksb,
+                          u32 flags,
+                          void *astarg);
+
+        /*
+         * Return the status of the current lock status block.  The fs
+         * code should never dereference the union.  The ->lock_status()
+         * callback pulls out the stack-specific lksb, converts the status
+         * to a proper errno, and returns it.
+         */
+        int (*lock_status)(union ocfs2_dlm_lksb *lksb);
+
+        /*
+         * Pull the lvb pointer off of the stack-specific lksb.
+         */
+        void *(*lock_lvb)(union ocfs2_dlm_lksb *lksb);
+
+        /*
+         * This is an optoinal debugging hook.  If provided, the
+         * stack can dump debugging information about this lock.
+         */
+        void (*dump_lksb)(union ocfs2_dlm_lksb *lksb);
+};
+
+/*
+ * Each stack plugin must describe itself by registering a
+ * ocfs2_stack_plugin structure.  This is only seen by stackglue and the
+ * stack driver.
+ */
+struct ocfs2_stack_plugin {
+        char *sp_name;
+        struct ocfs2_stack_operations *sp_ops;
+        struct module *sp_owner;
+
+        /* These are managed by the stackglue code. */
+        struct list_head sp_list;
+        unsigned int sp_count;
+        struct ocfs2_locking_protocol *sp_proto;
+};
+
+
+/* Used by the filesystem */
+int ocfs2_cluster_connect(const char *stack_name,
+                          const char *group,
+                          int grouplen,
+                          void (*recovery_handler)(int node_num,
+                                                   void *recovery_data),
+                          void *recovery_data,
+                          struct ocfs2_cluster_connection **conn);
+int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+                             int hangup_pending);
+void ocfs2_cluster_hangup(const char *group, int grouplen);
+int ocfs2_cluster_this_node(unsigned int *node);
+
+struct ocfs2_lock_res;
+int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
+                   int mode,
+                   union ocfs2_dlm_lksb *lksb,
+                   u32 flags,
+                   void *name,
+                   unsigned int namelen,
+                   struct ocfs2_lock_res *astarg);
+int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
+                     union ocfs2_dlm_lksb *lksb,
+                     u32 flags,
+                     struct ocfs2_lock_res *astarg);
+
+int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb);
+void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb);
+void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb);
+
+void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto);
+
+
+/* Used by stack plugins */
+int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
+void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
+#endif  /* STACKGLUE_H */
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 72c198a004df..d2d278fb9819 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -46,6 +46,11 @@
 
 #include "buffer_head_io.h"
 
+#define NOT_ALLOC_NEW_GROUP             0
+#define ALLOC_NEW_GROUP                 1
+
+#define OCFS2_MAX_INODES_TO_STEAL       1024
+
 static inline void ocfs2_debug_bg(struct ocfs2_group_desc *bg);
 static inline void ocfs2_debug_suballoc_inode(struct ocfs2_dinode *fe);
 static inline u16 ocfs2_find_victim_chain(struct ocfs2_chain_list *cl);
@@ -106,7 +111,7 @@ static inline void ocfs2_block_to_cluster_group(struct inode *inode,
                                                 u64 *bg_blkno,
                                                 u16 *bg_bit_off);
 
-void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac)
+static void ocfs2_free_ac_resource(struct ocfs2_alloc_context *ac)
 {
         struct inode *inode = ac->ac_inode;
 
@@ -117,9 +122,17 @@ void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac)
                 mutex_unlock(&inode->i_mutex);
 
                 iput(inode);
+                ac->ac_inode = NULL;
         }
-        if (ac->ac_bh)
+        if (ac->ac_bh) {
                 brelse(ac->ac_bh);
+                ac->ac_bh = NULL;
+        }
+}
+
+void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac)
+{
+        ocfs2_free_ac_resource(ac);
         kfree(ac);
 }
 
@@ -391,7 +404,8 @@ bail:
 static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
                                        struct ocfs2_alloc_context *ac,
                                        int type,
-                                       u32 slot)
+                                       u32 slot,
+                                       int alloc_new_group)
 {
         int status;
         u32 bits_wanted = ac->ac_bits_wanted;
@@ -420,6 +434,7 @@ static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
         }
 
         ac->ac_inode = alloc_inode;
+        ac->ac_alloc_slot = slot;
 
         fe = (struct ocfs2_dinode *) bh->b_data;
         if (!OCFS2_IS_VALID_DINODE(fe)) {
@@ -446,6 +461,14 @@ static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
                         goto bail;
                 }
 
+                if (alloc_new_group != ALLOC_NEW_GROUP) {
+                        mlog(0, "Alloc File %u Full: wanted=%u, free_bits=%u, "
+                             "and we don't alloc a new group for it.\n",
+                             slot, bits_wanted, free_bits);
+                        status = -ENOSPC;
+                        goto bail;
+                }
+
                 status = ocfs2_block_group_alloc(osb, alloc_inode, bh);
                 if (status < 0) {
                         if (status != -ENOSPC)
@@ -490,7 +513,8 @@ int ocfs2_reserve_new_metadata(struct ocfs2_super *osb,
         (*ac)->ac_group_search = ocfs2_block_group_search;
 
         status = ocfs2_reserve_suballoc_bits(osb, (*ac),
-                                             EXTENT_ALLOC_SYSTEM_INODE, slot);
+                                             EXTENT_ALLOC_SYSTEM_INODE,
+                                             slot, ALLOC_NEW_GROUP);
         if (status < 0) {
                 if (status != -ENOSPC)
                         mlog_errno(status);
@@ -508,10 +532,42 @@ bail:
         return status;
 }
 
+static int ocfs2_steal_inode_from_other_nodes(struct ocfs2_super *osb,
+                                              struct ocfs2_alloc_context *ac)
+{
+        int i, status = -ENOSPC;
+        s16 slot = ocfs2_get_inode_steal_slot(osb);
+
+        /* Start to steal inodes from the first slot after ours. */
+        if (slot == OCFS2_INVALID_SLOT)
+                slot = osb->slot_num + 1;
+
+        for (i = 0; i < osb->max_slots; i++, slot++) {
+                if (slot == osb->max_slots)
+                        slot = 0;
+
+                if (slot == osb->slot_num)
+                        continue;
+
+                status = ocfs2_reserve_suballoc_bits(osb, ac,
+                                                     INODE_ALLOC_SYSTEM_INODE,
+                                                     slot, NOT_ALLOC_NEW_GROUP);
+                if (status >= 0) {
+                        ocfs2_set_inode_steal_slot(osb, slot);
+                        break;
+                }
+
+                ocfs2_free_ac_resource(ac);
+        }
+
+        return status;
+}
+
 int ocfs2_reserve_new_inode(struct ocfs2_super *osb,
                             struct ocfs2_alloc_context **ac)
 {
         int status;
+        s16 slot = ocfs2_get_inode_steal_slot(osb);
 
         *ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
         if (!(*ac)) {
@@ -525,9 +581,43 @@ int ocfs2_reserve_new_inode(struct ocfs2_super *osb,
 
         (*ac)->ac_group_search = ocfs2_block_group_search;
 
+        /*
+         * slot is set when we successfully steal inode from other nodes.
+         * It is reset in 3 places:
+         * 1. when we flush the truncate log
+         * 2. when we complete local alloc recovery.
+         * 3. when we successfully allocate from our own slot.
+         * After it is set, we will go on stealing inodes until we find the
+         * need to check our slots to see whether there is some space for us.
+         */
+        if (slot != OCFS2_INVALID_SLOT &&
+            atomic_read(&osb->s_num_inodes_stolen) < OCFS2_MAX_INODES_TO_STEAL)
+                goto inode_steal;
+
+        atomic_set(&osb->s_num_inodes_stolen, 0);
         status = ocfs2_reserve_suballoc_bits(osb, *ac,
                                              INODE_ALLOC_SYSTEM_INODE,
-                                             osb->slot_num);
+                                             osb->slot_num, ALLOC_NEW_GROUP);
+        if (status >= 0) {
+                status = 0;
+
+                /*
+                 * Some inodes must be freed by us, so try to allocate
+                 * from our own next time.
+                 */
+                if (slot != OCFS2_INVALID_SLOT)
+                        ocfs2_init_inode_steal_slot(osb);
+                goto bail;
+        } else if (status < 0 && status != -ENOSPC) {
+                mlog_errno(status);
+                goto bail;
+        }
+
+        ocfs2_free_ac_resource(*ac);
+
+inode_steal:
+        status = ocfs2_steal_inode_from_other_nodes(osb, *ac);
+        atomic_inc(&osb->s_num_inodes_stolen);
         if (status < 0) {
                 if (status != -ENOSPC)
                         mlog_errno(status);
@@ -557,7 +647,8 @@ int ocfs2_reserve_cluster_bitmap_bits(struct ocfs2_super *osb,
 
         status = ocfs2_reserve_suballoc_bits(osb, ac,
                                              GLOBAL_BITMAP_SYSTEM_INODE,
-                                             OCFS2_INVALID_SLOT);
+                                             OCFS2_INVALID_SLOT,
+                                             ALLOC_NEW_GROUP);
         if (status < 0 && status != -ENOSPC) {
                 mlog_errno(status);
                 goto bail;
diff --git a/fs/ocfs2/suballoc.h b/fs/ocfs2/suballoc.h
index 8799033bb459..544c600662bd 100644
--- a/fs/ocfs2/suballoc.h
+++ b/fs/ocfs2/suballoc.h
@@ -36,6 +36,7 @@ typedef int (group_search_t)(struct inode *,
 struct ocfs2_alloc_context {
         struct inode *ac_inode;    /* which bitmap are we allocating from? */
         struct buffer_head *ac_bh; /* file entry bh */
+        u32    ac_alloc_slot;   /* which slot are we allocating from? */
         u32    ac_bits_wanted;
         u32    ac_bits_given;
 #define OCFS2_AC_USE_LOCAL 1
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index bec75aff3d9f..df63ba20ae90 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -40,8 +40,7 @@
 #include <linux/crc32.h>
 #include <linux/debugfs.h>
 #include <linux/mount.h>
-
-#include <cluster/nodemanager.h>
+#include <linux/seq_file.h>
 
 #define MLOG_MASK_PREFIX ML_SUPER
 #include <cluster/masklog.h>
@@ -88,6 +87,7 @@ struct mount_options
         unsigned int    atime_quantum;
         signed short    slot;
         unsigned int    localalloc_opt;
+        char            cluster_stack[OCFS2_STACK_LABEL_LEN + 1];
 };
 
 static int ocfs2_parse_options(struct super_block *sb, char *options,
@@ -109,7 +109,6 @@ static int ocfs2_sync_fs(struct super_block *sb, int wait);
 static int ocfs2_init_global_system_inodes(struct ocfs2_super *osb);
 static int ocfs2_init_local_system_inodes(struct ocfs2_super *osb);
 static void ocfs2_release_system_inodes(struct ocfs2_super *osb);
-static int ocfs2_fill_local_node_info(struct ocfs2_super *osb);
 static int ocfs2_check_volume(struct ocfs2_super *osb);
 static int ocfs2_verify_volume(struct ocfs2_dinode *di,
                                struct buffer_head *bh,
@@ -154,6 +153,7 @@ enum {
         Opt_commit,
         Opt_localalloc,
         Opt_localflocks,
+        Opt_stack,
         Opt_err,
 };
 
@@ -172,6 +172,7 @@ static match_table_t tokens = {
         {Opt_commit, "commit=%u"},
         {Opt_localalloc, "localalloc=%d"},
         {Opt_localflocks, "localflocks"},
+        {Opt_stack, "cluster_stack=%s"},
         {Opt_err, NULL}
 };
 
@@ -551,8 +552,17 @@ static int ocfs2_verify_heartbeat(struct ocfs2_super *osb)
                 }
         }
 
+        if (ocfs2_userspace_stack(osb)) {
+                if (osb->s_mount_opt & OCFS2_MOUNT_HB_LOCAL) {
+                        mlog(ML_ERROR, "Userspace stack expected, but "
+                             "o2cb heartbeat arguments passed to mount\n");
+                        return -EINVAL;
+                }
+        }
+
         if (!(osb->s_mount_opt & OCFS2_MOUNT_HB_LOCAL)) {
-                if (!ocfs2_mount_local(osb) && !ocfs2_is_hard_readonly(osb)) {
+                if (!ocfs2_mount_local(osb) && !ocfs2_is_hard_readonly(osb) &&
+                    !ocfs2_userspace_stack(osb)) {
                         mlog(ML_ERROR, "Heartbeat has to be started to mount "
                              "a read-write clustered device.\n");
                         return -EINVAL;
@@ -562,6 +572,35 @@ static int ocfs2_verify_heartbeat(struct ocfs2_super *osb)
         return 0;
 }
 
+/*
+ * If we're using a userspace stack, mount should have passed
+ * a name that matches the disk.  If not, mount should not
+ * have passed a stack.
+ */
+static int ocfs2_verify_userspace_stack(struct ocfs2_super *osb,
+                                        struct mount_options *mopt)
+{
+        if (!ocfs2_userspace_stack(osb) && mopt->cluster_stack[0]) {
+                mlog(ML_ERROR,
+                     "cluster stack passed to mount, but this filesystem "
+                     "does not support it\n");
+                return -EINVAL;
+        }
+
+        if (ocfs2_userspace_stack(osb) &&
+            strncmp(osb->osb_cluster_stack, mopt->cluster_stack,
+                    OCFS2_STACK_LABEL_LEN)) {
+                mlog(ML_ERROR,
+                     "cluster stack passed to mount (\"%s\") does not "
+                     "match the filesystem (\"%s\")\n",
+                     mopt->cluster_stack,
+                     osb->osb_cluster_stack);
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
 static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
 {
         struct dentry *root;
@@ -579,15 +618,6 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
                 goto read_super_error;
         }
 
-        /* for now we only have one cluster/node, make sure we see it
-         * in the heartbeat universe */
-        if (parsed_options.mount_opt & OCFS2_MOUNT_HB_LOCAL) {
-                if (!o2hb_check_local_node_heartbeating()) {
-                        status = -EINVAL;
-                        goto read_super_error;
-                }
-        }
-
         /* probe for superblock */
         status = ocfs2_sb_probe(sb, &bh, &sector_size);
         if (status < 0) {
@@ -609,6 +639,10 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
         osb->osb_commit_interval = parsed_options.commit_interval;
         osb->local_alloc_size = parsed_options.localalloc_opt;
 
+        status = ocfs2_verify_userspace_stack(osb, &parsed_options);
+        if (status)
+                goto read_super_error;
+
         sb->s_magic = OCFS2_SUPER_MAGIC;
 
         /* Hard readonly mode only if: bdev_read_only, MS_RDONLY,
@@ -694,7 +728,7 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
         if (ocfs2_mount_local(osb))
                 snprintf(nodestr, sizeof(nodestr), "local");
         else
-                snprintf(nodestr, sizeof(nodestr), "%d", osb->node_num);
+                snprintf(nodestr, sizeof(nodestr), "%u", osb->node_num);
 
         printk(KERN_INFO "ocfs2: Mounting device (%s) on (node %s, slot %d) "
                "with %s data mode.\n",
@@ -763,6 +797,7 @@ static int ocfs2_parse_options(struct super_block *sb,
         mopt->atime_quantum = OCFS2_DEFAULT_ATIME_QUANTUM;
         mopt->slot = OCFS2_INVALID_SLOT;
         mopt->localalloc_opt = OCFS2_DEFAULT_LOCAL_ALLOC_SIZE;
+        mopt->cluster_stack[0] = '\0';
 
         if (!options) {
                 status = 1;
@@ -864,6 +899,25 @@ static int ocfs2_parse_options(struct super_block *sb,
                         if (!is_remount)
                                 mopt->mount_opt |= OCFS2_MOUNT_LOCALFLOCKS;
                         break;
+                case Opt_stack:
+                        /* Check both that the option we were passed
+                         * is of the right length and that it is a proper
+                         * string of the right length.
+                         */
+                        if (((args[0].to - args[0].from) !=
+                             OCFS2_STACK_LABEL_LEN) ||
+                            (strnlen(args[0].from,
+                                     OCFS2_STACK_LABEL_LEN) !=
+                             OCFS2_STACK_LABEL_LEN)) {
+                                mlog(ML_ERROR,
+                                     "Invalid cluster_stack option\n");
+                                status = 0;
+                                goto bail;
+                        }
+                        memcpy(mopt->cluster_stack, args[0].from,
+                               OCFS2_STACK_LABEL_LEN);
+                        mopt->cluster_stack[OCFS2_STACK_LABEL_LEN] = '\0';
+                        break;
                 default:
                         mlog(ML_ERROR,
                              "Unrecognized mount option \"%s\" "
@@ -922,6 +976,10 @@ static int ocfs2_show_options(struct seq_file *s, struct vfsmount *mnt)
         if (opts & OCFS2_MOUNT_LOCALFLOCKS)
                 seq_printf(s, ",localflocks,");
 
+        if (osb->osb_cluster_stack[0])
+                seq_printf(s, ",cluster_stack=%.*s", OCFS2_STACK_LABEL_LEN,
+                           osb->osb_cluster_stack);
+
         return 0;
 }
 
@@ -957,6 +1015,8 @@ static int __init ocfs2_init(void)
                 mlog(ML_ERROR, "Unable to create ocfs2 debugfs root.\n");
         }
 
+        ocfs2_set_locking_protocol();
+
 leave:
         if (status < 0) {
                 ocfs2_free_mem_caches();
@@ -1132,31 +1192,6 @@ static int ocfs2_get_sector(struct super_block *sb,
         return 0;
 }
 
-/* ocfs2 1.0 only allows one cluster and node identity per kernel image. */
-static int ocfs2_fill_local_node_info(struct ocfs2_super *osb)
-{
-        int status;
-
-        /* XXX hold a ref on the node while mounte?  easy enough, if
-         * desirable. */
-        if (ocfs2_mount_local(osb))
-                osb->node_num = 0;
-        else
-                osb->node_num = o2nm_this_node();
-
-        if (osb->node_num == O2NM_MAX_NODES) {
-                mlog(ML_ERROR, "could not find this host's node number\n");
-                status = -ENOENT;
-                goto bail;
-        }
-
-        mlog(0, "I am node %d\n", osb->node_num);
-
-        status = 0;
-bail:
-        return status;
-}
-
 static int ocfs2_mount_volume(struct super_block *sb)
 {
         int status = 0;
@@ -1168,12 +1203,6 @@ static int ocfs2_mount_volume(struct super_block *sb)
         if (ocfs2_is_hard_readonly(osb))
                 goto leave;
 
-        status = ocfs2_fill_local_node_info(osb);
-        if (status < 0) {
-                mlog_errno(status);
-                goto leave;
-        }
-
         status = ocfs2_dlm_init(osb);
         if (status < 0) {
                 mlog_errno(status);
@@ -1224,18 +1253,9 @@ leave:
         return status;
 }
 
-/* we can't grab the goofy sem lock from inside wait_event, so we use
- * memory barriers to make sure that we'll see the null task before
- * being woken up */
-static int ocfs2_recovery_thread_running(struct ocfs2_super *osb)
-{
-        mb();
-        return osb->recovery_thread_task != NULL;
-}
-
 static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
 {
-        int tmp;
+        int tmp, hangup_needed = 0;
         struct ocfs2_super *osb = NULL;
         char nodestr[8];
 
@@ -1249,25 +1269,16 @@ static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
 
         ocfs2_truncate_log_shutdown(osb);
 
-        /* disable any new recovery threads and wait for any currently
-         * running ones to exit. Do this before setting the vol_state. */
-        mutex_lock(&osb->recovery_lock);
-        osb->disable_recovery = 1;
-        mutex_unlock(&osb->recovery_lock);
-        wait_event(osb->recovery_event, !ocfs2_recovery_thread_running(osb));
-
-        /* At this point, we know that no more recovery threads can be
-         * launched, so wait for any recovery completion work to
-         * complete. */
-        flush_workqueue(ocfs2_wq);
+        /* This will disable recovery and flush any recovery work. */
+        ocfs2_recovery_exit(osb);
 
         ocfs2_journal_shutdown(osb);
 
         ocfs2_sync_blockdev(sb);
 
-        /* No dlm means we've failed during mount, so skip all the
-         * steps which depended on that to complete. */
-        if (osb->dlm) {
+        /* No cluster connection means we've failed during mount, so skip
+         * all the steps which depended on that to complete. */
+        if (osb->cconn) {
                 tmp = ocfs2_super_lock(osb, 1);
                 if (tmp < 0) {
                         mlog_errno(tmp);
@@ -1278,25 +1289,34 @@ static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
         if (osb->slot_num != OCFS2_INVALID_SLOT)
                 ocfs2_put_slot(osb);
 
-        if (osb->dlm)
+        if (osb->cconn)
                 ocfs2_super_unlock(osb, 1);
 
         ocfs2_release_system_inodes(osb);
 
-        if (osb->dlm)
-                ocfs2_dlm_shutdown(osb);
+        /*
+         * If we're dismounting due to mount error, mount.ocfs2 will clean
+         * up heartbeat.  If we're a local mount, there is no heartbeat.
+         * If we failed before we got a uuid_str yet, we can't stop
+         * heartbeat.  Otherwise, do it.
+         */
+        if (!mnt_err && !ocfs2_mount_local(osb) && osb->uuid_str)
+                hangup_needed = 1;
+
+        if (osb->cconn)
+                ocfs2_dlm_shutdown(osb, hangup_needed);
 
         debugfs_remove(osb->osb_debug_root);
 
-        if (!mnt_err)
-                ocfs2_stop_heartbeat(osb);
+        if (hangup_needed)
+                ocfs2_cluster_hangup(osb->uuid_str, strlen(osb->uuid_str));
 
         atomic_set(&osb->vol_state, VOLUME_DISMOUNTED);
 
         if (ocfs2_mount_local(osb))
                 snprintf(nodestr, sizeof(nodestr), "local");
         else
-                snprintf(nodestr, sizeof(nodestr), "%d", osb->node_num);
+                snprintf(nodestr, sizeof(nodestr), "%u", osb->node_num);
 
         printk(KERN_INFO "ocfs2: Unmounting device (%s) on (node %s)\n",
                osb->dev_str, nodestr);
@@ -1355,7 +1375,6 @@ static int ocfs2_initialize_super(struct super_block *sb,
         sb->s_fs_info = osb;
         sb->s_op = &ocfs2_sops;
         sb->s_export_op = &ocfs2_export_ops;
-        osb->osb_locking_proto = ocfs2_locking_protocol;
         sb->s_time_gran = 1;
         sb->s_flags |= MS_NOATIME;
         /* this is needed to support O_LARGEFILE */
@@ -1368,7 +1387,6 @@ static int ocfs2_initialize_super(struct super_block *sb,
         osb->s_sectsize_bits = blksize_bits(sector_size);
         BUG_ON(!osb->s_sectsize_bits);
 
-        init_waitqueue_head(&osb->recovery_event);
         spin_lock_init(&osb->dc_task_lock);
         init_waitqueue_head(&osb->dc_event);
         osb->dc_work_sequence = 0;
@@ -1376,6 +1394,7 @@ static int ocfs2_initialize_super(struct super_block *sb,
         INIT_LIST_HEAD(&osb->blocked_lock_list);
         osb->blocked_lock_count = 0;
         spin_lock_init(&osb->osb_lock);
+        ocfs2_init_inode_steal_slot(osb);
 
         atomic_set(&osb->alloc_stats.moves, 0);
         atomic_set(&osb->alloc_stats.local_data, 0);
@@ -1388,24 +1407,23 @@ static int ocfs2_initialize_super(struct super_block *sb,
         snprintf(osb->dev_str, sizeof(osb->dev_str), "%u,%u",
                  MAJOR(osb->sb->s_dev), MINOR(osb->sb->s_dev));
 
-        mutex_init(&osb->recovery_lock);
-
-        osb->disable_recovery = 0;
-        osb->recovery_thread_task = NULL;
+        status = ocfs2_recovery_init(osb);
+        if (status) {
+                mlog(ML_ERROR, "Unable to initialize recovery state\n");
+                mlog_errno(status);
+                goto bail;
+        }
 
         init_waitqueue_head(&osb->checkpoint_event);
         atomic_set(&osb->needs_checkpoint, 0);
 
         osb->s_atime_quantum = OCFS2_DEFAULT_ATIME_QUANTUM;
 
-        osb->node_num = O2NM_INVALID_NODE_NUM;
         osb->slot_num = OCFS2_INVALID_SLOT;
 
         osb->local_alloc_state = OCFS2_LA_UNUSED;
         osb->local_alloc_bh = NULL;
 
-        ocfs2_setup_hb_callbacks(osb);
-
         init_waitqueue_head(&osb->osb_mount_event);
 
         osb->vol_label = kmalloc(OCFS2_MAX_VOL_LABEL_LEN, GFP_KERNEL);
@@ -1455,6 +1473,25 @@ static int ocfs2_initialize_super(struct super_block *sb,
                 goto bail;
         }
 
+        if (ocfs2_userspace_stack(osb)) {
+                memcpy(osb->osb_cluster_stack,
+                       OCFS2_RAW_SB(di)->s_cluster_info.ci_stack,
+                       OCFS2_STACK_LABEL_LEN);
+                osb->osb_cluster_stack[OCFS2_STACK_LABEL_LEN] = '\0';
+                if (strlen(osb->osb_cluster_stack) != OCFS2_STACK_LABEL_LEN) {
+                        mlog(ML_ERROR,
+                             "couldn't mount because of an invalid "
+                             "cluster stack label (%s) \n",
+                             osb->osb_cluster_stack);
+                        status = -EINVAL;
+                        goto bail;
+                }
+        } else {
+                /* The empty string is identical with classic tools that
+                 * don't know about s_cluster_info. */
+                osb->osb_cluster_stack[0] = '\0';
+        }
+
         get_random_bytes(&osb->s_next_generation, sizeof(u32));
 
         /* FIXME
@@ -1724,8 +1761,7 @@ static void ocfs2_delete_osb(struct ocfs2_super *osb)
 
         /* This function assumes that the caller has the main osb resource */
 
-        if (osb->slot_info)
-                ocfs2_free_slot_info(osb->slot_info);
+        ocfs2_free_slot_info(osb);
 
         kfree(osb->osb_orphan_wipes);
         /* FIXME
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 5f66c4466151..817f5966edca 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -87,7 +87,14 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
 
 void sysfs_remove_link(struct kobject * kobj, const char * name)
 {
-        sysfs_hash_and_remove(kobj->sd, name);
+        struct sysfs_dirent *parent_sd = NULL;
+
+        if (!kobj)
+                parent_sd = &sysfs_root;
+        else
+                parent_sd = kobj->sd;
+
+        sysfs_hash_and_remove(parent_sd, name);
 }
 
 static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,