ocfs2: Add the USERSPACE_STACK incompat bit.

The filesystem gains the USERSPACE_STACK incomat bit and the
s_cluster_info field on the superblock.  When a userspace stack is in
use, the name of the stack is stored on-disk for mount-time
verification.

The "cluster_stack" option is added to mount(2) processing.  The mount
process needs to pass the matching stack name.  If the passed name and
the on-disk name do not match, the mount is failed.

When using the classic o2cb stack, the incompat bit is *not* set and no
mount option is used other than the usual heartbeat=local.  Thus, the
filesystem is compatible with older tools.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 89 insertions, 1 deletions

diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index e27a0d47ea2b..96ebe36d5d77 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -87,6 +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,
@@ -152,6 +153,7 @@ enum {
         Opt_commit,
         Opt_localalloc,
         Opt_localflocks,
+        Opt_stack,
         Opt_err,
 };
 
@@ -170,6 +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}
 };
 
@@ -549,8 +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;
@@ -560,6 +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;
@@ -598,6 +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,
@@ -752,6 +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;
@@ -853,6 +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\" "
@@ -911,6 +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;
 }
 
@@ -1403,6 +1472,25 @@ 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