12 files changed, 579 insertions, 214 deletions

diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index 7ed6b39e42d2..0e2dcc718de2 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -6,7 +6,7 @@ btrfs-y := super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
            hash.o file-item.o inode-item.o inode-map.o disk-io.o \
            transaction.o bit-radix.o inode.o file.o tree-defrag.o \
            extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \
-           extent_io.o volumes.o async-thread.o ioctl.o
+           extent_io.o volumes.o async-thread.o ioctl.o locking.o
 
 btrfs-$(CONFIG_FS_POSIX_ACL)    += acl.o
 else
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 1d404bde3cfa..75625c68fdd8 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -21,6 +21,7 @@
 #include "disk-io.h"
 #include "transaction.h"
 #include "print-tree.h"
+#include "locking.h"
 
 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
                       *root, struct btrfs_path *path, int level);
@@ -64,12 +65,47 @@ void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
         int i;
         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
                 if (!p->nodes[i])
-                        break;
+                        continue;
+                if (p->locks[i]) {
+                        btrfs_tree_unlock(p->nodes[i]);
+                        p->locks[i] = 0;
+                }
                 free_extent_buffer(p->nodes[i]);
         }
         memset(p, 0, sizeof(*p));
 }
 
+struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
+{
+        struct extent_buffer *eb;
+        spin_lock(&root->node_lock);
+        eb = root->node;
+        extent_buffer_get(eb);
+        spin_unlock(&root->node_lock);
+        return eb;
+}
+
+struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
+{
+        struct extent_buffer *eb;
+
+        while(1) {
+                eb = btrfs_root_node(root);
+                btrfs_tree_lock(eb);
+
+                spin_lock(&root->node_lock);
+                if (eb == root->node) {
+                        spin_unlock(&root->node_lock);
+                        break;
+                }
+                spin_unlock(&root->node_lock);
+
+                btrfs_tree_unlock(eb);
+                free_extent_buffer(eb);
+        }
+        return eb;
+}
+
 static void add_root_to_dirty_list(struct btrfs_root *root)
 {
         if (root->track_dirty && list_empty(&root->dirty_list)) {
@@ -111,7 +147,7 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
         } else {
                 first_key.objectid = 0;
         }
-        cow = __btrfs_alloc_free_block(trans, new_root, buf->len,
+        cow = btrfs_alloc_free_block(trans, new_root, buf->len,
                                        new_root_objectid,
                                        trans->transid, first_key.objectid,
                                        level, buf->start, 0);
@@ -151,8 +187,14 @@ int __btrfs_cow_block(struct btrfs_trans_handle *trans,
         int ret = 0;
         int different_trans = 0;
         int level;
+        int unlock_orig = 0;
         struct btrfs_key first_key;
 
+        if (*cow_ret == buf)
+                unlock_orig = 1;
+
+        WARN_ON(!btrfs_tree_locked(buf));
+
         if (root->ref_cows) {
                 root_gen = trans->transid;
         } else {
@@ -172,7 +214,7 @@ int __btrfs_cow_block(struct btrfs_trans_handle *trans,
         } else {
                 first_key.objectid = 0;
         }
-        cow = __btrfs_alloc_free_block(trans, root, buf->len,
+        cow = btrfs_alloc_free_block(trans, root, buf->len,
                                      root->root_key.objectid,
                                      root_gen, first_key.objectid, level,
                                      search_start, empty_size);
@@ -196,9 +238,14 @@ int __btrfs_cow_block(struct btrfs_trans_handle *trans,
         }
 
         if (buf == root->node) {
+                WARN_ON(parent && parent != buf);
                 root_gen = btrfs_header_generation(buf);
+
+                spin_lock(&root->node_lock);
                 root->node = cow;
                 extent_buffer_get(cow);
+                spin_unlock(&root->node_lock);
+
                 if (buf != root->commit_root) {
                         btrfs_free_extent(trans, root, buf->start,
                                           buf->len, root->root_key.objectid,
@@ -219,6 +266,8 @@ int __btrfs_cow_block(struct btrfs_trans_handle *trans,
                                   btrfs_header_owner(parent), root_gen,
                                   0, 0, 1);
         }
+        if (unlock_orig)
+                btrfs_tree_unlock(buf);
         free_extent_buffer(buf);
         btrfs_mark_buffer_dirty(cow);
         *cow_ret = cow;
@@ -316,6 +365,9 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans,
         int progress_passed = 0;
         struct btrfs_disk_key disk_key;
 
+        /* FIXME this code needs locking */
+        return 0;
+
         parent_level = btrfs_header_level(parent);
         if (cache_only && parent_level != 1)
                 return 0;
@@ -729,6 +781,7 @@ static int balance_level(struct btrfs_trans_handle *trans,
                 return 0;
 
         mid = path->nodes[level];
+        WARN_ON(!path->locks[level]);
         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 
         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
@@ -749,14 +802,21 @@ static int balance_level(struct btrfs_trans_handle *trans,
 
                 /* promote the child to a root */
                 child = read_node_slot(root, mid, 0);
+                btrfs_tree_lock(child);
                 BUG_ON(!child);
                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
                 BUG_ON(ret);
 
+                spin_lock(&root->node_lock);
                 root->node = child;
+                spin_unlock(&root->node_lock);
+
                 add_root_to_dirty_list(root);
+                btrfs_tree_unlock(child);
+                path->locks[level] = 0;
                 path->nodes[level] = NULL;
                 clean_tree_block(trans, root, mid);
+                btrfs_tree_unlock(mid);
                 /* once for the path */
                 free_extent_buffer(mid);
                 ret = btrfs_free_extent(trans, root, mid->start, mid->len,
@@ -775,6 +835,7 @@ static int balance_level(struct btrfs_trans_handle *trans,
 
         left = read_node_slot(root, parent, pslot - 1);
         if (left) {
+                btrfs_tree_lock(left);
                 wret = btrfs_cow_block(trans, root, left,
                                        parent, pslot - 1, &left);
                 if (wret) {
@@ -784,6 +845,7 @@ static int balance_level(struct btrfs_trans_handle *trans,
         }
         right = read_node_slot(root, parent, pslot + 1);
         if (right) {
+                btrfs_tree_lock(right);
                 wret = btrfs_cow_block(trans, root, right,
                                        parent, pslot + 1, &right);
                 if (wret) {
@@ -815,6 +877,7 @@ static int balance_level(struct btrfs_trans_handle *trans,
                         u32 blocksize = right->len;
 
                         clean_tree_block(trans, root, right);
+                        btrfs_tree_unlock(right);
                         free_extent_buffer(right);
                         right = NULL;
                         wret = del_ptr(trans, root, path, level + 1, pslot +
@@ -862,7 +925,9 @@ static int balance_level(struct btrfs_trans_handle *trans,
                 u64 root_gen = btrfs_header_generation(parent);
                 u64 bytenr = mid->start;
                 u32 blocksize = mid->len;
+
                 clean_tree_block(trans, root, mid);
+                btrfs_tree_unlock(mid);
                 free_extent_buffer(mid);
                 mid = NULL;
                 wret = del_ptr(trans, root, path, level + 1, pslot);
@@ -885,11 +950,14 @@ static int balance_level(struct btrfs_trans_handle *trans,
         if (left) {
                 if (btrfs_header_nritems(left) > orig_slot) {
                         extent_buffer_get(left);
+                        /* left was locked after cow */
                         path->nodes[level] = left;
                         path->slots[level + 1] -= 1;
                         path->slots[level] = orig_slot;
-                        if (mid)
+                        if (mid) {
+                                btrfs_tree_unlock(mid);
                                 free_extent_buffer(mid);
+                        }
                 } else {
                         orig_slot -= btrfs_header_nritems(left);
                         path->slots[level] = orig_slot;
@@ -901,10 +969,15 @@ static int balance_level(struct btrfs_trans_handle *trans,
             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
                 BUG();
 enospc:
-        if (right)
+        if (right) {
+                btrfs_tree_unlock(right);
                 free_extent_buffer(right);
-        if (left)
+        }
+        if (left) {
+                if (path->nodes[level] != left)
+                        btrfs_tree_unlock(left);
                 free_extent_buffer(left);
+        }
         return ret;
 }
 
@@ -942,6 +1015,8 @@ static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans,
         /* first, try to make some room in the middle buffer */
         if (left) {
                 u32 left_nr;
+
+                btrfs_tree_lock(left);
                 left_nr = btrfs_header_nritems(left);
                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
                         wret = 1;
@@ -967,24 +1042,28 @@ static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans,
                                 path->nodes[level] = left;
                                 path->slots[level + 1] -= 1;
                                 path->slots[level] = orig_slot;
+                                btrfs_tree_unlock(mid);
                                 free_extent_buffer(mid);
                         } else {
                                 orig_slot -=
                                         btrfs_header_nritems(left);
                                 path->slots[level] = orig_slot;
+                                btrfs_tree_unlock(left);
                                 free_extent_buffer(left);
                         }
                         return 0;
                 }
+                btrfs_tree_unlock(left);
                 free_extent_buffer(left);
         }
-        right= read_node_slot(root, parent, pslot + 1);
+        right = read_node_slot(root, parent, pslot + 1);
 
         /*
          * then try to empty the right most buffer into the middle
          */
         if (right) {
                 u32 right_nr;
+                btrfs_tree_lock(right);
                 right_nr = btrfs_header_nritems(right);
                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
                         wret = 1;
@@ -1013,12 +1092,15 @@ static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans,
                                 path->slots[level + 1] += 1;
                                 path->slots[level] = orig_slot -
                                         btrfs_header_nritems(mid);
+                                btrfs_tree_unlock(mid);
                                 free_extent_buffer(mid);
                         } else {
+                                btrfs_tree_unlock(right);
                                 free_extent_buffer(right);
                         }
                         return 0;
                 }
+                btrfs_tree_unlock(right);
                 free_extent_buffer(right);
         }
         return 1;
@@ -1050,6 +1132,8 @@ static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
                 return;
 
         node = path->nodes[level];
+        WARN_ON(!path->skip_locking && !btrfs_tree_locked(node));
+
         search = btrfs_node_blockptr(node, slot);
         blocksize = btrfs_level_size(root, level - 1);
         eb = btrfs_find_tree_block(root, search, blocksize);
@@ -1098,6 +1182,39 @@ static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
                         highest_read = search;
         }
 }
+
+static void unlock_up(struct btrfs_path *path, int level, int lowest_unlock)
+{
+        int i;
+        int skip_level = level;
+        struct extent_buffer *t;
+
+        for (i = level; i < BTRFS_MAX_LEVEL; i++) {
+                if (!path->nodes[i])
+                        break;
+                if (!path->locks[i])
+                        break;
+                if (path->slots[i] == 0) {
+                        skip_level = i + 1;
+                        continue;
+                }
+                if (path->keep_locks) {
+                        u32 nritems;
+                        t = path->nodes[i];
+                        nritems = btrfs_header_nritems(t);
+                        if (path->slots[i] >= nritems - 1) {
+                                skip_level = i + 1;
+                                continue;
+                        }
+                }
+                t = path->nodes[i];
+                if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
+                        btrfs_tree_unlock(t);
+                        path->locks[i] = 0;
+                }
+        }
+}
+
 /*
  * look for key in the tree.  path is filled in with nodes along the way
  * if key is found, we return zero and you can find the item in the leaf
@@ -1120,15 +1237,27 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
         int ret;
         int level;
         int should_reada = p->reada;
+        int lowest_unlock = 1;
         u8 lowest_level = 0;
 
         lowest_level = p->lowest_level;
         WARN_ON(lowest_level && ins_len);
         WARN_ON(p->nodes[0] != NULL);
-        WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
+        // WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
+        WARN_ON(root == root->fs_info->extent_root &&
+                !mutex_is_locked(&root->fs_info->alloc_mutex));
+        WARN_ON(root == root->fs_info->chunk_root &&
+                !mutex_is_locked(&root->fs_info->chunk_mutex));
+        WARN_ON(root == root->fs_info->dev_root &&
+                !mutex_is_locked(&root->fs_info->chunk_mutex));
+        if (ins_len < 0)
+                lowest_unlock = 2;
 again:
-        b = root->node;
-        extent_buffer_get(b);
+        if (!p->skip_locking)
+                b = btrfs_lock_root_node(root);
+        else
+                b = btrfs_root_node(root);
+
         while (b) {
                 level = btrfs_header_level(b);
                 if (cow) {
@@ -1147,9 +1276,12 @@ again:
                         WARN_ON(1);
                 level = btrfs_header_level(b);
                 p->nodes[level] = b;
+                if (!p->skip_locking)
+                        p->locks[level] = 1;
                 ret = check_block(root, p, level);
                 if (ret)
                         return -1;
+
                 ret = bin_search(b, key, level, &slot);
                 if (level != 0) {
                         if (ret && slot > 0)
@@ -1177,14 +1309,19 @@ again:
                                 BUG_ON(btrfs_header_nritems(b) == 1);
                         }
                         /* this is only true while dropping a snapshot */
-                        if (level == lowest_level)
+                        if (level == lowest_level) {
+                                unlock_up(p, level, lowest_unlock);
                                 break;
+                        }
 
                         if (should_reada)
                                 reada_for_search(root, p, level, slot,
                                                  key->objectid);
 
                         b = read_node_slot(root, b, slot);
+                        if (!p->skip_locking)
+                                btrfs_tree_lock(b);
+                        unlock_up(p, level, lowest_unlock);
                 } else {
                         p->slots[level] = slot;
                         if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
@@ -1195,6 +1332,7 @@ again:
                                 if (sret)
                                         return sret;
                         }
+                        unlock_up(p, level, lowest_unlock);
                         return ret;
                 }
         }
@@ -1225,6 +1363,13 @@ static int fixup_low_keys(struct btrfs_trans_handle *trans,
                         break;
                 t = path->nodes[i];
                 btrfs_set_node_key(t, key, tslot);
+                if (!btrfs_tree_locked(path->nodes[i])) {
+                        int ii;
+printk("fixup without lock on level %d\n", btrfs_header_level(path->nodes[i]));
+                        for (ii = 0; ii < BTRFS_MAX_LEVEL; ii++) {
+printk("level %d slot %d\n", ii, path->slots[ii]);
+                        }
+                }
                 btrfs_mark_buffer_dirty(path->nodes[i]);
                 if (tslot != 0)
                         break;
@@ -1370,6 +1515,7 @@ static int noinline insert_new_root(struct btrfs_trans_handle *trans,
         u64 lower_gen;
         struct extent_buffer *lower;
         struct extent_buffer *c;
+        struct extent_buffer *old;
         struct btrfs_disk_key lower_key;
 
         BUG_ON(path->nodes[level]);
@@ -1386,12 +1532,13 @@ static int noinline insert_new_root(struct btrfs_trans_handle *trans,
         else
                 btrfs_node_key(lower, &lower_key, 0);
 
-        c = __btrfs_alloc_free_block(trans, root, root->nodesize,
+        c = btrfs_alloc_free_block(trans, root, root->nodesize,
                                    root->root_key.objectid,
                                    root_gen, lower_key.objectid, level,
                                    root->node->start, 0);
         if (IS_ERR(c))
                 return PTR_ERR(c);
+
         memset_extent_buffer(c, 0, 0, root->nodesize);
         btrfs_set_header_nritems(c, 1);
         btrfs_set_header_level(c, level);
@@ -1416,23 +1563,31 @@ static int noinline insert_new_root(struct btrfs_trans_handle *trans,
 
         btrfs_mark_buffer_dirty(c);
 
-        /* the super has an extra ref to root->node */
-        free_extent_buffer(root->node);
+        spin_lock(&root->node_lock);
+        old = root->node;
         root->node = c;
+        spin_unlock(&root->node_lock);
+
+        /* the super has an extra ref to root->node */
+        free_extent_buffer(old);
+
         add_root_to_dirty_list(root);
         extent_buffer_get(c);
         path->nodes[level] = c;
+        path->locks[level] = 1;
         path->slots[level] = 0;
 
         if (root->ref_cows && lower_gen != trans->transid) {
                 struct btrfs_path *back_path = btrfs_alloc_path();
                 int ret;
+                mutex_lock(&root->fs_info->alloc_mutex);
                 ret = btrfs_insert_extent_backref(trans,
                                                   root->fs_info->extent_root,
                                                   path, lower->start,
                                                   root->root_key.objectid,
                                                   trans->transid, 0, 0);
                 BUG_ON(ret);
+                mutex_unlock(&root->fs_info->alloc_mutex);
                 btrfs_free_path(back_path);
         }
         return 0;
@@ -1521,7 +1676,7 @@ static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
                 root_gen = 0;
 
         btrfs_node_key(c, &disk_key, 0);
-        split = __btrfs_alloc_free_block(trans, root, root->nodesize,
+        split = btrfs_alloc_free_block(trans, root, root->nodesize,
                                          root->root_key.objectid,
                                          root_gen,
                                          btrfs_disk_key_objectid(&disk_key),
@@ -1564,10 +1719,12 @@ static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
 
         if (path->slots[level] >= mid) {
                 path->slots[level] -= mid;
+                btrfs_tree_unlock(c);
                 free_extent_buffer(c);
                 path->nodes[level] = split;
                 path->slots[level + 1] += 1;
         } else {
+                btrfs_tree_unlock(split);
                 free_extent_buffer(split);
         }
         return ret;
@@ -1648,30 +1805,24 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
                 return 1;
 
         right = read_node_slot(root, upper, slot + 1);
+        btrfs_tree_lock(right);
         free_space = btrfs_leaf_free_space(root, right);
-        if (free_space < data_size + sizeof(struct btrfs_item)) {
-                free_extent_buffer(right);
-                return 1;
-        }
+        if (free_space < data_size + sizeof(struct btrfs_item))
+                goto out_unlock;
 
         /* cow and double check */
         ret = btrfs_cow_block(trans, root, right, upper,
                               slot + 1, &right);
-        if (ret) {
-                free_extent_buffer(right);
-                return 1;
-        }
+        if (ret)
+                goto out_unlock;
+
         free_space = btrfs_leaf_free_space(root, right);
-        if (free_space < data_size + sizeof(struct btrfs_item)) {
-                free_extent_buffer(right);
-                return 1;
-        }
+        if (free_space < data_size + sizeof(struct btrfs_item))
+                goto out_unlock;
 
         left_nritems = btrfs_header_nritems(left);
-        if (left_nritems == 0) {
-                free_extent_buffer(right);
-                return 1;
-        }
+        if (left_nritems == 0)
+                goto out_unlock;
 
         if (empty)
                 nr = 0;
@@ -1707,10 +1858,8 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
                 left->map_token = NULL;
         }
 
-        if (push_items == 0) {
-                free_extent_buffer(right);
-                return 1;
-        }
+        if (push_items == 0)
+                goto out_unlock;
 
         if (!empty && push_items == left_nritems)
                 WARN_ON(1);
@@ -1778,14 +1927,24 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
         /* then fixup the leaf pointer in the path */
         if (path->slots[0] >= left_nritems) {
                 path->slots[0] -= left_nritems;
+                if (btrfs_header_nritems(path->nodes[0]) == 0)
+                        clean_tree_block(trans, root, path->nodes[0]);
+                btrfs_tree_unlock(path->nodes[0]);
                 free_extent_buffer(path->nodes[0]);
                 path->nodes[0] = right;
                 path->slots[1] += 1;
         } else {
+                btrfs_tree_unlock(right);
                 free_extent_buffer(right);
         }
         return 0;
+
+out_unlock:
+        btrfs_tree_unlock(right);
+        free_extent_buffer(right);
+        return 1;
 }
+
 /*
  * push some data in the path leaf to the left, trying to free up at
  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
@@ -1823,10 +1982,11 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
         }
 
         left = read_node_slot(root, path->nodes[1], slot - 1);
+        btrfs_tree_lock(left);
         free_space = btrfs_leaf_free_space(root, left);
         if (free_space < data_size + sizeof(struct btrfs_item)) {
-                free_extent_buffer(left);
-                return 1;
+                ret = 1;
+                goto out;
         }
 
         /* cow and double check */
@@ -1834,14 +1994,14 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
                               path->nodes[1], slot - 1, &left);
         if (ret) {
                 /* we hit -ENOSPC, but it isn't fatal here */
-                free_extent_buffer(left);
-                return 1;
+                ret = 1;
+                goto out;
         }
 
         free_space = btrfs_leaf_free_space(root, left);
         if (free_space < data_size + sizeof(struct btrfs_item)) {
-                free_extent_buffer(left);
-                return 1;
+                ret = 1;
+                goto out;
         }
 
         if (empty)
@@ -1876,8 +2036,8 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
         }
 
         if (push_items == 0) {
-                free_extent_buffer(left);
-                return 1;
+                ret = 1;
+                goto out;
         }
         if (!empty && push_items == btrfs_header_nritems(right))
                 WARN_ON(1);
@@ -1975,15 +2135,23 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
         /* then fixup the leaf pointer in the path */
         if (path->slots[0] < push_items) {
                 path->slots[0] += old_left_nritems;
+                if (btrfs_header_nritems(path->nodes[0]) == 0)
+                        clean_tree_block(trans, root, path->nodes[0]);
+                btrfs_tree_unlock(path->nodes[0]);
                 free_extent_buffer(path->nodes[0]);
                 path->nodes[0] = left;
                 path->slots[1] -= 1;
         } else {
+                btrfs_tree_unlock(left);
                 free_extent_buffer(left);
                 path->slots[0] -= push_items;
         }
         BUG_ON(path->slots[0] < 0);
         return ret;
+out:
+        btrfs_tree_unlock(left);
+        free_extent_buffer(left);
+        return ret;
 }
 
 /*
@@ -2052,7 +2220,7 @@ again:
 
         btrfs_item_key(l, &disk_key, 0);
 
-        right = __btrfs_alloc_free_block(trans, root, root->leafsize,
+        right = btrfs_alloc_free_block(trans, root, root->leafsize,
                                          root->root_key.objectid,
                                          root_gen, disk_key.objectid, 0,
                                          l->start, 0);
@@ -2085,6 +2253,8 @@ again:
                                                   path->slots[1] + 1, 1);
                                 if (wret)
                                         ret = wret;
+
+                                btrfs_tree_unlock(path->nodes[0]);
                                 free_extent_buffer(path->nodes[0]);
                                 path->nodes[0] = right;
                                 path->slots[0] = 0;
@@ -2111,6 +2281,7 @@ again:
                                                   path->slots[1], 1);
                                 if (wret)
                                         ret = wret;
+                                btrfs_tree_unlock(path->nodes[0]);
                                 free_extent_buffer(path->nodes[0]);
                                 path->nodes[0] = right;
                                 path->slots[0] = 0;
@@ -2184,12 +2355,15 @@ again:
         BUG_ON(path->slots[0] != slot);
 
         if (mid <= slot) {
+                btrfs_tree_unlock(path->nodes[0]);
                 free_extent_buffer(path->nodes[0]);
                 path->nodes[0] = right;
                 path->slots[0] -= mid;
                 path->slots[1] += 1;
-        } else
+        } else {
+                btrfs_tree_unlock(right);
                 free_extent_buffer(right);
+        }
 
         BUG_ON(path->slots[0] < 0);
 
@@ -2418,10 +2592,6 @@ int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
                 total_data += data_size[i];
         }
 
-        /* create a root if there isn't one */
-        if (!root->node)
-                BUG();
-
         total_size = total_data + (nr - 1) * sizeof(struct btrfs_item);
         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
         if (ret == 0) {
@@ -2516,7 +2686,6 @@ int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
                 btrfs_print_leaf(root, leaf);
                 BUG();
         }
-
 out:
         return ret;
 }
@@ -2655,7 +2824,6 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                         btrfs_set_header_level(leaf, 0);
                 } else {
                         u64 root_gen = btrfs_header_generation(path->nodes[1]);
-                        clean_tree_block(trans, root, leaf);
                         wret = del_ptr(trans, root, path, 1, path->slots[1]);
                         if (wret)
                                 ret = wret;
@@ -2706,8 +2874,6 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                                 root_gen = btrfs_header_generation(
                                                            path->nodes[1]);
 
-                                clean_tree_block(trans, root, leaf);
-
                                 wret = del_ptr(trans, root, path, 1, slot);
                                 if (wret)
                                         ret = wret;
@@ -2720,7 +2886,13 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                                 if (wret)
                                         ret = wret;
                         } else {
-                                btrfs_mark_buffer_dirty(leaf);
+                                /* if we're still in the path, make sure
+                                 * we're dirty.  Otherwise, one of the
+                                 * push_leaf functions must have already
+                                 * dirtied this buffer
+                                 */
+                                if (path->nodes[0] == leaf)
+                                        btrfs_mark_buffer_dirty(leaf);
                                 free_extent_buffer(leaf);
                         }
                 } else {
@@ -2731,56 +2903,40 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 }
 
 /*
- * walk up the tree as far as required to find the previous leaf.
+ * search the tree again to find a leaf with lesser keys
  * returns 0 if it found something or 1 if there are no lesser leaves.
  * returns < 0 on io errors.
  */
 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
 {
-        int slot;
-        int level = 1;
-        struct extent_buffer *c;
-        struct extent_buffer *next = NULL;
+        struct btrfs_key key;
+        struct btrfs_disk_key found_key;
+        int ret;
 
-        while(level < BTRFS_MAX_LEVEL) {
-                if (!path->nodes[level])
-                        return 1;
+        btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
 
-                slot = path->slots[level];
-                c = path->nodes[level];
-                if (slot == 0) {
-                        level++;
-                        if (level == BTRFS_MAX_LEVEL)
-                                return 1;
-                        continue;
-                }
-                slot--;
-
-                if (next)
-                        free_extent_buffer(next);
+        if (key.offset > 0)
+                key.offset--;
+        else if (key.type > 0)
+                key.type--;
+        else if (key.objectid > 0)
+                key.objectid--;
+        else
+                return 1;
 
-                next = read_node_slot(root, c, slot);
-                break;
-        }
-        path->slots[level] = slot;
-        while(1) {
-                level--;
-                c = path->nodes[level];
-                free_extent_buffer(c);
-                slot = btrfs_header_nritems(next);
-                if (slot != 0)
-                        slot--;
-                path->nodes[level] = next;
-                path->slots[level] = slot;
-                if (!level)
-                        break;
-                next = read_node_slot(root, next, slot);
-        }
-        return 0;
+        btrfs_release_path(root, path);
+        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+        if (ret < 0)
+                return ret;
+        btrfs_item_key(path->nodes[0], &found_key, 0);
+        ret = comp_keys(&found_key, &key);
+        if (ret < 0)
+                return 0;
+        return 1;
 }
 
 /*
- * walk up the tree as far as required to find the next leaf.
+ * search the tree again to find a leaf with greater keys
  * returns 0 if it found something or 1 if there are no greater leaves.
  * returns < 0 on io errors.
  */
@@ -2790,6 +2946,28 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
         int level = 1;
         struct extent_buffer *c;
         struct extent_buffer *next = NULL;
+        struct btrfs_key key;
+        u32 nritems;
+        int ret;
+
+        nritems = btrfs_header_nritems(path->nodes[0]);
+        if (nritems == 0) {
+                return 1;
+        }
+
+        btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
+
+        path->keep_locks = 1;
+        btrfs_release_path(root, path);
+        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+        path->keep_locks = 0;
+
+        if (ret < 0)
+                return ret;
+
+        if (path->slots[0] < nritems - 1) {
+                goto done;
+        }
 
         while(level < BTRFS_MAX_LEVEL) {
                 if (!path->nodes[level])
@@ -2799,33 +2977,45 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
                 c = path->nodes[level];
                 if (slot >= btrfs_header_nritems(c)) {
                         level++;
-                        if (level == BTRFS_MAX_LEVEL)
+                        if (level == BTRFS_MAX_LEVEL) {
                                 return 1;
+                        }
                         continue;
                 }
 
-                if (next)
+                if (next) {
+                        btrfs_tree_unlock(next);
                         free_extent_buffer(next);
+                }
 
-                if (path->reada)
+                if (level == 1 && path->locks[1] && path->reada)
                         reada_for_search(root, path, level, slot, 0);
 
                 next = read_node_slot(root, c, slot);
+                if (!path->skip_locking)
+                        btrfs_tree_lock(next);
                 break;
         }
         path->slots[level] = slot;
         while(1) {
                 level--;
                 c = path->nodes[level];
+                if (path->locks[level])
+                        btrfs_tree_unlock(c);
                 free_extent_buffer(c);
                 path->nodes[level] = next;
                 path->slots[level] = 0;
+                path->locks[level] = 1;
                 if (!level)
                         break;
-                if (path->reada)
-                        reada_for_search(root, path, level, 0, 0);
+                if (level == 1 && path->locks[1] && path->reada)
+                        reada_for_search(root, path, level, slot, 0);
                 next = read_node_slot(root, next, 0);
+                if (!path->skip_locking)
+                        btrfs_tree_lock(next);
         }
+done:
+        unlock_up(path, 0, 1);
         return 0;
 }
 
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index dcea9d706d9b..50891b39f366 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -330,8 +330,13 @@ struct btrfs_node {
 struct btrfs_path {
         struct extent_buffer *nodes[BTRFS_MAX_LEVEL];
         int slots[BTRFS_MAX_LEVEL];
+        /* if there is real range locking, this locks field will change */
+        int locks[BTRFS_MAX_LEVEL];
         int reada;
+        /* keep some upper locks as we walk down */
+        int keep_locks;
         int lowest_level;
+        int skip_locking;
 };
 
 /*
@@ -515,6 +520,8 @@ struct btrfs_fs_info {
         spinlock_t hash_lock;
         struct mutex trans_mutex;
         struct mutex fs_mutex;
+        struct mutex alloc_mutex;
+        struct mutex chunk_mutex;
         struct list_head trans_list;
         struct list_head hashers;
         struct list_head dead_roots;
@@ -576,6 +583,10 @@ struct btrfs_fs_info {
  */
 struct btrfs_root {
         struct extent_buffer *node;
+
+        /* the node lock is held while changing the node pointer */
+        spinlock_t node_lock;
+
         struct extent_buffer *commit_root;
         struct btrfs_root_item root_item;
         struct btrfs_key root_key;
@@ -1353,13 +1364,7 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
                                                  struct btrfs_block_group_cache
                                                  *hint, u64 search_start,
                                                  int data, int owner);
-int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
-                       struct btrfs_root *root, u64 owner_objectid);
 struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
-                                            struct btrfs_root *root, u32 size,
-                                            u64 root_objectid,
-                                            u64 hint, u64 empty_size);
-struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                                              struct btrfs_root *root,
                                              u32 blocksize,
                                              u64 root_objectid,
@@ -1368,8 +1373,6 @@ struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                                              int level,
                                              u64 hint,
                                              u64 empty_size);
-int btrfs_grow_extent_tree(struct btrfs_trans_handle *trans,
-                           struct btrfs_root *root, u64 new_size);
 int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 new_size);
 int btrfs_insert_extent_backref(struct btrfs_trans_handle *trans,
                                  struct btrfs_root *root,
@@ -1409,6 +1412,10 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
 int btrfs_previous_item(struct btrfs_root *root,
                         struct btrfs_path *path, u64 min_objectid,
                         int type);
+
+struct extent_buffer *btrfs_root_node(struct btrfs_root *root);
+struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root);
+
 int btrfs_cow_block(struct btrfs_trans_handle *trans,
                     struct btrfs_root *root, struct extent_buffer *buf,
                     struct extent_buffer *parent, int parent_slot,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e5c758e306d5..fe40bdd984ff 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -32,6 +32,7 @@
 #include "volumes.h"
 #include "print-tree.h"
 #include "async-thread.h"
+#include "locking.h"
 
 #if 0
 static int check_tree_block(struct btrfs_root *root, struct extent_buffer *buf)
@@ -681,9 +682,11 @@ int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 {
         struct inode *btree_inode = root->fs_info->btree_inode;
         if (btrfs_header_generation(buf) ==
-            root->fs_info->running_transaction->transid)
+            root->fs_info->running_transaction->transid) {
+                WARN_ON(!btrfs_tree_locked(buf));
                 clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree,
                                           buf);
+        }
         return 0;
 }
 
@@ -720,6 +723,7 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
         root->in_sysfs = 0;
 
         INIT_LIST_HEAD(&root->dirty_list);
+        spin_lock_init(&root->node_lock);
         memset(&root->root_key, 0, sizeof(root->root_key));
         memset(&root->root_item, 0, sizeof(root->root_item));
         memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
@@ -1196,6 +1200,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 
         mutex_init(&fs_info->trans_mutex);
         mutex_init(&fs_info->fs_mutex);
+        mutex_init(&fs_info->alloc_mutex);
+        mutex_init(&fs_info->chunk_mutex);
 
 #if 0
         ret = add_hasher(fs_info, "crc32c");
@@ -1274,7 +1280,9 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 
         mutex_lock(&fs_info->fs_mutex);
 
+        mutex_lock(&fs_info->chunk_mutex);
         ret = btrfs_read_sys_array(tree_root);
+        mutex_unlock(&fs_info->chunk_mutex);
         if (ret) {
                 printk("btrfs: failed to read the system array on %s\n",
                        sb->s_id);
@@ -1296,7 +1304,9 @@ struct btrfs_root *open_ctree(struct super_block *sb,
                  (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
                  BTRFS_UUID_SIZE);
 
+        mutex_lock(&fs_info->chunk_mutex);
         ret = btrfs_read_chunk_tree(chunk_root);
+        mutex_unlock(&fs_info->chunk_mutex);
         BUG_ON(ret);
 
         btrfs_close_extra_devices(fs_devices);
@@ -1654,6 +1664,7 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
         u64 transid = btrfs_header_generation(buf);
         struct inode *btree_inode = root->fs_info->btree_inode;
 
+        WARN_ON(!btrfs_tree_locked(buf));
         if (transid != root->fs_info->generation) {
                 printk(KERN_CRIT "transid mismatch buffer %llu, found %Lu running %Lu\n",
                         (unsigned long long)buf->start,
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 41a63462d3eb..7e40c516fe62 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -25,6 +25,7 @@
 #include "print-tree.h"
 #include "transaction.h"
 #include "volumes.h"
+#include "locking.h"
 
 #define BLOCK_GROUP_DATA     EXTENT_WRITEBACK
 #define BLOCK_GROUP_METADATA EXTENT_UPTODATE
@@ -36,7 +37,28 @@ static int finish_current_insert(struct btrfs_trans_handle *trans, struct
                                  btrfs_root *extent_root);
 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
                                btrfs_root *extent_root);
+static struct btrfs_block_group_cache *
+__btrfs_find_block_group(struct btrfs_root *root,
+                         struct btrfs_block_group_cache *hint,
+                         u64 search_start, int data, int owner);
 
+void maybe_lock_mutex(struct btrfs_root *root)
+{
+        if (root != root->fs_info->extent_root &&
+            root != root->fs_info->chunk_root &&
+            root != root->fs_info->dev_root) {
+                mutex_lock(&root->fs_info->alloc_mutex);
+        }
+}
+
+void maybe_unlock_mutex(struct btrfs_root *root)
+{
+        if (root != root->fs_info->extent_root &&
+            root != root->fs_info->chunk_root &&
+            root != root->fs_info->dev_root) {
+                mutex_unlock(&root->fs_info->alloc_mutex);
+        }
+}
 
 static int cache_block_group(struct btrfs_root *root,
                              struct btrfs_block_group_cache *block_group)
@@ -66,6 +88,7 @@ static int cache_block_group(struct btrfs_root *root,
                 return -ENOMEM;
 
         path->reada = 2;
+        path->skip_locking = 1;
         first_free = block_group->key.objectid;
         key.objectid = block_group->key.objectid;
         key.offset = 0;
@@ -290,7 +313,7 @@ no_cache:
                 cache = btrfs_lookup_first_block_group(root->fs_info, last);
         }
         cache_miss = 0;
-        cache = btrfs_find_block_group(root, cache, last, data, 0);
+        cache = __btrfs_find_block_group(root, cache, last, data, 0);
         if (!cache)
                 goto no_cache;
         *cache_ret = cache;
@@ -318,10 +341,10 @@ static int block_group_state_bits(u64 flags)
         return bits;
 }
 
-struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
-                                                 struct btrfs_block_group_cache
-                                                 *hint, u64 search_start,
-                                                 int data, int owner)
+static struct btrfs_block_group_cache *
+__btrfs_find_block_group(struct btrfs_root *root,
+                         struct btrfs_block_group_cache *hint,
+                         u64 search_start, int data, int owner)
 {
         struct btrfs_block_group_cache *cache;
         struct extent_io_tree *block_group_cache;
@@ -411,6 +434,18 @@ found:
         return found_group;
 }
 
+struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
+                                                 struct btrfs_block_group_cache
+                                                 *hint, u64 search_start,
+                                                 int data, int owner)
+{
+
+        struct btrfs_block_group_cache *ret;
+        mutex_lock(&root->fs_info->alloc_mutex);
+        ret = __btrfs_find_block_group(root, hint, search_start, data, owner);
+        mutex_unlock(&root->fs_info->alloc_mutex);
+        return ret;
+}
 static u64 hash_extent_ref(u64 root_objectid, u64 ref_generation,
                            u64 owner, u64 owner_offset)
 {
@@ -646,7 +681,7 @@ out:
         return ret;
 }
 
-int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
+static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
                                 struct btrfs_root *root,
                                 u64 bytenr, u64 num_bytes,
                                 u64 root_objectid, u64 ref_generation,
@@ -696,6 +731,22 @@ int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
         return 0;
 }
 
+int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *root,
+                                u64 bytenr, u64 num_bytes,
+                                u64 root_objectid, u64 ref_generation,
+                                u64 owner, u64 owner_offset)
+{
+        int ret;
+
+        mutex_lock(&root->fs_info->alloc_mutex);
+        ret = __btrfs_inc_extent_ref(trans, root, bytenr, num_bytes,
+                                     root_objectid, ref_generation,
+                                     owner, owner_offset);
+        mutex_unlock(&root->fs_info->alloc_mutex);
+        return ret;
+}
+
 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
                          struct btrfs_root *root)
 {
@@ -760,6 +811,10 @@ u32 btrfs_count_snapshots_in_path(struct btrfs_root *root,
         struct btrfs_extent_ref *ref_item;
         int level = -1;
 
+        /* FIXME, needs locking */
+        BUG();
+
+        mutex_lock(&root->fs_info->alloc_mutex);
         path = btrfs_alloc_path();
 again:
         if (level == -1)
@@ -854,33 +909,9 @@ again:
 
 out:
         btrfs_free_path(path);
+        mutex_unlock(&root->fs_info->alloc_mutex);
         return total_count;
 }
-int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
-                       struct btrfs_root *root, u64 owner_objectid)
-{
-        u64 generation;
-        u64 key_objectid;
-        u64 level;
-        u32 nritems;
-        struct btrfs_disk_key disk_key;
-
-        level = btrfs_header_level(root->node);
-        generation = trans->transid;
-        nritems = btrfs_header_nritems(root->node);
-        if (nritems > 0) {
-                if (level == 0)
-                        btrfs_item_key(root->node, &disk_key, 0);
-                else
-                        btrfs_node_key(root->node, &disk_key, 0);
-                key_objectid = btrfs_disk_key_objectid(&disk_key);
-        } else {
-                key_objectid = 0;
-        }
-        return btrfs_inc_extent_ref(trans, root, root->node->start,
-                                    root->node->len, owner_objectid,
-                                    generation, level, key_objectid);
-}
 
 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                   struct extent_buffer *buf)
@@ -897,6 +928,7 @@ int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
         if (!root->ref_cows)
                 return 0;
 
+        mutex_lock(&root->fs_info->alloc_mutex);
         level = btrfs_header_level(buf);
         nritems = btrfs_header_nritems(buf);
         for (i = 0; i < nritems; i++) {
@@ -913,7 +945,7 @@ int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                         disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
                         if (disk_bytenr == 0)
                                 continue;
-                        ret = btrfs_inc_extent_ref(trans, root, disk_bytenr,
+                        ret = __btrfs_inc_extent_ref(trans, root, disk_bytenr,
                                     btrfs_file_extent_disk_num_bytes(buf, fi),
                                     root->root_key.objectid, trans->transid,
                                     key.objectid, key.offset);
@@ -924,7 +956,7 @@ int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                 } else {
                         bytenr = btrfs_node_blockptr(buf, i);
                         btrfs_node_key_to_cpu(buf, &key, i);
-                        ret = btrfs_inc_extent_ref(trans, root, bytenr,
+                        ret = __btrfs_inc_extent_ref(trans, root, bytenr,
                                            btrfs_level_size(root, level - 1),
                                            root->root_key.objectid,
                                            trans->transid,
@@ -935,6 +967,7 @@ int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                         }
                 }
         }
+        mutex_unlock(&root->fs_info->alloc_mutex);
         return 0;
 fail:
         WARN_ON(1);
@@ -965,6 +998,7 @@ fail:
                 }
         }
 #endif
+        mutex_unlock(&root->fs_info->alloc_mutex);
         return ret;
 }
 
@@ -1019,6 +1053,7 @@ int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
         if (!path)
                 return -ENOMEM;
 
+        mutex_lock(&root->fs_info->alloc_mutex);
         while(1) {
                 ret = find_first_extent_bit(block_group_cache, last,
                                             &start, &end, BLOCK_GROUP_DIRTY);
@@ -1045,6 +1080,7 @@ int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
                                   BLOCK_GROUP_DIRTY, GFP_NOFS);
         }
         btrfs_free_path(path);
+        mutex_unlock(&root->fs_info->alloc_mutex);
         return werr;
 }
 
@@ -1162,26 +1198,28 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
                 space_info->force_alloc = 0;
         }
         if (space_info->full)
-                return 0;
+                goto out;
 
         thresh = div_factor(space_info->total_bytes, 6);
         if (!force &&
            (space_info->bytes_used + space_info->bytes_pinned + alloc_bytes) <
             thresh)
-                return 0;
+                goto out;
 
+        mutex_lock(&extent_root->fs_info->chunk_mutex);
         ret = btrfs_alloc_chunk(trans, extent_root, &start, &num_bytes, flags);
         if (ret == -ENOSPC) {
 printk("space info full %Lu\n", flags);
                 space_info->full = 1;
-                return 0;
+                goto out;
         }
         BUG_ON(ret);
 
         ret = btrfs_make_block_group(trans, extent_root, 0, flags,
                      BTRFS_FIRST_CHUNK_TREE_OBJECTID, start, num_bytes);
         BUG_ON(ret);
-
+        mutex_unlock(&extent_root->fs_info->chunk_mutex);
+out:
         return 0;
 }
 
@@ -1318,6 +1356,7 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
         struct extent_io_tree *free_space_cache;
         free_space_cache = &root->fs_info->free_space_cache;
 
+        mutex_lock(&root->fs_info->alloc_mutex);
         while(1) {
                 ret = find_first_extent_bit(unpin, 0, &start, &end,
                                             EXTENT_DIRTY);
@@ -1327,6 +1366,7 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
                 clear_extent_dirty(unpin, start, end, GFP_NOFS);
                 set_extent_dirty(free_space_cache, start, end, GFP_NOFS);
         }
+        mutex_unlock(&root->fs_info->alloc_mutex);
         return 0;
 }
 
@@ -1363,18 +1403,24 @@ static int finish_current_insert(struct btrfs_trans_handle *trans,
                                   GFP_NOFS);
                 eb = read_tree_block(extent_root, ins.objectid, ins.offset,
                                      trans->transid);
+                btrfs_tree_lock(eb);
                 level = btrfs_header_level(eb);
                 if (level == 0) {
                         btrfs_item_key(eb, &first, 0);
                 } else {
                         btrfs_node_key(eb, &first, 0);
                 }
+                btrfs_tree_unlock(eb);
+                free_extent_buffer(eb);
+                /*
+                 * the first key is just a hint, so the race we've created
+                 * against reading it is fine
+                 */
                 err = btrfs_insert_extent_backref(trans, extent_root, path,
                                           start, extent_root->root_key.objectid,
                                           0, level,
                                           btrfs_disk_key_objectid(&first));
                 BUG_ON(err);
-                free_extent_buffer(eb);
         }
         btrfs_free_path(path);
         return 0;
@@ -1384,12 +1430,14 @@ static int pin_down_bytes(struct btrfs_root *root, u64 bytenr, u32 num_bytes,
                           int pending)
 {
         int err = 0;
-        struct extent_buffer *buf;
 
         if (!pending) {
+#if 0
+                struct extent_buffer *buf;
                 buf = btrfs_find_tree_block(root, bytenr, num_bytes);
                 if (buf) {
-                        if (btrfs_buffer_uptodate(buf, 0)) {
+                        if (!btrfs_try_tree_lock(buf) &&
+                            btrfs_buffer_uptodate(buf, 0)) {
                                 u64 transid =
                                     root->fs_info->running_transaction->transid;
                                 u64 header_transid =
@@ -1398,12 +1446,15 @@ static int pin_down_bytes(struct btrfs_root *root, u64 bytenr, u32 num_bytes,
                                     !btrfs_header_flag(buf,
                                                BTRFS_HEADER_FLAG_WRITTEN)) {
                                         clean_tree_block(NULL, root, buf);
+                                        btrfs_tree_unlock(buf);
                                         free_extent_buffer(buf);
                                         return 1;
                                 }
+                                btrfs_tree_unlock(buf);
                         }
                         free_extent_buffer(buf);
                 }
+#endif
                 update_pinned_extents(root, bytenr, num_bytes, 1);
         } else {
                 set_extent_bits(&root->fs_info->pending_del,
@@ -1586,10 +1637,11 @@ static int del_pending_extents(struct btrfs_trans_handle *trans, struct
 /*
  * remove an extent from the root, returns 0 on success
  */
-int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
-                      *root, u64 bytenr, u64 num_bytes,
-                      u64 root_objectid, u64 ref_generation,
-                      u64 owner_objectid, u64 owner_offset, int pin)
+static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
+                               struct btrfs_root *root, u64 bytenr,
+                               u64 num_bytes, u64 root_objectid,
+                               u64 ref_generation, u64 owner_objectid,
+                               u64 owner_offset, int pin)
 {
         struct btrfs_root *extent_root = root->fs_info->extent_root;
         int pending_ret;
@@ -1610,6 +1662,22 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
         return ret ? ret : pending_ret;
 }
 
+int btrfs_free_extent(struct btrfs_trans_handle *trans,
+                      struct btrfs_root *root, u64 bytenr,
+                      u64 num_bytes, u64 root_objectid,
+                      u64 ref_generation, u64 owner_objectid,
+                      u64 owner_offset, int pin)
+{
+        int ret;
+
+        maybe_lock_mutex(root);
+        ret = __btrfs_free_extent(trans, root, bytenr, num_bytes,
+                                  root_objectid, ref_generation,
+                                  owner_objectid, owner_offset, pin);
+        maybe_unlock_mutex(root);
+        return ret;
+}
+
 static u64 stripe_align(struct btrfs_root *root, u64 val)
 {
         u64 mask = ((u64)root->stripesize - 1);
@@ -1679,12 +1747,12 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans,
                 block_group = btrfs_lookup_first_block_group(info, hint_byte);
                 if (!block_group)
                         hint_byte = search_start;
-                block_group = btrfs_find_block_group(root, block_group,
+                block_group = __btrfs_find_block_group(root, block_group,
                                                      hint_byte, data, 1);
                 if (last_ptr && *last_ptr == 0 && block_group)
                         hint_byte = block_group->key.objectid;
         } else {
-                block_group = btrfs_find_block_group(root,
+                block_group = __btrfs_find_block_group(root,
                                                      trans->block_group,
                                                      search_start, data, 1);
         }
@@ -1806,7 +1874,7 @@ enospc:
         }
         block_group = btrfs_lookup_first_block_group(info, search_start);
         cond_resched();
-        block_group = btrfs_find_block_group(root, block_group,
+        block_group = __btrfs_find_block_group(root, block_group,
                                              search_start, data, 0);
         goto check_failed;
 
@@ -1843,6 +1911,8 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
         struct btrfs_path *path;
         struct btrfs_key keys[2];
 
+        maybe_lock_mutex(root);
+
         if (data) {
                 alloc_profile = info->avail_data_alloc_bits &
                                 info->data_alloc_profile;
@@ -1892,9 +1962,10 @@ again:
         if (ret) {
                 printk("allocation failed flags %Lu\n", data);
         }
-        BUG_ON(ret);
-        if (ret)
-                return ret;
+        if (ret) {
+                BUG();
+                goto out;
+        }
 
         /* block accounting for super block */
         super_used = btrfs_super_bytes_used(&info->super_copy);
@@ -1953,11 +2024,11 @@ again:
         finish_current_insert(trans, extent_root);
         pending_ret = del_pending_extents(trans, extent_root);
 
-        if (ret) {
-                return ret;
-        }
+        if (ret)
+                goto out;
         if (pending_ret) {
-                return pending_ret;
+                ret = pending_ret;
+                goto out;
         }
 
 update_block:
@@ -1967,9 +2038,10 @@ update_block:
                        ins->objectid, ins->offset);
                 BUG();
         }
-        return 0;
+out:
+        maybe_unlock_mutex(root);
+        return ret;
 }
-
 /*
  * helper function to allocate a block for a given tree
  * returns the tree buffer or NULL.
@@ -1977,28 +2049,6 @@ update_block:
 struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                                              struct btrfs_root *root,
                                              u32 blocksize,
-                                             u64 root_objectid, u64 hint,
-                                             u64 empty_size)
-{
-        u64 ref_generation;
-
-        if (root->ref_cows)
-                ref_generation = trans->transid;
-        else
-                ref_generation = 0;
-
-
-        return __btrfs_alloc_free_block(trans, root, blocksize, root_objectid,
-                                        ref_generation, 0, 0, hint, empty_size);
-}
-
-/*
- * helper function to allocate a block for a given tree
- * returns the tree buffer or NULL.
- */
-struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
-                                             struct btrfs_root *root,
-                                             u32 blocksize,
                                              u64 root_objectid,
                                              u64 ref_generation,
                                              u64 first_objectid,
@@ -2026,6 +2076,7 @@ struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                 return ERR_PTR(-ENOMEM);
         }
         btrfs_set_header_generation(buf, trans->transid);
+        btrfs_tree_lock(buf);
         clean_tree_block(trans, root, buf);
         btrfs_set_buffer_uptodate(buf);
 
@@ -2076,7 +2127,7 @@ static int noinline drop_leaf_ref(struct btrfs_trans_handle *trans,
                 disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
                 if (disk_bytenr == 0)
                         continue;
-                ret = btrfs_free_extent(trans, root, disk_bytenr,
+                ret = __btrfs_free_extent(trans, root, disk_bytenr,
                                 btrfs_file_extent_disk_num_bytes(leaf, fi),
                                 leaf_owner, leaf_generation,
                                 key.objectid, key.offset, 0);
@@ -2151,6 +2202,8 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
         int ret;
         u32 refs;
 
+        mutex_lock(&root->fs_info->alloc_mutex);
+
         WARN_ON(*level < 0);
         WARN_ON(*level >= BTRFS_MAX_LEVEL);
         ret = lookup_extent_ref(trans, root,
@@ -2182,6 +2235,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
                 bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
                 ptr_gen = btrfs_node_ptr_generation(cur, path->slots[*level]);
                 blocksize = btrfs_level_size(root, *level - 1);
+
                 ret = lookup_extent_ref(trans, root, bytenr, blocksize, &refs);
                 BUG_ON(ret);
                 if (refs != 1) {
@@ -2189,7 +2243,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
                         root_owner = btrfs_header_owner(parent);
                         root_gen = btrfs_header_generation(parent);
                         path->slots[*level]++;
-                        ret = btrfs_free_extent(trans, root, bytenr,
+                        ret = __btrfs_free_extent(trans, root, bytenr,
                                                 blocksize, root_owner,
                                                 root_gen, 0, 0, 1);
                         BUG_ON(ret);
@@ -2201,9 +2255,11 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
                         reada_walk_down(root, cur, path->slots[*level]);
 
                         mutex_unlock(&root->fs_info->fs_mutex);
+                        mutex_unlock(&root->fs_info->alloc_mutex);
                         next = read_tree_block(root, bytenr, blocksize,
                                                ptr_gen);
                         mutex_lock(&root->fs_info->fs_mutex);
+                        mutex_lock(&root->fs_info->alloc_mutex);
 
                         /* we've dropped the lock, double check */
                         ret = lookup_extent_ref(trans, root, bytenr,
@@ -2216,7 +2272,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
 
                                 path->slots[*level]++;
                                 free_extent_buffer(next);
-                                ret = btrfs_free_extent(trans, root, bytenr,
+                                ret = __btrfs_free_extent(trans, root, bytenr,
                                                         blocksize,
                                                         root_owner,
                                                         root_gen, 0, 0, 1);
@@ -2244,13 +2300,14 @@ out:
         }
 
         root_gen = btrfs_header_generation(parent);
-        ret = btrfs_free_extent(trans, root, path->nodes[*level]->start,
+        ret = __btrfs_free_extent(trans, root, path->nodes[*level]->start,
                                 path->nodes[*level]->len,
                                 root_owner, root_gen, 0, 0, 1);
         free_extent_buffer(path->nodes[*level]);
         path->nodes[*level] = NULL;
         *level += 1;
         BUG_ON(ret);
+        mutex_unlock(&root->fs_info->alloc_mutex);
         return 0;
 }
 
@@ -2350,6 +2407,12 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
                 btrfs_node_key(node, &found_key, path->slots[level]);
                 WARN_ON(memcmp(&found_key, &root_item->drop_progress,
                                sizeof(found_key)));
+                for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
+                        if (path->nodes[i] && path->locks[i]) {
+                                path->locks[i] = 0;
+                                btrfs_tree_unlock(path->nodes[i]);
+                        }
+                }
         }
         while(1) {
                 wret = walk_down_tree(trans, root, path, &level);
@@ -2383,6 +2446,8 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info)
         u64 end;
         u64 ptr;
         int ret;
+
+        mutex_lock(&info->alloc_mutex);
         while(1) {
                 ret = find_first_extent_bit(&info->block_group_cache, 0,
                                             &start, &end, (unsigned int)-1);
@@ -2402,6 +2467,7 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info)
                 clear_extent_dirty(&info->free_space_cache, start,
                                    end, GFP_NOFS);
         }
+        mutex_unlock(&info->alloc_mutex);
         return 0;
 }
 
@@ -2678,6 +2744,7 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
 
                 eb = read_tree_block(found_root, extent_key->objectid,
                                      extent_key->offset, 0);
+                btrfs_tree_lock(eb);
                 level = btrfs_header_level(eb);
 
                 if (level == 0)
@@ -2685,6 +2752,7 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
                 else
                         btrfs_node_key_to_cpu(eb, &found_key, 0);
 
+                btrfs_tree_unlock(eb);
                 free_extent_buffer(eb);
 
                 ret = find_root_for_ref(extent_root, path, &found_key,
@@ -2888,6 +2956,7 @@ int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 shrink_start)
         int ret;
         int progress;
 
+        mutex_lock(&root->fs_info->alloc_mutex);
         shrink_block_group = btrfs_lookup_block_group(root->fs_info,
                                                       shrink_start);
         BUG_ON(!shrink_block_group);
@@ -3044,20 +3113,22 @@ next:
                            (unsigned int)-1, GFP_NOFS);
 out:
         btrfs_free_path(path);
+        mutex_unlock(&root->fs_info->alloc_mutex);
         return ret;
 }
 
 int find_first_block_group(struct btrfs_root *root, struct btrfs_path *path,
                            struct btrfs_key *key)
 {
-        int ret;
+        int ret = 0;
         struct btrfs_key found_key;
         struct extent_buffer *leaf;
         int slot;
 
         ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
         if (ret < 0)
-                return ret;
+                goto out;
+
         while(1) {
                 slot = path->slots[0];
                 leaf = path->nodes[0];
@@ -3066,18 +3137,20 @@ int find_first_block_group(struct btrfs_root *root, struct btrfs_path *path,
                         if (ret == 0)
                                 continue;
                         if (ret < 0)
-                                goto error;
+                                goto out;
                         break;
                 }
                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 
                 if (found_key.objectid >= key->objectid &&
-                    found_key.type == BTRFS_BLOCK_GROUP_ITEM_KEY)
-                        return 0;
+                    found_key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
+                        ret = 0;
+                        goto out;
+                }
                 path->slots[0]++;
         }
         ret = -ENOENT;
-error:
+out:
         return ret;
 }
 
@@ -3103,6 +3176,7 @@ int btrfs_read_block_groups(struct btrfs_root *root)
         if (!path)
                 return -ENOMEM;
 
+        mutex_lock(&root->fs_info->alloc_mutex);
         while(1) {
                 ret = find_first_block_group(root, path, &key);
                 if (ret > 0) {
@@ -3158,6 +3232,7 @@ int btrfs_read_block_groups(struct btrfs_root *root)
         ret = 0;
 error:
         btrfs_free_path(path);
+        mutex_unlock(&root->fs_info->alloc_mutex);
         return ret;
 }
 
@@ -3205,5 +3280,6 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
         ret = del_pending_extents(trans, extent_root);
         BUG_ON(ret);
         set_avail_alloc_bits(extent_root->fs_info, type);
+
         return 0;
 }
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 17c508a941eb..bd15cdcaba95 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2889,7 +2889,6 @@ int clear_extent_buffer_dirty(struct extent_io_tree *tree,
 
         for (i = 0; i < num_pages; i++) {
                 page = extent_buffer_page(eb, i);
-                lock_page(page);
                 if (i == 0)
                         set_page_extent_head(page, eb->len);
                 else
@@ -2907,7 +2906,6 @@ int clear_extent_buffer_dirty(struct extent_io_tree *tree,
                         end  = start + PAGE_CACHE_SIZE - 1;
                         if (test_range_bit(tree, start, end,
                                            EXTENT_DIRTY, 0)) {
-                                unlock_page(page);
                                 continue;
                         }
                 }
@@ -2919,7 +2917,6 @@ int clear_extent_buffer_dirty(struct extent_io_tree *tree,
                                                 PAGECACHE_TAG_DIRTY);
                 }
                 read_unlock_irq(&page->mapping->tree_lock);
-                unlock_page(page);
         }
         return 0;
 }
@@ -2948,17 +2945,12 @@ int set_extent_buffer_dirty(struct extent_io_tree *tree,
                  * on us if the page isn't already dirty.
                  */
                 if (i == 0) {
-                        lock_page(page);
                         set_page_extent_head(page, eb->len);
                 } else if (PagePrivate(page) &&
                            page->private != EXTENT_PAGE_PRIVATE) {
-                        lock_page(page);
                         set_page_extent_mapped(page);
-                        unlock_page(page);
                 }
                 __set_page_dirty_nobuffers(extent_buffer_page(eb, i));
-                if (i == 0)
-                        unlock_page(page);
         }
         return set_extent_dirty(tree, eb->start,
                                 eb->start + eb->len - 1, GFP_NOFS);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 0c79346fd2c9..61bd8953a683 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -115,6 +115,7 @@ static int cow_file_range(struct inode *inode, u64 start, u64 end)
         trans = btrfs_start_transaction(root, 1);
         BUG_ON(!trans);
         btrfs_set_trans_block_group(trans, inode);
+        mutex_unlock(&root->fs_info->fs_mutex);
 
         num_bytes = (end - start + blocksize) & ~(blocksize - 1);
         num_bytes = max(blocksize,  num_bytes);
@@ -159,6 +160,7 @@ static int cow_file_range(struct inode *inode, u64 start, u64 end)
         btrfs_add_ordered_inode(inode);
         btrfs_update_inode(trans, root, inode);
 out:
+        mutex_lock(&root->fs_info->fs_mutex);
         btrfs_end_transaction(trans, root);
         return ret;
 }
@@ -349,10 +351,12 @@ int __btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
 
         mutex_lock(&root->fs_info->fs_mutex);
         trans = btrfs_start_transaction(root, 1);
+        mutex_unlock(&root->fs_info->fs_mutex);
 
         btrfs_set_trans_block_group(trans, inode);
         btrfs_csum_file_blocks(trans, root, inode, bio, sums);
 
+        mutex_lock(&root->fs_info->fs_mutex);
         ret = btrfs_end_transaction(trans, root);
         BUG_ON(ret);
         mutex_unlock(&root->fs_info->fs_mutex);
@@ -807,6 +811,7 @@ static int btrfs_unlink_trans(struct btrfs_trans_handle *trans,
                 goto err;
         }
         ret = btrfs_delete_one_dir_name(trans, root, path, di);
+        btrfs_release_path(root, path);
 
         dentry->d_inode->i_ctime = dir->i_ctime;
         ret = btrfs_del_inode_ref(trans, root, name, name_len,
@@ -881,8 +886,9 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
         struct btrfs_trans_handle *trans;
         unsigned long nr = 0;
 
-        if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
+        if (inode->i_size > BTRFS_EMPTY_DIR_SIZE) {
                 return -ENOTEMPTY;
+        }
 
         mutex_lock(&root->fs_info->fs_mutex);
         ret = btrfs_check_free_space(root, 1, 1);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 6fb455802759..3fbf74e93dba 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -43,6 +43,7 @@
 #include "ioctl.h"
 #include "print-tree.h"
 #include "volumes.h"
+#include "locking.h"
 
 
 
@@ -75,9 +76,9 @@ static noinline int create_subvol(struct btrfs_root *root, char *name,
         if (ret)
                 goto fail;
 
-        leaf = __btrfs_alloc_free_block(trans, root, root->leafsize,
-                                        objectid, trans->transid, 0, 0,
-                                        0, 0);
+        leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
+                                      objectid, trans->transid, 0, 0,
+                                      0, 0);
         if (IS_ERR(leaf))
                 return PTR_ERR(leaf);
 
@@ -108,6 +109,7 @@ static noinline int create_subvol(struct btrfs_root *root, char *name,
         memset(&root_item.drop_progress, 0, sizeof(root_item.drop_progress));
         root_item.drop_level = 0;
 
+        btrfs_tree_unlock(leaf);
         free_extent_buffer(leaf);
         leaf = NULL;
 
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
new file mode 100644
index 000000000000..80813a307b4b
--- /dev/null
+++ b/fs/btrfs/locking.c
@@ -0,0 +1,50 @@
+/*
+ * 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 v2 as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+#include <linux/sched.h>
+#include <linux/gfp.h>
+#include <linux/pagemap.h>
+#include <linux/spinlock.h>
+#include <linux/page-flags.h>
+#include <linux/bug.h>
+#include "ctree.h"
+#include "extent_io.h"
+#include "locking.h"
+
+int btrfs_tree_lock(struct extent_buffer *eb)
+{
+        lock_page(eb->first_page);
+        return 0;
+}
+
+int btrfs_try_tree_lock(struct extent_buffer *eb)
+{
+        return TestSetPageLocked(eb->first_page);
+}
+
+int btrfs_tree_unlock(struct extent_buffer *eb)
+{
+        WARN_ON(!PageLocked(eb->first_page));
+        unlock_page(eb->first_page);
+        return 0;
+}
+
+int btrfs_tree_locked(struct extent_buffer *eb)
+{
+        return PageLocked(eb->first_page);
+}
+
diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h
new file mode 100644
index 000000000000..2dab96d8280e
--- /dev/null
+++ b/fs/btrfs/locking.h
@@ -0,0 +1,26 @@
+/*
+ * 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 v2 as published by the Free Software Foundation.
+ *
+ * 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 __BTRFS_LOCKING_
+#define __BTRFS_LOCKING_
+
+int btrfs_tree_lock(struct extent_buffer *eb);
+int btrfs_tree_unlock(struct extent_buffer *eb);
+int btrfs_tree_locked(struct extent_buffer *eb);
+int btrfs_try_tree_lock(struct extent_buffer *eb);
+#endif
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index f04684f7fea3..1ed433a71493 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -23,6 +23,7 @@
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
+#include "locking.h"
 
 static int total_trans = 0;
 extern struct kmem_cache *btrfs_trans_handle_cachep;
@@ -96,8 +97,7 @@ static noinline int record_root_in_trans(struct btrfs_root *root)
                         radix_tree_tag_set(&root->fs_info->fs_roots_radix,
                                    (unsigned long)root->root_key.objectid,
                                    BTRFS_ROOT_DEFRAG_TAG);
-                        root->commit_root = root->node;
-                        extent_buffer_get(root->node);
+                        root->commit_root = btrfs_root_node(root);
                 } else {
                         WARN_ON(1);
                 }
@@ -559,6 +559,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         struct btrfs_root *tree_root = fs_info->tree_root;
         struct btrfs_root *root = pending->root;
         struct extent_buffer *tmp;
+        struct extent_buffer *old;
         int ret;
         int namelen;
         u64 objectid;
@@ -578,16 +579,18 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         key.offset = 1;
         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 
-        extent_buffer_get(root->node);
-        btrfs_cow_block(trans, root, root->node, NULL, 0, &tmp);
-        free_extent_buffer(tmp);
+        old = btrfs_lock_root_node(root);
+        btrfs_cow_block(trans, root, old, NULL, 0, &old);
 
-        btrfs_copy_root(trans, root, root->node, &tmp, objectid);
+        btrfs_copy_root(trans, root, old, &tmp, objectid);
+        btrfs_tree_unlock(old);
+        free_extent_buffer(old);
 
         btrfs_set_root_bytenr(new_root_item, tmp->start);
         btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
         ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
                                 new_root_item);
+        btrfs_tree_unlock(tmp);
         free_extent_buffer(tmp);
         if (ret)
                 goto fail;
diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c
index 155961c7b4d5..fab851d85383 100644
--- a/fs/btrfs/tree-defrag.c
+++ b/fs/btrfs/tree-defrag.c
@@ -181,6 +181,8 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
         if (root->fs_info->extent_root == root)
                 is_extent = 1;
 
+        goto out;
+
         if (root->ref_cows == 0 && !is_extent)
                 goto out;