1 files changed, 50 insertions, 28 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index f64aad613727..5a6c39b44c84 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -968,6 +968,48 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
         return 0;
 }
 
+static struct extent_buffer *alloc_tree_block_no_bg_flush(
+                                          struct btrfs_trans_handle *trans,
+                                          struct btrfs_root *root,
+                                          u64 parent_start,
+                                          const struct btrfs_disk_key *disk_key,
+                                          int level,
+                                          u64 hint,
+                                          u64 empty_size)
+{
+        struct btrfs_fs_info *fs_info = root->fs_info;
+        struct extent_buffer *ret;
+
+        /*
+         * If we are COWing a node/leaf from the extent, chunk, device or free
+         * space trees, make sure that we do not finish block group creation of
+         * pending block groups. We do this to avoid a deadlock.
+         * COWing can result in allocation of a new chunk, and flushing pending
+         * block groups (btrfs_create_pending_block_groups()) can be triggered
+         * when finishing allocation of a new chunk. Creation of a pending block
+         * group modifies the extent, chunk, device and free space trees,
+         * therefore we could deadlock with ourselves since we are holding a
+         * lock on an extent buffer that btrfs_create_pending_block_groups() may
+         * try to COW later.
+         * For similar reasons, we also need to delay flushing pending block
+         * groups when splitting a leaf or node, from one of those trees, since
+         * we are holding a write lock on it and its parent or when inserting a
+         * new root node for one of those trees.
+         */
+        if (root == fs_info->extent_root ||
+            root == fs_info->chunk_root ||
+            root == fs_info->dev_root ||
+            root == fs_info->free_space_root)
+                trans->can_flush_pending_bgs = false;
+
+        ret = btrfs_alloc_tree_block(trans, root, parent_start,
+                                     root->root_key.objectid, disk_key, level,
+                                     hint, empty_size);
+        trans->can_flush_pending_bgs = true;
+
+        return ret;
+}
+
 /*
  * does the dirty work in cow of a single block.  The parent block (if
  * supplied) is updated to point to the new cow copy.  The new buffer is marked
@@ -1015,28 +1057,8 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
         if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
                 parent_start = parent->start;
 
-        /*
-         * If we are COWing a node/leaf from the extent, chunk, device or free
-         * space trees, make sure that we do not finish block group creation of
-         * pending block groups. We do this to avoid a deadlock.
-         * COWing can result in allocation of a new chunk, and flushing pending
-         * block groups (btrfs_create_pending_block_groups()) can be triggered
-         * when finishing allocation of a new chunk. Creation of a pending block
-         * group modifies the extent, chunk, device and free space trees,
-         * therefore we could deadlock with ourselves since we are holding a
-         * lock on an extent buffer that btrfs_create_pending_block_groups() may
-         * try to COW later.
-         */
-        if (root == fs_info->extent_root ||
-            root == fs_info->chunk_root ||
-            root == fs_info->dev_root ||
-            root == fs_info->free_space_root)
-                trans->can_flush_pending_bgs = false;
-
-        cow = btrfs_alloc_tree_block(trans, root, parent_start,
-                        root->root_key.objectid, &disk_key, level,
-                        search_start, empty_size);
-        trans->can_flush_pending_bgs = true;
+        cow = alloc_tree_block_no_bg_flush(trans, root, parent_start, &disk_key,
+                                           level, search_start, empty_size);
         if (IS_ERR(cow))
                 return PTR_ERR(cow);
 
@@ -3345,8 +3367,8 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
         else
                 btrfs_node_key(lower, &lower_key, 0);
 
-        c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
-                                   &lower_key, level, root->node->start, 0);
+        c = alloc_tree_block_no_bg_flush(trans, root, 0, &lower_key, level,
+                                         root->node->start, 0);
         if (IS_ERR(c))
                 return PTR_ERR(c);
 
@@ -3475,8 +3497,8 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
         mid = (c_nritems + 1) / 2;
         btrfs_node_key(c, &disk_key, mid);
 
-        split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
-                        &disk_key, level, c->start, 0);
+        split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level,
+                                             c->start, 0);
         if (IS_ERR(split))
                 return PTR_ERR(split);
 
@@ -4260,8 +4282,8 @@ again:
         else
                 btrfs_item_key(l, &disk_key, mid);
 
-        right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
-                        &disk_key, 0, l->start, 0);
+        right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
+                                             l->start, 0);
         if (IS_ERR(right))
                 return PTR_ERR(right);