From: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx> commit f6033c5e333238f299c3ae03fac8cc1365b23b77 upstream. btrfs_remove_block_group() invokes btrfs_lookup_block_group(), which returns a local reference of the block group that contains the given bytenr to "block_group" with increased refcount. When btrfs_remove_block_group() returns, "block_group" becomes invalid, so the refcount should be decreased to keep refcount balanced. The reference counting issue happens in several exception handling paths of btrfs_remove_block_group(). When those error scenarios occur such as btrfs_alloc_path() returns NULL, the function forgets to decrease its refcnt increased by btrfs_lookup_block_group() and will cause a refcnt leak. Fix this issue by jumping to "out_put_group" label and calling btrfs_put_block_group() when those error scenarios occur. CC: stable@xxxxxxxxxxxxxxx # 4.4+ Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx> Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx> Reviewed-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/btrfs/extent-tree.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -10645,7 +10645,7 @@ int btrfs_remove_block_group(struct btrf path = btrfs_alloc_path(); if (!path) { ret = -ENOMEM; - goto out; + goto out_put_group; } /* @@ -10684,7 +10684,7 @@ int btrfs_remove_block_group(struct btrf ret = btrfs_orphan_add(trans, inode); if (ret) { btrfs_add_delayed_iput(inode); - goto out; + goto out_put_group; } clear_nlink(inode); /* One for the block groups ref */ @@ -10707,13 +10707,13 @@ int btrfs_remove_block_group(struct btrf ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1); if (ret < 0) - goto out; + goto out_put_group; if (ret > 0) btrfs_release_path(path); if (ret == 0) { ret = btrfs_del_item(trans, tree_root, path); if (ret) - goto out; + goto out_put_group; btrfs_release_path(path); } @@ -10871,9 +10871,9 @@ int btrfs_remove_block_group(struct btrf ret = remove_block_group_free_space(trans, root->fs_info, block_group); if (ret) - goto out; + goto out_put_group; - btrfs_put_block_group(block_group); + /* Once for the block groups rbtree */ btrfs_put_block_group(block_group); ret = btrfs_search_slot(trans, root, &key, path, -1, 1); @@ -10883,6 +10883,10 @@ int btrfs_remove_block_group(struct btrf goto out; ret = btrfs_del_item(trans, root, path); + +out_put_group: + /* Once for the lookup reference */ + btrfs_put_block_group(block_group); out: btrfs_free_path(path); return ret;