Btrfs: fix locking issue in btrfs_remove_block_group

We should hold the block_group_cache_lock while modifying the
block groups red-black tree. Thank you,

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a4e36c38b81e..3bed6a7e4b22 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5952,9 +5952,11 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
         path = btrfs_alloc_path();
         BUG_ON(!path);
 
-        btrfs_remove_free_space_cache(block_group);
+        spin_lock(&root->fs_info->block_group_cache_lock);
         rb_erase(&block_group->cache_node,
                  &root->fs_info->block_group_cache_tree);
+        spin_unlock(&root->fs_info->block_group_cache_lock);
+        btrfs_remove_free_space_cache(block_group);
         down_write(&block_group->space_info->groups_sem);
         list_del(&block_group->list);
         up_write(&block_group->space_info->groups_sem);