1 files changed, 1 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 7e607416755a..0b180708bf79 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1171,6 +1171,7 @@ struct btrfs_space_info {
         struct percpu_counter total_bytes_pinned;
 
         struct list_head list;
+        /* Protected by the spinlock 'lock'. */
         struct list_head ro_bgs;
 
         struct rw_semaphore groups_sem;