btrfs: comment waitqueue_active implied by locks

Suggested-by: Chris Mason <clm@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 1bbaace73383..d0deb4643502 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2950,6 +2950,9 @@ out_wake_log_root:
         atomic_set(&log_root_tree->log_commit[index2], 0);
         mutex_unlock(&log_root_tree->log_mutex);
 
+        /*
+         * The barrier before waitqueue_active is implied by mutex_unlock
+         */
         if (waitqueue_active(&log_root_tree->log_commit_wait[index2]))
                 wake_up(&log_root_tree->log_commit_wait[index2]);
 out:
@@ -2961,6 +2964,9 @@ out:
         atomic_set(&root->log_commit[index1], 0);
         mutex_unlock(&root->log_mutex);
 
+        /*
+         * The barrier before waitqueue_active is implied by mutex_unlock
+         */
         if (waitqueue_active(&root->log_commit_wait[index1]))
                 wake_up(&root->log_commit_wait[index1]);
         return ret;