btrfs: comment the rest of implicit barriers before waitqueue_active

[linux-2.6-block.git] / fs / btrfs / volumes.c

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6fc735869c186c35fb79fa66decc7d3519ed2e93..ff3527192409ae5a928464e16af7643ddbe0aa5c 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -345,6 +345,9 @@ loop_lock:
                pending = pending->bi_next;
                cur->bi_next = NULL;
 
+               /*
+                * atomic_dec_return implies a barrier for waitqueue_active
+                */
                if (atomic_dec_return(&fs_info->nr_async_bios) < limit &&
                    waitqueue_active(&fs_info->async_submit_wait))
                        wake_up(&fs_info->async_submit_wait);