btrfs: comment the rest of implicit barriers before waitqueue_active

[firefly-linux-kernel-4.4.55.git] / fs / btrfs / disk-io.c

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 295795aebe0b42330cc1147e02340eb2c59f1d7b..379526ffd84d296f2b900ff23e3bf47db73dab3c 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -802,6 +802,9 @@ static void run_one_async_done(struct btrfs_work *work)
        limit = btrfs_async_submit_limit(fs_info);
        limit = limit * 2 / 3;
 
+       /*
+        * atomic_dec_return implies a barrier for waitqueue_active
+        */
        if (atomic_dec_return(&fs_info->nr_async_submits) < limit &&
            waitqueue_active(&fs_info->async_submit_wait))
                wake_up(&fs_info->async_submit_wait);