writeback: remove smp_mb(), it's not needed with list_add_tail_rcu()

list_add_tail_rcu contains required barriers.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 3475775..59c99e7 100644 (file)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -151,10 +151,10 @@ static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work)
        BUG_ON(!bdi->wb_cnt);
 
        /*
        BUG_ON(!bdi->wb_cnt);
 
        /*

-        * Make sure stores are seen before it appears on the list
+        * list_add_tail_rcu() contains the necessary barriers to
+        * make sure the above stores are seen before the item is
+        * noticed on the list

         */
         */

-       smp_mb();
-

        spin_lock(&bdi->wb_lock);
        list_add_tail_rcu(&work->list, &bdi->work_list);
        spin_unlock(&bdi->wb_lock);
        spin_lock(&bdi->wb_lock);
        list_add_tail_rcu(&work->list, &bdi->work_list);
        spin_unlock(&bdi->wb_lock);