1 files changed, 10 insertions, 6 deletions

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index b03d88013e1e..c63044e9c4c0 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -162,6 +162,14 @@ static inline bool start_ordered(struct request_queue *q, struct request **rqp)
         q->ordered = q->next_ordered;
         q->ordseq |= QUEUE_ORDSEQ_STARTED;
 
+        /*
+         * For an empty barrier, there's no actual BAR request, which
+         * in turn makes POSTFLUSH unnecessary.  Mask them off.
+         */
+        if (!rq->hard_nr_sectors)
+                q->ordered &= ~(QUEUE_ORDERED_DO_BAR |
+                                QUEUE_ORDERED_DO_POSTFLUSH);
+
         /* stash away the original request */
         elv_dequeue_request(q, rq);
         q->orig_bar_rq = rq;
@@ -171,13 +179,9 @@ static inline bool start_ordered(struct request_queue *q, struct request **rqp)
          * Queue ordered sequence.  As we stack them at the head, we
          * need to queue in reverse order.  Note that we rely on that
          * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
-         * request gets inbetween ordered sequence. If this request is
-         * an empty barrier, we don't need to do a postflush ever since
-         * there will be no data written between the pre and post flush.
-         * Hence a single flush will suffice.
+         * request gets inbetween ordered sequence.
          */
-        if ((q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) &&
-            !blk_empty_barrier(q->orig_bar_rq)) {
+        if (q->ordered & QUEUE_ORDERED_DO_POSTFLUSH) {
                 queue_flush(q, QUEUE_ORDERED_DO_POSTFLUSH);
                 rq = &q->post_flush_rq;
         } else