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-rw-r--r--block/blk-barrier.c16
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