---

yaml
---
r: 123290
b: refs/heads/master
c: 58eea92
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8f11b3e99a1136fcbb67316c3260f085299c0bff
+refs/heads/master: 58eea927d2de43dc6f03d1ba2c46e55854b31540

trunk/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

trunk/block/elevator.c

@@ -755,14 +755,6 @@ struct request *elv_next_request(struct request_queue *q)
 	int ret;
 
 	while ((rq = __elv_next_request(q)) != NULL) {
-		/*
-		 * Kill the empty barrier place holder, the driver must
-		 * not ever see it.
-		 */
-		if (blk_empty_barrier(rq)) {
-			__blk_end_request(rq, 0, blk_rq_bytes(rq));
-			continue;
-		}
 		if (!(rq->cmd_flags & REQ_STARTED)) {
 			/*
 			 * This is the first time the device driver

trunk/include/linux/blkdev.h

@@ -596,7 +596,6 @@ enum {
 #define blk_fua_rq(rq)		((rq)->cmd_flags & REQ_FUA)
 #define blk_discard_rq(rq)	((rq)->cmd_flags & REQ_DISCARD)
 #define blk_bidi_rq(rq)		((rq)->next_rq != NULL)
-#define blk_empty_barrier(rq)	(blk_barrier_rq(rq) && blk_fs_request(rq) && !(rq)->hard_nr_sectors)
 /* rq->queuelist of dequeued request must be list_empty() */
 #define blk_queued_rq(rq)	(!list_empty(&(rq)->queuelist))