blk-mq: fix nr_requests wrong value when modify it from sysfs

if blk-mq use "none" io scheduler, nr_request get a wrong value when input a number > tag_set->queue_depth. blk_mq_tag_update_depth will get the smaller one min(nr, set->queue_depth), and then q->nr_request get a wrong value.

Reproduce:

echo none > /sys/block/nvme0n1/queue/ioscheduler echo 1000000 > /sys/block/nvme0n1/queue/nr_requests cat /sys/block/nvme0n1/queue/nr_requests 1000000

---
 block/blk-mq.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

index 98a1860..491e336 100644
@@ -2642,8 +2642,7 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 		 * queue depth. This is similar to what the old code would do.
 		 */
 		if (!hctx->sched_tags) {
-			ret = blk_mq_tag_update_depth(hctx, &hctx->tags,
-							min(nr, set->queue_depth),
+			ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
 							false);
 		} else {
 			ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,

2.9.4