[PATCH 2/2] blk-mq: always call into the scheduler in blk_mq_make_request()

From: Hannes Reinecke <hare@suse.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-scsi@vger.kernel.org,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	James Bottomley <james.bottomley@hansenpartnership.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-block@vger.kernel.org,
	Hans Holmberg <hans.holmberg@wdc.com>,
	Damien Le Moal <damien.lemoal@wdc.com>,
	Hannes Reinecke <hare@suse.com>
Subject: [PATCH 2/2] blk-mq: always call into the scheduler in blk_mq_make_request()
Date: Thu, 19 Sep 2019 11:45:47 +0200	[thread overview]
Message-ID: <20190919094547.67194-3-hare@suse.de> (raw)
In-Reply-To: <20190919094547.67194-1-hare@suse.de>

From: Hannes Reinecke <hare@suse.com>

A scheduler might be attached even for devices exposing more than
one hardware queue, so the check for the number of hardware queue
is pointless and should be removed.

Signed-off-by: Hannes Reinecke <hare@suse.com>
---
 block/blk-mq.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 44ff3c1442a4..faab542e4836 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1931,7 +1931,6 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
 
 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 {
-	const int is_sync = op_is_sync(bio->bi_opf);
 	const int is_flush_fua = op_is_flush(bio->bi_opf);
 	struct blk_mq_alloc_data data = { .flags = 0};
 	struct request *rq;
@@ -1977,7 +1976,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 		/* bypass scheduler for flush rq */
 		blk_insert_flush(rq);
 		blk_mq_run_hw_queue(data.hctx, true);
-	} else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs)) {
+	} else if (plug && q->mq_ops->commit_rqs) {
 		/*
 		 * Use plugging if we have a ->commit_rqs() hook as well, as
 		 * we know the driver uses bd->last in a smart fashion.
@@ -2020,9 +2019,6 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
 			blk_mq_try_issue_directly(data.hctx, same_queue_rq,
 					&cookie);
 		}
-	} else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
-			!data.hctx->dispatch_busy)) {
-		blk_mq_try_issue_directly(data.hctx, rq, &cookie);
 	} else {
 		blk_mq_sched_insert_request(rq, false, true, true);
 	}
-- 
2.16.4

