linux-kernel - [PATCH 1/3] block: Requeue req as head if driver touched it

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Date:   Wed, 26 Oct 2022 07:30:39 +0000
From:   Christian Löhle <CLoehle@...erstone.com>
To:     "axboe@...nel.dk" <axboe@...nel.dk>,
        "ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>
CC:     Avri Altman <Avri.Altman@....com>,
        "adrian.hunter@...el.com" <adrian.hunter@...el.com>,
        "vincent.whitchurch@...s.com" <vincent.whitchurch@...s.com>,
        Christian Löhle <CLoehle@...erstone.com>
Subject: [PATCH 1/3] block: Requeue req as head if driver touched it

In case the driver set RQF_DONTPREP flag, requeue the request as head as
it is likely that the backing storage already had a request to an
adjacent region, so getting the requeued request out as soon as possible
may give us some performance benefit.

Signed-off-by: Christian Loehle <cloehle@...erstone.com>
---
 block/blk-mq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 33292c01875d..d863c826fb23 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1429,7 +1429,7 @@ static void blk_mq_requeue_work(struct work_struct *work)
 		 * merge.
 		 */
 		if (rq->rq_flags & RQF_DONTPREP)
-			blk_mq_request_bypass_insert(rq, false, false);
+			blk_mq_request_bypass_insert(rq, true, false);
 		else
 			blk_mq_sched_insert_request(rq, true, false, false);
 	}
-- 
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