linux-kernel - [PATCH 4.15 098/122] blk-mq: dont call io scheds .requeue

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Message-Id: <20180307191743.516746398@linuxfoundation.org>
Date:   Wed,  7 Mar 2018 11:38:30 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Paolo Valente <paolo.valente@...aro.org>,
        Omar Sandoval <osandov@...com>,
        Bart Van Assche <bart.vanassche@....com>,
        Ming Lei <ming.lei@...hat.com>, Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 4.15 098/122] blk-mq: dont call io scheds .requeue_request when requeueing rq to ->dispatch

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ming Lei <ming.lei@...hat.com>

commit 105976f517791aed3b11f8f53b308a2069d42055 upstream.

__blk_mq_requeue_request() covers two cases:

- one is that the requeued request is added to hctx->dispatch, such as
blk_mq_dispatch_rq_list()

- another case is that the request is requeued to io scheduler, such as
blk_mq_requeue_request().

We should call io sched's .requeue_request callback only for the 2nd
case.

Cc: Paolo Valente <paolo.valente@...aro.org>
Cc: Omar Sandoval <osandov@...com>
Fixes: bd166ef183c2 ("blk-mq-sched: add framework for MQ capable IO schedulers")
Cc: stable@...r.kernel.org
Reviewed-by: Bart Van Assche <bart.vanassche@....com>
Acked-by: Paolo Valente <paolo.valente@...aro.org>
Signed-off-by: Ming Lei <ming.lei@...hat.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 block/blk-mq.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -655,7 +655,6 @@ static void __blk_mq_requeue_request(str
 
 	trace_block_rq_requeue(q, rq);
 	wbt_requeue(q->rq_wb, &rq->issue_stat);
-	blk_mq_sched_requeue_request(rq);
 
 	if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
 		if (q->dma_drain_size && blk_rq_bytes(rq))
@@ -667,6 +666,9 @@ void blk_mq_requeue_request(struct reque
 {
 	__blk_mq_requeue_request(rq);
 
+	/* this request will be re-inserted to io scheduler queue */
+	blk_mq_sched_requeue_request(rq);
+
 	BUG_ON(blk_queued_rq(rq));
 	blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
 }