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Commit 23d4ee19 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

blk-mq: don't dispatch request in blk_mq_request_direct_issue if queue is busy 



If we run into blk_mq_request_direct_issue(), when queue is busy, we
don't want to dispatch this request into hctx->dispatch_list, and
what we need to do is to return the queue busy info to caller, so
that caller can deal with it well.

Fixes: 396eaf21 ("blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback")
Reported-by: default avatarLaurence Oberman <loberman@redhat.com>
Reviewed-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent de99a346

block/blk-mq.c

+10 −12
Original line number Diff line number Diff line
@@ -1773,15 +1773,6 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx, 
	return ret;

}



static void __blk_mq_fallback_to_insert(struct request *rq,

					bool run_queue, bool bypass_insert)

{

	if (!bypass_insert)

		blk_mq_sched_insert_request(rq, false, run_queue, false);

	else

		blk_mq_request_bypass_insert(rq, run_queue);

}



static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,

						struct request *rq,

						blk_qc_t *cookie,
@@ -1790,9 +1781,16 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, 
	struct request_queue *q = rq->q;

	bool run_queue = true;



	/* RCU or SRCU read lock is needed before checking quiesced flag */

	/*

	 * RCU or SRCU read lock is needed before checking quiesced flag.

	 *

	 * When queue is stopped or quiesced, ignore 'bypass_insert' from

	 * blk_mq_request_direct_issue(), and return BLK_STS_OK to caller,

	 * and avoid driver to try to dispatch again.

	 */

	if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {

		run_queue = false;

		bypass_insert = false;

		goto insert;

	}
@@ -1809,10 +1807,10 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, 


	return __blk_mq_issue_directly(hctx, rq, cookie);

insert:

	__blk_mq_fallback_to_insert(rq, run_queue, bypass_insert);

	if (bypass_insert)

		return BLK_STS_RESOURCE;



	blk_mq_sched_insert_request(rq, false, run_queue, false);

	return BLK_STS_OK;

}
@@ -1828,7 +1826,7 @@ static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, 


	ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false);

	if (ret == BLK_STS_RESOURCE)

		__blk_mq_fallback_to_insert(rq, true, false);

		blk_mq_sched_insert_request(rq, false, true, false);

	else if (ret != BLK_STS_OK)

		blk_mq_end_request(rq, ret);