Commit 1e9c2303 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

blk-mq: move more plug handling from blk_mq_submit_bio into blk_add_rq_to_plug 



Keep all the functionality for adding a request to a plug in a single place.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123160443.1315598-3-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 0c5bcc92

block/blk-mq.c

+27 −37
Original line number Diff line number Diff line
@@ -2662,21 +2662,6 @@ void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx, 
		hctx->queue->mq_ops->commit_rqs(hctx);

}



static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)

{

	if (!plug->multiple_queues) {

		struct request *nxt = rq_list_peek(&plug->mq_list);



		if (nxt && nxt->q != rq->q)

			plug->multiple_queues = true;

	}

	if (!plug->has_elevator && (rq->rq_flags & RQF_ELV))

		plug->has_elevator = true;

	rq->rq_next = NULL;

	rq_list_add(&plug->mq_list, rq);

	plug->rq_count++;

}



/*

 * Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple

 * queues. This is important for md arrays to benefit from merging
@@ -2689,6 +2674,28 @@ static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug) 
	return BLK_MAX_REQUEST_COUNT;

}



static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)

{

	struct request *last = rq_list_peek(&plug->mq_list);



	if (!plug->rq_count) {

		trace_block_plug(rq->q);

	} else if (plug->rq_count >= blk_plug_max_rq_count(plug) ||

		   (!blk_queue_nomerges(rq->q) &&

		    blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {

		blk_mq_flush_plug_list(plug, false);

		trace_block_plug(rq->q);

	}



	if (!plug->multiple_queues && last && last->q != rq->q)

		plug->multiple_queues = true;

	if (!plug->has_elevator && (rq->rq_flags & RQF_ELV))

		plug->has_elevator = true;

	rq->rq_next = NULL;

	rq_list_add(&plug->mq_list, rq);

	plug->rq_count++;

}



static bool blk_mq_attempt_bio_merge(struct request_queue *q,

				     struct bio *bio, unsigned int nr_segs)

{
@@ -2841,32 +2848,15 @@ void blk_mq_submit_bio(struct bio *bio) 
		return;

	}



	if (plug) {

		unsigned int request_count = plug->rq_count;

		struct request *last = NULL;



		if (!request_count) {

			trace_block_plug(q);

		} else if (!blk_queue_nomerges(q)) {

			last = rq_list_peek(&plug->mq_list);

			if (blk_rq_bytes(last) < BLK_PLUG_FLUSH_SIZE)

				last = NULL;

		}



		if (request_count >= blk_plug_max_rq_count(plug) || last) {

			blk_mq_flush_plug_list(plug, false);

			trace_block_plug(q);

		}



	if (plug)

		blk_add_rq_to_plug(plug, rq);

	} else if ((rq->rq_flags & RQF_ELV) ||

	else if ((rq->rq_flags & RQF_ELV) ||

		 (rq->mq_hctx->dispatch_busy &&

		    (q->nr_hw_queues == 1 || !is_sync))) {

		  (q->nr_hw_queues == 1 || !is_sync)))

		blk_mq_sched_insert_request(rq, false, true, true);

	} else {

	else

		blk_mq_try_issue_directly(rq->mq_hctx, rq);

}

}



/**

 * blk_cloned_rq_check_limits - Helper function to check a cloned request