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Commit 9c558734 authored by Jens Axboe's avatar Jens Axboe
Browse files

blk-mq: abstract out blk-mq-sched rq list iteration bio merge helper 



No functional changes in this patch, just a prep patch for utilizing
this in an IO scheduler.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Reviewed-by: default avatarOmar Sandoval <osandov@fb.com>
parent 5de815a7

block/blk-mq-sched.c

+24 −10
Original line number Diff line number Diff line
@@ -268,19 +268,16 @@ bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio, 
EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge);



/*

 * Reverse check our software queue for entries that we could potentially

 * merge with. Currently includes a hand-wavy stop count of 8, to not spend

 * too much time checking for merges.

 * Iterate list of requests and see if we can merge this bio with any

 * of them.

 */

static bool blk_mq_attempt_merge(struct request_queue *q,

				 struct blk_mq_ctx *ctx, struct bio *bio)

bool blk_mq_bio_list_merge(struct request_queue *q, struct list_head *list,

			   struct bio *bio)

{

	struct request *rq;

	int checked = 8;



	lockdep_assert_held(&ctx->lock);



	list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {

	list_for_each_entry_reverse(rq, list, queuelist) {

		bool merged = false;



		if (!checked--)
@@ -305,13 +302,30 @@ static bool blk_mq_attempt_merge(struct request_queue *q, 
			continue;

		}



		if (merged)

			ctx->rq_merged++;

		return merged;

	}



	return false;

}

EXPORT_SYMBOL_GPL(blk_mq_bio_list_merge);



/*

 * Reverse check our software queue for entries that we could potentially

 * merge with. Currently includes a hand-wavy stop count of 8, to not spend

 * too much time checking for merges.

 */

static bool blk_mq_attempt_merge(struct request_queue *q,

				 struct blk_mq_ctx *ctx, struct bio *bio)

{

	lockdep_assert_held(&ctx->lock);



	if (blk_mq_bio_list_merge(q, &ctx->rq_list, bio)) {

		ctx->rq_merged++;

		return true;

	}



	return false;

}



bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)

{

include/linux/blk-mq.h

+2 −1
Original line number Diff line number Diff line
@@ -259,7 +259,8 @@ void blk_mq_add_to_requeue_list(struct request *rq, bool at_head, 
void blk_mq_kick_requeue_list(struct request_queue *q);

void blk_mq_delay_kick_requeue_list(struct request_queue *q, unsigned long msecs);

void blk_mq_complete_request(struct request *rq);



bool blk_mq_bio_list_merge(struct request_queue *q, struct list_head *list,

			   struct bio *bio);

bool blk_mq_queue_stopped(struct request_queue *q);

void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx);

void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx);