Commit 7d7ca7c5 authored by Baolin Wang's avatar Baolin Wang Committed by Jens Axboe
Browse files

block: Add a new helper to attempt to merge a bio 



There are lots of duplicated code when trying to merge a bio from
plug list and sw queue, we can introduce a new helper to attempt
to merge a bio, which can simplify the blk_bio_list_merge()
and blk_attempt_plug_merge().

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent bdc6a287

block/blk-merge.c

+53 −51
Original line number Diff line number Diff line
@@ -907,13 +907,14 @@ static void blk_account_io_merge_bio(struct request *req) 
	part_stat_unlock();

}



bool bio_attempt_back_merge(struct request *req, struct bio *bio,

enum bio_merge_status bio_attempt_back_merge(struct request *req,

					     struct bio *bio,

					     unsigned int nr_segs)

{

	const int ff = bio->bi_opf & REQ_FAILFAST_MASK;



	if (!ll_back_merge_fn(req, bio, nr_segs))

		return false;

		return BIO_MERGE_FAILED;



	trace_block_bio_backmerge(req->q, req, bio);

	rq_qos_merge(req->q, req, bio);
@@ -928,16 +929,17 @@ bool bio_attempt_back_merge(struct request *req, struct bio *bio, 
	bio_crypt_free_ctx(bio);



	blk_account_io_merge_bio(req);

	return true;

	return BIO_MERGE_OK;

}



bool bio_attempt_front_merge(struct request *req, struct bio *bio,

enum bio_merge_status bio_attempt_front_merge(struct request *req,

					      struct bio *bio,

					      unsigned int nr_segs)

{

	const int ff = bio->bi_opf & REQ_FAILFAST_MASK;



	if (!ll_front_merge_fn(req, bio, nr_segs))

		return false;

		return BIO_MERGE_FAILED;



	trace_block_bio_frontmerge(req->q, req, bio);

	rq_qos_merge(req->q, req, bio);
@@ -954,10 +956,11 @@ bool bio_attempt_front_merge(struct request *req, struct bio *bio, 
	bio_crypt_do_front_merge(req, bio);



	blk_account_io_merge_bio(req);

	return true;

	return BIO_MERGE_OK;

}



bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,

enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q,

						struct request *req,

						struct bio *bio)

{

	unsigned short segments = blk_rq_nr_discard_segments(req);
@@ -976,10 +979,39 @@ bool bio_attempt_discard_merge(struct request_queue *q, struct request *req, 
	req->nr_phys_segments = segments + 1;



	blk_account_io_merge_bio(req);

	return true;

	return BIO_MERGE_OK;

no_merge:

	req_set_nomerge(q, req);

	return false;

	return BIO_MERGE_FAILED;

}



static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q,

						   struct request *rq,

						   struct bio *bio,

						   unsigned int nr_segs,

						   bool sched_allow_merge)

{

	if (!blk_rq_merge_ok(rq, bio))

		return BIO_MERGE_NONE;



	switch (blk_try_merge(rq, bio)) {

	case ELEVATOR_BACK_MERGE:

		if (!sched_allow_merge ||

		    (sched_allow_merge && blk_mq_sched_allow_merge(q, rq, bio)))

			return bio_attempt_back_merge(rq, bio, nr_segs);

		break;

	case ELEVATOR_FRONT_MERGE:

		if (!sched_allow_merge ||

		    (sched_allow_merge && blk_mq_sched_allow_merge(q, rq, bio)))

			return bio_attempt_front_merge(rq, bio, nr_segs);

		break;

	case ELEVATOR_DISCARD_MERGE:

		return bio_attempt_discard_merge(q, rq, bio);

	default:

		return BIO_MERGE_NONE;

	}



	return BIO_MERGE_FAILED;

}



/**
@@ -1018,8 +1050,6 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 
	plug_list = &plug->mq_list;



	list_for_each_entry_reverse(rq, plug_list, queuelist) {

		bool merged = false;



		if (rq->q == q && same_queue_rq) {

			/*

			 * Only blk-mq multiple hardware queues case checks the
@@ -1029,24 +1059,11 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 
			*same_queue_rq = rq;

		}



		if (rq->q != q || !blk_rq_merge_ok(rq, bio))

		if (rq->q != q)

			continue;



		switch (blk_try_merge(rq, bio)) {

		case ELEVATOR_BACK_MERGE:

			merged = bio_attempt_back_merge(rq, bio, nr_segs);

			break;

		case ELEVATOR_FRONT_MERGE:

			merged = bio_attempt_front_merge(rq, bio, nr_segs);

			break;

		case ELEVATOR_DISCARD_MERGE:

			merged = bio_attempt_discard_merge(q, rq, bio);

			break;

		default:

			break;

		}



		if (merged)

		if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) ==

		    BIO_MERGE_OK)

			return true;

	}
@@ -1064,33 +1081,18 @@ bool blk_bio_list_merge(struct request_queue *q, struct list_head *list, 
	int checked = 8;



	list_for_each_entry_reverse(rq, list, queuelist) {

		bool merged = false;



		if (!checked--)

			break;



		if (!blk_rq_merge_ok(rq, bio))

			continue;



		switch (blk_try_merge(rq, bio)) {

		case ELEVATOR_BACK_MERGE:

			if (blk_mq_sched_allow_merge(q, rq, bio))

				merged = bio_attempt_back_merge(rq, bio,

						nr_segs);

			break;

		case ELEVATOR_FRONT_MERGE:

			if (blk_mq_sched_allow_merge(q, rq, bio))

				merged = bio_attempt_front_merge(rq, bio,

						nr_segs);

			break;

		case ELEVATOR_DISCARD_MERGE:

			merged = bio_attempt_discard_merge(q, rq, bio);

			break;

		default:

		switch (blk_attempt_bio_merge(q, rq, bio, nr_segs, true)) {

		case BIO_MERGE_NONE:

			continue;

		case BIO_MERGE_OK:

			return true;

		case BIO_MERGE_FAILED:

			return false;

		}



		return merged;

	}



	return false;

block/blk-mq-sched.c

+3 −3
Original line number Diff line number Diff line
@@ -368,7 +368,7 @@ bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio, 
	case ELEVATOR_BACK_MERGE:

		if (!blk_mq_sched_allow_merge(q, rq, bio))

			return false;

		if (!bio_attempt_back_merge(rq, bio, nr_segs))

		if (bio_attempt_back_merge(rq, bio, nr_segs) != BIO_MERGE_OK)

			return false;

		*merged_request = attempt_back_merge(q, rq);

		if (!*merged_request)
@@ -377,14 +377,14 @@ bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio, 
	case ELEVATOR_FRONT_MERGE:

		if (!blk_mq_sched_allow_merge(q, rq, bio))

			return false;

		if (!bio_attempt_front_merge(rq, bio, nr_segs))

		if (bio_attempt_front_merge(rq, bio, nr_segs) != BIO_MERGE_OK)

			return false;

		*merged_request = attempt_front_merge(q, rq);

		if (!*merged_request)

			elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE);

		return true;

	case ELEVATOR_DISCARD_MERGE:

		return bio_attempt_discard_merge(q, rq, bio);

		return bio_attempt_discard_merge(q, rq, bio) == BIO_MERGE_OK;

	default:

		return false;

	}

block/blk.h

+15 −6
Original line number Diff line number Diff line
@@ -29,6 +29,12 @@ struct blk_flush_queue { 
	spinlock_t		mq_flush_lock;

};



enum bio_merge_status {

	BIO_MERGE_OK,

	BIO_MERGE_NONE,

	BIO_MERGE_FAILED,

};



extern struct kmem_cache *blk_requestq_cachep;

extern struct kobj_type blk_queue_ktype;

extern struct ida blk_queue_ida;
@@ -169,11 +175,14 @@ static inline void blk_integrity_del(struct gendisk *disk) 
unsigned long blk_rq_timeout(unsigned long timeout);

void blk_add_timer(struct request *req);



bool bio_attempt_front_merge(struct request *req, struct bio *bio,

enum bio_merge_status bio_attempt_front_merge(struct request *req,

					      struct bio *bio,

					      unsigned int nr_segs);

bool bio_attempt_back_merge(struct request *req, struct bio *bio,

enum bio_merge_status bio_attempt_back_merge(struct request *req,

					     struct bio *bio,

					     unsigned int nr_segs);

bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,

enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q,

						struct request *req,

						struct bio *bio);

bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,

		unsigned int nr_segs, struct request **same_queue_rq);

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