Commit bdced438 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: setup bi_phys_segments after splitting 



The number of bio->bi_phys_segments is always obtained
during bio splitting, so it is natural to setup it
just after bio splitting, then we can avoid to compute
nr_segment again during merge.

Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 0809e3ac

block/blk-merge.c

+22 −7
Original line number Diff line number Diff line
@@ -11,13 +11,16 @@ 


static struct bio *blk_bio_discard_split(struct request_queue *q,

					 struct bio *bio,

					 struct bio_set *bs)

					 struct bio_set *bs,

					 unsigned *nsegs)

{

	unsigned int max_discard_sectors, granularity;

	int alignment;

	sector_t tmp;

	unsigned split_sectors;



	*nsegs = 1;



	/* Zero-sector (unknown) and one-sector granularities are the same.  */

	granularity = max(q->limits.discard_granularity >> 9, 1U);
@@ -51,8 +54,11 @@ static struct bio *blk_bio_discard_split(struct request_queue *q, 


static struct bio *blk_bio_write_same_split(struct request_queue *q,

					    struct bio *bio,

					    struct bio_set *bs)

					    struct bio_set *bs,

					    unsigned *nsegs)

{

	*nsegs = 1;



	if (!q->limits.max_write_same_sectors)

		return NULL;
@@ -64,7 +70,8 @@ static struct bio *blk_bio_write_same_split(struct request_queue *q, 


static struct bio *blk_bio_segment_split(struct request_queue *q,

					 struct bio *bio,

					 struct bio_set *bs)

					 struct bio_set *bs,

					 unsigned *segs)

{

	struct bio_vec bv, bvprv, *bvprvp = NULL;

	struct bvec_iter iter;
@@ -106,22 +113,30 @@ new_segment: 
		sectors += bv.bv_len >> 9;

	}



	*segs = nsegs;

	return NULL;

split:

	*segs = nsegs;

	return bio_split(bio, sectors, GFP_NOIO, bs);

}



void blk_queue_split(struct request_queue *q, struct bio **bio,

		     struct bio_set *bs)

{

	struct bio *split;

	struct bio *split, *res;

	unsigned nsegs;



	if ((*bio)->bi_rw & REQ_DISCARD)

		split = blk_bio_discard_split(q, *bio, bs);

		split = blk_bio_discard_split(q, *bio, bs, &nsegs);

	else if ((*bio)->bi_rw & REQ_WRITE_SAME)

		split = blk_bio_write_same_split(q, *bio, bs);

		split = blk_bio_write_same_split(q, *bio, bs, &nsegs);

	else

		split = blk_bio_segment_split(q, *bio, q->bio_split);

		split = blk_bio_segment_split(q, *bio, q->bio_split, &nsegs);



	/* physical segments can be figured out during splitting */

	res = split ? split : *bio;

	res->bi_phys_segments = nsegs;

	bio_set_flag(res, BIO_SEG_VALID);



	if (split) {

		bio_chain(split, *bio);

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