diff options
Diffstat (limited to 'block/blk-merge.c')
| -rw-r--r-- | block/blk-merge.c | 69 |
1 files changed, 42 insertions, 27 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c index 3e934ee9a907..8f96d683b577 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -354,11 +354,11 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, struct bio *bio) { struct bio_vec bv, bvprv = { NULL }; - int prev = 0; unsigned int seg_size, nr_phys_segs; unsigned front_seg_size; struct bio *fbio, *bbio; struct bvec_iter iter; + bool new_bio = false; if (!bio) return 0; @@ -379,7 +379,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, nr_phys_segs = 0; for_each_bio(bio) { bio_for_each_bvec(bv, bio, iter) { - if (prev) { + if (new_bio) { if (seg_size + bv.bv_len > queue_max_segment_size(q)) goto new_segment; @@ -387,7 +387,6 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, goto new_segment; seg_size += bv.bv_len; - bvprv = bv; if (nr_phys_segs == 1 && seg_size > front_seg_size) @@ -396,12 +395,13 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, continue; } new_segment: - bvprv = bv; - prev = 1; bvec_split_segs(q, &bv, &nr_phys_segs, &seg_size, &front_seg_size, NULL, UINT_MAX); + new_bio = false; } bbio = bio; + bvprv = bv; + new_bio = true; } fbio->bi_seg_front_size = front_seg_size; @@ -501,29 +501,26 @@ static inline int __blk_bvec_map_sg(struct bio_vec bv, return 1; } -static inline void -__blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, - struct scatterlist *sglist, struct bio_vec *bvprv, - struct scatterlist **sg, int *nsegs) +/* only try to merge bvecs into one sg if they are from two bios */ +static inline bool +__blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec, + struct bio_vec *bvprv, struct scatterlist **sg) { int nbytes = bvec->bv_len; - if (*sg) { - if ((*sg)->length + nbytes > queue_max_segment_size(q)) - goto new_segment; - if (!biovec_phys_mergeable(q, bvprv, bvec)) - goto new_segment; + if (!*sg) + return false; - (*sg)->length += nbytes; - } else { -new_segment: - if (bvec->bv_offset + bvec->bv_len <= PAGE_SIZE) { - (*nsegs) += __blk_bvec_map_sg(*bvec, sglist, sg); - } else - (*nsegs) += blk_bvec_map_sg(q, bvec, sglist, sg); - } - *bvprv = *bvec; + if ((*sg)->length + nbytes > queue_max_segment_size(q)) + return false; + + if (!biovec_phys_mergeable(q, bvprv, bvec)) + return false; + + (*sg)->length += nbytes; + + return true; } static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, @@ -533,11 +530,29 @@ static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, struct bio_vec bvec, bvprv = { NULL }; struct bvec_iter iter; int nsegs = 0; + bool new_bio = false; - for_each_bio(bio) - bio_for_each_bvec(bvec, bio, iter) - __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, - &nsegs); + for_each_bio(bio) { + bio_for_each_bvec(bvec, bio, iter) { + /* + * Only try to merge bvecs from two bios given we + * have done bio internal merge when adding pages + * to bio + */ + if (new_bio && + __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg)) + goto next_bvec; + + if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE) + nsegs += __blk_bvec_map_sg(bvec, sglist, sg); + else + nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg); + next_bvec: + new_bio = false; + } + bvprv = bvec; + new_bio = true; + } return nsegs; } |