1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 2d6d48196SJens Axboe /* 3d6d48196SJens Axboe * Functions related to segment and merge handling 4d6d48196SJens Axboe */ 5d6d48196SJens Axboe #include <linux/kernel.h> 6d6d48196SJens Axboe #include <linux/module.h> 7d6d48196SJens Axboe #include <linux/bio.h> 8d6d48196SJens Axboe #include <linux/blkdev.h> 9d6d48196SJens Axboe #include <linux/scatterlist.h> 10d6d48196SJens Axboe 11cda22646SMike Krinkin #include <trace/events/block.h> 12cda22646SMike Krinkin 13d6d48196SJens Axboe #include "blk.h" 14d6d48196SJens Axboe 15e9907009SChristoph Hellwig /* 16e9907009SChristoph Hellwig * Check if the two bvecs from two bios can be merged to one segment. If yes, 17e9907009SChristoph Hellwig * no need to check gap between the two bios since the 1st bio and the 1st bvec 18e9907009SChristoph Hellwig * in the 2nd bio can be handled in one segment. 19e9907009SChristoph Hellwig */ 20e9907009SChristoph Hellwig static inline bool bios_segs_mergeable(struct request_queue *q, 21e9907009SChristoph Hellwig struct bio *prev, struct bio_vec *prev_last_bv, 22e9907009SChristoph Hellwig struct bio_vec *next_first_bv) 23e9907009SChristoph Hellwig { 243dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, prev_last_bv, next_first_bv)) 25e9907009SChristoph Hellwig return false; 26e9907009SChristoph Hellwig if (prev->bi_seg_back_size + next_first_bv->bv_len > 27e9907009SChristoph Hellwig queue_max_segment_size(q)) 28e9907009SChristoph Hellwig return false; 29e9907009SChristoph Hellwig return true; 30e9907009SChristoph Hellwig } 31e9907009SChristoph Hellwig 32e9907009SChristoph Hellwig static inline bool bio_will_gap(struct request_queue *q, 33e9907009SChristoph Hellwig struct request *prev_rq, struct bio *prev, struct bio *next) 34e9907009SChristoph Hellwig { 35e9907009SChristoph Hellwig struct bio_vec pb, nb; 36e9907009SChristoph Hellwig 37e9907009SChristoph Hellwig if (!bio_has_data(prev) || !queue_virt_boundary(q)) 38e9907009SChristoph Hellwig return false; 39e9907009SChristoph Hellwig 40e9907009SChristoph Hellwig /* 41e9907009SChristoph Hellwig * Don't merge if the 1st bio starts with non-zero offset, otherwise it 42e9907009SChristoph Hellwig * is quite difficult to respect the sg gap limit. We work hard to 43e9907009SChristoph Hellwig * merge a huge number of small single bios in case of mkfs. 44e9907009SChristoph Hellwig */ 45e9907009SChristoph Hellwig if (prev_rq) 46e9907009SChristoph Hellwig bio_get_first_bvec(prev_rq->bio, &pb); 47e9907009SChristoph Hellwig else 48e9907009SChristoph Hellwig bio_get_first_bvec(prev, &pb); 49df376b2eSJohannes Thumshirn if (pb.bv_offset & queue_virt_boundary(q)) 50e9907009SChristoph Hellwig return true; 51e9907009SChristoph Hellwig 52e9907009SChristoph Hellwig /* 53e9907009SChristoph Hellwig * We don't need to worry about the situation that the merged segment 54e9907009SChristoph Hellwig * ends in unaligned virt boundary: 55e9907009SChristoph Hellwig * 56e9907009SChristoph Hellwig * - if 'pb' ends aligned, the merged segment ends aligned 57e9907009SChristoph Hellwig * - if 'pb' ends unaligned, the next bio must include 58e9907009SChristoph Hellwig * one single bvec of 'nb', otherwise the 'nb' can't 59e9907009SChristoph Hellwig * merge with 'pb' 60e9907009SChristoph Hellwig */ 61e9907009SChristoph Hellwig bio_get_last_bvec(prev, &pb); 62e9907009SChristoph Hellwig bio_get_first_bvec(next, &nb); 63e9907009SChristoph Hellwig if (bios_segs_mergeable(q, prev, &pb, &nb)) 64e9907009SChristoph Hellwig return false; 65e9907009SChristoph Hellwig return __bvec_gap_to_prev(q, &pb, nb.bv_offset); 66e9907009SChristoph Hellwig } 67e9907009SChristoph Hellwig 68e9907009SChristoph Hellwig static inline bool req_gap_back_merge(struct request *req, struct bio *bio) 69e9907009SChristoph Hellwig { 70e9907009SChristoph Hellwig return bio_will_gap(req->q, req, req->biotail, bio); 71e9907009SChristoph Hellwig } 72e9907009SChristoph Hellwig 73e9907009SChristoph Hellwig static inline bool req_gap_front_merge(struct request *req, struct bio *bio) 74e9907009SChristoph Hellwig { 75e9907009SChristoph Hellwig return bio_will_gap(req->q, NULL, bio, req->bio); 76e9907009SChristoph Hellwig } 77e9907009SChristoph Hellwig 7854efd50bSKent Overstreet static struct bio *blk_bio_discard_split(struct request_queue *q, 7954efd50bSKent Overstreet struct bio *bio, 80bdced438SMing Lei struct bio_set *bs, 81bdced438SMing Lei unsigned *nsegs) 8254efd50bSKent Overstreet { 8354efd50bSKent Overstreet unsigned int max_discard_sectors, granularity; 8454efd50bSKent Overstreet int alignment; 8554efd50bSKent Overstreet sector_t tmp; 8654efd50bSKent Overstreet unsigned split_sectors; 8754efd50bSKent Overstreet 88bdced438SMing Lei *nsegs = 1; 89bdced438SMing Lei 9054efd50bSKent Overstreet /* Zero-sector (unknown) and one-sector granularities are the same. */ 9154efd50bSKent Overstreet granularity = max(q->limits.discard_granularity >> 9, 1U); 9254efd50bSKent Overstreet 931adfc5e4SMing Lei max_discard_sectors = min(q->limits.max_discard_sectors, 941adfc5e4SMing Lei bio_allowed_max_sectors(q)); 9554efd50bSKent Overstreet max_discard_sectors -= max_discard_sectors % granularity; 9654efd50bSKent Overstreet 9754efd50bSKent Overstreet if (unlikely(!max_discard_sectors)) { 9854efd50bSKent Overstreet /* XXX: warn */ 9954efd50bSKent Overstreet return NULL; 10054efd50bSKent Overstreet } 10154efd50bSKent Overstreet 10254efd50bSKent Overstreet if (bio_sectors(bio) <= max_discard_sectors) 10354efd50bSKent Overstreet return NULL; 10454efd50bSKent Overstreet 10554efd50bSKent Overstreet split_sectors = max_discard_sectors; 10654efd50bSKent Overstreet 10754efd50bSKent Overstreet /* 10854efd50bSKent Overstreet * If the next starting sector would be misaligned, stop the discard at 10954efd50bSKent Overstreet * the previous aligned sector. 11054efd50bSKent Overstreet */ 11154efd50bSKent Overstreet alignment = (q->limits.discard_alignment >> 9) % granularity; 11254efd50bSKent Overstreet 11354efd50bSKent Overstreet tmp = bio->bi_iter.bi_sector + split_sectors - alignment; 11454efd50bSKent Overstreet tmp = sector_div(tmp, granularity); 11554efd50bSKent Overstreet 11654efd50bSKent Overstreet if (split_sectors > tmp) 11754efd50bSKent Overstreet split_sectors -= tmp; 11854efd50bSKent Overstreet 11954efd50bSKent Overstreet return bio_split(bio, split_sectors, GFP_NOIO, bs); 12054efd50bSKent Overstreet } 12154efd50bSKent Overstreet 122885fa13fSChristoph Hellwig static struct bio *blk_bio_write_zeroes_split(struct request_queue *q, 123885fa13fSChristoph Hellwig struct bio *bio, struct bio_set *bs, unsigned *nsegs) 124885fa13fSChristoph Hellwig { 125885fa13fSChristoph Hellwig *nsegs = 1; 126885fa13fSChristoph Hellwig 127885fa13fSChristoph Hellwig if (!q->limits.max_write_zeroes_sectors) 128885fa13fSChristoph Hellwig return NULL; 129885fa13fSChristoph Hellwig 130885fa13fSChristoph Hellwig if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors) 131885fa13fSChristoph Hellwig return NULL; 132885fa13fSChristoph Hellwig 133885fa13fSChristoph Hellwig return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs); 134885fa13fSChristoph Hellwig } 135885fa13fSChristoph Hellwig 13654efd50bSKent Overstreet static struct bio *blk_bio_write_same_split(struct request_queue *q, 13754efd50bSKent Overstreet struct bio *bio, 138bdced438SMing Lei struct bio_set *bs, 139bdced438SMing Lei unsigned *nsegs) 14054efd50bSKent Overstreet { 141bdced438SMing Lei *nsegs = 1; 142bdced438SMing Lei 14354efd50bSKent Overstreet if (!q->limits.max_write_same_sectors) 14454efd50bSKent Overstreet return NULL; 14554efd50bSKent Overstreet 14654efd50bSKent Overstreet if (bio_sectors(bio) <= q->limits.max_write_same_sectors) 14754efd50bSKent Overstreet return NULL; 14854efd50bSKent Overstreet 14954efd50bSKent Overstreet return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); 15054efd50bSKent Overstreet } 15154efd50bSKent Overstreet 152d0e5fbb0SMing Lei static inline unsigned get_max_io_size(struct request_queue *q, 153d0e5fbb0SMing Lei struct bio *bio) 154d0e5fbb0SMing Lei { 155d0e5fbb0SMing Lei unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector); 156d0e5fbb0SMing Lei unsigned mask = queue_logical_block_size(q) - 1; 157d0e5fbb0SMing Lei 158d0e5fbb0SMing Lei /* aligned to logical block size */ 159d0e5fbb0SMing Lei sectors &= ~(mask >> 9); 160d0e5fbb0SMing Lei 161d0e5fbb0SMing Lei return sectors; 162d0e5fbb0SMing Lei } 163d0e5fbb0SMing Lei 16454efd50bSKent Overstreet static struct bio *blk_bio_segment_split(struct request_queue *q, 16554efd50bSKent Overstreet struct bio *bio, 166bdced438SMing Lei struct bio_set *bs, 167bdced438SMing Lei unsigned *segs) 16854efd50bSKent Overstreet { 1695014c311SJens Axboe struct bio_vec bv, bvprv, *bvprvp = NULL; 17054efd50bSKent Overstreet struct bvec_iter iter; 1718ae12666SKent Overstreet unsigned seg_size = 0, nsegs = 0, sectors = 0; 17202e70742SMing Lei unsigned front_seg_size = bio->bi_seg_front_size; 17302e70742SMing Lei bool do_split = true; 17402e70742SMing Lei struct bio *new = NULL; 175d0e5fbb0SMing Lei const unsigned max_sectors = get_max_io_size(q, bio); 17654efd50bSKent Overstreet 17754efd50bSKent Overstreet bio_for_each_segment(bv, bio, iter) { 17854efd50bSKent Overstreet /* 17954efd50bSKent Overstreet * If the queue doesn't support SG gaps and adding this 18054efd50bSKent Overstreet * offset would create a gap, disallow it. 18154efd50bSKent Overstreet */ 1825014c311SJens Axboe if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) 18354efd50bSKent Overstreet goto split; 18454efd50bSKent Overstreet 185d0e5fbb0SMing Lei if (sectors + (bv.bv_len >> 9) > max_sectors) { 186e36f6204SKeith Busch /* 187e36f6204SKeith Busch * Consider this a new segment if we're splitting in 188e36f6204SKeith Busch * the middle of this vector. 189e36f6204SKeith Busch */ 190e36f6204SKeith Busch if (nsegs < queue_max_segments(q) && 191d0e5fbb0SMing Lei sectors < max_sectors) { 192e36f6204SKeith Busch nsegs++; 193d0e5fbb0SMing Lei sectors = max_sectors; 194e36f6204SKeith Busch } 195e36f6204SKeith Busch goto split; 196e36f6204SKeith Busch } 197e36f6204SKeith Busch 19838417468SChristoph Hellwig if (bvprvp) { 199b4b6cb61SMing Lei if (seg_size + bv.bv_len > queue_max_segment_size(q)) 200b4b6cb61SMing Lei goto new_segment; 2013dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, bvprvp, &bv)) 20254efd50bSKent Overstreet goto new_segment; 20354efd50bSKent Overstreet 20454efd50bSKent Overstreet seg_size += bv.bv_len; 20554efd50bSKent Overstreet bvprv = bv; 206578270bfSMing Lei bvprvp = &bvprv; 20752cc6eeaSMing Lei sectors += bv.bv_len >> 9; 208a88d32afSMing Lei 20954efd50bSKent Overstreet continue; 21054efd50bSKent Overstreet } 21154efd50bSKent Overstreet new_segment: 21254efd50bSKent Overstreet if (nsegs == queue_max_segments(q)) 21354efd50bSKent Overstreet goto split; 21454efd50bSKent Overstreet 2156a501bf0SMing Lei if (nsegs == 1 && seg_size > front_seg_size) 2166a501bf0SMing Lei front_seg_size = seg_size; 2176a501bf0SMing Lei 21854efd50bSKent Overstreet nsegs++; 21954efd50bSKent Overstreet bvprv = bv; 220578270bfSMing Lei bvprvp = &bvprv; 22154efd50bSKent Overstreet seg_size = bv.bv_len; 22252cc6eeaSMing Lei sectors += bv.bv_len >> 9; 22302e70742SMing Lei 22454efd50bSKent Overstreet } 22554efd50bSKent Overstreet 22602e70742SMing Lei do_split = false; 22754efd50bSKent Overstreet split: 228bdced438SMing Lei *segs = nsegs; 22902e70742SMing Lei 23002e70742SMing Lei if (do_split) { 23102e70742SMing Lei new = bio_split(bio, sectors, GFP_NOIO, bs); 23202e70742SMing Lei if (new) 23302e70742SMing Lei bio = new; 23402e70742SMing Lei } 23502e70742SMing Lei 2366a501bf0SMing Lei if (nsegs == 1 && seg_size > front_seg_size) 2376a501bf0SMing Lei front_seg_size = seg_size; 23802e70742SMing Lei bio->bi_seg_front_size = front_seg_size; 23902e70742SMing Lei if (seg_size > bio->bi_seg_back_size) 24002e70742SMing Lei bio->bi_seg_back_size = seg_size; 24102e70742SMing Lei 24202e70742SMing Lei return do_split ? new : NULL; 24354efd50bSKent Overstreet } 24454efd50bSKent Overstreet 245af67c31fSNeilBrown void blk_queue_split(struct request_queue *q, struct bio **bio) 24654efd50bSKent Overstreet { 247bdced438SMing Lei struct bio *split, *res; 248bdced438SMing Lei unsigned nsegs; 24954efd50bSKent Overstreet 2507afafc8aSAdrian Hunter switch (bio_op(*bio)) { 2517afafc8aSAdrian Hunter case REQ_OP_DISCARD: 2527afafc8aSAdrian Hunter case REQ_OP_SECURE_ERASE: 253338aa96dSKent Overstreet split = blk_bio_discard_split(q, *bio, &q->bio_split, &nsegs); 2547afafc8aSAdrian Hunter break; 255a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 256338aa96dSKent Overstreet split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split, &nsegs); 257a6f0788eSChaitanya Kulkarni break; 2587afafc8aSAdrian Hunter case REQ_OP_WRITE_SAME: 259338aa96dSKent Overstreet split = blk_bio_write_same_split(q, *bio, &q->bio_split, &nsegs); 2607afafc8aSAdrian Hunter break; 2617afafc8aSAdrian Hunter default: 262338aa96dSKent Overstreet split = blk_bio_segment_split(q, *bio, &q->bio_split, &nsegs); 2637afafc8aSAdrian Hunter break; 2647afafc8aSAdrian Hunter } 265bdced438SMing Lei 266bdced438SMing Lei /* physical segments can be figured out during splitting */ 267bdced438SMing Lei res = split ? split : *bio; 268bdced438SMing Lei res->bi_phys_segments = nsegs; 269bdced438SMing Lei bio_set_flag(res, BIO_SEG_VALID); 27054efd50bSKent Overstreet 27154efd50bSKent Overstreet if (split) { 2726ac45aebSMing Lei /* there isn't chance to merge the splitted bio */ 2731eff9d32SJens Axboe split->bi_opf |= REQ_NOMERGE; 2746ac45aebSMing Lei 275947b7ac1SJens Axboe /* 276947b7ac1SJens Axboe * Since we're recursing into make_request here, ensure 277947b7ac1SJens Axboe * that we mark this bio as already having entered the queue. 278947b7ac1SJens Axboe * If not, and the queue is going away, we can get stuck 279947b7ac1SJens Axboe * forever on waiting for the queue reference to drop. But 280947b7ac1SJens Axboe * that will never happen, as we're already holding a 281947b7ac1SJens Axboe * reference to it. 282947b7ac1SJens Axboe */ 283947b7ac1SJens Axboe bio_set_flag(*bio, BIO_QUEUE_ENTERED); 284947b7ac1SJens Axboe 28554efd50bSKent Overstreet bio_chain(split, *bio); 286cda22646SMike Krinkin trace_block_split(q, split, (*bio)->bi_iter.bi_sector); 28754efd50bSKent Overstreet generic_make_request(*bio); 28854efd50bSKent Overstreet *bio = split; 28954efd50bSKent Overstreet } 29054efd50bSKent Overstreet } 29154efd50bSKent Overstreet EXPORT_SYMBOL(blk_queue_split); 29254efd50bSKent Overstreet 2931e428079SJens Axboe static unsigned int __blk_recalc_rq_segments(struct request_queue *q, 29407388549SMing Lei struct bio *bio, 29507388549SMing Lei bool no_sg_merge) 296d6d48196SJens Axboe { 2977988613bSKent Overstreet struct bio_vec bv, bvprv = { NULL }; 29838417468SChristoph Hellwig int prev = 0; 2991e428079SJens Axboe unsigned int seg_size, nr_phys_segs; 30059247eaeSJens Axboe struct bio *fbio, *bbio; 3017988613bSKent Overstreet struct bvec_iter iter; 302d6d48196SJens Axboe 3031e428079SJens Axboe if (!bio) 3041e428079SJens Axboe return 0; 305d6d48196SJens Axboe 306a6f0788eSChaitanya Kulkarni switch (bio_op(bio)) { 307a6f0788eSChaitanya Kulkarni case REQ_OP_DISCARD: 308a6f0788eSChaitanya Kulkarni case REQ_OP_SECURE_ERASE: 309a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 310f9d03f96SChristoph Hellwig return 0; 311f9d03f96SChristoph Hellwig case REQ_OP_WRITE_SAME: 3125cb8850cSKent Overstreet return 1; 313a6f0788eSChaitanya Kulkarni } 3145cb8850cSKent Overstreet 3151e428079SJens Axboe fbio = bio; 3165df97b91SMikulas Patocka seg_size = 0; 3172c8919deSAndi Kleen nr_phys_segs = 0; 3181e428079SJens Axboe for_each_bio(bio) { 3197988613bSKent Overstreet bio_for_each_segment(bv, bio, iter) { 320d6d48196SJens Axboe /* 32105f1dd53SJens Axboe * If SG merging is disabled, each bio vector is 32205f1dd53SJens Axboe * a segment 32305f1dd53SJens Axboe */ 32405f1dd53SJens Axboe if (no_sg_merge) 32505f1dd53SJens Axboe goto new_segment; 32605f1dd53SJens Axboe 32738417468SChristoph Hellwig if (prev) { 3287988613bSKent Overstreet if (seg_size + bv.bv_len 329ae03bf63SMartin K. Petersen > queue_max_segment_size(q)) 330d6d48196SJens Axboe goto new_segment; 3313dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, &bvprv, &bv)) 332d6d48196SJens Axboe goto new_segment; 333d6d48196SJens Axboe 3347988613bSKent Overstreet seg_size += bv.bv_len; 335d6d48196SJens Axboe bvprv = bv; 336d6d48196SJens Axboe continue; 337d6d48196SJens Axboe } 338d6d48196SJens Axboe new_segment: 3391e428079SJens Axboe if (nr_phys_segs == 1 && seg_size > 3401e428079SJens Axboe fbio->bi_seg_front_size) 3411e428079SJens Axboe fbio->bi_seg_front_size = seg_size; 34286771427SFUJITA Tomonori 343d6d48196SJens Axboe nr_phys_segs++; 344d6d48196SJens Axboe bvprv = bv; 34554efd50bSKent Overstreet prev = 1; 3467988613bSKent Overstreet seg_size = bv.bv_len; 347d6d48196SJens Axboe } 34859247eaeSJens Axboe bbio = bio; 3491e428079SJens Axboe } 350d6d48196SJens Axboe 35159247eaeSJens Axboe if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) 35259247eaeSJens Axboe fbio->bi_seg_front_size = seg_size; 35359247eaeSJens Axboe if (seg_size > bbio->bi_seg_back_size) 35459247eaeSJens Axboe bbio->bi_seg_back_size = seg_size; 3551e428079SJens Axboe 3561e428079SJens Axboe return nr_phys_segs; 3571e428079SJens Axboe } 3581e428079SJens Axboe 3591e428079SJens Axboe void blk_recalc_rq_segments(struct request *rq) 3601e428079SJens Axboe { 36107388549SMing Lei bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, 36207388549SMing Lei &rq->q->queue_flags); 36307388549SMing Lei 36407388549SMing Lei rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio, 36507388549SMing Lei no_sg_merge); 366d6d48196SJens Axboe } 367d6d48196SJens Axboe 368d6d48196SJens Axboe void blk_recount_segments(struct request_queue *q, struct bio *bio) 369d6d48196SJens Axboe { 3707f60dcaaSMing Lei unsigned short seg_cnt; 371764f612cSMing Lei 3727f60dcaaSMing Lei /* estimate segment number by bi_vcnt for non-cloned bio */ 3737f60dcaaSMing Lei if (bio_flagged(bio, BIO_CLONED)) 3747f60dcaaSMing Lei seg_cnt = bio_segments(bio); 3757f60dcaaSMing Lei else 3767f60dcaaSMing Lei seg_cnt = bio->bi_vcnt; 3777f60dcaaSMing Lei 3787f60dcaaSMing Lei if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) && 3797f60dcaaSMing Lei (seg_cnt < queue_max_segments(q))) 3807f60dcaaSMing Lei bio->bi_phys_segments = seg_cnt; 38105f1dd53SJens Axboe else { 382d6d48196SJens Axboe struct bio *nxt = bio->bi_next; 3831e428079SJens Axboe 384d6d48196SJens Axboe bio->bi_next = NULL; 3857f60dcaaSMing Lei bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false); 386d6d48196SJens Axboe bio->bi_next = nxt; 38705f1dd53SJens Axboe } 38805f1dd53SJens Axboe 389b7c44ed9SJens Axboe bio_set_flag(bio, BIO_SEG_VALID); 390d6d48196SJens Axboe } 391d6d48196SJens Axboe 392d6d48196SJens Axboe static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, 393d6d48196SJens Axboe struct bio *nxt) 394d6d48196SJens Axboe { 3952b8221e1SKent Overstreet struct bio_vec end_bv = { NULL }, nxt_bv; 396f619d254SKent Overstreet 39786771427SFUJITA Tomonori if (bio->bi_seg_back_size + nxt->bi_seg_front_size > 398ae03bf63SMartin K. Petersen queue_max_segment_size(q)) 399d6d48196SJens Axboe return 0; 400d6d48196SJens Axboe 401e17fc0a1SDavid Woodhouse if (!bio_has_data(bio)) 402e17fc0a1SDavid Woodhouse return 1; 403e17fc0a1SDavid Woodhouse 404e827091cSMing Lei bio_get_last_bvec(bio, &end_bv); 405e827091cSMing Lei bio_get_first_bvec(nxt, &nxt_bv); 406f619d254SKent Overstreet 4073dccdae5SChristoph Hellwig return biovec_phys_mergeable(q, &end_bv, &nxt_bv); 408d6d48196SJens Axboe } 409d6d48196SJens Axboe 4107988613bSKent Overstreet static inline void 411963ab9e5SAsias He __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, 4127988613bSKent Overstreet struct scatterlist *sglist, struct bio_vec *bvprv, 41338417468SChristoph Hellwig struct scatterlist **sg, int *nsegs) 414963ab9e5SAsias He { 415963ab9e5SAsias He 416963ab9e5SAsias He int nbytes = bvec->bv_len; 417963ab9e5SAsias He 41838417468SChristoph Hellwig if (*sg) { 419b4b6cb61SMing Lei if ((*sg)->length + nbytes > queue_max_segment_size(q)) 420b4b6cb61SMing Lei goto new_segment; 4213dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, bvprv, bvec)) 422963ab9e5SAsias He goto new_segment; 423963ab9e5SAsias He 424963ab9e5SAsias He (*sg)->length += nbytes; 425963ab9e5SAsias He } else { 426963ab9e5SAsias He new_segment: 427963ab9e5SAsias He if (!*sg) 428963ab9e5SAsias He *sg = sglist; 429963ab9e5SAsias He else { 430963ab9e5SAsias He /* 431963ab9e5SAsias He * If the driver previously mapped a shorter 432963ab9e5SAsias He * list, we could see a termination bit 433963ab9e5SAsias He * prematurely unless it fully inits the sg 434963ab9e5SAsias He * table on each mapping. We KNOW that there 435963ab9e5SAsias He * must be more entries here or the driver 436963ab9e5SAsias He * would be buggy, so force clear the 437963ab9e5SAsias He * termination bit to avoid doing a full 438963ab9e5SAsias He * sg_init_table() in drivers for each command. 439963ab9e5SAsias He */ 440c8164d89SPaolo Bonzini sg_unmark_end(*sg); 441963ab9e5SAsias He *sg = sg_next(*sg); 442963ab9e5SAsias He } 443963ab9e5SAsias He 444963ab9e5SAsias He sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); 445963ab9e5SAsias He (*nsegs)++; 446963ab9e5SAsias He } 4477988613bSKent Overstreet *bvprv = *bvec; 448963ab9e5SAsias He } 449963ab9e5SAsias He 450f9d03f96SChristoph Hellwig static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, 451f9d03f96SChristoph Hellwig struct scatterlist *sglist, struct scatterlist **sg) 452f9d03f96SChristoph Hellwig { 453f9d03f96SChristoph Hellwig *sg = sglist; 454f9d03f96SChristoph Hellwig sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); 455f9d03f96SChristoph Hellwig return 1; 456f9d03f96SChristoph Hellwig } 457f9d03f96SChristoph Hellwig 4585cb8850cSKent Overstreet static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, 4595cb8850cSKent Overstreet struct scatterlist *sglist, 4605cb8850cSKent Overstreet struct scatterlist **sg) 4615cb8850cSKent Overstreet { 4625cb8850cSKent Overstreet struct bio_vec bvec, bvprv = { NULL }; 4635cb8850cSKent Overstreet struct bvec_iter iter; 46438417468SChristoph Hellwig int nsegs = 0; 4655cb8850cSKent Overstreet 4665cb8850cSKent Overstreet for_each_bio(bio) 4675cb8850cSKent Overstreet bio_for_each_segment(bvec, bio, iter) 4685cb8850cSKent Overstreet __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, 46938417468SChristoph Hellwig &nsegs); 4705cb8850cSKent Overstreet 4715cb8850cSKent Overstreet return nsegs; 4725cb8850cSKent Overstreet } 4735cb8850cSKent Overstreet 474d6d48196SJens Axboe /* 475d6d48196SJens Axboe * map a request to scatterlist, return number of sg entries setup. Caller 476d6d48196SJens Axboe * must make sure sg can hold rq->nr_phys_segments entries 477d6d48196SJens Axboe */ 478d6d48196SJens Axboe int blk_rq_map_sg(struct request_queue *q, struct request *rq, 479d6d48196SJens Axboe struct scatterlist *sglist) 480d6d48196SJens Axboe { 4815cb8850cSKent Overstreet struct scatterlist *sg = NULL; 4825cb8850cSKent Overstreet int nsegs = 0; 483d6d48196SJens Axboe 484f9d03f96SChristoph Hellwig if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) 485f9d03f96SChristoph Hellwig nsegs = __blk_bvec_map_sg(q, rq->special_vec, sglist, &sg); 486f9d03f96SChristoph Hellwig else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME) 487f9d03f96SChristoph Hellwig nsegs = __blk_bvec_map_sg(q, bio_iovec(rq->bio), sglist, &sg); 488f9d03f96SChristoph Hellwig else if (rq->bio) 4895cb8850cSKent Overstreet nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); 490f18573abSFUJITA Tomonori 491e8064021SChristoph Hellwig if (unlikely(rq->rq_flags & RQF_COPY_USER) && 4922e46e8b2STejun Heo (blk_rq_bytes(rq) & q->dma_pad_mask)) { 4932e46e8b2STejun Heo unsigned int pad_len = 4942e46e8b2STejun Heo (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; 495f18573abSFUJITA Tomonori 496f18573abSFUJITA Tomonori sg->length += pad_len; 497f18573abSFUJITA Tomonori rq->extra_len += pad_len; 498f18573abSFUJITA Tomonori } 499f18573abSFUJITA Tomonori 5002fb98e84STejun Heo if (q->dma_drain_size && q->dma_drain_needed(rq)) { 501a8ebb056SMike Christie if (op_is_write(req_op(rq))) 502db0a2e00STejun Heo memset(q->dma_drain_buffer, 0, q->dma_drain_size); 503db0a2e00STejun Heo 504da81ed16SDan Williams sg_unmark_end(sg); 505d6d48196SJens Axboe sg = sg_next(sg); 506d6d48196SJens Axboe sg_set_page(sg, virt_to_page(q->dma_drain_buffer), 507d6d48196SJens Axboe q->dma_drain_size, 508d6d48196SJens Axboe ((unsigned long)q->dma_drain_buffer) & 509d6d48196SJens Axboe (PAGE_SIZE - 1)); 510d6d48196SJens Axboe nsegs++; 5117a85f889SFUJITA Tomonori rq->extra_len += q->dma_drain_size; 512d6d48196SJens Axboe } 513d6d48196SJens Axboe 514d6d48196SJens Axboe if (sg) 515d6d48196SJens Axboe sg_mark_end(sg); 516d6d48196SJens Axboe 51712e57f59SMing Lei /* 51812e57f59SMing Lei * Something must have been wrong if the figured number of 51912e57f59SMing Lei * segment is bigger than number of req's physical segments 52012e57f59SMing Lei */ 521f9d03f96SChristoph Hellwig WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); 52212e57f59SMing Lei 523d6d48196SJens Axboe return nsegs; 524d6d48196SJens Axboe } 525d6d48196SJens Axboe EXPORT_SYMBOL(blk_rq_map_sg); 526d6d48196SJens Axboe 527d6d48196SJens Axboe static inline int ll_new_hw_segment(struct request_queue *q, 528d6d48196SJens Axboe struct request *req, 529d6d48196SJens Axboe struct bio *bio) 530d6d48196SJens Axboe { 531d6d48196SJens Axboe int nr_phys_segs = bio_phys_segments(q, bio); 532d6d48196SJens Axboe 53313f05c8dSMartin K. Petersen if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) 53413f05c8dSMartin K. Petersen goto no_merge; 53513f05c8dSMartin K. Petersen 5364eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(q, req, bio) == false) 53713f05c8dSMartin K. Petersen goto no_merge; 538d6d48196SJens Axboe 539d6d48196SJens Axboe /* 540d6d48196SJens Axboe * This will form the start of a new hw segment. Bump both 541d6d48196SJens Axboe * counters. 542d6d48196SJens Axboe */ 543d6d48196SJens Axboe req->nr_phys_segments += nr_phys_segs; 544d6d48196SJens Axboe return 1; 54513f05c8dSMartin K. Petersen 54613f05c8dSMartin K. Petersen no_merge: 547e0c72300SRitesh Harjani req_set_nomerge(q, req); 54813f05c8dSMartin K. Petersen return 0; 549d6d48196SJens Axboe } 550d6d48196SJens Axboe 551d6d48196SJens Axboe int ll_back_merge_fn(struct request_queue *q, struct request *req, 552d6d48196SJens Axboe struct bio *bio) 553d6d48196SJens Axboe { 5545e7c4274SJens Axboe if (req_gap_back_merge(req, bio)) 5555e7c4274SJens Axboe return 0; 5567f39add3SSagi Grimberg if (blk_integrity_rq(req) && 5577f39add3SSagi Grimberg integrity_req_gap_back_merge(req, bio)) 5587f39add3SSagi Grimberg return 0; 559f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 56017007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) { 561e0c72300SRitesh Harjani req_set_nomerge(q, req); 562d6d48196SJens Axboe return 0; 563d6d48196SJens Axboe } 5642cdf79caSJens Axboe if (!bio_flagged(req->biotail, BIO_SEG_VALID)) 565d6d48196SJens Axboe blk_recount_segments(q, req->biotail); 5662cdf79caSJens Axboe if (!bio_flagged(bio, BIO_SEG_VALID)) 567d6d48196SJens Axboe blk_recount_segments(q, bio); 568d6d48196SJens Axboe 569d6d48196SJens Axboe return ll_new_hw_segment(q, req, bio); 570d6d48196SJens Axboe } 571d6d48196SJens Axboe 572d6d48196SJens Axboe int ll_front_merge_fn(struct request_queue *q, struct request *req, 573d6d48196SJens Axboe struct bio *bio) 574d6d48196SJens Axboe { 5755e7c4274SJens Axboe 5765e7c4274SJens Axboe if (req_gap_front_merge(req, bio)) 5775e7c4274SJens Axboe return 0; 5787f39add3SSagi Grimberg if (blk_integrity_rq(req) && 5797f39add3SSagi Grimberg integrity_req_gap_front_merge(req, bio)) 5807f39add3SSagi Grimberg return 0; 581f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 58217007f39SDamien Le Moal blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { 583e0c72300SRitesh Harjani req_set_nomerge(q, req); 584d6d48196SJens Axboe return 0; 585d6d48196SJens Axboe } 5862cdf79caSJens Axboe if (!bio_flagged(bio, BIO_SEG_VALID)) 587d6d48196SJens Axboe blk_recount_segments(q, bio); 5882cdf79caSJens Axboe if (!bio_flagged(req->bio, BIO_SEG_VALID)) 589d6d48196SJens Axboe blk_recount_segments(q, req->bio); 590d6d48196SJens Axboe 591d6d48196SJens Axboe return ll_new_hw_segment(q, req, bio); 592d6d48196SJens Axboe } 593d6d48196SJens Axboe 594445251d0SJens Axboe static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, 595445251d0SJens Axboe struct request *next) 596445251d0SJens Axboe { 597445251d0SJens Axboe unsigned short segments = blk_rq_nr_discard_segments(req); 598445251d0SJens Axboe 599445251d0SJens Axboe if (segments >= queue_max_discard_segments(q)) 600445251d0SJens Axboe goto no_merge; 601445251d0SJens Axboe if (blk_rq_sectors(req) + bio_sectors(next->bio) > 602445251d0SJens Axboe blk_rq_get_max_sectors(req, blk_rq_pos(req))) 603445251d0SJens Axboe goto no_merge; 604445251d0SJens Axboe 605445251d0SJens Axboe req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); 606445251d0SJens Axboe return true; 607445251d0SJens Axboe no_merge: 608445251d0SJens Axboe req_set_nomerge(q, req); 609445251d0SJens Axboe return false; 610445251d0SJens Axboe } 611445251d0SJens Axboe 612d6d48196SJens Axboe static int ll_merge_requests_fn(struct request_queue *q, struct request *req, 613d6d48196SJens Axboe struct request *next) 614d6d48196SJens Axboe { 615d6d48196SJens Axboe int total_phys_segments; 61686771427SFUJITA Tomonori unsigned int seg_size = 61786771427SFUJITA Tomonori req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; 618d6d48196SJens Axboe 6195e7c4274SJens Axboe if (req_gap_back_merge(req, next->bio)) 620854fbb9cSKeith Busch return 0; 621854fbb9cSKeith Busch 622d6d48196SJens Axboe /* 623d6d48196SJens Axboe * Will it become too large? 624d6d48196SJens Axboe */ 625f31dc1cdSMartin K. Petersen if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > 62617007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) 627d6d48196SJens Axboe return 0; 628d6d48196SJens Axboe 629d6d48196SJens Axboe total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; 63086771427SFUJITA Tomonori if (blk_phys_contig_segment(q, req->biotail, next->bio)) { 63186771427SFUJITA Tomonori if (req->nr_phys_segments == 1) 63286771427SFUJITA Tomonori req->bio->bi_seg_front_size = seg_size; 63386771427SFUJITA Tomonori if (next->nr_phys_segments == 1) 63486771427SFUJITA Tomonori next->biotail->bi_seg_back_size = seg_size; 635d6d48196SJens Axboe total_phys_segments--; 63686771427SFUJITA Tomonori } 637d6d48196SJens Axboe 6388a78362cSMartin K. Petersen if (total_phys_segments > queue_max_segments(q)) 639d6d48196SJens Axboe return 0; 640d6d48196SJens Axboe 6414eaf99beSMartin K. Petersen if (blk_integrity_merge_rq(q, req, next) == false) 64213f05c8dSMartin K. Petersen return 0; 64313f05c8dSMartin K. Petersen 644d6d48196SJens Axboe /* Merge is OK... */ 645d6d48196SJens Axboe req->nr_phys_segments = total_phys_segments; 646d6d48196SJens Axboe return 1; 647d6d48196SJens Axboe } 648d6d48196SJens Axboe 64980a761fdSTejun Heo /** 65080a761fdSTejun Heo * blk_rq_set_mixed_merge - mark a request as mixed merge 65180a761fdSTejun Heo * @rq: request to mark as mixed merge 65280a761fdSTejun Heo * 65380a761fdSTejun Heo * Description: 65480a761fdSTejun Heo * @rq is about to be mixed merged. Make sure the attributes 65580a761fdSTejun Heo * which can be mixed are set in each bio and mark @rq as mixed 65680a761fdSTejun Heo * merged. 65780a761fdSTejun Heo */ 65880a761fdSTejun Heo void blk_rq_set_mixed_merge(struct request *rq) 65980a761fdSTejun Heo { 66080a761fdSTejun Heo unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 66180a761fdSTejun Heo struct bio *bio; 66280a761fdSTejun Heo 663e8064021SChristoph Hellwig if (rq->rq_flags & RQF_MIXED_MERGE) 66480a761fdSTejun Heo return; 66580a761fdSTejun Heo 66680a761fdSTejun Heo /* 66780a761fdSTejun Heo * @rq will no longer represent mixable attributes for all the 66880a761fdSTejun Heo * contained bios. It will just track those of the first one. 66980a761fdSTejun Heo * Distributes the attributs to each bio. 67080a761fdSTejun Heo */ 67180a761fdSTejun Heo for (bio = rq->bio; bio; bio = bio->bi_next) { 6721eff9d32SJens Axboe WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && 6731eff9d32SJens Axboe (bio->bi_opf & REQ_FAILFAST_MASK) != ff); 6741eff9d32SJens Axboe bio->bi_opf |= ff; 67580a761fdSTejun Heo } 676e8064021SChristoph Hellwig rq->rq_flags |= RQF_MIXED_MERGE; 67780a761fdSTejun Heo } 67880a761fdSTejun Heo 67926308eabSJerome Marchand static void blk_account_io_merge(struct request *req) 68026308eabSJerome Marchand { 68126308eabSJerome Marchand if (blk_do_io_stat(req)) { 68226308eabSJerome Marchand struct hd_struct *part; 68326308eabSJerome Marchand 684112f158fSMike Snitzer part_stat_lock(); 68509e099d4SJerome Marchand part = req->part; 68626308eabSJerome Marchand 687d62e26b3SJens Axboe part_dec_in_flight(req->q, part, rq_data_dir(req)); 68826308eabSJerome Marchand 6896c23a968SJens Axboe hd_struct_put(part); 69026308eabSJerome Marchand part_stat_unlock(); 69126308eabSJerome Marchand } 69226308eabSJerome Marchand } 69369840466SJianchao Wang /* 69469840466SJianchao Wang * Two cases of handling DISCARD merge: 69569840466SJianchao Wang * If max_discard_segments > 1, the driver takes every bio 69669840466SJianchao Wang * as a range and send them to controller together. The ranges 69769840466SJianchao Wang * needn't to be contiguous. 69869840466SJianchao Wang * Otherwise, the bios/requests will be handled as same as 69969840466SJianchao Wang * others which should be contiguous. 70069840466SJianchao Wang */ 70169840466SJianchao Wang static inline bool blk_discard_mergable(struct request *req) 70269840466SJianchao Wang { 70369840466SJianchao Wang if (req_op(req) == REQ_OP_DISCARD && 70469840466SJianchao Wang queue_max_discard_segments(req->q) > 1) 70569840466SJianchao Wang return true; 70669840466SJianchao Wang return false; 70769840466SJianchao Wang } 70869840466SJianchao Wang 709e96c0d83SEric Biggers static enum elv_merge blk_try_req_merge(struct request *req, 710e96c0d83SEric Biggers struct request *next) 71169840466SJianchao Wang { 71269840466SJianchao Wang if (blk_discard_mergable(req)) 71369840466SJianchao Wang return ELEVATOR_DISCARD_MERGE; 71469840466SJianchao Wang else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) 71569840466SJianchao Wang return ELEVATOR_BACK_MERGE; 71669840466SJianchao Wang 71769840466SJianchao Wang return ELEVATOR_NO_MERGE; 71869840466SJianchao Wang } 71926308eabSJerome Marchand 720d6d48196SJens Axboe /* 721b973cb7eSJens Axboe * For non-mq, this has to be called with the request spinlock acquired. 722b973cb7eSJens Axboe * For mq with scheduling, the appropriate queue wide lock should be held. 723d6d48196SJens Axboe */ 724b973cb7eSJens Axboe static struct request *attempt_merge(struct request_queue *q, 725b973cb7eSJens Axboe struct request *req, struct request *next) 726d6d48196SJens Axboe { 727d6d48196SJens Axboe if (!rq_mergeable(req) || !rq_mergeable(next)) 728b973cb7eSJens Axboe return NULL; 729d6d48196SJens Axboe 730288dab8aSChristoph Hellwig if (req_op(req) != req_op(next)) 731b973cb7eSJens Axboe return NULL; 732f31dc1cdSMartin K. Petersen 733d6d48196SJens Axboe if (rq_data_dir(req) != rq_data_dir(next) 7342081a56bSJens Axboe || req->rq_disk != next->rq_disk) 735b973cb7eSJens Axboe return NULL; 736d6d48196SJens Axboe 7378fe0d473SMike Christie if (req_op(req) == REQ_OP_WRITE_SAME && 7384363ac7cSMartin K. Petersen !blk_write_same_mergeable(req->bio, next->bio)) 739b973cb7eSJens Axboe return NULL; 7404363ac7cSMartin K. Petersen 741d6d48196SJens Axboe /* 742cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 743cb6934f8SJens Axboe * non-hint IO. 744cb6934f8SJens Axboe */ 745cb6934f8SJens Axboe if (req->write_hint != next->write_hint) 746cb6934f8SJens Axboe return NULL; 747cb6934f8SJens Axboe 748668ffc03SDamien Le Moal if (req->ioprio != next->ioprio) 749668ffc03SDamien Le Moal return NULL; 750668ffc03SDamien Le Moal 751cb6934f8SJens Axboe /* 752d6d48196SJens Axboe * If we are allowed to merge, then append bio list 753d6d48196SJens Axboe * from next to rq and release next. merge_requests_fn 754d6d48196SJens Axboe * will have updated segment counts, update sector 755445251d0SJens Axboe * counts here. Handle DISCARDs separately, as they 756445251d0SJens Axboe * have separate settings. 757d6d48196SJens Axboe */ 75869840466SJianchao Wang 75969840466SJianchao Wang switch (blk_try_req_merge(req, next)) { 76069840466SJianchao Wang case ELEVATOR_DISCARD_MERGE: 761445251d0SJens Axboe if (!req_attempt_discard_merge(q, req, next)) 762445251d0SJens Axboe return NULL; 76369840466SJianchao Wang break; 76469840466SJianchao Wang case ELEVATOR_BACK_MERGE: 76569840466SJianchao Wang if (!ll_merge_requests_fn(q, req, next)) 766b973cb7eSJens Axboe return NULL; 76769840466SJianchao Wang break; 76869840466SJianchao Wang default: 76969840466SJianchao Wang return NULL; 77069840466SJianchao Wang } 771d6d48196SJens Axboe 772d6d48196SJens Axboe /* 77380a761fdSTejun Heo * If failfast settings disagree or any of the two is already 77480a761fdSTejun Heo * a mixed merge, mark both as mixed before proceeding. This 77580a761fdSTejun Heo * makes sure that all involved bios have mixable attributes 77680a761fdSTejun Heo * set properly. 77780a761fdSTejun Heo */ 778e8064021SChristoph Hellwig if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || 77980a761fdSTejun Heo (req->cmd_flags & REQ_FAILFAST_MASK) != 78080a761fdSTejun Heo (next->cmd_flags & REQ_FAILFAST_MASK)) { 78180a761fdSTejun Heo blk_rq_set_mixed_merge(req); 78280a761fdSTejun Heo blk_rq_set_mixed_merge(next); 78380a761fdSTejun Heo } 78480a761fdSTejun Heo 78580a761fdSTejun Heo /* 786522a7775SOmar Sandoval * At this point we have either done a back merge or front merge. We 787522a7775SOmar Sandoval * need the smaller start_time_ns of the merged requests to be the 788522a7775SOmar Sandoval * current request for accounting purposes. 789d6d48196SJens Axboe */ 790522a7775SOmar Sandoval if (next->start_time_ns < req->start_time_ns) 791522a7775SOmar Sandoval req->start_time_ns = next->start_time_ns; 792d6d48196SJens Axboe 793d6d48196SJens Axboe req->biotail->bi_next = next->bio; 794d6d48196SJens Axboe req->biotail = next->biotail; 795d6d48196SJens Axboe 796a2dec7b3STejun Heo req->__data_len += blk_rq_bytes(next); 797d6d48196SJens Axboe 7982a5cf35cSMing Lei if (!blk_discard_mergable(req)) 799d6d48196SJens Axboe elv_merge_requests(q, req, next); 800d6d48196SJens Axboe 80142dad764SJerome Marchand /* 80242dad764SJerome Marchand * 'next' is going away, so update stats accordingly 80342dad764SJerome Marchand */ 80442dad764SJerome Marchand blk_account_io_merge(next); 805d6d48196SJens Axboe 806e4d750c9SJens Axboe /* 807e4d750c9SJens Axboe * ownership of bio passed from next to req, return 'next' for 808e4d750c9SJens Axboe * the caller to free 809e4d750c9SJens Axboe */ 8101cd96c24SBoaz Harrosh next->bio = NULL; 811b973cb7eSJens Axboe return next; 812d6d48196SJens Axboe } 813d6d48196SJens Axboe 814b973cb7eSJens Axboe struct request *attempt_back_merge(struct request_queue *q, struct request *rq) 815d6d48196SJens Axboe { 816d6d48196SJens Axboe struct request *next = elv_latter_request(q, rq); 817d6d48196SJens Axboe 818d6d48196SJens Axboe if (next) 819d6d48196SJens Axboe return attempt_merge(q, rq, next); 820d6d48196SJens Axboe 821b973cb7eSJens Axboe return NULL; 822d6d48196SJens Axboe } 823d6d48196SJens Axboe 824b973cb7eSJens Axboe struct request *attempt_front_merge(struct request_queue *q, struct request *rq) 825d6d48196SJens Axboe { 826d6d48196SJens Axboe struct request *prev = elv_former_request(q, rq); 827d6d48196SJens Axboe 828d6d48196SJens Axboe if (prev) 829d6d48196SJens Axboe return attempt_merge(q, prev, rq); 830d6d48196SJens Axboe 831b973cb7eSJens Axboe return NULL; 832d6d48196SJens Axboe } 8335e84ea3aSJens Axboe 8345e84ea3aSJens Axboe int blk_attempt_req_merge(struct request_queue *q, struct request *rq, 8355e84ea3aSJens Axboe struct request *next) 8365e84ea3aSJens Axboe { 837e4d750c9SJens Axboe struct request *free; 83872ef799bSTahsin Erdogan 839e4d750c9SJens Axboe free = attempt_merge(q, rq, next); 840e4d750c9SJens Axboe if (free) { 84192bc5a24SJens Axboe blk_put_request(free); 842e4d750c9SJens Axboe return 1; 843e4d750c9SJens Axboe } 844e4d750c9SJens Axboe 845e4d750c9SJens Axboe return 0; 8465e84ea3aSJens Axboe } 847050c8ea8STejun Heo 848050c8ea8STejun Heo bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 849050c8ea8STejun Heo { 850e2a60da7SMartin K. Petersen if (!rq_mergeable(rq) || !bio_mergeable(bio)) 851050c8ea8STejun Heo return false; 852050c8ea8STejun Heo 853288dab8aSChristoph Hellwig if (req_op(rq) != bio_op(bio)) 854f31dc1cdSMartin K. Petersen return false; 855f31dc1cdSMartin K. Petersen 856050c8ea8STejun Heo /* different data direction or already started, don't merge */ 857050c8ea8STejun Heo if (bio_data_dir(bio) != rq_data_dir(rq)) 858050c8ea8STejun Heo return false; 859050c8ea8STejun Heo 8602081a56bSJens Axboe /* must be same device */ 8612081a56bSJens Axboe if (rq->rq_disk != bio->bi_disk) 862050c8ea8STejun Heo return false; 863050c8ea8STejun Heo 864050c8ea8STejun Heo /* only merge integrity protected bio into ditto rq */ 8654eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(rq->q, rq, bio) == false) 866050c8ea8STejun Heo return false; 867050c8ea8STejun Heo 8684363ac7cSMartin K. Petersen /* must be using the same buffer */ 8698fe0d473SMike Christie if (req_op(rq) == REQ_OP_WRITE_SAME && 8704363ac7cSMartin K. Petersen !blk_write_same_mergeable(rq->bio, bio)) 8714363ac7cSMartin K. Petersen return false; 8724363ac7cSMartin K. Petersen 873cb6934f8SJens Axboe /* 874cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 875cb6934f8SJens Axboe * non-hint IO. 876cb6934f8SJens Axboe */ 877cb6934f8SJens Axboe if (rq->write_hint != bio->bi_write_hint) 878cb6934f8SJens Axboe return false; 879cb6934f8SJens Axboe 880668ffc03SDamien Le Moal if (rq->ioprio != bio_prio(bio)) 881668ffc03SDamien Le Moal return false; 882668ffc03SDamien Le Moal 883050c8ea8STejun Heo return true; 884050c8ea8STejun Heo } 885050c8ea8STejun Heo 88634fe7c05SChristoph Hellwig enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) 887050c8ea8STejun Heo { 88869840466SJianchao Wang if (blk_discard_mergable(rq)) 8891e739730SChristoph Hellwig return ELEVATOR_DISCARD_MERGE; 8901e739730SChristoph Hellwig else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) 891050c8ea8STejun Heo return ELEVATOR_BACK_MERGE; 8924f024f37SKent Overstreet else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) 893050c8ea8STejun Heo return ELEVATOR_FRONT_MERGE; 894050c8ea8STejun Heo return ELEVATOR_NO_MERGE; 895050c8ea8STejun Heo } 896