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); 49e9907009SChristoph Hellwig if (pb.bv_offset) 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 9354efd50bSKent Overstreet max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); 9454efd50bSKent Overstreet max_discard_sectors -= max_discard_sectors % granularity; 9554efd50bSKent Overstreet 9654efd50bSKent Overstreet if (unlikely(!max_discard_sectors)) { 9754efd50bSKent Overstreet /* XXX: warn */ 9854efd50bSKent Overstreet return NULL; 9954efd50bSKent Overstreet } 10054efd50bSKent Overstreet 10154efd50bSKent Overstreet if (bio_sectors(bio) <= max_discard_sectors) 10254efd50bSKent Overstreet return NULL; 10354efd50bSKent Overstreet 10454efd50bSKent Overstreet split_sectors = max_discard_sectors; 10554efd50bSKent Overstreet 10654efd50bSKent Overstreet /* 10754efd50bSKent Overstreet * If the next starting sector would be misaligned, stop the discard at 10854efd50bSKent Overstreet * the previous aligned sector. 10954efd50bSKent Overstreet */ 11054efd50bSKent Overstreet alignment = (q->limits.discard_alignment >> 9) % granularity; 11154efd50bSKent Overstreet 11254efd50bSKent Overstreet tmp = bio->bi_iter.bi_sector + split_sectors - alignment; 11354efd50bSKent Overstreet tmp = sector_div(tmp, granularity); 11454efd50bSKent Overstreet 11554efd50bSKent Overstreet if (split_sectors > tmp) 11654efd50bSKent Overstreet split_sectors -= tmp; 11754efd50bSKent Overstreet 11854efd50bSKent Overstreet return bio_split(bio, split_sectors, GFP_NOIO, bs); 11954efd50bSKent Overstreet } 12054efd50bSKent Overstreet 121885fa13fSChristoph Hellwig static struct bio *blk_bio_write_zeroes_split(struct request_queue *q, 122885fa13fSChristoph Hellwig struct bio *bio, struct bio_set *bs, unsigned *nsegs) 123885fa13fSChristoph Hellwig { 124885fa13fSChristoph Hellwig *nsegs = 1; 125885fa13fSChristoph Hellwig 126885fa13fSChristoph Hellwig if (!q->limits.max_write_zeroes_sectors) 127885fa13fSChristoph Hellwig return NULL; 128885fa13fSChristoph Hellwig 129885fa13fSChristoph Hellwig if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors) 130885fa13fSChristoph Hellwig return NULL; 131885fa13fSChristoph Hellwig 132885fa13fSChristoph Hellwig return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs); 133885fa13fSChristoph Hellwig } 134885fa13fSChristoph Hellwig 13554efd50bSKent Overstreet static struct bio *blk_bio_write_same_split(struct request_queue *q, 13654efd50bSKent Overstreet struct bio *bio, 137bdced438SMing Lei struct bio_set *bs, 138bdced438SMing Lei unsigned *nsegs) 13954efd50bSKent Overstreet { 140bdced438SMing Lei *nsegs = 1; 141bdced438SMing Lei 14254efd50bSKent Overstreet if (!q->limits.max_write_same_sectors) 14354efd50bSKent Overstreet return NULL; 14454efd50bSKent Overstreet 14554efd50bSKent Overstreet if (bio_sectors(bio) <= q->limits.max_write_same_sectors) 14654efd50bSKent Overstreet return NULL; 14754efd50bSKent Overstreet 14854efd50bSKent Overstreet return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); 14954efd50bSKent Overstreet } 15054efd50bSKent Overstreet 151d0e5fbb0SMing Lei static inline unsigned get_max_io_size(struct request_queue *q, 152d0e5fbb0SMing Lei struct bio *bio) 153d0e5fbb0SMing Lei { 154d0e5fbb0SMing Lei unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector); 155d0e5fbb0SMing Lei unsigned mask = queue_logical_block_size(q) - 1; 156d0e5fbb0SMing Lei 157d0e5fbb0SMing Lei /* aligned to logical block size */ 158d0e5fbb0SMing Lei sectors &= ~(mask >> 9); 159d0e5fbb0SMing Lei 160d0e5fbb0SMing Lei return sectors; 161d0e5fbb0SMing Lei } 162d0e5fbb0SMing Lei 16354efd50bSKent Overstreet static struct bio *blk_bio_segment_split(struct request_queue *q, 16454efd50bSKent Overstreet struct bio *bio, 165bdced438SMing Lei struct bio_set *bs, 166bdced438SMing Lei unsigned *segs) 16754efd50bSKent Overstreet { 1685014c311SJens Axboe struct bio_vec bv, bvprv, *bvprvp = NULL; 16954efd50bSKent Overstreet struct bvec_iter iter; 1708ae12666SKent Overstreet unsigned seg_size = 0, nsegs = 0, sectors = 0; 17102e70742SMing Lei unsigned front_seg_size = bio->bi_seg_front_size; 17202e70742SMing Lei bool do_split = true; 17302e70742SMing Lei struct bio *new = NULL; 174d0e5fbb0SMing Lei const unsigned max_sectors = get_max_io_size(q, bio); 17554efd50bSKent Overstreet 17654efd50bSKent Overstreet bio_for_each_segment(bv, bio, iter) { 17754efd50bSKent Overstreet /* 17854efd50bSKent Overstreet * If the queue doesn't support SG gaps and adding this 17954efd50bSKent Overstreet * offset would create a gap, disallow it. 18054efd50bSKent Overstreet */ 1815014c311SJens Axboe if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) 18254efd50bSKent Overstreet goto split; 18354efd50bSKent Overstreet 184d0e5fbb0SMing Lei if (sectors + (bv.bv_len >> 9) > max_sectors) { 185e36f6204SKeith Busch /* 186e36f6204SKeith Busch * Consider this a new segment if we're splitting in 187e36f6204SKeith Busch * the middle of this vector. 188e36f6204SKeith Busch */ 189e36f6204SKeith Busch if (nsegs < queue_max_segments(q) && 190d0e5fbb0SMing Lei sectors < max_sectors) { 191e36f6204SKeith Busch nsegs++; 192d0e5fbb0SMing Lei sectors = max_sectors; 193e36f6204SKeith Busch } 194e36f6204SKeith Busch goto split; 195e36f6204SKeith Busch } 196e36f6204SKeith Busch 19738417468SChristoph Hellwig if (bvprvp) { 198b4b6cb61SMing Lei if (seg_size + bv.bv_len > queue_max_segment_size(q)) 199b4b6cb61SMing Lei goto new_segment; 2003dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, bvprvp, &bv)) 20154efd50bSKent Overstreet goto new_segment; 20254efd50bSKent Overstreet 20354efd50bSKent Overstreet seg_size += bv.bv_len; 20454efd50bSKent Overstreet bvprv = bv; 205578270bfSMing Lei bvprvp = &bvprv; 20652cc6eeaSMing Lei sectors += bv.bv_len >> 9; 207a88d32afSMing Lei 20854efd50bSKent Overstreet continue; 20954efd50bSKent Overstreet } 21054efd50bSKent Overstreet new_segment: 21154efd50bSKent Overstreet if (nsegs == queue_max_segments(q)) 21254efd50bSKent Overstreet goto split; 21354efd50bSKent Overstreet 2146a501bf0SMing Lei if (nsegs == 1 && seg_size > front_seg_size) 2156a501bf0SMing Lei front_seg_size = seg_size; 2166a501bf0SMing Lei 21754efd50bSKent Overstreet nsegs++; 21854efd50bSKent Overstreet bvprv = bv; 219578270bfSMing Lei bvprvp = &bvprv; 22054efd50bSKent Overstreet seg_size = bv.bv_len; 22152cc6eeaSMing Lei sectors += bv.bv_len >> 9; 22202e70742SMing Lei 22354efd50bSKent Overstreet } 22454efd50bSKent Overstreet 22502e70742SMing Lei do_split = false; 22654efd50bSKent Overstreet split: 227bdced438SMing Lei *segs = nsegs; 22802e70742SMing Lei 22902e70742SMing Lei if (do_split) { 23002e70742SMing Lei new = bio_split(bio, sectors, GFP_NOIO, bs); 23102e70742SMing Lei if (new) 23202e70742SMing Lei bio = new; 23302e70742SMing Lei } 23402e70742SMing Lei 2356a501bf0SMing Lei if (nsegs == 1 && seg_size > front_seg_size) 2366a501bf0SMing Lei front_seg_size = seg_size; 23702e70742SMing Lei bio->bi_seg_front_size = front_seg_size; 23802e70742SMing Lei if (seg_size > bio->bi_seg_back_size) 23902e70742SMing Lei bio->bi_seg_back_size = seg_size; 24002e70742SMing Lei 24102e70742SMing Lei return do_split ? new : NULL; 24254efd50bSKent Overstreet } 24354efd50bSKent Overstreet 244af67c31fSNeilBrown void blk_queue_split(struct request_queue *q, struct bio **bio) 24554efd50bSKent Overstreet { 246bdced438SMing Lei struct bio *split, *res; 247bdced438SMing Lei unsigned nsegs; 24854efd50bSKent Overstreet 2497afafc8aSAdrian Hunter switch (bio_op(*bio)) { 2507afafc8aSAdrian Hunter case REQ_OP_DISCARD: 2517afafc8aSAdrian Hunter case REQ_OP_SECURE_ERASE: 252338aa96dSKent Overstreet split = blk_bio_discard_split(q, *bio, &q->bio_split, &nsegs); 2537afafc8aSAdrian Hunter break; 254a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 255338aa96dSKent Overstreet split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split, &nsegs); 256a6f0788eSChaitanya Kulkarni break; 2577afafc8aSAdrian Hunter case REQ_OP_WRITE_SAME: 258338aa96dSKent Overstreet split = blk_bio_write_same_split(q, *bio, &q->bio_split, &nsegs); 2597afafc8aSAdrian Hunter break; 2607afafc8aSAdrian Hunter default: 261338aa96dSKent Overstreet split = blk_bio_segment_split(q, *bio, &q->bio_split, &nsegs); 2627afafc8aSAdrian Hunter break; 2637afafc8aSAdrian Hunter } 264bdced438SMing Lei 265bdced438SMing Lei /* physical segments can be figured out during splitting */ 266bdced438SMing Lei res = split ? split : *bio; 267bdced438SMing Lei res->bi_phys_segments = nsegs; 268bdced438SMing Lei bio_set_flag(res, BIO_SEG_VALID); 26954efd50bSKent Overstreet 27054efd50bSKent Overstreet if (split) { 2716ac45aebSMing Lei /* there isn't chance to merge the splitted bio */ 2721eff9d32SJens Axboe split->bi_opf |= REQ_NOMERGE; 2736ac45aebSMing Lei 274cd4a4ae4SJens Axboe /* 275cd4a4ae4SJens Axboe * Since we're recursing into make_request here, ensure 276cd4a4ae4SJens Axboe * that we mark this bio as already having entered the queue. 277cd4a4ae4SJens Axboe * If not, and the queue is going away, we can get stuck 278cd4a4ae4SJens Axboe * forever on waiting for the queue reference to drop. But 279cd4a4ae4SJens Axboe * that will never happen, as we're already holding a 280cd4a4ae4SJens Axboe * reference to it. 281cd4a4ae4SJens Axboe */ 282cd4a4ae4SJens Axboe bio_set_flag(*bio, BIO_QUEUE_ENTERED); 283cd4a4ae4SJens Axboe 28454efd50bSKent Overstreet bio_chain(split, *bio); 285cda22646SMike Krinkin trace_block_split(q, split, (*bio)->bi_iter.bi_sector); 28654efd50bSKent Overstreet generic_make_request(*bio); 28754efd50bSKent Overstreet *bio = split; 28854efd50bSKent Overstreet } 28954efd50bSKent Overstreet } 29054efd50bSKent Overstreet EXPORT_SYMBOL(blk_queue_split); 29154efd50bSKent Overstreet 2921e428079SJens Axboe static unsigned int __blk_recalc_rq_segments(struct request_queue *q, 29307388549SMing Lei struct bio *bio, 29407388549SMing Lei bool no_sg_merge) 295d6d48196SJens Axboe { 2967988613bSKent Overstreet struct bio_vec bv, bvprv = { NULL }; 29738417468SChristoph Hellwig int prev = 0; 2981e428079SJens Axboe unsigned int seg_size, nr_phys_segs; 29959247eaeSJens Axboe struct bio *fbio, *bbio; 3007988613bSKent Overstreet struct bvec_iter iter; 301d6d48196SJens Axboe 3021e428079SJens Axboe if (!bio) 3031e428079SJens Axboe return 0; 304d6d48196SJens Axboe 305a6f0788eSChaitanya Kulkarni switch (bio_op(bio)) { 306a6f0788eSChaitanya Kulkarni case REQ_OP_DISCARD: 307a6f0788eSChaitanya Kulkarni case REQ_OP_SECURE_ERASE: 308a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 309f9d03f96SChristoph Hellwig return 0; 310f9d03f96SChristoph Hellwig case REQ_OP_WRITE_SAME: 3115cb8850cSKent Overstreet return 1; 312a6f0788eSChaitanya Kulkarni } 3135cb8850cSKent Overstreet 3141e428079SJens Axboe fbio = bio; 3155df97b91SMikulas Patocka seg_size = 0; 3162c8919deSAndi Kleen nr_phys_segs = 0; 3171e428079SJens Axboe for_each_bio(bio) { 3187988613bSKent Overstreet bio_for_each_segment(bv, bio, iter) { 319d6d48196SJens Axboe /* 32005f1dd53SJens Axboe * If SG merging is disabled, each bio vector is 32105f1dd53SJens Axboe * a segment 32205f1dd53SJens Axboe */ 32305f1dd53SJens Axboe if (no_sg_merge) 32405f1dd53SJens Axboe goto new_segment; 32505f1dd53SJens Axboe 32638417468SChristoph Hellwig if (prev) { 3277988613bSKent Overstreet if (seg_size + bv.bv_len 328ae03bf63SMartin K. Petersen > queue_max_segment_size(q)) 329d6d48196SJens Axboe goto new_segment; 3303dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, &bvprv, &bv)) 331d6d48196SJens Axboe goto new_segment; 332d6d48196SJens Axboe 3337988613bSKent Overstreet seg_size += bv.bv_len; 334d6d48196SJens Axboe bvprv = bv; 335d6d48196SJens Axboe continue; 336d6d48196SJens Axboe } 337d6d48196SJens Axboe new_segment: 3381e428079SJens Axboe if (nr_phys_segs == 1 && seg_size > 3391e428079SJens Axboe fbio->bi_seg_front_size) 3401e428079SJens Axboe fbio->bi_seg_front_size = seg_size; 34186771427SFUJITA Tomonori 342d6d48196SJens Axboe nr_phys_segs++; 343d6d48196SJens Axboe bvprv = bv; 34454efd50bSKent Overstreet prev = 1; 3457988613bSKent Overstreet seg_size = bv.bv_len; 346d6d48196SJens Axboe } 34759247eaeSJens Axboe bbio = bio; 3481e428079SJens Axboe } 349d6d48196SJens Axboe 35059247eaeSJens Axboe if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) 35159247eaeSJens Axboe fbio->bi_seg_front_size = seg_size; 35259247eaeSJens Axboe if (seg_size > bbio->bi_seg_back_size) 35359247eaeSJens Axboe bbio->bi_seg_back_size = seg_size; 3541e428079SJens Axboe 3551e428079SJens Axboe return nr_phys_segs; 3561e428079SJens Axboe } 3571e428079SJens Axboe 3581e428079SJens Axboe void blk_recalc_rq_segments(struct request *rq) 3591e428079SJens Axboe { 36007388549SMing Lei bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, 36107388549SMing Lei &rq->q->queue_flags); 36207388549SMing Lei 36307388549SMing Lei rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio, 36407388549SMing Lei no_sg_merge); 365d6d48196SJens Axboe } 366d6d48196SJens Axboe 367d6d48196SJens Axboe void blk_recount_segments(struct request_queue *q, struct bio *bio) 368d6d48196SJens Axboe { 3697f60dcaaSMing Lei unsigned short seg_cnt; 370764f612cSMing Lei 3717f60dcaaSMing Lei /* estimate segment number by bi_vcnt for non-cloned bio */ 3727f60dcaaSMing Lei if (bio_flagged(bio, BIO_CLONED)) 3737f60dcaaSMing Lei seg_cnt = bio_segments(bio); 3747f60dcaaSMing Lei else 3757f60dcaaSMing Lei seg_cnt = bio->bi_vcnt; 3767f60dcaaSMing Lei 3777f60dcaaSMing Lei if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) && 3787f60dcaaSMing Lei (seg_cnt < queue_max_segments(q))) 3797f60dcaaSMing Lei bio->bi_phys_segments = seg_cnt; 38005f1dd53SJens Axboe else { 381d6d48196SJens Axboe struct bio *nxt = bio->bi_next; 3821e428079SJens Axboe 383d6d48196SJens Axboe bio->bi_next = NULL; 3847f60dcaaSMing Lei bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false); 385d6d48196SJens Axboe bio->bi_next = nxt; 38605f1dd53SJens Axboe } 38705f1dd53SJens Axboe 388b7c44ed9SJens Axboe bio_set_flag(bio, BIO_SEG_VALID); 389d6d48196SJens Axboe } 390d6d48196SJens Axboe EXPORT_SYMBOL(blk_recount_segments); 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 594e7e24500SJens Axboe /* 595e7e24500SJens Axboe * blk-mq uses req->special to carry normal driver per-request payload, it 596e7e24500SJens Axboe * does not indicate a prepared command that we cannot merge with. 597e7e24500SJens Axboe */ 598e7e24500SJens Axboe static bool req_no_special_merge(struct request *req) 599e7e24500SJens Axboe { 600e7e24500SJens Axboe struct request_queue *q = req->q; 601e7e24500SJens Axboe 602e7e24500SJens Axboe return !q->mq_ops && req->special; 603e7e24500SJens Axboe } 604e7e24500SJens Axboe 605445251d0SJens Axboe static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, 606445251d0SJens Axboe struct request *next) 607445251d0SJens Axboe { 608445251d0SJens Axboe unsigned short segments = blk_rq_nr_discard_segments(req); 609445251d0SJens Axboe 610445251d0SJens Axboe if (segments >= queue_max_discard_segments(q)) 611445251d0SJens Axboe goto no_merge; 612445251d0SJens Axboe if (blk_rq_sectors(req) + bio_sectors(next->bio) > 613445251d0SJens Axboe blk_rq_get_max_sectors(req, blk_rq_pos(req))) 614445251d0SJens Axboe goto no_merge; 615445251d0SJens Axboe 616445251d0SJens Axboe req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); 617445251d0SJens Axboe return true; 618445251d0SJens Axboe no_merge: 619445251d0SJens Axboe req_set_nomerge(q, req); 620445251d0SJens Axboe return false; 621445251d0SJens Axboe } 622445251d0SJens Axboe 623d6d48196SJens Axboe static int ll_merge_requests_fn(struct request_queue *q, struct request *req, 624d6d48196SJens Axboe struct request *next) 625d6d48196SJens Axboe { 626d6d48196SJens Axboe int total_phys_segments; 62786771427SFUJITA Tomonori unsigned int seg_size = 62886771427SFUJITA Tomonori req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; 629d6d48196SJens Axboe 630d6d48196SJens Axboe /* 631d6d48196SJens Axboe * First check if the either of the requests are re-queued 632d6d48196SJens Axboe * requests. Can't merge them if they are. 633d6d48196SJens Axboe */ 634e7e24500SJens Axboe if (req_no_special_merge(req) || req_no_special_merge(next)) 635d6d48196SJens Axboe return 0; 636d6d48196SJens Axboe 6375e7c4274SJens Axboe if (req_gap_back_merge(req, next->bio)) 638854fbb9cSKeith Busch return 0; 639854fbb9cSKeith Busch 640d6d48196SJens Axboe /* 641d6d48196SJens Axboe * Will it become too large? 642d6d48196SJens Axboe */ 643f31dc1cdSMartin K. Petersen if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > 64417007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) 645d6d48196SJens Axboe return 0; 646d6d48196SJens Axboe 647d6d48196SJens Axboe total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; 64886771427SFUJITA Tomonori if (blk_phys_contig_segment(q, req->biotail, next->bio)) { 64986771427SFUJITA Tomonori if (req->nr_phys_segments == 1) 65086771427SFUJITA Tomonori req->bio->bi_seg_front_size = seg_size; 65186771427SFUJITA Tomonori if (next->nr_phys_segments == 1) 65286771427SFUJITA Tomonori next->biotail->bi_seg_back_size = seg_size; 653d6d48196SJens Axboe total_phys_segments--; 65486771427SFUJITA Tomonori } 655d6d48196SJens Axboe 6568a78362cSMartin K. Petersen if (total_phys_segments > queue_max_segments(q)) 657d6d48196SJens Axboe return 0; 658d6d48196SJens Axboe 6594eaf99beSMartin K. Petersen if (blk_integrity_merge_rq(q, req, next) == false) 66013f05c8dSMartin K. Petersen return 0; 66113f05c8dSMartin K. Petersen 662d6d48196SJens Axboe /* Merge is OK... */ 663d6d48196SJens Axboe req->nr_phys_segments = total_phys_segments; 664d6d48196SJens Axboe return 1; 665d6d48196SJens Axboe } 666d6d48196SJens Axboe 66780a761fdSTejun Heo /** 66880a761fdSTejun Heo * blk_rq_set_mixed_merge - mark a request as mixed merge 66980a761fdSTejun Heo * @rq: request to mark as mixed merge 67080a761fdSTejun Heo * 67180a761fdSTejun Heo * Description: 67280a761fdSTejun Heo * @rq is about to be mixed merged. Make sure the attributes 67380a761fdSTejun Heo * which can be mixed are set in each bio and mark @rq as mixed 67480a761fdSTejun Heo * merged. 67580a761fdSTejun Heo */ 67680a761fdSTejun Heo void blk_rq_set_mixed_merge(struct request *rq) 67780a761fdSTejun Heo { 67880a761fdSTejun Heo unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 67980a761fdSTejun Heo struct bio *bio; 68080a761fdSTejun Heo 681e8064021SChristoph Hellwig if (rq->rq_flags & RQF_MIXED_MERGE) 68280a761fdSTejun Heo return; 68380a761fdSTejun Heo 68480a761fdSTejun Heo /* 68580a761fdSTejun Heo * @rq will no longer represent mixable attributes for all the 68680a761fdSTejun Heo * contained bios. It will just track those of the first one. 68780a761fdSTejun Heo * Distributes the attributs to each bio. 68880a761fdSTejun Heo */ 68980a761fdSTejun Heo for (bio = rq->bio; bio; bio = bio->bi_next) { 6901eff9d32SJens Axboe WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && 6911eff9d32SJens Axboe (bio->bi_opf & REQ_FAILFAST_MASK) != ff); 6921eff9d32SJens Axboe bio->bi_opf |= ff; 69380a761fdSTejun Heo } 694e8064021SChristoph Hellwig rq->rq_flags |= RQF_MIXED_MERGE; 69580a761fdSTejun Heo } 69680a761fdSTejun Heo 69726308eabSJerome Marchand static void blk_account_io_merge(struct request *req) 69826308eabSJerome Marchand { 69926308eabSJerome Marchand if (blk_do_io_stat(req)) { 70026308eabSJerome Marchand struct hd_struct *part; 70126308eabSJerome Marchand int cpu; 70226308eabSJerome Marchand 70326308eabSJerome Marchand cpu = part_stat_lock(); 70409e099d4SJerome Marchand part = req->part; 70526308eabSJerome Marchand 706d62e26b3SJens Axboe part_round_stats(req->q, cpu, part); 707d62e26b3SJens Axboe part_dec_in_flight(req->q, part, rq_data_dir(req)); 70826308eabSJerome Marchand 7096c23a968SJens Axboe hd_struct_put(part); 71026308eabSJerome Marchand part_stat_unlock(); 71126308eabSJerome Marchand } 71226308eabSJerome Marchand } 71369840466SJianchao Wang /* 71469840466SJianchao Wang * Two cases of handling DISCARD merge: 71569840466SJianchao Wang * If max_discard_segments > 1, the driver takes every bio 71669840466SJianchao Wang * as a range and send them to controller together. The ranges 71769840466SJianchao Wang * needn't to be contiguous. 71869840466SJianchao Wang * Otherwise, the bios/requests will be handled as same as 71969840466SJianchao Wang * others which should be contiguous. 72069840466SJianchao Wang */ 72169840466SJianchao Wang static inline bool blk_discard_mergable(struct request *req) 72269840466SJianchao Wang { 72369840466SJianchao Wang if (req_op(req) == REQ_OP_DISCARD && 72469840466SJianchao Wang queue_max_discard_segments(req->q) > 1) 72569840466SJianchao Wang return true; 72669840466SJianchao Wang return false; 72769840466SJianchao Wang } 72869840466SJianchao Wang 72969840466SJianchao Wang enum elv_merge blk_try_req_merge(struct request *req, struct request *next) 73069840466SJianchao Wang { 73169840466SJianchao Wang if (blk_discard_mergable(req)) 73269840466SJianchao Wang return ELEVATOR_DISCARD_MERGE; 73369840466SJianchao Wang else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) 73469840466SJianchao Wang return ELEVATOR_BACK_MERGE; 73569840466SJianchao Wang 73669840466SJianchao Wang return ELEVATOR_NO_MERGE; 73769840466SJianchao Wang } 73826308eabSJerome Marchand 739d6d48196SJens Axboe /* 740b973cb7eSJens Axboe * For non-mq, this has to be called with the request spinlock acquired. 741b973cb7eSJens Axboe * For mq with scheduling, the appropriate queue wide lock should be held. 742d6d48196SJens Axboe */ 743b973cb7eSJens Axboe static struct request *attempt_merge(struct request_queue *q, 744b973cb7eSJens Axboe struct request *req, struct request *next) 745d6d48196SJens Axboe { 7462fff8a92SBart Van Assche if (!q->mq_ops) 7472fff8a92SBart Van Assche lockdep_assert_held(q->queue_lock); 7482fff8a92SBart Van Assche 749d6d48196SJens Axboe if (!rq_mergeable(req) || !rq_mergeable(next)) 750b973cb7eSJens Axboe return NULL; 751d6d48196SJens Axboe 752288dab8aSChristoph Hellwig if (req_op(req) != req_op(next)) 753b973cb7eSJens Axboe return NULL; 754f31dc1cdSMartin K. Petersen 755d6d48196SJens Axboe if (rq_data_dir(req) != rq_data_dir(next) 756d6d48196SJens Axboe || req->rq_disk != next->rq_disk 757e7e24500SJens Axboe || req_no_special_merge(next)) 758b973cb7eSJens Axboe return NULL; 759d6d48196SJens Axboe 7608fe0d473SMike Christie if (req_op(req) == REQ_OP_WRITE_SAME && 7614363ac7cSMartin K. Petersen !blk_write_same_mergeable(req->bio, next->bio)) 762b973cb7eSJens Axboe return NULL; 7634363ac7cSMartin K. Petersen 764d6d48196SJens Axboe /* 765cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 766cb6934f8SJens Axboe * non-hint IO. 767cb6934f8SJens Axboe */ 768cb6934f8SJens Axboe if (req->write_hint != next->write_hint) 769cb6934f8SJens Axboe return NULL; 770cb6934f8SJens Axboe 771cb6934f8SJens Axboe /* 772d6d48196SJens Axboe * If we are allowed to merge, then append bio list 773d6d48196SJens Axboe * from next to rq and release next. merge_requests_fn 774d6d48196SJens Axboe * will have updated segment counts, update sector 775445251d0SJens Axboe * counts here. Handle DISCARDs separately, as they 776445251d0SJens Axboe * have separate settings. 777d6d48196SJens Axboe */ 77869840466SJianchao Wang 77969840466SJianchao Wang switch (blk_try_req_merge(req, next)) { 78069840466SJianchao Wang case ELEVATOR_DISCARD_MERGE: 781445251d0SJens Axboe if (!req_attempt_discard_merge(q, req, next)) 782445251d0SJens Axboe return NULL; 78369840466SJianchao Wang break; 78469840466SJianchao Wang case ELEVATOR_BACK_MERGE: 78569840466SJianchao Wang if (!ll_merge_requests_fn(q, req, next)) 786b973cb7eSJens Axboe return NULL; 78769840466SJianchao Wang break; 78869840466SJianchao Wang default: 78969840466SJianchao Wang return NULL; 79069840466SJianchao Wang } 791d6d48196SJens Axboe 792d6d48196SJens Axboe /* 79380a761fdSTejun Heo * If failfast settings disagree or any of the two is already 79480a761fdSTejun Heo * a mixed merge, mark both as mixed before proceeding. This 79580a761fdSTejun Heo * makes sure that all involved bios have mixable attributes 79680a761fdSTejun Heo * set properly. 79780a761fdSTejun Heo */ 798e8064021SChristoph Hellwig if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || 79980a761fdSTejun Heo (req->cmd_flags & REQ_FAILFAST_MASK) != 80080a761fdSTejun Heo (next->cmd_flags & REQ_FAILFAST_MASK)) { 80180a761fdSTejun Heo blk_rq_set_mixed_merge(req); 80280a761fdSTejun Heo blk_rq_set_mixed_merge(next); 80380a761fdSTejun Heo } 80480a761fdSTejun Heo 80580a761fdSTejun Heo /* 806522a7775SOmar Sandoval * At this point we have either done a back merge or front merge. We 807522a7775SOmar Sandoval * need the smaller start_time_ns of the merged requests to be the 808522a7775SOmar Sandoval * current request for accounting purposes. 809d6d48196SJens Axboe */ 810522a7775SOmar Sandoval if (next->start_time_ns < req->start_time_ns) 811522a7775SOmar Sandoval req->start_time_ns = next->start_time_ns; 812d6d48196SJens Axboe 813d6d48196SJens Axboe req->biotail->bi_next = next->bio; 814d6d48196SJens Axboe req->biotail = next->biotail; 815d6d48196SJens Axboe 816a2dec7b3STejun Heo req->__data_len += blk_rq_bytes(next); 817d6d48196SJens Axboe 818445251d0SJens Axboe if (req_op(req) != REQ_OP_DISCARD) 819d6d48196SJens Axboe elv_merge_requests(q, req, next); 820d6d48196SJens Axboe 82142dad764SJerome Marchand /* 82242dad764SJerome Marchand * 'next' is going away, so update stats accordingly 82342dad764SJerome Marchand */ 82442dad764SJerome Marchand blk_account_io_merge(next); 825d6d48196SJens Axboe 826d6d48196SJens Axboe req->ioprio = ioprio_best(req->ioprio, next->ioprio); 827ab780f1eSJens Axboe if (blk_rq_cpu_valid(next)) 828ab780f1eSJens Axboe req->cpu = next->cpu; 829d6d48196SJens Axboe 830e4d750c9SJens Axboe /* 831e4d750c9SJens Axboe * ownership of bio passed from next to req, return 'next' for 832e4d750c9SJens Axboe * the caller to free 833e4d750c9SJens Axboe */ 8341cd96c24SBoaz Harrosh next->bio = NULL; 835b973cb7eSJens Axboe return next; 836d6d48196SJens Axboe } 837d6d48196SJens Axboe 838b973cb7eSJens Axboe struct request *attempt_back_merge(struct request_queue *q, struct request *rq) 839d6d48196SJens Axboe { 840d6d48196SJens Axboe struct request *next = elv_latter_request(q, rq); 841d6d48196SJens Axboe 842d6d48196SJens Axboe if (next) 843d6d48196SJens Axboe return attempt_merge(q, rq, next); 844d6d48196SJens Axboe 845b973cb7eSJens Axboe return NULL; 846d6d48196SJens Axboe } 847d6d48196SJens Axboe 848b973cb7eSJens Axboe struct request *attempt_front_merge(struct request_queue *q, struct request *rq) 849d6d48196SJens Axboe { 850d6d48196SJens Axboe struct request *prev = elv_former_request(q, rq); 851d6d48196SJens Axboe 852d6d48196SJens Axboe if (prev) 853d6d48196SJens Axboe return attempt_merge(q, prev, rq); 854d6d48196SJens Axboe 855b973cb7eSJens Axboe return NULL; 856d6d48196SJens Axboe } 8575e84ea3aSJens Axboe 8585e84ea3aSJens Axboe int blk_attempt_req_merge(struct request_queue *q, struct request *rq, 8595e84ea3aSJens Axboe struct request *next) 8605e84ea3aSJens Axboe { 86172ef799bSTahsin Erdogan struct elevator_queue *e = q->elevator; 862e4d750c9SJens Axboe struct request *free; 86372ef799bSTahsin Erdogan 864bd166ef1SJens Axboe if (!e->uses_mq && e->type->ops.sq.elevator_allow_rq_merge_fn) 865c51ca6cfSJens Axboe if (!e->type->ops.sq.elevator_allow_rq_merge_fn(q, rq, next)) 86672ef799bSTahsin Erdogan return 0; 86772ef799bSTahsin Erdogan 868e4d750c9SJens Axboe free = attempt_merge(q, rq, next); 869e4d750c9SJens Axboe if (free) { 870e4d750c9SJens Axboe __blk_put_request(q, free); 871e4d750c9SJens Axboe return 1; 872e4d750c9SJens Axboe } 873e4d750c9SJens Axboe 874e4d750c9SJens Axboe return 0; 8755e84ea3aSJens Axboe } 876050c8ea8STejun Heo 877050c8ea8STejun Heo bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 878050c8ea8STejun Heo { 879e2a60da7SMartin K. Petersen if (!rq_mergeable(rq) || !bio_mergeable(bio)) 880050c8ea8STejun Heo return false; 881050c8ea8STejun Heo 882288dab8aSChristoph Hellwig if (req_op(rq) != bio_op(bio)) 883f31dc1cdSMartin K. Petersen return false; 884f31dc1cdSMartin K. Petersen 885050c8ea8STejun Heo /* different data direction or already started, don't merge */ 886050c8ea8STejun Heo if (bio_data_dir(bio) != rq_data_dir(rq)) 887050c8ea8STejun Heo return false; 888050c8ea8STejun Heo 889050c8ea8STejun Heo /* must be same device and not a special request */ 89074d46992SChristoph Hellwig if (rq->rq_disk != bio->bi_disk || req_no_special_merge(rq)) 891050c8ea8STejun Heo return false; 892050c8ea8STejun Heo 893050c8ea8STejun Heo /* only merge integrity protected bio into ditto rq */ 8944eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(rq->q, rq, bio) == false) 895050c8ea8STejun Heo return false; 896050c8ea8STejun Heo 8974363ac7cSMartin K. Petersen /* must be using the same buffer */ 8988fe0d473SMike Christie if (req_op(rq) == REQ_OP_WRITE_SAME && 8994363ac7cSMartin K. Petersen !blk_write_same_mergeable(rq->bio, bio)) 9004363ac7cSMartin K. Petersen return false; 9014363ac7cSMartin K. Petersen 902cb6934f8SJens Axboe /* 903cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 904cb6934f8SJens Axboe * non-hint IO. 905cb6934f8SJens Axboe */ 906cb6934f8SJens Axboe if (rq->write_hint != bio->bi_write_hint) 907cb6934f8SJens Axboe return false; 908cb6934f8SJens Axboe 909050c8ea8STejun Heo return true; 910050c8ea8STejun Heo } 911050c8ea8STejun Heo 91234fe7c05SChristoph Hellwig enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) 913050c8ea8STejun Heo { 91469840466SJianchao Wang if (blk_discard_mergable(rq)) 9151e739730SChristoph Hellwig return ELEVATOR_DISCARD_MERGE; 9161e739730SChristoph Hellwig else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) 917050c8ea8STejun Heo return ELEVATOR_BACK_MERGE; 9184f024f37SKent Overstreet else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) 919050c8ea8STejun Heo return ELEVATOR_FRONT_MERGE; 920050c8ea8STejun Heo return ELEVATOR_NO_MERGE; 921050c8ea8STejun Heo } 922