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 static inline bool bio_will_gap(struct request_queue *q, 16e9907009SChristoph Hellwig struct request *prev_rq, struct bio *prev, struct bio *next) 17e9907009SChristoph Hellwig { 18e9907009SChristoph Hellwig struct bio_vec pb, nb; 19e9907009SChristoph Hellwig 20e9907009SChristoph Hellwig if (!bio_has_data(prev) || !queue_virt_boundary(q)) 21e9907009SChristoph Hellwig return false; 22e9907009SChristoph Hellwig 23e9907009SChristoph Hellwig /* 24e9907009SChristoph Hellwig * Don't merge if the 1st bio starts with non-zero offset, otherwise it 25e9907009SChristoph Hellwig * is quite difficult to respect the sg gap limit. We work hard to 26e9907009SChristoph Hellwig * merge a huge number of small single bios in case of mkfs. 27e9907009SChristoph Hellwig */ 28e9907009SChristoph Hellwig if (prev_rq) 29e9907009SChristoph Hellwig bio_get_first_bvec(prev_rq->bio, &pb); 30e9907009SChristoph Hellwig else 31e9907009SChristoph Hellwig bio_get_first_bvec(prev, &pb); 32df376b2eSJohannes Thumshirn if (pb.bv_offset & queue_virt_boundary(q)) 33e9907009SChristoph Hellwig return true; 34e9907009SChristoph Hellwig 35e9907009SChristoph Hellwig /* 36e9907009SChristoph Hellwig * We don't need to worry about the situation that the merged segment 37e9907009SChristoph Hellwig * ends in unaligned virt boundary: 38e9907009SChristoph Hellwig * 39e9907009SChristoph Hellwig * - if 'pb' ends aligned, the merged segment ends aligned 40e9907009SChristoph Hellwig * - if 'pb' ends unaligned, the next bio must include 41e9907009SChristoph Hellwig * one single bvec of 'nb', otherwise the 'nb' can't 42e9907009SChristoph Hellwig * merge with 'pb' 43e9907009SChristoph Hellwig */ 44e9907009SChristoph Hellwig bio_get_last_bvec(prev, &pb); 45e9907009SChristoph Hellwig bio_get_first_bvec(next, &nb); 46200a9affSChristoph Hellwig if (biovec_phys_mergeable(q, &pb, &nb)) 47e9907009SChristoph Hellwig return false; 48e9907009SChristoph Hellwig return __bvec_gap_to_prev(q, &pb, nb.bv_offset); 49e9907009SChristoph Hellwig } 50e9907009SChristoph Hellwig 51e9907009SChristoph Hellwig static inline bool req_gap_back_merge(struct request *req, struct bio *bio) 52e9907009SChristoph Hellwig { 53e9907009SChristoph Hellwig return bio_will_gap(req->q, req, req->biotail, bio); 54e9907009SChristoph Hellwig } 55e9907009SChristoph Hellwig 56e9907009SChristoph Hellwig static inline bool req_gap_front_merge(struct request *req, struct bio *bio) 57e9907009SChristoph Hellwig { 58e9907009SChristoph Hellwig return bio_will_gap(req->q, NULL, bio, req->bio); 59e9907009SChristoph Hellwig } 60e9907009SChristoph Hellwig 6154efd50bSKent Overstreet static struct bio *blk_bio_discard_split(struct request_queue *q, 6254efd50bSKent Overstreet struct bio *bio, 63bdced438SMing Lei struct bio_set *bs, 64bdced438SMing Lei unsigned *nsegs) 6554efd50bSKent Overstreet { 6654efd50bSKent Overstreet unsigned int max_discard_sectors, granularity; 6754efd50bSKent Overstreet int alignment; 6854efd50bSKent Overstreet sector_t tmp; 6954efd50bSKent Overstreet unsigned split_sectors; 7054efd50bSKent Overstreet 71bdced438SMing Lei *nsegs = 1; 72bdced438SMing Lei 7354efd50bSKent Overstreet /* Zero-sector (unknown) and one-sector granularities are the same. */ 7454efd50bSKent Overstreet granularity = max(q->limits.discard_granularity >> 9, 1U); 7554efd50bSKent Overstreet 761adfc5e4SMing Lei max_discard_sectors = min(q->limits.max_discard_sectors, 771adfc5e4SMing Lei bio_allowed_max_sectors(q)); 7854efd50bSKent Overstreet max_discard_sectors -= max_discard_sectors % granularity; 7954efd50bSKent Overstreet 8054efd50bSKent Overstreet if (unlikely(!max_discard_sectors)) { 8154efd50bSKent Overstreet /* XXX: warn */ 8254efd50bSKent Overstreet return NULL; 8354efd50bSKent Overstreet } 8454efd50bSKent Overstreet 8554efd50bSKent Overstreet if (bio_sectors(bio) <= max_discard_sectors) 8654efd50bSKent Overstreet return NULL; 8754efd50bSKent Overstreet 8854efd50bSKent Overstreet split_sectors = max_discard_sectors; 8954efd50bSKent Overstreet 9054efd50bSKent Overstreet /* 9154efd50bSKent Overstreet * If the next starting sector would be misaligned, stop the discard at 9254efd50bSKent Overstreet * the previous aligned sector. 9354efd50bSKent Overstreet */ 9454efd50bSKent Overstreet alignment = (q->limits.discard_alignment >> 9) % granularity; 9554efd50bSKent Overstreet 9654efd50bSKent Overstreet tmp = bio->bi_iter.bi_sector + split_sectors - alignment; 9754efd50bSKent Overstreet tmp = sector_div(tmp, granularity); 9854efd50bSKent Overstreet 9954efd50bSKent Overstreet if (split_sectors > tmp) 10054efd50bSKent Overstreet split_sectors -= tmp; 10154efd50bSKent Overstreet 10254efd50bSKent Overstreet return bio_split(bio, split_sectors, GFP_NOIO, bs); 10354efd50bSKent Overstreet } 10454efd50bSKent Overstreet 105885fa13fSChristoph Hellwig static struct bio *blk_bio_write_zeroes_split(struct request_queue *q, 106885fa13fSChristoph Hellwig struct bio *bio, struct bio_set *bs, unsigned *nsegs) 107885fa13fSChristoph Hellwig { 108885fa13fSChristoph Hellwig *nsegs = 1; 109885fa13fSChristoph Hellwig 110885fa13fSChristoph Hellwig if (!q->limits.max_write_zeroes_sectors) 111885fa13fSChristoph Hellwig return NULL; 112885fa13fSChristoph Hellwig 113885fa13fSChristoph Hellwig if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors) 114885fa13fSChristoph Hellwig return NULL; 115885fa13fSChristoph Hellwig 116885fa13fSChristoph Hellwig return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs); 117885fa13fSChristoph Hellwig } 118885fa13fSChristoph Hellwig 11954efd50bSKent Overstreet static struct bio *blk_bio_write_same_split(struct request_queue *q, 12054efd50bSKent Overstreet struct bio *bio, 121bdced438SMing Lei struct bio_set *bs, 122bdced438SMing Lei unsigned *nsegs) 12354efd50bSKent Overstreet { 124bdced438SMing Lei *nsegs = 1; 125bdced438SMing Lei 12654efd50bSKent Overstreet if (!q->limits.max_write_same_sectors) 12754efd50bSKent Overstreet return NULL; 12854efd50bSKent Overstreet 12954efd50bSKent Overstreet if (bio_sectors(bio) <= q->limits.max_write_same_sectors) 13054efd50bSKent Overstreet return NULL; 13154efd50bSKent Overstreet 13254efd50bSKent Overstreet return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); 13354efd50bSKent Overstreet } 13454efd50bSKent Overstreet 135d0e5fbb0SMing Lei static inline unsigned get_max_io_size(struct request_queue *q, 136d0e5fbb0SMing Lei struct bio *bio) 137d0e5fbb0SMing Lei { 138d0e5fbb0SMing Lei unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector); 139d0e5fbb0SMing Lei unsigned mask = queue_logical_block_size(q) - 1; 140d0e5fbb0SMing Lei 141d0e5fbb0SMing Lei /* aligned to logical block size */ 142d0e5fbb0SMing Lei sectors &= ~(mask >> 9); 143d0e5fbb0SMing Lei 144d0e5fbb0SMing Lei return sectors; 145d0e5fbb0SMing Lei } 146d0e5fbb0SMing Lei 147dcebd755SMing Lei static unsigned get_max_segment_size(struct request_queue *q, 148dcebd755SMing Lei unsigned offset) 149dcebd755SMing Lei { 150dcebd755SMing Lei unsigned long mask = queue_segment_boundary(q); 151dcebd755SMing Lei 152dcebd755SMing Lei /* default segment boundary mask means no boundary limit */ 153dcebd755SMing Lei if (mask == BLK_SEG_BOUNDARY_MASK) 154dcebd755SMing Lei return queue_max_segment_size(q); 155dcebd755SMing Lei 156dcebd755SMing Lei return min_t(unsigned long, mask - (mask & offset) + 1, 157dcebd755SMing Lei queue_max_segment_size(q)); 158dcebd755SMing Lei } 159dcebd755SMing Lei 160dcebd755SMing Lei /* 161dcebd755SMing Lei * Split the bvec @bv into segments, and update all kinds of 162dcebd755SMing Lei * variables. 163dcebd755SMing Lei */ 164dcebd755SMing Lei static bool bvec_split_segs(struct request_queue *q, struct bio_vec *bv, 1656869875fSChristoph Hellwig unsigned *nsegs, unsigned *sectors, unsigned max_segs) 166dcebd755SMing Lei { 167dcebd755SMing Lei unsigned len = bv->bv_len; 168dcebd755SMing Lei unsigned total_len = 0; 169dcebd755SMing Lei unsigned new_nsegs = 0, seg_size = 0; 170dcebd755SMing Lei 171dcebd755SMing Lei /* 172dcebd755SMing Lei * Multi-page bvec may be too big to hold in one segment, so the 173dcebd755SMing Lei * current bvec has to be splitted as multiple segments. 174dcebd755SMing Lei */ 17505b700baSMing Lei while (len && new_nsegs + *nsegs < max_segs) { 176dcebd755SMing Lei seg_size = get_max_segment_size(q, bv->bv_offset + total_len); 177dcebd755SMing Lei seg_size = min(seg_size, len); 178dcebd755SMing Lei 179dcebd755SMing Lei new_nsegs++; 180dcebd755SMing Lei total_len += seg_size; 181dcebd755SMing Lei len -= seg_size; 182dcebd755SMing Lei 183dcebd755SMing Lei if ((bv->bv_offset + total_len) & queue_virt_boundary(q)) 184dcebd755SMing Lei break; 185dcebd755SMing Lei } 186dcebd755SMing Lei 1876869875fSChristoph Hellwig if (new_nsegs) { 188dcebd755SMing Lei *nsegs += new_nsegs; 189dcebd755SMing Lei if (sectors) 190dcebd755SMing Lei *sectors += total_len >> 9; 1916869875fSChristoph Hellwig } 192dcebd755SMing Lei 193dcebd755SMing Lei /* split in the middle of the bvec if len != 0 */ 194dcebd755SMing Lei return !!len; 195dcebd755SMing Lei } 196dcebd755SMing Lei 19754efd50bSKent Overstreet static struct bio *blk_bio_segment_split(struct request_queue *q, 19854efd50bSKent Overstreet struct bio *bio, 199bdced438SMing Lei struct bio_set *bs, 200bdced438SMing Lei unsigned *segs) 20154efd50bSKent Overstreet { 2025014c311SJens Axboe struct bio_vec bv, bvprv, *bvprvp = NULL; 20354efd50bSKent Overstreet struct bvec_iter iter; 2046869875fSChristoph Hellwig unsigned nsegs = 0, sectors = 0; 20502e70742SMing Lei bool do_split = true; 20602e70742SMing Lei struct bio *new = NULL; 207d0e5fbb0SMing Lei const unsigned max_sectors = get_max_io_size(q, bio); 20805b700baSMing Lei const unsigned max_segs = queue_max_segments(q); 20954efd50bSKent Overstreet 210dcebd755SMing Lei bio_for_each_bvec(bv, bio, iter) { 21154efd50bSKent Overstreet /* 21254efd50bSKent Overstreet * If the queue doesn't support SG gaps and adding this 21354efd50bSKent Overstreet * offset would create a gap, disallow it. 21454efd50bSKent Overstreet */ 2155014c311SJens Axboe if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) 21654efd50bSKent Overstreet goto split; 21754efd50bSKent Overstreet 218d0e5fbb0SMing Lei if (sectors + (bv.bv_len >> 9) > max_sectors) { 219e36f6204SKeith Busch /* 220e36f6204SKeith Busch * Consider this a new segment if we're splitting in 221e36f6204SKeith Busch * the middle of this vector. 222e36f6204SKeith Busch */ 22305b700baSMing Lei if (nsegs < max_segs && 224d0e5fbb0SMing Lei sectors < max_sectors) { 225dcebd755SMing Lei /* split in the middle of bvec */ 226dcebd755SMing Lei bv.bv_len = (max_sectors - sectors) << 9; 227dcebd755SMing Lei bvec_split_segs(q, &bv, &nsegs, 22805b700baSMing Lei §ors, max_segs); 229e36f6204SKeith Busch } 230e36f6204SKeith Busch goto split; 231e36f6204SKeith Busch } 232e36f6204SKeith Busch 23305b700baSMing Lei if (nsegs == max_segs) 23454efd50bSKent Overstreet goto split; 23554efd50bSKent Overstreet 23654efd50bSKent Overstreet bvprv = bv; 237578270bfSMing Lei bvprvp = &bvprv; 238dcebd755SMing Lei 239bbcbbd56SMing Lei if (bv.bv_offset + bv.bv_len <= PAGE_SIZE) { 240bbcbbd56SMing Lei nsegs++; 241bbcbbd56SMing Lei sectors += bv.bv_len >> 9; 2426869875fSChristoph Hellwig } else if (bvec_split_segs(q, &bv, &nsegs, §ors, 2436869875fSChristoph Hellwig max_segs)) { 244dcebd755SMing Lei goto split; 245bbcbbd56SMing Lei } 24654efd50bSKent Overstreet } 24754efd50bSKent Overstreet 24802e70742SMing Lei do_split = false; 24954efd50bSKent Overstreet split: 250bdced438SMing Lei *segs = nsegs; 25102e70742SMing Lei 25202e70742SMing Lei if (do_split) { 25302e70742SMing Lei new = bio_split(bio, sectors, GFP_NOIO, bs); 25402e70742SMing Lei if (new) 25502e70742SMing Lei bio = new; 25602e70742SMing Lei } 25702e70742SMing Lei 25802e70742SMing Lei return do_split ? new : NULL; 25954efd50bSKent Overstreet } 26054efd50bSKent Overstreet 261af67c31fSNeilBrown void blk_queue_split(struct request_queue *q, struct bio **bio) 26254efd50bSKent Overstreet { 263bdced438SMing Lei struct bio *split, *res; 264bdced438SMing Lei unsigned nsegs; 26554efd50bSKent Overstreet 2667afafc8aSAdrian Hunter switch (bio_op(*bio)) { 2677afafc8aSAdrian Hunter case REQ_OP_DISCARD: 2687afafc8aSAdrian Hunter case REQ_OP_SECURE_ERASE: 269338aa96dSKent Overstreet split = blk_bio_discard_split(q, *bio, &q->bio_split, &nsegs); 2707afafc8aSAdrian Hunter break; 271a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 272338aa96dSKent Overstreet split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split, &nsegs); 273a6f0788eSChaitanya Kulkarni break; 2747afafc8aSAdrian Hunter case REQ_OP_WRITE_SAME: 275338aa96dSKent Overstreet split = blk_bio_write_same_split(q, *bio, &q->bio_split, &nsegs); 2767afafc8aSAdrian Hunter break; 2777afafc8aSAdrian Hunter default: 278338aa96dSKent Overstreet split = blk_bio_segment_split(q, *bio, &q->bio_split, &nsegs); 2797afafc8aSAdrian Hunter break; 2807afafc8aSAdrian Hunter } 281bdced438SMing Lei 282bdced438SMing Lei /* physical segments can be figured out during splitting */ 283bdced438SMing Lei res = split ? split : *bio; 284bdced438SMing Lei res->bi_phys_segments = nsegs; 285bdced438SMing Lei bio_set_flag(res, BIO_SEG_VALID); 28654efd50bSKent Overstreet 28754efd50bSKent Overstreet if (split) { 2886ac45aebSMing Lei /* there isn't chance to merge the splitted bio */ 2891eff9d32SJens Axboe split->bi_opf |= REQ_NOMERGE; 2906ac45aebSMing Lei 291947b7ac1SJens Axboe /* 292947b7ac1SJens Axboe * Since we're recursing into make_request here, ensure 293947b7ac1SJens Axboe * that we mark this bio as already having entered the queue. 294947b7ac1SJens Axboe * If not, and the queue is going away, we can get stuck 295947b7ac1SJens Axboe * forever on waiting for the queue reference to drop. But 296947b7ac1SJens Axboe * that will never happen, as we're already holding a 297947b7ac1SJens Axboe * reference to it. 298947b7ac1SJens Axboe */ 299947b7ac1SJens Axboe bio_set_flag(*bio, BIO_QUEUE_ENTERED); 300947b7ac1SJens Axboe 30154efd50bSKent Overstreet bio_chain(split, *bio); 302cda22646SMike Krinkin trace_block_split(q, split, (*bio)->bi_iter.bi_sector); 30354efd50bSKent Overstreet generic_make_request(*bio); 30454efd50bSKent Overstreet *bio = split; 30554efd50bSKent Overstreet } 30654efd50bSKent Overstreet } 30754efd50bSKent Overstreet EXPORT_SYMBOL(blk_queue_split); 30854efd50bSKent Overstreet 3091e428079SJens Axboe static unsigned int __blk_recalc_rq_segments(struct request_queue *q, 3102705c937SMing Lei struct bio *bio) 311d6d48196SJens Axboe { 3126869875fSChristoph Hellwig unsigned int nr_phys_segs = 0; 3137988613bSKent Overstreet struct bvec_iter iter; 3146869875fSChristoph Hellwig struct bio_vec bv; 315d6d48196SJens Axboe 3161e428079SJens Axboe if (!bio) 3171e428079SJens Axboe return 0; 318d6d48196SJens Axboe 319a6f0788eSChaitanya Kulkarni switch (bio_op(bio)) { 320a6f0788eSChaitanya Kulkarni case REQ_OP_DISCARD: 321a6f0788eSChaitanya Kulkarni case REQ_OP_SECURE_ERASE: 322a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 323f9d03f96SChristoph Hellwig return 0; 324f9d03f96SChristoph Hellwig case REQ_OP_WRITE_SAME: 3255cb8850cSKent Overstreet return 1; 326a6f0788eSChaitanya Kulkarni } 3275cb8850cSKent Overstreet 3281e428079SJens Axboe for_each_bio(bio) { 3296869875fSChristoph Hellwig bio_for_each_bvec(bv, bio, iter) 3306869875fSChristoph Hellwig bvec_split_segs(q, &bv, &nr_phys_segs, NULL, UINT_MAX); 331d6d48196SJens Axboe } 3321e428079SJens Axboe 3331e428079SJens Axboe return nr_phys_segs; 3341e428079SJens Axboe } 3351e428079SJens Axboe 3361e428079SJens Axboe void blk_recalc_rq_segments(struct request *rq) 3371e428079SJens Axboe { 3382705c937SMing Lei rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio); 339d6d48196SJens Axboe } 340d6d48196SJens Axboe 341d6d48196SJens Axboe void blk_recount_segments(struct request_queue *q, struct bio *bio) 342d6d48196SJens Axboe { 343d6d48196SJens Axboe struct bio *nxt = bio->bi_next; 3441e428079SJens Axboe 345d6d48196SJens Axboe bio->bi_next = NULL; 3462705c937SMing Lei bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio); 347d6d48196SJens Axboe bio->bi_next = nxt; 34805f1dd53SJens Axboe 349b7c44ed9SJens Axboe bio_set_flag(bio, BIO_SEG_VALID); 350d6d48196SJens Axboe } 351d6d48196SJens Axboe 35248d7727cSMing Lei static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, 353862e5a5eSMing Lei struct scatterlist *sglist) 354862e5a5eSMing Lei { 355862e5a5eSMing Lei if (!*sg) 356862e5a5eSMing Lei return sglist; 357862e5a5eSMing Lei 358862e5a5eSMing Lei /* 359862e5a5eSMing Lei * If the driver previously mapped a shorter list, we could see a 360862e5a5eSMing Lei * termination bit prematurely unless it fully inits the sg table 361862e5a5eSMing Lei * on each mapping. We KNOW that there must be more entries here 362862e5a5eSMing Lei * or the driver would be buggy, so force clear the termination bit 363862e5a5eSMing Lei * to avoid doing a full sg_init_table() in drivers for each command. 364862e5a5eSMing Lei */ 365862e5a5eSMing Lei sg_unmark_end(*sg); 366862e5a5eSMing Lei return sg_next(*sg); 367862e5a5eSMing Lei } 368862e5a5eSMing Lei 369862e5a5eSMing Lei static unsigned blk_bvec_map_sg(struct request_queue *q, 370862e5a5eSMing Lei struct bio_vec *bvec, struct scatterlist *sglist, 371862e5a5eSMing Lei struct scatterlist **sg) 372862e5a5eSMing Lei { 373862e5a5eSMing Lei unsigned nbytes = bvec->bv_len; 3748a96a0e4SChristoph Hellwig unsigned nsegs = 0, total = 0; 375862e5a5eSMing Lei 376862e5a5eSMing Lei while (nbytes > 0) { 3778a96a0e4SChristoph Hellwig unsigned offset = bvec->bv_offset + total; 3788a96a0e4SChristoph Hellwig unsigned len = min(get_max_segment_size(q, offset), nbytes); 379f9f76879SChristoph Hellwig struct page *page = bvec->bv_page; 380f9f76879SChristoph Hellwig 381f9f76879SChristoph Hellwig /* 382f9f76879SChristoph Hellwig * Unfortunately a fair number of drivers barf on scatterlists 383f9f76879SChristoph Hellwig * that have an offset larger than PAGE_SIZE, despite other 384f9f76879SChristoph Hellwig * subsystems dealing with that invariant just fine. For now 385f9f76879SChristoph Hellwig * stick to the legacy format where we never present those from 386f9f76879SChristoph Hellwig * the block layer, but the code below should be removed once 387f9f76879SChristoph Hellwig * these offenders (mostly MMC/SD drivers) are fixed. 388f9f76879SChristoph Hellwig */ 389f9f76879SChristoph Hellwig page += (offset >> PAGE_SHIFT); 390f9f76879SChristoph Hellwig offset &= ~PAGE_MASK; 391862e5a5eSMing Lei 392862e5a5eSMing Lei *sg = blk_next_sg(sg, sglist); 393f9f76879SChristoph Hellwig sg_set_page(*sg, page, len, offset); 394862e5a5eSMing Lei 3958a96a0e4SChristoph Hellwig total += len; 3968a96a0e4SChristoph Hellwig nbytes -= len; 397862e5a5eSMing Lei nsegs++; 398862e5a5eSMing Lei } 399862e5a5eSMing Lei 400862e5a5eSMing Lei return nsegs; 401862e5a5eSMing Lei } 402862e5a5eSMing Lei 40316e3e418SMing Lei static inline int __blk_bvec_map_sg(struct bio_vec bv, 40416e3e418SMing Lei struct scatterlist *sglist, struct scatterlist **sg) 40516e3e418SMing Lei { 40616e3e418SMing Lei *sg = blk_next_sg(sg, sglist); 40716e3e418SMing Lei sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); 40816e3e418SMing Lei return 1; 40916e3e418SMing Lei } 41016e3e418SMing Lei 411f6970f83SMing Lei /* only try to merge bvecs into one sg if they are from two bios */ 412f6970f83SMing Lei static inline bool 413f6970f83SMing Lei __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec, 414f6970f83SMing Lei struct bio_vec *bvprv, struct scatterlist **sg) 415963ab9e5SAsias He { 416963ab9e5SAsias He 417963ab9e5SAsias He int nbytes = bvec->bv_len; 418963ab9e5SAsias He 419f6970f83SMing Lei if (!*sg) 420f6970f83SMing Lei return false; 421f6970f83SMing Lei 422b4b6cb61SMing Lei if ((*sg)->length + nbytes > queue_max_segment_size(q)) 423f6970f83SMing Lei return false; 424f6970f83SMing Lei 4253dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, bvprv, bvec)) 426f6970f83SMing Lei return false; 427963ab9e5SAsias He 428963ab9e5SAsias He (*sg)->length += nbytes; 429f6970f83SMing Lei 430f6970f83SMing Lei return true; 431963ab9e5SAsias He } 432963ab9e5SAsias He 4335cb8850cSKent Overstreet static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, 4345cb8850cSKent Overstreet struct scatterlist *sglist, 4355cb8850cSKent Overstreet struct scatterlist **sg) 4365cb8850cSKent Overstreet { 437b21e11c5SMing Lei struct bio_vec uninitialized_var(bvec), bvprv = { NULL }; 4385cb8850cSKent Overstreet struct bvec_iter iter; 43938417468SChristoph Hellwig int nsegs = 0; 440f6970f83SMing Lei bool new_bio = false; 4415cb8850cSKent Overstreet 442f6970f83SMing Lei for_each_bio(bio) { 443f6970f83SMing Lei bio_for_each_bvec(bvec, bio, iter) { 444f6970f83SMing Lei /* 445f6970f83SMing Lei * Only try to merge bvecs from two bios given we 446f6970f83SMing Lei * have done bio internal merge when adding pages 447f6970f83SMing Lei * to bio 448f6970f83SMing Lei */ 449f6970f83SMing Lei if (new_bio && 450f6970f83SMing Lei __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg)) 451f6970f83SMing Lei goto next_bvec; 452f6970f83SMing Lei 453f6970f83SMing Lei if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE) 454f6970f83SMing Lei nsegs += __blk_bvec_map_sg(bvec, sglist, sg); 455f6970f83SMing Lei else 456f6970f83SMing Lei nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg); 457f6970f83SMing Lei next_bvec: 458f6970f83SMing Lei new_bio = false; 459f6970f83SMing Lei } 460b21e11c5SMing Lei if (likely(bio->bi_iter.bi_size)) { 461f6970f83SMing Lei bvprv = bvec; 462f6970f83SMing Lei new_bio = true; 463f6970f83SMing Lei } 464b21e11c5SMing Lei } 4655cb8850cSKent Overstreet 4665cb8850cSKent Overstreet return nsegs; 4675cb8850cSKent Overstreet } 4685cb8850cSKent Overstreet 469d6d48196SJens Axboe /* 470d6d48196SJens Axboe * map a request to scatterlist, return number of sg entries setup. Caller 471d6d48196SJens Axboe * must make sure sg can hold rq->nr_phys_segments entries 472d6d48196SJens Axboe */ 473d6d48196SJens Axboe int blk_rq_map_sg(struct request_queue *q, struct request *rq, 474d6d48196SJens Axboe struct scatterlist *sglist) 475d6d48196SJens Axboe { 4765cb8850cSKent Overstreet struct scatterlist *sg = NULL; 4775cb8850cSKent Overstreet int nsegs = 0; 478d6d48196SJens Axboe 479f9d03f96SChristoph Hellwig if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) 480cae6c2e5SMing Lei nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, &sg); 481f9d03f96SChristoph Hellwig else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME) 482cae6c2e5SMing Lei nsegs = __blk_bvec_map_sg(bio_iovec(rq->bio), sglist, &sg); 483f9d03f96SChristoph Hellwig else if (rq->bio) 4845cb8850cSKent Overstreet nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); 485f18573abSFUJITA Tomonori 486e8064021SChristoph Hellwig if (unlikely(rq->rq_flags & RQF_COPY_USER) && 4872e46e8b2STejun Heo (blk_rq_bytes(rq) & q->dma_pad_mask)) { 4882e46e8b2STejun Heo unsigned int pad_len = 4892e46e8b2STejun Heo (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; 490f18573abSFUJITA Tomonori 491f18573abSFUJITA Tomonori sg->length += pad_len; 492f18573abSFUJITA Tomonori rq->extra_len += pad_len; 493f18573abSFUJITA Tomonori } 494f18573abSFUJITA Tomonori 4952fb98e84STejun Heo if (q->dma_drain_size && q->dma_drain_needed(rq)) { 496a8ebb056SMike Christie if (op_is_write(req_op(rq))) 497db0a2e00STejun Heo memset(q->dma_drain_buffer, 0, q->dma_drain_size); 498db0a2e00STejun Heo 499da81ed16SDan Williams sg_unmark_end(sg); 500d6d48196SJens Axboe sg = sg_next(sg); 501d6d48196SJens Axboe sg_set_page(sg, virt_to_page(q->dma_drain_buffer), 502d6d48196SJens Axboe q->dma_drain_size, 503d6d48196SJens Axboe ((unsigned long)q->dma_drain_buffer) & 504d6d48196SJens Axboe (PAGE_SIZE - 1)); 505d6d48196SJens Axboe nsegs++; 5067a85f889SFUJITA Tomonori rq->extra_len += q->dma_drain_size; 507d6d48196SJens Axboe } 508d6d48196SJens Axboe 509d6d48196SJens Axboe if (sg) 510d6d48196SJens Axboe sg_mark_end(sg); 511d6d48196SJens Axboe 51212e57f59SMing Lei /* 51312e57f59SMing Lei * Something must have been wrong if the figured number of 51412e57f59SMing Lei * segment is bigger than number of req's physical segments 51512e57f59SMing Lei */ 516f9d03f96SChristoph Hellwig WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); 51712e57f59SMing Lei 518d6d48196SJens Axboe return nsegs; 519d6d48196SJens Axboe } 520d6d48196SJens Axboe EXPORT_SYMBOL(blk_rq_map_sg); 521d6d48196SJens Axboe 522d6d48196SJens Axboe static inline int ll_new_hw_segment(struct request_queue *q, 523d6d48196SJens Axboe struct request *req, 524d6d48196SJens Axboe struct bio *bio) 525d6d48196SJens Axboe { 526d6d48196SJens Axboe int nr_phys_segs = bio_phys_segments(q, bio); 527d6d48196SJens Axboe 52813f05c8dSMartin K. Petersen if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) 52913f05c8dSMartin K. Petersen goto no_merge; 53013f05c8dSMartin K. Petersen 5314eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(q, req, bio) == false) 53213f05c8dSMartin K. Petersen goto no_merge; 533d6d48196SJens Axboe 534d6d48196SJens Axboe /* 535d6d48196SJens Axboe * This will form the start of a new hw segment. Bump both 536d6d48196SJens Axboe * counters. 537d6d48196SJens Axboe */ 538d6d48196SJens Axboe req->nr_phys_segments += nr_phys_segs; 539d6d48196SJens Axboe return 1; 54013f05c8dSMartin K. Petersen 54113f05c8dSMartin K. Petersen no_merge: 542e0c72300SRitesh Harjani req_set_nomerge(q, req); 54313f05c8dSMartin K. Petersen return 0; 544d6d48196SJens Axboe } 545d6d48196SJens Axboe 546d6d48196SJens Axboe int ll_back_merge_fn(struct request_queue *q, struct request *req, 547d6d48196SJens Axboe struct bio *bio) 548d6d48196SJens Axboe { 5495e7c4274SJens Axboe if (req_gap_back_merge(req, bio)) 5505e7c4274SJens Axboe return 0; 5517f39add3SSagi Grimberg if (blk_integrity_rq(req) && 5527f39add3SSagi Grimberg integrity_req_gap_back_merge(req, bio)) 5537f39add3SSagi Grimberg return 0; 554f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 55517007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) { 556e0c72300SRitesh Harjani req_set_nomerge(q, req); 557d6d48196SJens Axboe return 0; 558d6d48196SJens Axboe } 5592cdf79caSJens Axboe if (!bio_flagged(req->biotail, BIO_SEG_VALID)) 560d6d48196SJens Axboe blk_recount_segments(q, req->biotail); 5612cdf79caSJens Axboe if (!bio_flagged(bio, BIO_SEG_VALID)) 562d6d48196SJens Axboe blk_recount_segments(q, bio); 563d6d48196SJens Axboe 564d6d48196SJens Axboe return ll_new_hw_segment(q, req, bio); 565d6d48196SJens Axboe } 566d6d48196SJens Axboe 567d6d48196SJens Axboe int ll_front_merge_fn(struct request_queue *q, struct request *req, 568d6d48196SJens Axboe struct bio *bio) 569d6d48196SJens Axboe { 5705e7c4274SJens Axboe 5715e7c4274SJens Axboe if (req_gap_front_merge(req, bio)) 5725e7c4274SJens Axboe return 0; 5737f39add3SSagi Grimberg if (blk_integrity_rq(req) && 5747f39add3SSagi Grimberg integrity_req_gap_front_merge(req, bio)) 5757f39add3SSagi Grimberg return 0; 576f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 57717007f39SDamien Le Moal blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { 578e0c72300SRitesh Harjani req_set_nomerge(q, req); 579d6d48196SJens Axboe return 0; 580d6d48196SJens Axboe } 5812cdf79caSJens Axboe if (!bio_flagged(bio, BIO_SEG_VALID)) 582d6d48196SJens Axboe blk_recount_segments(q, bio); 5832cdf79caSJens Axboe if (!bio_flagged(req->bio, BIO_SEG_VALID)) 584d6d48196SJens Axboe blk_recount_segments(q, req->bio); 585d6d48196SJens Axboe 586d6d48196SJens Axboe return ll_new_hw_segment(q, req, bio); 587d6d48196SJens Axboe } 588d6d48196SJens Axboe 589445251d0SJens Axboe static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, 590445251d0SJens Axboe struct request *next) 591445251d0SJens Axboe { 592445251d0SJens Axboe unsigned short segments = blk_rq_nr_discard_segments(req); 593445251d0SJens Axboe 594445251d0SJens Axboe if (segments >= queue_max_discard_segments(q)) 595445251d0SJens Axboe goto no_merge; 596445251d0SJens Axboe if (blk_rq_sectors(req) + bio_sectors(next->bio) > 597445251d0SJens Axboe blk_rq_get_max_sectors(req, blk_rq_pos(req))) 598445251d0SJens Axboe goto no_merge; 599445251d0SJens Axboe 600445251d0SJens Axboe req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); 601445251d0SJens Axboe return true; 602445251d0SJens Axboe no_merge: 603445251d0SJens Axboe req_set_nomerge(q, req); 604445251d0SJens Axboe return false; 605445251d0SJens Axboe } 606445251d0SJens Axboe 607d6d48196SJens Axboe static int ll_merge_requests_fn(struct request_queue *q, struct request *req, 608d6d48196SJens Axboe struct request *next) 609d6d48196SJens Axboe { 610d6d48196SJens Axboe int total_phys_segments; 611d6d48196SJens Axboe 6125e7c4274SJens Axboe if (req_gap_back_merge(req, next->bio)) 613854fbb9cSKeith Busch return 0; 614854fbb9cSKeith Busch 615d6d48196SJens Axboe /* 616d6d48196SJens Axboe * Will it become too large? 617d6d48196SJens Axboe */ 618f31dc1cdSMartin K. Petersen if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > 61917007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) 620d6d48196SJens Axboe return 0; 621d6d48196SJens Axboe 622d6d48196SJens Axboe total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; 6238a78362cSMartin K. Petersen if (total_phys_segments > queue_max_segments(q)) 624d6d48196SJens Axboe return 0; 625d6d48196SJens Axboe 6264eaf99beSMartin K. Petersen if (blk_integrity_merge_rq(q, req, next) == false) 62713f05c8dSMartin K. Petersen return 0; 62813f05c8dSMartin K. Petersen 629d6d48196SJens Axboe /* Merge is OK... */ 630d6d48196SJens Axboe req->nr_phys_segments = total_phys_segments; 631d6d48196SJens Axboe return 1; 632d6d48196SJens Axboe } 633d6d48196SJens Axboe 63480a761fdSTejun Heo /** 63580a761fdSTejun Heo * blk_rq_set_mixed_merge - mark a request as mixed merge 63680a761fdSTejun Heo * @rq: request to mark as mixed merge 63780a761fdSTejun Heo * 63880a761fdSTejun Heo * Description: 63980a761fdSTejun Heo * @rq is about to be mixed merged. Make sure the attributes 64080a761fdSTejun Heo * which can be mixed are set in each bio and mark @rq as mixed 64180a761fdSTejun Heo * merged. 64280a761fdSTejun Heo */ 64380a761fdSTejun Heo void blk_rq_set_mixed_merge(struct request *rq) 64480a761fdSTejun Heo { 64580a761fdSTejun Heo unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 64680a761fdSTejun Heo struct bio *bio; 64780a761fdSTejun Heo 648e8064021SChristoph Hellwig if (rq->rq_flags & RQF_MIXED_MERGE) 64980a761fdSTejun Heo return; 65080a761fdSTejun Heo 65180a761fdSTejun Heo /* 65280a761fdSTejun Heo * @rq will no longer represent mixable attributes for all the 65380a761fdSTejun Heo * contained bios. It will just track those of the first one. 65480a761fdSTejun Heo * Distributes the attributs to each bio. 65580a761fdSTejun Heo */ 65680a761fdSTejun Heo for (bio = rq->bio; bio; bio = bio->bi_next) { 6571eff9d32SJens Axboe WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && 6581eff9d32SJens Axboe (bio->bi_opf & REQ_FAILFAST_MASK) != ff); 6591eff9d32SJens Axboe bio->bi_opf |= ff; 66080a761fdSTejun Heo } 661e8064021SChristoph Hellwig rq->rq_flags |= RQF_MIXED_MERGE; 66280a761fdSTejun Heo } 66380a761fdSTejun Heo 66426308eabSJerome Marchand static void blk_account_io_merge(struct request *req) 66526308eabSJerome Marchand { 66626308eabSJerome Marchand if (blk_do_io_stat(req)) { 66726308eabSJerome Marchand struct hd_struct *part; 66826308eabSJerome Marchand 669112f158fSMike Snitzer part_stat_lock(); 67009e099d4SJerome Marchand part = req->part; 67126308eabSJerome Marchand 672d62e26b3SJens Axboe part_dec_in_flight(req->q, part, rq_data_dir(req)); 67326308eabSJerome Marchand 6746c23a968SJens Axboe hd_struct_put(part); 67526308eabSJerome Marchand part_stat_unlock(); 67626308eabSJerome Marchand } 67726308eabSJerome Marchand } 67869840466SJianchao Wang /* 67969840466SJianchao Wang * Two cases of handling DISCARD merge: 68069840466SJianchao Wang * If max_discard_segments > 1, the driver takes every bio 68169840466SJianchao Wang * as a range and send them to controller together. The ranges 68269840466SJianchao Wang * needn't to be contiguous. 68369840466SJianchao Wang * Otherwise, the bios/requests will be handled as same as 68469840466SJianchao Wang * others which should be contiguous. 68569840466SJianchao Wang */ 68669840466SJianchao Wang static inline bool blk_discard_mergable(struct request *req) 68769840466SJianchao Wang { 68869840466SJianchao Wang if (req_op(req) == REQ_OP_DISCARD && 68969840466SJianchao Wang queue_max_discard_segments(req->q) > 1) 69069840466SJianchao Wang return true; 69169840466SJianchao Wang return false; 69269840466SJianchao Wang } 69369840466SJianchao Wang 694e96c0d83SEric Biggers static enum elv_merge blk_try_req_merge(struct request *req, 695e96c0d83SEric Biggers struct request *next) 69669840466SJianchao Wang { 69769840466SJianchao Wang if (blk_discard_mergable(req)) 69869840466SJianchao Wang return ELEVATOR_DISCARD_MERGE; 69969840466SJianchao Wang else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) 70069840466SJianchao Wang return ELEVATOR_BACK_MERGE; 70169840466SJianchao Wang 70269840466SJianchao Wang return ELEVATOR_NO_MERGE; 70369840466SJianchao Wang } 70426308eabSJerome Marchand 705d6d48196SJens Axboe /* 706b973cb7eSJens Axboe * For non-mq, this has to be called with the request spinlock acquired. 707b973cb7eSJens Axboe * For mq with scheduling, the appropriate queue wide lock should be held. 708d6d48196SJens Axboe */ 709b973cb7eSJens Axboe static struct request *attempt_merge(struct request_queue *q, 710b973cb7eSJens Axboe struct request *req, struct request *next) 711d6d48196SJens Axboe { 712d6d48196SJens Axboe if (!rq_mergeable(req) || !rq_mergeable(next)) 713b973cb7eSJens Axboe return NULL; 714d6d48196SJens Axboe 715288dab8aSChristoph Hellwig if (req_op(req) != req_op(next)) 716b973cb7eSJens Axboe return NULL; 717f31dc1cdSMartin K. Petersen 718d6d48196SJens Axboe if (rq_data_dir(req) != rq_data_dir(next) 7192081a56bSJens Axboe || req->rq_disk != next->rq_disk) 720b973cb7eSJens Axboe return NULL; 721d6d48196SJens Axboe 7228fe0d473SMike Christie if (req_op(req) == REQ_OP_WRITE_SAME && 7234363ac7cSMartin K. Petersen !blk_write_same_mergeable(req->bio, next->bio)) 724b973cb7eSJens Axboe return NULL; 7254363ac7cSMartin K. Petersen 726d6d48196SJens Axboe /* 727cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 728cb6934f8SJens Axboe * non-hint IO. 729cb6934f8SJens Axboe */ 730cb6934f8SJens Axboe if (req->write_hint != next->write_hint) 731cb6934f8SJens Axboe return NULL; 732cb6934f8SJens Axboe 733668ffc03SDamien Le Moal if (req->ioprio != next->ioprio) 734668ffc03SDamien Le Moal return NULL; 735668ffc03SDamien Le Moal 736cb6934f8SJens Axboe /* 737d6d48196SJens Axboe * If we are allowed to merge, then append bio list 738d6d48196SJens Axboe * from next to rq and release next. merge_requests_fn 739d6d48196SJens Axboe * will have updated segment counts, update sector 740445251d0SJens Axboe * counts here. Handle DISCARDs separately, as they 741445251d0SJens Axboe * have separate settings. 742d6d48196SJens Axboe */ 74369840466SJianchao Wang 74469840466SJianchao Wang switch (blk_try_req_merge(req, next)) { 74569840466SJianchao Wang case ELEVATOR_DISCARD_MERGE: 746445251d0SJens Axboe if (!req_attempt_discard_merge(q, req, next)) 747445251d0SJens Axboe return NULL; 74869840466SJianchao Wang break; 74969840466SJianchao Wang case ELEVATOR_BACK_MERGE: 75069840466SJianchao Wang if (!ll_merge_requests_fn(q, req, next)) 751b973cb7eSJens Axboe return NULL; 75269840466SJianchao Wang break; 75369840466SJianchao Wang default: 75469840466SJianchao Wang return NULL; 75569840466SJianchao Wang } 756d6d48196SJens Axboe 757d6d48196SJens Axboe /* 75880a761fdSTejun Heo * If failfast settings disagree or any of the two is already 75980a761fdSTejun Heo * a mixed merge, mark both as mixed before proceeding. This 76080a761fdSTejun Heo * makes sure that all involved bios have mixable attributes 76180a761fdSTejun Heo * set properly. 76280a761fdSTejun Heo */ 763e8064021SChristoph Hellwig if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || 76480a761fdSTejun Heo (req->cmd_flags & REQ_FAILFAST_MASK) != 76580a761fdSTejun Heo (next->cmd_flags & REQ_FAILFAST_MASK)) { 76680a761fdSTejun Heo blk_rq_set_mixed_merge(req); 76780a761fdSTejun Heo blk_rq_set_mixed_merge(next); 76880a761fdSTejun Heo } 76980a761fdSTejun Heo 77080a761fdSTejun Heo /* 771522a7775SOmar Sandoval * At this point we have either done a back merge or front merge. We 772522a7775SOmar Sandoval * need the smaller start_time_ns of the merged requests to be the 773522a7775SOmar Sandoval * current request for accounting purposes. 774d6d48196SJens Axboe */ 775522a7775SOmar Sandoval if (next->start_time_ns < req->start_time_ns) 776522a7775SOmar Sandoval req->start_time_ns = next->start_time_ns; 777d6d48196SJens Axboe 778d6d48196SJens Axboe req->biotail->bi_next = next->bio; 779d6d48196SJens Axboe req->biotail = next->biotail; 780d6d48196SJens Axboe 781a2dec7b3STejun Heo req->__data_len += blk_rq_bytes(next); 782d6d48196SJens Axboe 7832a5cf35cSMing Lei if (!blk_discard_mergable(req)) 784d6d48196SJens Axboe elv_merge_requests(q, req, next); 785d6d48196SJens Axboe 78642dad764SJerome Marchand /* 78742dad764SJerome Marchand * 'next' is going away, so update stats accordingly 78842dad764SJerome Marchand */ 78942dad764SJerome Marchand blk_account_io_merge(next); 790d6d48196SJens Axboe 791e4d750c9SJens Axboe /* 792e4d750c9SJens Axboe * ownership of bio passed from next to req, return 'next' for 793e4d750c9SJens Axboe * the caller to free 794e4d750c9SJens Axboe */ 7951cd96c24SBoaz Harrosh next->bio = NULL; 796b973cb7eSJens Axboe return next; 797d6d48196SJens Axboe } 798d6d48196SJens Axboe 799b973cb7eSJens Axboe struct request *attempt_back_merge(struct request_queue *q, struct request *rq) 800d6d48196SJens Axboe { 801d6d48196SJens Axboe struct request *next = elv_latter_request(q, rq); 802d6d48196SJens Axboe 803d6d48196SJens Axboe if (next) 804d6d48196SJens Axboe return attempt_merge(q, rq, next); 805d6d48196SJens Axboe 806b973cb7eSJens Axboe return NULL; 807d6d48196SJens Axboe } 808d6d48196SJens Axboe 809b973cb7eSJens Axboe struct request *attempt_front_merge(struct request_queue *q, struct request *rq) 810d6d48196SJens Axboe { 811d6d48196SJens Axboe struct request *prev = elv_former_request(q, rq); 812d6d48196SJens Axboe 813d6d48196SJens Axboe if (prev) 814d6d48196SJens Axboe return attempt_merge(q, prev, rq); 815d6d48196SJens Axboe 816b973cb7eSJens Axboe return NULL; 817d6d48196SJens Axboe } 8185e84ea3aSJens Axboe 8195e84ea3aSJens Axboe int blk_attempt_req_merge(struct request_queue *q, struct request *rq, 8205e84ea3aSJens Axboe struct request *next) 8215e84ea3aSJens Axboe { 822e4d750c9SJens Axboe struct request *free; 82372ef799bSTahsin Erdogan 824e4d750c9SJens Axboe free = attempt_merge(q, rq, next); 825e4d750c9SJens Axboe if (free) { 82692bc5a24SJens Axboe blk_put_request(free); 827e4d750c9SJens Axboe return 1; 828e4d750c9SJens Axboe } 829e4d750c9SJens Axboe 830e4d750c9SJens Axboe return 0; 8315e84ea3aSJens Axboe } 832050c8ea8STejun Heo 833050c8ea8STejun Heo bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 834050c8ea8STejun Heo { 835e2a60da7SMartin K. Petersen if (!rq_mergeable(rq) || !bio_mergeable(bio)) 836050c8ea8STejun Heo return false; 837050c8ea8STejun Heo 838288dab8aSChristoph Hellwig if (req_op(rq) != bio_op(bio)) 839f31dc1cdSMartin K. Petersen return false; 840f31dc1cdSMartin K. Petersen 841050c8ea8STejun Heo /* different data direction or already started, don't merge */ 842050c8ea8STejun Heo if (bio_data_dir(bio) != rq_data_dir(rq)) 843050c8ea8STejun Heo return false; 844050c8ea8STejun Heo 8452081a56bSJens Axboe /* must be same device */ 8462081a56bSJens Axboe if (rq->rq_disk != bio->bi_disk) 847050c8ea8STejun Heo return false; 848050c8ea8STejun Heo 849050c8ea8STejun Heo /* only merge integrity protected bio into ditto rq */ 8504eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(rq->q, rq, bio) == false) 851050c8ea8STejun Heo return false; 852050c8ea8STejun Heo 8534363ac7cSMartin K. Petersen /* must be using the same buffer */ 8548fe0d473SMike Christie if (req_op(rq) == REQ_OP_WRITE_SAME && 8554363ac7cSMartin K. Petersen !blk_write_same_mergeable(rq->bio, bio)) 8564363ac7cSMartin K. Petersen return false; 8574363ac7cSMartin K. Petersen 858cb6934f8SJens Axboe /* 859cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 860cb6934f8SJens Axboe * non-hint IO. 861cb6934f8SJens Axboe */ 862cb6934f8SJens Axboe if (rq->write_hint != bio->bi_write_hint) 863cb6934f8SJens Axboe return false; 864cb6934f8SJens Axboe 865668ffc03SDamien Le Moal if (rq->ioprio != bio_prio(bio)) 866668ffc03SDamien Le Moal return false; 867668ffc03SDamien Le Moal 868050c8ea8STejun Heo return true; 869050c8ea8STejun Heo } 870050c8ea8STejun Heo 87134fe7c05SChristoph Hellwig enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) 872050c8ea8STejun Heo { 87369840466SJianchao Wang if (blk_discard_mergable(rq)) 8741e739730SChristoph Hellwig return ELEVATOR_DISCARD_MERGE; 8751e739730SChristoph Hellwig else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) 876050c8ea8STejun Heo return ELEVATOR_BACK_MERGE; 8774f024f37SKent Overstreet else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) 878050c8ea8STejun Heo return ELEVATOR_FRONT_MERGE; 879050c8ea8STejun Heo return ELEVATOR_NO_MERGE; 880050c8ea8STejun Heo } 881