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, 165dcebd755SMing Lei unsigned *nsegs, unsigned *last_seg_size, 16605b700baSMing Lei unsigned *front_seg_size, unsigned *sectors, unsigned max_segs) 167dcebd755SMing Lei { 168dcebd755SMing Lei unsigned len = bv->bv_len; 169dcebd755SMing Lei unsigned total_len = 0; 170dcebd755SMing Lei unsigned new_nsegs = 0, seg_size = 0; 171dcebd755SMing Lei 172dcebd755SMing Lei /* 173dcebd755SMing Lei * Multi-page bvec may be too big to hold in one segment, so the 174dcebd755SMing Lei * current bvec has to be splitted as multiple segments. 175dcebd755SMing Lei */ 17605b700baSMing Lei while (len && new_nsegs + *nsegs < max_segs) { 177dcebd755SMing Lei seg_size = get_max_segment_size(q, bv->bv_offset + total_len); 178dcebd755SMing Lei seg_size = min(seg_size, len); 179dcebd755SMing Lei 180dcebd755SMing Lei new_nsegs++; 181dcebd755SMing Lei total_len += seg_size; 182dcebd755SMing Lei len -= seg_size; 183dcebd755SMing Lei 184dcebd755SMing Lei if ((bv->bv_offset + total_len) & queue_virt_boundary(q)) 185dcebd755SMing Lei break; 186dcebd755SMing Lei } 187dcebd755SMing Lei 188dcebd755SMing Lei if (!new_nsegs) 189dcebd755SMing Lei return !!len; 190dcebd755SMing Lei 191dcebd755SMing Lei /* update front segment size */ 192dcebd755SMing Lei if (!*nsegs) { 193dcebd755SMing Lei unsigned first_seg_size; 194dcebd755SMing Lei 195dcebd755SMing Lei if (new_nsegs == 1) 196dcebd755SMing Lei first_seg_size = get_max_segment_size(q, bv->bv_offset); 197dcebd755SMing Lei else 198dcebd755SMing Lei first_seg_size = queue_max_segment_size(q); 199dcebd755SMing Lei 200dcebd755SMing Lei if (*front_seg_size < first_seg_size) 201dcebd755SMing Lei *front_seg_size = first_seg_size; 202dcebd755SMing Lei } 203dcebd755SMing Lei 204dcebd755SMing Lei /* update other varibles */ 205dcebd755SMing Lei *last_seg_size = seg_size; 206dcebd755SMing Lei *nsegs += new_nsegs; 207dcebd755SMing Lei if (sectors) 208dcebd755SMing Lei *sectors += total_len >> 9; 209dcebd755SMing Lei 210dcebd755SMing Lei /* split in the middle of the bvec if len != 0 */ 211dcebd755SMing Lei return !!len; 212dcebd755SMing Lei } 213dcebd755SMing Lei 21454efd50bSKent Overstreet static struct bio *blk_bio_segment_split(struct request_queue *q, 21554efd50bSKent Overstreet struct bio *bio, 216bdced438SMing Lei struct bio_set *bs, 217bdced438SMing Lei unsigned *segs) 21854efd50bSKent Overstreet { 2195014c311SJens Axboe struct bio_vec bv, bvprv, *bvprvp = NULL; 22054efd50bSKent Overstreet struct bvec_iter iter; 2218ae12666SKent Overstreet unsigned seg_size = 0, nsegs = 0, sectors = 0; 22202e70742SMing Lei unsigned front_seg_size = bio->bi_seg_front_size; 22302e70742SMing Lei bool do_split = true; 22402e70742SMing Lei struct bio *new = NULL; 225d0e5fbb0SMing Lei const unsigned max_sectors = get_max_io_size(q, bio); 22605b700baSMing Lei const unsigned max_segs = queue_max_segments(q); 22754efd50bSKent Overstreet 228dcebd755SMing Lei bio_for_each_bvec(bv, bio, iter) { 22954efd50bSKent Overstreet /* 23054efd50bSKent Overstreet * If the queue doesn't support SG gaps and adding this 23154efd50bSKent Overstreet * offset would create a gap, disallow it. 23254efd50bSKent Overstreet */ 2335014c311SJens Axboe if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) 23454efd50bSKent Overstreet goto split; 23554efd50bSKent Overstreet 236d0e5fbb0SMing Lei if (sectors + (bv.bv_len >> 9) > max_sectors) { 237e36f6204SKeith Busch /* 238e36f6204SKeith Busch * Consider this a new segment if we're splitting in 239e36f6204SKeith Busch * the middle of this vector. 240e36f6204SKeith Busch */ 24105b700baSMing Lei if (nsegs < max_segs && 242d0e5fbb0SMing Lei sectors < max_sectors) { 243dcebd755SMing Lei /* split in the middle of bvec */ 244dcebd755SMing Lei bv.bv_len = (max_sectors - sectors) << 9; 245dcebd755SMing Lei bvec_split_segs(q, &bv, &nsegs, 246dcebd755SMing Lei &seg_size, 247dcebd755SMing Lei &front_seg_size, 24805b700baSMing Lei §ors, max_segs); 249e36f6204SKeith Busch } 250e36f6204SKeith Busch goto split; 251e36f6204SKeith Busch } 252e36f6204SKeith Busch 25305b700baSMing Lei if (nsegs == max_segs) 25454efd50bSKent Overstreet goto split; 25554efd50bSKent Overstreet 25654efd50bSKent Overstreet bvprv = bv; 257578270bfSMing Lei bvprvp = &bvprv; 258dcebd755SMing Lei 259bbcbbd56SMing Lei if (bv.bv_offset + bv.bv_len <= PAGE_SIZE) { 260bbcbbd56SMing Lei nsegs++; 261bbcbbd56SMing Lei seg_size = bv.bv_len; 262bbcbbd56SMing Lei sectors += bv.bv_len >> 9; 263bbcbbd56SMing Lei if (nsegs == 1 && seg_size > front_seg_size) 264bbcbbd56SMing Lei front_seg_size = seg_size; 265bbcbbd56SMing Lei } else if (bvec_split_segs(q, &bv, &nsegs, &seg_size, 26605b700baSMing Lei &front_seg_size, §ors, max_segs)) { 267dcebd755SMing Lei goto split; 268bbcbbd56SMing Lei } 26954efd50bSKent Overstreet } 27054efd50bSKent Overstreet 27102e70742SMing Lei do_split = false; 27254efd50bSKent Overstreet split: 273bdced438SMing Lei *segs = nsegs; 27402e70742SMing Lei 27502e70742SMing Lei if (do_split) { 27602e70742SMing Lei new = bio_split(bio, sectors, GFP_NOIO, bs); 27702e70742SMing Lei if (new) 27802e70742SMing Lei bio = new; 27902e70742SMing Lei } 28002e70742SMing Lei 28102e70742SMing Lei bio->bi_seg_front_size = front_seg_size; 28202e70742SMing Lei if (seg_size > bio->bi_seg_back_size) 28302e70742SMing Lei bio->bi_seg_back_size = seg_size; 28402e70742SMing Lei 28502e70742SMing Lei return do_split ? new : NULL; 28654efd50bSKent Overstreet } 28754efd50bSKent Overstreet 288af67c31fSNeilBrown void blk_queue_split(struct request_queue *q, struct bio **bio) 28954efd50bSKent Overstreet { 290bdced438SMing Lei struct bio *split, *res; 291bdced438SMing Lei unsigned nsegs; 29254efd50bSKent Overstreet 2937afafc8aSAdrian Hunter switch (bio_op(*bio)) { 2947afafc8aSAdrian Hunter case REQ_OP_DISCARD: 2957afafc8aSAdrian Hunter case REQ_OP_SECURE_ERASE: 296338aa96dSKent Overstreet split = blk_bio_discard_split(q, *bio, &q->bio_split, &nsegs); 2977afafc8aSAdrian Hunter break; 298a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 299338aa96dSKent Overstreet split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split, &nsegs); 300a6f0788eSChaitanya Kulkarni break; 3017afafc8aSAdrian Hunter case REQ_OP_WRITE_SAME: 302338aa96dSKent Overstreet split = blk_bio_write_same_split(q, *bio, &q->bio_split, &nsegs); 3037afafc8aSAdrian Hunter break; 3047afafc8aSAdrian Hunter default: 305338aa96dSKent Overstreet split = blk_bio_segment_split(q, *bio, &q->bio_split, &nsegs); 3067afafc8aSAdrian Hunter break; 3077afafc8aSAdrian Hunter } 308bdced438SMing Lei 309bdced438SMing Lei /* physical segments can be figured out during splitting */ 310bdced438SMing Lei res = split ? split : *bio; 311bdced438SMing Lei res->bi_phys_segments = nsegs; 312bdced438SMing Lei bio_set_flag(res, BIO_SEG_VALID); 31354efd50bSKent Overstreet 31454efd50bSKent Overstreet if (split) { 3156ac45aebSMing Lei /* there isn't chance to merge the splitted bio */ 3161eff9d32SJens Axboe split->bi_opf |= REQ_NOMERGE; 3176ac45aebSMing Lei 318947b7ac1SJens Axboe /* 319947b7ac1SJens Axboe * Since we're recursing into make_request here, ensure 320947b7ac1SJens Axboe * that we mark this bio as already having entered the queue. 321947b7ac1SJens Axboe * If not, and the queue is going away, we can get stuck 322947b7ac1SJens Axboe * forever on waiting for the queue reference to drop. But 323947b7ac1SJens Axboe * that will never happen, as we're already holding a 324947b7ac1SJens Axboe * reference to it. 325947b7ac1SJens Axboe */ 326947b7ac1SJens Axboe bio_set_flag(*bio, BIO_QUEUE_ENTERED); 327947b7ac1SJens Axboe 32854efd50bSKent Overstreet bio_chain(split, *bio); 329cda22646SMike Krinkin trace_block_split(q, split, (*bio)->bi_iter.bi_sector); 33054efd50bSKent Overstreet generic_make_request(*bio); 33154efd50bSKent Overstreet *bio = split; 33254efd50bSKent Overstreet } 33354efd50bSKent Overstreet } 33454efd50bSKent Overstreet EXPORT_SYMBOL(blk_queue_split); 33554efd50bSKent Overstreet 3361e428079SJens Axboe static unsigned int __blk_recalc_rq_segments(struct request_queue *q, 3372705c937SMing Lei struct bio *bio) 338d6d48196SJens Axboe { 339b21e11c5SMing Lei struct bio_vec uninitialized_var(bv), bvprv = { NULL }; 3401e428079SJens Axboe unsigned int seg_size, nr_phys_segs; 34149b1f22bSMing Lei unsigned front_seg_size; 34259247eaeSJens Axboe struct bio *fbio, *bbio; 3437988613bSKent Overstreet struct bvec_iter iter; 344d6d48196SJens Axboe 3451e428079SJens Axboe if (!bio) 3461e428079SJens Axboe return 0; 347d6d48196SJens Axboe 34849b1f22bSMing Lei front_seg_size = bio->bi_seg_front_size; 34949b1f22bSMing Lei 350a6f0788eSChaitanya Kulkarni switch (bio_op(bio)) { 351a6f0788eSChaitanya Kulkarni case REQ_OP_DISCARD: 352a6f0788eSChaitanya Kulkarni case REQ_OP_SECURE_ERASE: 353a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 354f9d03f96SChristoph Hellwig return 0; 355f9d03f96SChristoph Hellwig case REQ_OP_WRITE_SAME: 3565cb8850cSKent Overstreet return 1; 357a6f0788eSChaitanya Kulkarni } 3585cb8850cSKent Overstreet 3591e428079SJens Axboe fbio = bio; 3605df97b91SMikulas Patocka seg_size = 0; 3612c8919deSAndi Kleen nr_phys_segs = 0; 3621e428079SJens Axboe for_each_bio(bio) { 363dcebd755SMing Lei bio_for_each_bvec(bv, bio, iter) { 364dcebd755SMing Lei bvec_split_segs(q, &bv, &nr_phys_segs, &seg_size, 36505b700baSMing Lei &front_seg_size, NULL, UINT_MAX); 366d6d48196SJens Axboe } 36759247eaeSJens Axboe bbio = bio; 368eded341cSChristoph Hellwig if (likely(bio->bi_iter.bi_size)) 369f6970f83SMing Lei bvprv = bv; 370b21e11c5SMing Lei } 371d6d48196SJens Axboe 372dcebd755SMing Lei fbio->bi_seg_front_size = front_seg_size; 37359247eaeSJens Axboe if (seg_size > bbio->bi_seg_back_size) 37459247eaeSJens Axboe bbio->bi_seg_back_size = seg_size; 3751e428079SJens Axboe 3761e428079SJens Axboe return nr_phys_segs; 3771e428079SJens Axboe } 3781e428079SJens Axboe 3791e428079SJens Axboe void blk_recalc_rq_segments(struct request *rq) 3801e428079SJens Axboe { 3812705c937SMing Lei rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio); 382d6d48196SJens Axboe } 383d6d48196SJens Axboe 384d6d48196SJens Axboe void blk_recount_segments(struct request_queue *q, struct bio *bio) 385d6d48196SJens Axboe { 386d6d48196SJens Axboe struct bio *nxt = bio->bi_next; 3871e428079SJens Axboe 388d6d48196SJens Axboe bio->bi_next = NULL; 3892705c937SMing Lei bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio); 390d6d48196SJens Axboe bio->bi_next = nxt; 39105f1dd53SJens Axboe 392b7c44ed9SJens Axboe bio_set_flag(bio, BIO_SEG_VALID); 393d6d48196SJens Axboe } 394d6d48196SJens Axboe 395d6d48196SJens Axboe static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, 396d6d48196SJens Axboe struct bio *nxt) 397d6d48196SJens Axboe { 3982b8221e1SKent Overstreet struct bio_vec end_bv = { NULL }, nxt_bv; 399f619d254SKent Overstreet 40086771427SFUJITA Tomonori if (bio->bi_seg_back_size + nxt->bi_seg_front_size > 401ae03bf63SMartin K. Petersen queue_max_segment_size(q)) 402d6d48196SJens Axboe return 0; 403d6d48196SJens Axboe 404e17fc0a1SDavid Woodhouse if (!bio_has_data(bio)) 405e17fc0a1SDavid Woodhouse return 1; 406e17fc0a1SDavid Woodhouse 407e827091cSMing Lei bio_get_last_bvec(bio, &end_bv); 408e827091cSMing Lei bio_get_first_bvec(nxt, &nxt_bv); 409f619d254SKent Overstreet 4103dccdae5SChristoph Hellwig return biovec_phys_mergeable(q, &end_bv, &nxt_bv); 411d6d48196SJens Axboe } 412d6d48196SJens Axboe 41348d7727cSMing Lei static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, 414862e5a5eSMing Lei struct scatterlist *sglist) 415862e5a5eSMing Lei { 416862e5a5eSMing Lei if (!*sg) 417862e5a5eSMing Lei return sglist; 418862e5a5eSMing Lei 419862e5a5eSMing Lei /* 420862e5a5eSMing Lei * If the driver previously mapped a shorter list, we could see a 421862e5a5eSMing Lei * termination bit prematurely unless it fully inits the sg table 422862e5a5eSMing Lei * on each mapping. We KNOW that there must be more entries here 423862e5a5eSMing Lei * or the driver would be buggy, so force clear the termination bit 424862e5a5eSMing Lei * to avoid doing a full sg_init_table() in drivers for each command. 425862e5a5eSMing Lei */ 426862e5a5eSMing Lei sg_unmark_end(*sg); 427862e5a5eSMing Lei return sg_next(*sg); 428862e5a5eSMing Lei } 429862e5a5eSMing Lei 430862e5a5eSMing Lei static unsigned blk_bvec_map_sg(struct request_queue *q, 431862e5a5eSMing Lei struct bio_vec *bvec, struct scatterlist *sglist, 432862e5a5eSMing Lei struct scatterlist **sg) 433862e5a5eSMing Lei { 434862e5a5eSMing Lei unsigned nbytes = bvec->bv_len; 4358a96a0e4SChristoph Hellwig unsigned nsegs = 0, total = 0; 436862e5a5eSMing Lei 437862e5a5eSMing Lei while (nbytes > 0) { 4388a96a0e4SChristoph Hellwig unsigned offset = bvec->bv_offset + total; 4398a96a0e4SChristoph Hellwig unsigned len = min(get_max_segment_size(q, offset), nbytes); 440f9f76879SChristoph Hellwig struct page *page = bvec->bv_page; 441f9f76879SChristoph Hellwig 442f9f76879SChristoph Hellwig /* 443f9f76879SChristoph Hellwig * Unfortunately a fair number of drivers barf on scatterlists 444f9f76879SChristoph Hellwig * that have an offset larger than PAGE_SIZE, despite other 445f9f76879SChristoph Hellwig * subsystems dealing with that invariant just fine. For now 446f9f76879SChristoph Hellwig * stick to the legacy format where we never present those from 447f9f76879SChristoph Hellwig * the block layer, but the code below should be removed once 448f9f76879SChristoph Hellwig * these offenders (mostly MMC/SD drivers) are fixed. 449f9f76879SChristoph Hellwig */ 450f9f76879SChristoph Hellwig page += (offset >> PAGE_SHIFT); 451f9f76879SChristoph Hellwig offset &= ~PAGE_MASK; 452862e5a5eSMing Lei 453862e5a5eSMing Lei *sg = blk_next_sg(sg, sglist); 454f9f76879SChristoph Hellwig sg_set_page(*sg, page, len, offset); 455862e5a5eSMing Lei 4568a96a0e4SChristoph Hellwig total += len; 4578a96a0e4SChristoph Hellwig nbytes -= len; 458862e5a5eSMing Lei nsegs++; 459862e5a5eSMing Lei } 460862e5a5eSMing Lei 461862e5a5eSMing Lei return nsegs; 462862e5a5eSMing Lei } 463862e5a5eSMing Lei 46416e3e418SMing Lei static inline int __blk_bvec_map_sg(struct bio_vec bv, 46516e3e418SMing Lei struct scatterlist *sglist, struct scatterlist **sg) 46616e3e418SMing Lei { 46716e3e418SMing Lei *sg = blk_next_sg(sg, sglist); 46816e3e418SMing Lei sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); 46916e3e418SMing Lei return 1; 47016e3e418SMing Lei } 47116e3e418SMing Lei 472f6970f83SMing Lei /* only try to merge bvecs into one sg if they are from two bios */ 473f6970f83SMing Lei static inline bool 474f6970f83SMing Lei __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec, 475f6970f83SMing Lei struct bio_vec *bvprv, struct scatterlist **sg) 476963ab9e5SAsias He { 477963ab9e5SAsias He 478963ab9e5SAsias He int nbytes = bvec->bv_len; 479963ab9e5SAsias He 480f6970f83SMing Lei if (!*sg) 481f6970f83SMing Lei return false; 482f6970f83SMing Lei 483b4b6cb61SMing Lei if ((*sg)->length + nbytes > queue_max_segment_size(q)) 484f6970f83SMing Lei return false; 485f6970f83SMing Lei 4863dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, bvprv, bvec)) 487f6970f83SMing Lei return false; 488963ab9e5SAsias He 489963ab9e5SAsias He (*sg)->length += nbytes; 490f6970f83SMing Lei 491f6970f83SMing Lei return true; 492963ab9e5SAsias He } 493963ab9e5SAsias He 4945cb8850cSKent Overstreet static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, 4955cb8850cSKent Overstreet struct scatterlist *sglist, 4965cb8850cSKent Overstreet struct scatterlist **sg) 4975cb8850cSKent Overstreet { 498b21e11c5SMing Lei struct bio_vec uninitialized_var(bvec), bvprv = { NULL }; 4995cb8850cSKent Overstreet struct bvec_iter iter; 50038417468SChristoph Hellwig int nsegs = 0; 501f6970f83SMing Lei bool new_bio = false; 5025cb8850cSKent Overstreet 503f6970f83SMing Lei for_each_bio(bio) { 504f6970f83SMing Lei bio_for_each_bvec(bvec, bio, iter) { 505f6970f83SMing Lei /* 506f6970f83SMing Lei * Only try to merge bvecs from two bios given we 507f6970f83SMing Lei * have done bio internal merge when adding pages 508f6970f83SMing Lei * to bio 509f6970f83SMing Lei */ 510f6970f83SMing Lei if (new_bio && 511f6970f83SMing Lei __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg)) 512f6970f83SMing Lei goto next_bvec; 513f6970f83SMing Lei 514f6970f83SMing Lei if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE) 515f6970f83SMing Lei nsegs += __blk_bvec_map_sg(bvec, sglist, sg); 516f6970f83SMing Lei else 517f6970f83SMing Lei nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg); 518f6970f83SMing Lei next_bvec: 519f6970f83SMing Lei new_bio = false; 520f6970f83SMing Lei } 521b21e11c5SMing Lei if (likely(bio->bi_iter.bi_size)) { 522f6970f83SMing Lei bvprv = bvec; 523f6970f83SMing Lei new_bio = true; 524f6970f83SMing Lei } 525b21e11c5SMing Lei } 5265cb8850cSKent Overstreet 5275cb8850cSKent Overstreet return nsegs; 5285cb8850cSKent Overstreet } 5295cb8850cSKent Overstreet 530d6d48196SJens Axboe /* 531d6d48196SJens Axboe * map a request to scatterlist, return number of sg entries setup. Caller 532d6d48196SJens Axboe * must make sure sg can hold rq->nr_phys_segments entries 533d6d48196SJens Axboe */ 534d6d48196SJens Axboe int blk_rq_map_sg(struct request_queue *q, struct request *rq, 535d6d48196SJens Axboe struct scatterlist *sglist) 536d6d48196SJens Axboe { 5375cb8850cSKent Overstreet struct scatterlist *sg = NULL; 5385cb8850cSKent Overstreet int nsegs = 0; 539d6d48196SJens Axboe 540f9d03f96SChristoph Hellwig if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) 541cae6c2e5SMing Lei nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, &sg); 542f9d03f96SChristoph Hellwig else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME) 543cae6c2e5SMing Lei nsegs = __blk_bvec_map_sg(bio_iovec(rq->bio), sglist, &sg); 544f9d03f96SChristoph Hellwig else if (rq->bio) 5455cb8850cSKent Overstreet nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); 546f18573abSFUJITA Tomonori 547e8064021SChristoph Hellwig if (unlikely(rq->rq_flags & RQF_COPY_USER) && 5482e46e8b2STejun Heo (blk_rq_bytes(rq) & q->dma_pad_mask)) { 5492e46e8b2STejun Heo unsigned int pad_len = 5502e46e8b2STejun Heo (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; 551f18573abSFUJITA Tomonori 552f18573abSFUJITA Tomonori sg->length += pad_len; 553f18573abSFUJITA Tomonori rq->extra_len += pad_len; 554f18573abSFUJITA Tomonori } 555f18573abSFUJITA Tomonori 5562fb98e84STejun Heo if (q->dma_drain_size && q->dma_drain_needed(rq)) { 557a8ebb056SMike Christie if (op_is_write(req_op(rq))) 558db0a2e00STejun Heo memset(q->dma_drain_buffer, 0, q->dma_drain_size); 559db0a2e00STejun Heo 560da81ed16SDan Williams sg_unmark_end(sg); 561d6d48196SJens Axboe sg = sg_next(sg); 562d6d48196SJens Axboe sg_set_page(sg, virt_to_page(q->dma_drain_buffer), 563d6d48196SJens Axboe q->dma_drain_size, 564d6d48196SJens Axboe ((unsigned long)q->dma_drain_buffer) & 565d6d48196SJens Axboe (PAGE_SIZE - 1)); 566d6d48196SJens Axboe nsegs++; 5677a85f889SFUJITA Tomonori rq->extra_len += q->dma_drain_size; 568d6d48196SJens Axboe } 569d6d48196SJens Axboe 570d6d48196SJens Axboe if (sg) 571d6d48196SJens Axboe sg_mark_end(sg); 572d6d48196SJens Axboe 57312e57f59SMing Lei /* 57412e57f59SMing Lei * Something must have been wrong if the figured number of 57512e57f59SMing Lei * segment is bigger than number of req's physical segments 57612e57f59SMing Lei */ 577f9d03f96SChristoph Hellwig WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); 57812e57f59SMing Lei 579d6d48196SJens Axboe return nsegs; 580d6d48196SJens Axboe } 581d6d48196SJens Axboe EXPORT_SYMBOL(blk_rq_map_sg); 582d6d48196SJens Axboe 583d6d48196SJens Axboe static inline int ll_new_hw_segment(struct request_queue *q, 584d6d48196SJens Axboe struct request *req, 585d6d48196SJens Axboe struct bio *bio) 586d6d48196SJens Axboe { 587d6d48196SJens Axboe int nr_phys_segs = bio_phys_segments(q, bio); 588d6d48196SJens Axboe 58913f05c8dSMartin K. Petersen if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) 59013f05c8dSMartin K. Petersen goto no_merge; 59113f05c8dSMartin K. Petersen 5924eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(q, req, bio) == false) 59313f05c8dSMartin K. Petersen goto no_merge; 594d6d48196SJens Axboe 595d6d48196SJens Axboe /* 596d6d48196SJens Axboe * This will form the start of a new hw segment. Bump both 597d6d48196SJens Axboe * counters. 598d6d48196SJens Axboe */ 599d6d48196SJens Axboe req->nr_phys_segments += nr_phys_segs; 600d6d48196SJens Axboe return 1; 60113f05c8dSMartin K. Petersen 60213f05c8dSMartin K. Petersen no_merge: 603e0c72300SRitesh Harjani req_set_nomerge(q, req); 60413f05c8dSMartin K. Petersen return 0; 605d6d48196SJens Axboe } 606d6d48196SJens Axboe 607d6d48196SJens Axboe int ll_back_merge_fn(struct request_queue *q, struct request *req, 608d6d48196SJens Axboe struct bio *bio) 609d6d48196SJens Axboe { 6105e7c4274SJens Axboe if (req_gap_back_merge(req, bio)) 6115e7c4274SJens Axboe return 0; 6127f39add3SSagi Grimberg if (blk_integrity_rq(req) && 6137f39add3SSagi Grimberg integrity_req_gap_back_merge(req, bio)) 6147f39add3SSagi Grimberg return 0; 615f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 61617007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) { 617e0c72300SRitesh Harjani req_set_nomerge(q, req); 618d6d48196SJens Axboe return 0; 619d6d48196SJens Axboe } 6202cdf79caSJens Axboe if (!bio_flagged(req->biotail, BIO_SEG_VALID)) 621d6d48196SJens Axboe blk_recount_segments(q, req->biotail); 6222cdf79caSJens Axboe if (!bio_flagged(bio, BIO_SEG_VALID)) 623d6d48196SJens Axboe blk_recount_segments(q, bio); 624d6d48196SJens Axboe 625d6d48196SJens Axboe return ll_new_hw_segment(q, req, bio); 626d6d48196SJens Axboe } 627d6d48196SJens Axboe 628d6d48196SJens Axboe int ll_front_merge_fn(struct request_queue *q, struct request *req, 629d6d48196SJens Axboe struct bio *bio) 630d6d48196SJens Axboe { 6315e7c4274SJens Axboe 6325e7c4274SJens Axboe if (req_gap_front_merge(req, bio)) 6335e7c4274SJens Axboe return 0; 6347f39add3SSagi Grimberg if (blk_integrity_rq(req) && 6357f39add3SSagi Grimberg integrity_req_gap_front_merge(req, bio)) 6367f39add3SSagi Grimberg return 0; 637f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 63817007f39SDamien Le Moal blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { 639e0c72300SRitesh Harjani req_set_nomerge(q, req); 640d6d48196SJens Axboe return 0; 641d6d48196SJens Axboe } 6422cdf79caSJens Axboe if (!bio_flagged(bio, BIO_SEG_VALID)) 643d6d48196SJens Axboe blk_recount_segments(q, bio); 6442cdf79caSJens Axboe if (!bio_flagged(req->bio, BIO_SEG_VALID)) 645d6d48196SJens Axboe blk_recount_segments(q, req->bio); 646d6d48196SJens Axboe 647d6d48196SJens Axboe return ll_new_hw_segment(q, req, bio); 648d6d48196SJens Axboe } 649d6d48196SJens Axboe 650445251d0SJens Axboe static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, 651445251d0SJens Axboe struct request *next) 652445251d0SJens Axboe { 653445251d0SJens Axboe unsigned short segments = blk_rq_nr_discard_segments(req); 654445251d0SJens Axboe 655445251d0SJens Axboe if (segments >= queue_max_discard_segments(q)) 656445251d0SJens Axboe goto no_merge; 657445251d0SJens Axboe if (blk_rq_sectors(req) + bio_sectors(next->bio) > 658445251d0SJens Axboe blk_rq_get_max_sectors(req, blk_rq_pos(req))) 659445251d0SJens Axboe goto no_merge; 660445251d0SJens Axboe 661445251d0SJens Axboe req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); 662445251d0SJens Axboe return true; 663445251d0SJens Axboe no_merge: 664445251d0SJens Axboe req_set_nomerge(q, req); 665445251d0SJens Axboe return false; 666445251d0SJens Axboe } 667445251d0SJens Axboe 668d6d48196SJens Axboe static int ll_merge_requests_fn(struct request_queue *q, struct request *req, 669d6d48196SJens Axboe struct request *next) 670d6d48196SJens Axboe { 671d6d48196SJens Axboe int total_phys_segments; 67286771427SFUJITA Tomonori unsigned int seg_size = 67386771427SFUJITA Tomonori req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; 674d6d48196SJens Axboe 6755e7c4274SJens Axboe if (req_gap_back_merge(req, next->bio)) 676854fbb9cSKeith Busch return 0; 677854fbb9cSKeith Busch 678d6d48196SJens Axboe /* 679d6d48196SJens Axboe * Will it become too large? 680d6d48196SJens Axboe */ 681f31dc1cdSMartin K. Petersen if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > 68217007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) 683d6d48196SJens Axboe return 0; 684d6d48196SJens Axboe 685d6d48196SJens Axboe total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; 68686771427SFUJITA Tomonori if (blk_phys_contig_segment(q, req->biotail, next->bio)) { 68786771427SFUJITA Tomonori if (req->nr_phys_segments == 1) 68886771427SFUJITA Tomonori req->bio->bi_seg_front_size = seg_size; 68986771427SFUJITA Tomonori if (next->nr_phys_segments == 1) 69086771427SFUJITA Tomonori next->biotail->bi_seg_back_size = seg_size; 69186771427SFUJITA Tomonori } 692d6d48196SJens Axboe 6938a78362cSMartin K. Petersen if (total_phys_segments > queue_max_segments(q)) 694d6d48196SJens Axboe return 0; 695d6d48196SJens Axboe 6964eaf99beSMartin K. Petersen if (blk_integrity_merge_rq(q, req, next) == false) 69713f05c8dSMartin K. Petersen return 0; 69813f05c8dSMartin K. Petersen 699d6d48196SJens Axboe /* Merge is OK... */ 700d6d48196SJens Axboe req->nr_phys_segments = total_phys_segments; 701d6d48196SJens Axboe return 1; 702d6d48196SJens Axboe } 703d6d48196SJens Axboe 70480a761fdSTejun Heo /** 70580a761fdSTejun Heo * blk_rq_set_mixed_merge - mark a request as mixed merge 70680a761fdSTejun Heo * @rq: request to mark as mixed merge 70780a761fdSTejun Heo * 70880a761fdSTejun Heo * Description: 70980a761fdSTejun Heo * @rq is about to be mixed merged. Make sure the attributes 71080a761fdSTejun Heo * which can be mixed are set in each bio and mark @rq as mixed 71180a761fdSTejun Heo * merged. 71280a761fdSTejun Heo */ 71380a761fdSTejun Heo void blk_rq_set_mixed_merge(struct request *rq) 71480a761fdSTejun Heo { 71580a761fdSTejun Heo unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 71680a761fdSTejun Heo struct bio *bio; 71780a761fdSTejun Heo 718e8064021SChristoph Hellwig if (rq->rq_flags & RQF_MIXED_MERGE) 71980a761fdSTejun Heo return; 72080a761fdSTejun Heo 72180a761fdSTejun Heo /* 72280a761fdSTejun Heo * @rq will no longer represent mixable attributes for all the 72380a761fdSTejun Heo * contained bios. It will just track those of the first one. 72480a761fdSTejun Heo * Distributes the attributs to each bio. 72580a761fdSTejun Heo */ 72680a761fdSTejun Heo for (bio = rq->bio; bio; bio = bio->bi_next) { 7271eff9d32SJens Axboe WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && 7281eff9d32SJens Axboe (bio->bi_opf & REQ_FAILFAST_MASK) != ff); 7291eff9d32SJens Axboe bio->bi_opf |= ff; 73080a761fdSTejun Heo } 731e8064021SChristoph Hellwig rq->rq_flags |= RQF_MIXED_MERGE; 73280a761fdSTejun Heo } 73380a761fdSTejun Heo 73426308eabSJerome Marchand static void blk_account_io_merge(struct request *req) 73526308eabSJerome Marchand { 73626308eabSJerome Marchand if (blk_do_io_stat(req)) { 73726308eabSJerome Marchand struct hd_struct *part; 73826308eabSJerome Marchand 739112f158fSMike Snitzer part_stat_lock(); 74009e099d4SJerome Marchand part = req->part; 74126308eabSJerome Marchand 742d62e26b3SJens Axboe part_dec_in_flight(req->q, part, rq_data_dir(req)); 74326308eabSJerome Marchand 7446c23a968SJens Axboe hd_struct_put(part); 74526308eabSJerome Marchand part_stat_unlock(); 74626308eabSJerome Marchand } 74726308eabSJerome Marchand } 74869840466SJianchao Wang /* 74969840466SJianchao Wang * Two cases of handling DISCARD merge: 75069840466SJianchao Wang * If max_discard_segments > 1, the driver takes every bio 75169840466SJianchao Wang * as a range and send them to controller together. The ranges 75269840466SJianchao Wang * needn't to be contiguous. 75369840466SJianchao Wang * Otherwise, the bios/requests will be handled as same as 75469840466SJianchao Wang * others which should be contiguous. 75569840466SJianchao Wang */ 75669840466SJianchao Wang static inline bool blk_discard_mergable(struct request *req) 75769840466SJianchao Wang { 75869840466SJianchao Wang if (req_op(req) == REQ_OP_DISCARD && 75969840466SJianchao Wang queue_max_discard_segments(req->q) > 1) 76069840466SJianchao Wang return true; 76169840466SJianchao Wang return false; 76269840466SJianchao Wang } 76369840466SJianchao Wang 764e96c0d83SEric Biggers static enum elv_merge blk_try_req_merge(struct request *req, 765e96c0d83SEric Biggers struct request *next) 76669840466SJianchao Wang { 76769840466SJianchao Wang if (blk_discard_mergable(req)) 76869840466SJianchao Wang return ELEVATOR_DISCARD_MERGE; 76969840466SJianchao Wang else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) 77069840466SJianchao Wang return ELEVATOR_BACK_MERGE; 77169840466SJianchao Wang 77269840466SJianchao Wang return ELEVATOR_NO_MERGE; 77369840466SJianchao Wang } 77426308eabSJerome Marchand 775d6d48196SJens Axboe /* 776b973cb7eSJens Axboe * For non-mq, this has to be called with the request spinlock acquired. 777b973cb7eSJens Axboe * For mq with scheduling, the appropriate queue wide lock should be held. 778d6d48196SJens Axboe */ 779b973cb7eSJens Axboe static struct request *attempt_merge(struct request_queue *q, 780b973cb7eSJens Axboe struct request *req, struct request *next) 781d6d48196SJens Axboe { 782d6d48196SJens Axboe if (!rq_mergeable(req) || !rq_mergeable(next)) 783b973cb7eSJens Axboe return NULL; 784d6d48196SJens Axboe 785288dab8aSChristoph Hellwig if (req_op(req) != req_op(next)) 786b973cb7eSJens Axboe return NULL; 787f31dc1cdSMartin K. Petersen 788d6d48196SJens Axboe if (rq_data_dir(req) != rq_data_dir(next) 7892081a56bSJens Axboe || req->rq_disk != next->rq_disk) 790b973cb7eSJens Axboe return NULL; 791d6d48196SJens Axboe 7928fe0d473SMike Christie if (req_op(req) == REQ_OP_WRITE_SAME && 7934363ac7cSMartin K. Petersen !blk_write_same_mergeable(req->bio, next->bio)) 794b973cb7eSJens Axboe return NULL; 7954363ac7cSMartin K. Petersen 796d6d48196SJens Axboe /* 797cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 798cb6934f8SJens Axboe * non-hint IO. 799cb6934f8SJens Axboe */ 800cb6934f8SJens Axboe if (req->write_hint != next->write_hint) 801cb6934f8SJens Axboe return NULL; 802cb6934f8SJens Axboe 803668ffc03SDamien Le Moal if (req->ioprio != next->ioprio) 804668ffc03SDamien Le Moal return NULL; 805668ffc03SDamien Le Moal 806cb6934f8SJens Axboe /* 807d6d48196SJens Axboe * If we are allowed to merge, then append bio list 808d6d48196SJens Axboe * from next to rq and release next. merge_requests_fn 809d6d48196SJens Axboe * will have updated segment counts, update sector 810445251d0SJens Axboe * counts here. Handle DISCARDs separately, as they 811445251d0SJens Axboe * have separate settings. 812d6d48196SJens Axboe */ 81369840466SJianchao Wang 81469840466SJianchao Wang switch (blk_try_req_merge(req, next)) { 81569840466SJianchao Wang case ELEVATOR_DISCARD_MERGE: 816445251d0SJens Axboe if (!req_attempt_discard_merge(q, req, next)) 817445251d0SJens Axboe return NULL; 81869840466SJianchao Wang break; 81969840466SJianchao Wang case ELEVATOR_BACK_MERGE: 82069840466SJianchao Wang if (!ll_merge_requests_fn(q, req, next)) 821b973cb7eSJens Axboe return NULL; 82269840466SJianchao Wang break; 82369840466SJianchao Wang default: 82469840466SJianchao Wang return NULL; 82569840466SJianchao Wang } 826d6d48196SJens Axboe 827d6d48196SJens Axboe /* 82880a761fdSTejun Heo * If failfast settings disagree or any of the two is already 82980a761fdSTejun Heo * a mixed merge, mark both as mixed before proceeding. This 83080a761fdSTejun Heo * makes sure that all involved bios have mixable attributes 83180a761fdSTejun Heo * set properly. 83280a761fdSTejun Heo */ 833e8064021SChristoph Hellwig if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || 83480a761fdSTejun Heo (req->cmd_flags & REQ_FAILFAST_MASK) != 83580a761fdSTejun Heo (next->cmd_flags & REQ_FAILFAST_MASK)) { 83680a761fdSTejun Heo blk_rq_set_mixed_merge(req); 83780a761fdSTejun Heo blk_rq_set_mixed_merge(next); 83880a761fdSTejun Heo } 83980a761fdSTejun Heo 84080a761fdSTejun Heo /* 841522a7775SOmar Sandoval * At this point we have either done a back merge or front merge. We 842522a7775SOmar Sandoval * need the smaller start_time_ns of the merged requests to be the 843522a7775SOmar Sandoval * current request for accounting purposes. 844d6d48196SJens Axboe */ 845522a7775SOmar Sandoval if (next->start_time_ns < req->start_time_ns) 846522a7775SOmar Sandoval req->start_time_ns = next->start_time_ns; 847d6d48196SJens Axboe 848d6d48196SJens Axboe req->biotail->bi_next = next->bio; 849d6d48196SJens Axboe req->biotail = next->biotail; 850d6d48196SJens Axboe 851a2dec7b3STejun Heo req->__data_len += blk_rq_bytes(next); 852d6d48196SJens Axboe 8532a5cf35cSMing Lei if (!blk_discard_mergable(req)) 854d6d48196SJens Axboe elv_merge_requests(q, req, next); 855d6d48196SJens Axboe 85642dad764SJerome Marchand /* 85742dad764SJerome Marchand * 'next' is going away, so update stats accordingly 85842dad764SJerome Marchand */ 85942dad764SJerome Marchand blk_account_io_merge(next); 860d6d48196SJens Axboe 861e4d750c9SJens Axboe /* 862e4d750c9SJens Axboe * ownership of bio passed from next to req, return 'next' for 863e4d750c9SJens Axboe * the caller to free 864e4d750c9SJens Axboe */ 8651cd96c24SBoaz Harrosh next->bio = NULL; 866b973cb7eSJens Axboe return next; 867d6d48196SJens Axboe } 868d6d48196SJens Axboe 869b973cb7eSJens Axboe struct request *attempt_back_merge(struct request_queue *q, struct request *rq) 870d6d48196SJens Axboe { 871d6d48196SJens Axboe struct request *next = elv_latter_request(q, rq); 872d6d48196SJens Axboe 873d6d48196SJens Axboe if (next) 874d6d48196SJens Axboe return attempt_merge(q, rq, next); 875d6d48196SJens Axboe 876b973cb7eSJens Axboe return NULL; 877d6d48196SJens Axboe } 878d6d48196SJens Axboe 879b973cb7eSJens Axboe struct request *attempt_front_merge(struct request_queue *q, struct request *rq) 880d6d48196SJens Axboe { 881d6d48196SJens Axboe struct request *prev = elv_former_request(q, rq); 882d6d48196SJens Axboe 883d6d48196SJens Axboe if (prev) 884d6d48196SJens Axboe return attempt_merge(q, prev, rq); 885d6d48196SJens Axboe 886b973cb7eSJens Axboe return NULL; 887d6d48196SJens Axboe } 8885e84ea3aSJens Axboe 8895e84ea3aSJens Axboe int blk_attempt_req_merge(struct request_queue *q, struct request *rq, 8905e84ea3aSJens Axboe struct request *next) 8915e84ea3aSJens Axboe { 892e4d750c9SJens Axboe struct request *free; 89372ef799bSTahsin Erdogan 894e4d750c9SJens Axboe free = attempt_merge(q, rq, next); 895e4d750c9SJens Axboe if (free) { 89692bc5a24SJens Axboe blk_put_request(free); 897e4d750c9SJens Axboe return 1; 898e4d750c9SJens Axboe } 899e4d750c9SJens Axboe 900e4d750c9SJens Axboe return 0; 9015e84ea3aSJens Axboe } 902050c8ea8STejun Heo 903050c8ea8STejun Heo bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 904050c8ea8STejun Heo { 905e2a60da7SMartin K. Petersen if (!rq_mergeable(rq) || !bio_mergeable(bio)) 906050c8ea8STejun Heo return false; 907050c8ea8STejun Heo 908288dab8aSChristoph Hellwig if (req_op(rq) != bio_op(bio)) 909f31dc1cdSMartin K. Petersen return false; 910f31dc1cdSMartin K. Petersen 911050c8ea8STejun Heo /* different data direction or already started, don't merge */ 912050c8ea8STejun Heo if (bio_data_dir(bio) != rq_data_dir(rq)) 913050c8ea8STejun Heo return false; 914050c8ea8STejun Heo 9152081a56bSJens Axboe /* must be same device */ 9162081a56bSJens Axboe if (rq->rq_disk != bio->bi_disk) 917050c8ea8STejun Heo return false; 918050c8ea8STejun Heo 919050c8ea8STejun Heo /* only merge integrity protected bio into ditto rq */ 9204eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(rq->q, rq, bio) == false) 921050c8ea8STejun Heo return false; 922050c8ea8STejun Heo 9234363ac7cSMartin K. Petersen /* must be using the same buffer */ 9248fe0d473SMike Christie if (req_op(rq) == REQ_OP_WRITE_SAME && 9254363ac7cSMartin K. Petersen !blk_write_same_mergeable(rq->bio, bio)) 9264363ac7cSMartin K. Petersen return false; 9274363ac7cSMartin K. Petersen 928cb6934f8SJens Axboe /* 929cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 930cb6934f8SJens Axboe * non-hint IO. 931cb6934f8SJens Axboe */ 932cb6934f8SJens Axboe if (rq->write_hint != bio->bi_write_hint) 933cb6934f8SJens Axboe return false; 934cb6934f8SJens Axboe 935668ffc03SDamien Le Moal if (rq->ioprio != bio_prio(bio)) 936668ffc03SDamien Le Moal return false; 937668ffc03SDamien Le Moal 938050c8ea8STejun Heo return true; 939050c8ea8STejun Heo } 940050c8ea8STejun Heo 94134fe7c05SChristoph Hellwig enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) 942050c8ea8STejun Heo { 94369840466SJianchao Wang if (blk_discard_mergable(rq)) 9441e739730SChristoph Hellwig return ELEVATOR_DISCARD_MERGE; 9451e739730SChristoph Hellwig else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) 946050c8ea8STejun Heo return ELEVATOR_BACK_MERGE; 9474f024f37SKent Overstreet else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) 948050c8ea8STejun Heo return ELEVATOR_FRONT_MERGE; 949050c8ea8STejun Heo return ELEVATOR_NO_MERGE; 950050c8ea8STejun Heo } 951