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> 9fe45e630SChristoph Hellwig #include <linux/blk-integrity.h> 10d6d48196SJens Axboe #include <linux/scatterlist.h> 1182d981d4SChristoph Hellwig #include <linux/part_stat.h> 126b2b0459STejun Heo #include <linux/blk-cgroup.h> 13d6d48196SJens Axboe 14cda22646SMike Krinkin #include <trace/events/block.h> 15cda22646SMike Krinkin 16d6d48196SJens Axboe #include "blk.h" 172aa7745bSChristoph Hellwig #include "blk-mq-sched.h" 188e756373SBaolin Wang #include "blk-rq-qos.h" 19a7b36ee6SJens Axboe #include "blk-throttle.h" 20d6d48196SJens Axboe 21ff18d77bSChristoph Hellwig static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv) 22ff18d77bSChristoph Hellwig { 23ff18d77bSChristoph Hellwig *bv = mp_bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); 24ff18d77bSChristoph Hellwig } 25ff18d77bSChristoph Hellwig 26ff18d77bSChristoph Hellwig static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv) 27ff18d77bSChristoph Hellwig { 28ff18d77bSChristoph Hellwig struct bvec_iter iter = bio->bi_iter; 29ff18d77bSChristoph Hellwig int idx; 30ff18d77bSChristoph Hellwig 31ff18d77bSChristoph Hellwig bio_get_first_bvec(bio, bv); 32ff18d77bSChristoph Hellwig if (bv->bv_len == bio->bi_iter.bi_size) 33ff18d77bSChristoph Hellwig return; /* this bio only has a single bvec */ 34ff18d77bSChristoph Hellwig 35ff18d77bSChristoph Hellwig bio_advance_iter(bio, &iter, iter.bi_size); 36ff18d77bSChristoph Hellwig 37ff18d77bSChristoph Hellwig if (!iter.bi_bvec_done) 38ff18d77bSChristoph Hellwig idx = iter.bi_idx - 1; 39ff18d77bSChristoph Hellwig else /* in the middle of bvec */ 40ff18d77bSChristoph Hellwig idx = iter.bi_idx; 41ff18d77bSChristoph Hellwig 42ff18d77bSChristoph Hellwig *bv = bio->bi_io_vec[idx]; 43ff18d77bSChristoph Hellwig 44ff18d77bSChristoph Hellwig /* 45ff18d77bSChristoph Hellwig * iter.bi_bvec_done records actual length of the last bvec 46ff18d77bSChristoph Hellwig * if this bio ends in the middle of one io vector 47ff18d77bSChristoph Hellwig */ 48ff18d77bSChristoph Hellwig if (iter.bi_bvec_done) 49ff18d77bSChristoph Hellwig bv->bv_len = iter.bi_bvec_done; 50ff18d77bSChristoph Hellwig } 51ff18d77bSChristoph Hellwig 52e9907009SChristoph Hellwig static inline bool bio_will_gap(struct request_queue *q, 53e9907009SChristoph Hellwig struct request *prev_rq, struct bio *prev, struct bio *next) 54e9907009SChristoph Hellwig { 55e9907009SChristoph Hellwig struct bio_vec pb, nb; 56e9907009SChristoph Hellwig 57e9907009SChristoph Hellwig if (!bio_has_data(prev) || !queue_virt_boundary(q)) 58e9907009SChristoph Hellwig return false; 59e9907009SChristoph Hellwig 60e9907009SChristoph Hellwig /* 61e9907009SChristoph Hellwig * Don't merge if the 1st bio starts with non-zero offset, otherwise it 62e9907009SChristoph Hellwig * is quite difficult to respect the sg gap limit. We work hard to 63e9907009SChristoph Hellwig * merge a huge number of small single bios in case of mkfs. 64e9907009SChristoph Hellwig */ 65e9907009SChristoph Hellwig if (prev_rq) 66e9907009SChristoph Hellwig bio_get_first_bvec(prev_rq->bio, &pb); 67e9907009SChristoph Hellwig else 68e9907009SChristoph Hellwig bio_get_first_bvec(prev, &pb); 69df376b2eSJohannes Thumshirn if (pb.bv_offset & queue_virt_boundary(q)) 70e9907009SChristoph Hellwig return true; 71e9907009SChristoph Hellwig 72e9907009SChristoph Hellwig /* 73e9907009SChristoph Hellwig * We don't need to worry about the situation that the merged segment 74e9907009SChristoph Hellwig * ends in unaligned virt boundary: 75e9907009SChristoph Hellwig * 76e9907009SChristoph Hellwig * - if 'pb' ends aligned, the merged segment ends aligned 77e9907009SChristoph Hellwig * - if 'pb' ends unaligned, the next bio must include 78e9907009SChristoph Hellwig * one single bvec of 'nb', otherwise the 'nb' can't 79e9907009SChristoph Hellwig * merge with 'pb' 80e9907009SChristoph Hellwig */ 81e9907009SChristoph Hellwig bio_get_last_bvec(prev, &pb); 82e9907009SChristoph Hellwig bio_get_first_bvec(next, &nb); 83200a9affSChristoph Hellwig if (biovec_phys_mergeable(q, &pb, &nb)) 84e9907009SChristoph Hellwig return false; 85e9907009SChristoph Hellwig return __bvec_gap_to_prev(q, &pb, nb.bv_offset); 86e9907009SChristoph Hellwig } 87e9907009SChristoph Hellwig 88e9907009SChristoph Hellwig static inline bool req_gap_back_merge(struct request *req, struct bio *bio) 89e9907009SChristoph Hellwig { 90e9907009SChristoph Hellwig return bio_will_gap(req->q, req, req->biotail, bio); 91e9907009SChristoph Hellwig } 92e9907009SChristoph Hellwig 93e9907009SChristoph Hellwig static inline bool req_gap_front_merge(struct request *req, struct bio *bio) 94e9907009SChristoph Hellwig { 95e9907009SChristoph Hellwig return bio_will_gap(req->q, NULL, bio, req->bio); 96e9907009SChristoph Hellwig } 97e9907009SChristoph Hellwig 9854efd50bSKent Overstreet static struct bio *blk_bio_discard_split(struct request_queue *q, 9954efd50bSKent Overstreet struct bio *bio, 100bdced438SMing Lei struct bio_set *bs, 101bdced438SMing Lei unsigned *nsegs) 10254efd50bSKent Overstreet { 10354efd50bSKent Overstreet unsigned int max_discard_sectors, granularity; 10454efd50bSKent Overstreet int alignment; 10554efd50bSKent Overstreet sector_t tmp; 10654efd50bSKent Overstreet unsigned split_sectors; 10754efd50bSKent Overstreet 108bdced438SMing Lei *nsegs = 1; 109bdced438SMing Lei 11054efd50bSKent Overstreet /* Zero-sector (unknown) and one-sector granularities are the same. */ 11154efd50bSKent Overstreet granularity = max(q->limits.discard_granularity >> 9, 1U); 11254efd50bSKent Overstreet 1131adfc5e4SMing Lei max_discard_sectors = min(q->limits.max_discard_sectors, 1141adfc5e4SMing Lei bio_allowed_max_sectors(q)); 11554efd50bSKent Overstreet max_discard_sectors -= max_discard_sectors % granularity; 11654efd50bSKent Overstreet 11754efd50bSKent Overstreet if (unlikely(!max_discard_sectors)) { 11854efd50bSKent Overstreet /* XXX: warn */ 11954efd50bSKent Overstreet return NULL; 12054efd50bSKent Overstreet } 12154efd50bSKent Overstreet 12254efd50bSKent Overstreet if (bio_sectors(bio) <= max_discard_sectors) 12354efd50bSKent Overstreet return NULL; 12454efd50bSKent Overstreet 12554efd50bSKent Overstreet split_sectors = max_discard_sectors; 12654efd50bSKent Overstreet 12754efd50bSKent Overstreet /* 12854efd50bSKent Overstreet * If the next starting sector would be misaligned, stop the discard at 12954efd50bSKent Overstreet * the previous aligned sector. 13054efd50bSKent Overstreet */ 13154efd50bSKent Overstreet alignment = (q->limits.discard_alignment >> 9) % granularity; 13254efd50bSKent Overstreet 13354efd50bSKent Overstreet tmp = bio->bi_iter.bi_sector + split_sectors - alignment; 13454efd50bSKent Overstreet tmp = sector_div(tmp, granularity); 13554efd50bSKent Overstreet 13654efd50bSKent Overstreet if (split_sectors > tmp) 13754efd50bSKent Overstreet split_sectors -= tmp; 13854efd50bSKent Overstreet 13954efd50bSKent Overstreet return bio_split(bio, split_sectors, GFP_NOIO, bs); 14054efd50bSKent Overstreet } 14154efd50bSKent Overstreet 142885fa13fSChristoph Hellwig static struct bio *blk_bio_write_zeroes_split(struct request_queue *q, 143885fa13fSChristoph Hellwig struct bio *bio, struct bio_set *bs, unsigned *nsegs) 144885fa13fSChristoph Hellwig { 145d665e12aSChristoph Hellwig *nsegs = 0; 146885fa13fSChristoph Hellwig 147885fa13fSChristoph Hellwig if (!q->limits.max_write_zeroes_sectors) 148885fa13fSChristoph Hellwig return NULL; 149885fa13fSChristoph Hellwig 150885fa13fSChristoph Hellwig if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors) 151885fa13fSChristoph Hellwig return NULL; 152885fa13fSChristoph Hellwig 153885fa13fSChristoph Hellwig return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs); 154885fa13fSChristoph Hellwig } 155885fa13fSChristoph Hellwig 1569cc5169cSBart Van Assche /* 1579cc5169cSBart Van Assche * Return the maximum number of sectors from the start of a bio that may be 1589cc5169cSBart Van Assche * submitted as a single request to a block device. If enough sectors remain, 1599cc5169cSBart Van Assche * align the end to the physical block size. Otherwise align the end to the 1609cc5169cSBart Van Assche * logical block size. This approach minimizes the number of non-aligned 1619cc5169cSBart Van Assche * requests that are submitted to a block device if the start of a bio is not 1629cc5169cSBart Van Assche * aligned to a physical block boundary. 1639cc5169cSBart Van Assche */ 164d0e5fbb0SMing Lei static inline unsigned get_max_io_size(struct request_queue *q, 165d0e5fbb0SMing Lei struct bio *bio) 166d0e5fbb0SMing Lei { 1673ee16db3SMike Snitzer unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector, 0); 1689cc5169cSBart Van Assche unsigned max_sectors = sectors; 1699cc5169cSBart Van Assche unsigned pbs = queue_physical_block_size(q) >> SECTOR_SHIFT; 1709cc5169cSBart Van Assche unsigned lbs = queue_logical_block_size(q) >> SECTOR_SHIFT; 1719cc5169cSBart Van Assche unsigned start_offset = bio->bi_iter.bi_sector & (pbs - 1); 172d0e5fbb0SMing Lei 1739cc5169cSBart Van Assche max_sectors += start_offset; 1749cc5169cSBart Van Assche max_sectors &= ~(pbs - 1); 1759cc5169cSBart Van Assche if (max_sectors > start_offset) 1769cc5169cSBart Van Assche return max_sectors - start_offset; 177d0e5fbb0SMing Lei 178e4b469c6SKeith Busch return sectors & ~(lbs - 1); 179d0e5fbb0SMing Lei } 180d0e5fbb0SMing Lei 181429120f3SMing Lei static inline unsigned get_max_segment_size(const struct request_queue *q, 182429120f3SMing Lei struct page *start_page, 183429120f3SMing Lei unsigned long offset) 184dcebd755SMing Lei { 185dcebd755SMing Lei unsigned long mask = queue_segment_boundary(q); 186dcebd755SMing Lei 187429120f3SMing Lei offset = mask & (page_to_phys(start_page) + offset); 1884a2f704eSMing Lei 1894a2f704eSMing Lei /* 1904a2f704eSMing Lei * overflow may be triggered in case of zero page physical address 1914a2f704eSMing Lei * on 32bit arch, use queue's max segment size when that happens. 1924a2f704eSMing Lei */ 1934a2f704eSMing Lei return min_not_zero(mask - offset + 1, 1944a2f704eSMing Lei (unsigned long)queue_max_segment_size(q)); 195dcebd755SMing Lei } 196dcebd755SMing Lei 197708b25b3SBart Van Assche /** 198708b25b3SBart Van Assche * bvec_split_segs - verify whether or not a bvec should be split in the middle 199708b25b3SBart Van Assche * @q: [in] request queue associated with the bio associated with @bv 200708b25b3SBart Van Assche * @bv: [in] bvec to examine 201708b25b3SBart Van Assche * @nsegs: [in,out] Number of segments in the bio being built. Incremented 202708b25b3SBart Van Assche * by the number of segments from @bv that may be appended to that 203708b25b3SBart Van Assche * bio without exceeding @max_segs 204708b25b3SBart Van Assche * @sectors: [in,out] Number of sectors in the bio being built. Incremented 205708b25b3SBart Van Assche * by the number of sectors from @bv that may be appended to that 206708b25b3SBart Van Assche * bio without exceeding @max_sectors 207708b25b3SBart Van Assche * @max_segs: [in] upper bound for *@nsegs 208708b25b3SBart Van Assche * @max_sectors: [in] upper bound for *@sectors 209708b25b3SBart Van Assche * 210708b25b3SBart Van Assche * When splitting a bio, it can happen that a bvec is encountered that is too 211708b25b3SBart Van Assche * big to fit in a single segment and hence that it has to be split in the 212708b25b3SBart Van Assche * middle. This function verifies whether or not that should happen. The value 213708b25b3SBart Van Assche * %true is returned if and only if appending the entire @bv to a bio with 214708b25b3SBart Van Assche * *@nsegs segments and *@sectors sectors would make that bio unacceptable for 215708b25b3SBart Van Assche * the block driver. 216dcebd755SMing Lei */ 217af2c68feSBart Van Assche static bool bvec_split_segs(const struct request_queue *q, 218af2c68feSBart Van Assche const struct bio_vec *bv, unsigned *nsegs, 219708b25b3SBart Van Assche unsigned *sectors, unsigned max_segs, 220708b25b3SBart Van Assche unsigned max_sectors) 221dcebd755SMing Lei { 222708b25b3SBart Van Assche unsigned max_len = (min(max_sectors, UINT_MAX >> 9) - *sectors) << 9; 223708b25b3SBart Van Assche unsigned len = min(bv->bv_len, max_len); 224dcebd755SMing Lei unsigned total_len = 0; 225ff9811b3SBart Van Assche unsigned seg_size = 0; 226dcebd755SMing Lei 227ff9811b3SBart Van Assche while (len && *nsegs < max_segs) { 228429120f3SMing Lei seg_size = get_max_segment_size(q, bv->bv_page, 229429120f3SMing Lei bv->bv_offset + total_len); 230dcebd755SMing Lei seg_size = min(seg_size, len); 231dcebd755SMing Lei 232ff9811b3SBart Van Assche (*nsegs)++; 233dcebd755SMing Lei total_len += seg_size; 234dcebd755SMing Lei len -= seg_size; 235dcebd755SMing Lei 236dcebd755SMing Lei if ((bv->bv_offset + total_len) & queue_virt_boundary(q)) 237dcebd755SMing Lei break; 238dcebd755SMing Lei } 239dcebd755SMing Lei 240dcebd755SMing Lei *sectors += total_len >> 9; 241dcebd755SMing Lei 242708b25b3SBart Van Assche /* tell the caller to split the bvec if it is too big to fit */ 243708b25b3SBart Van Assche return len > 0 || bv->bv_len > max_len; 244dcebd755SMing Lei } 245dcebd755SMing Lei 246dad77584SBart Van Assche /** 247dad77584SBart Van Assche * blk_bio_segment_split - split a bio in two bios 248dad77584SBart Van Assche * @q: [in] request queue pointer 249dad77584SBart Van Assche * @bio: [in] bio to be split 250dad77584SBart Van Assche * @bs: [in] bio set to allocate the clone from 251dad77584SBart Van Assche * @segs: [out] number of segments in the bio with the first half of the sectors 252dad77584SBart Van Assche * 253dad77584SBart Van Assche * Clone @bio, update the bi_iter of the clone to represent the first sectors 254dad77584SBart Van Assche * of @bio and update @bio->bi_iter to represent the remaining sectors. The 255dad77584SBart Van Assche * following is guaranteed for the cloned bio: 256dad77584SBart Van Assche * - That it has at most get_max_io_size(@q, @bio) sectors. 257dad77584SBart Van Assche * - That it has at most queue_max_segments(@q) segments. 258dad77584SBart Van Assche * 259dad77584SBart Van Assche * Except for discard requests the cloned bio will point at the bi_io_vec of 260dad77584SBart Van Assche * the original bio. It is the responsibility of the caller to ensure that the 261dad77584SBart Van Assche * original bio is not freed before the cloned bio. The caller is also 262dad77584SBart Van Assche * responsible for ensuring that @bs is only destroyed after processing of the 263dad77584SBart Van Assche * split bio has finished. 264dad77584SBart Van Assche */ 26554efd50bSKent Overstreet static struct bio *blk_bio_segment_split(struct request_queue *q, 26654efd50bSKent Overstreet struct bio *bio, 267bdced438SMing Lei struct bio_set *bs, 268bdced438SMing Lei unsigned *segs) 26954efd50bSKent Overstreet { 2705014c311SJens Axboe struct bio_vec bv, bvprv, *bvprvp = NULL; 27154efd50bSKent Overstreet struct bvec_iter iter; 2726869875fSChristoph Hellwig unsigned nsegs = 0, sectors = 0; 273d0e5fbb0SMing Lei const unsigned max_sectors = get_max_io_size(q, bio); 27405b700baSMing Lei const unsigned max_segs = queue_max_segments(q); 27554efd50bSKent Overstreet 276dcebd755SMing Lei bio_for_each_bvec(bv, bio, iter) { 27754efd50bSKent Overstreet /* 27854efd50bSKent Overstreet * If the queue doesn't support SG gaps and adding this 27954efd50bSKent Overstreet * offset would create a gap, disallow it. 28054efd50bSKent Overstreet */ 2815014c311SJens Axboe if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) 28254efd50bSKent Overstreet goto split; 28354efd50bSKent Overstreet 28405b700baSMing Lei if (nsegs < max_segs && 285708b25b3SBart Van Assche sectors + (bv.bv_len >> 9) <= max_sectors && 286708b25b3SBart Van Assche bv.bv_offset + bv.bv_len <= PAGE_SIZE) { 287708b25b3SBart Van Assche nsegs++; 288708b25b3SBart Van Assche sectors += bv.bv_len >> 9; 289708b25b3SBart Van Assche } else if (bvec_split_segs(q, &bv, &nsegs, §ors, max_segs, 290708b25b3SBart Van Assche max_sectors)) { 291e36f6204SKeith Busch goto split; 292e36f6204SKeith Busch } 293e36f6204SKeith Busch 29454efd50bSKent Overstreet bvprv = bv; 295578270bfSMing Lei bvprvp = &bvprv; 29654efd50bSKent Overstreet } 29754efd50bSKent Overstreet 298d627065dSChristoph Hellwig *segs = nsegs; 299d627065dSChristoph Hellwig return NULL; 30054efd50bSKent Overstreet split: 301bdced438SMing Lei *segs = nsegs; 302cc29e1bfSJeffle Xu 303cc29e1bfSJeffle Xu /* 304cc29e1bfSJeffle Xu * Bio splitting may cause subtle trouble such as hang when doing sync 305cc29e1bfSJeffle Xu * iopoll in direct IO routine. Given performance gain of iopoll for 306cc29e1bfSJeffle Xu * big IO can be trival, disable iopoll when split needed. 307cc29e1bfSJeffle Xu */ 3086ce913feSChristoph Hellwig bio_clear_polled(bio); 309d627065dSChristoph Hellwig return bio_split(bio, sectors, GFP_NOIO, bs); 31054efd50bSKent Overstreet } 31154efd50bSKent Overstreet 312dad77584SBart Van Assche /** 313dad77584SBart Van Assche * __blk_queue_split - split a bio and submit the second half 314abd45c15SJens Axboe * @q: [in] request_queue new bio is being queued at 315dad77584SBart Van Assche * @bio: [in, out] bio to be split 316dad77584SBart Van Assche * @nr_segs: [out] number of segments in the first bio 317dad77584SBart Van Assche * 318dad77584SBart Van Assche * Split a bio into two bios, chain the two bios, submit the second half and 319dad77584SBart Van Assche * store a pointer to the first half in *@bio. If the second bio is still too 320dad77584SBart Van Assche * big it will be split by a recursive call to this function. Since this 321309dca30SChristoph Hellwig * function may allocate a new bio from q->bio_split, it is the responsibility 322309dca30SChristoph Hellwig * of the caller to ensure that q->bio_split is only released after processing 323309dca30SChristoph Hellwig * of the split bio has finished. 324dad77584SBart Van Assche */ 325abd45c15SJens Axboe void __blk_queue_split(struct request_queue *q, struct bio **bio, 326abd45c15SJens Axboe unsigned int *nr_segs) 32754efd50bSKent Overstreet { 328fa532287SChristoph Hellwig struct bio *split = NULL; 32954efd50bSKent Overstreet 3307afafc8aSAdrian Hunter switch (bio_op(*bio)) { 3317afafc8aSAdrian Hunter case REQ_OP_DISCARD: 3327afafc8aSAdrian Hunter case REQ_OP_SECURE_ERASE: 33314ccb66bSChristoph Hellwig split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs); 3347afafc8aSAdrian Hunter break; 335a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 33614ccb66bSChristoph Hellwig split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split, 33714ccb66bSChristoph Hellwig nr_segs); 338a6f0788eSChaitanya Kulkarni break; 3397afafc8aSAdrian Hunter default: 34014ccb66bSChristoph Hellwig split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs); 3417afafc8aSAdrian Hunter break; 3427afafc8aSAdrian Hunter } 343bdced438SMing Lei 34454efd50bSKent Overstreet if (split) { 3456ac45aebSMing Lei /* there isn't chance to merge the splitted bio */ 3461eff9d32SJens Axboe split->bi_opf |= REQ_NOMERGE; 3476ac45aebSMing Lei 348*957a2b34SMuchun Song blkcg_bio_issue_init(split); 34954efd50bSKent Overstreet bio_chain(split, *bio); 350eb6f7f7cSChristoph Hellwig trace_block_split(split, (*bio)->bi_iter.bi_sector); 351ed00aabdSChristoph Hellwig submit_bio_noacct(*bio); 35254efd50bSKent Overstreet *bio = split; 35354efd50bSKent Overstreet } 35454efd50bSKent Overstreet } 35514ccb66bSChristoph Hellwig 356dad77584SBart Van Assche /** 357dad77584SBart Van Assche * blk_queue_split - split a bio and submit the second half 358dad77584SBart Van Assche * @bio: [in, out] bio to be split 359dad77584SBart Van Assche * 360dad77584SBart Van Assche * Split a bio into two bios, chains the two bios, submit the second half and 361dad77584SBart Van Assche * store a pointer to the first half in *@bio. Since this function may allocate 362309dca30SChristoph Hellwig * a new bio from q->bio_split, it is the responsibility of the caller to ensure 363309dca30SChristoph Hellwig * that q->bio_split is only released after processing of the split bio has 364309dca30SChristoph Hellwig * finished. 365dad77584SBart Van Assche */ 366f695ca38SChristoph Hellwig void blk_queue_split(struct bio **bio) 36714ccb66bSChristoph Hellwig { 368859897c3SPavel Begunkov struct request_queue *q = bdev_get_queue((*bio)->bi_bdev); 36914ccb66bSChristoph Hellwig unsigned int nr_segs; 37014ccb66bSChristoph Hellwig 371abd45c15SJens Axboe if (blk_may_split(q, *bio)) 372abd45c15SJens Axboe __blk_queue_split(q, bio, &nr_segs); 37314ccb66bSChristoph Hellwig } 37454efd50bSKent Overstreet EXPORT_SYMBOL(blk_queue_split); 37554efd50bSKent Overstreet 376e9cd19c0SChristoph Hellwig unsigned int blk_recalc_rq_segments(struct request *rq) 377d6d48196SJens Axboe { 3786869875fSChristoph Hellwig unsigned int nr_phys_segs = 0; 379ff9811b3SBart Van Assche unsigned int nr_sectors = 0; 380e9cd19c0SChristoph Hellwig struct req_iterator iter; 3816869875fSChristoph Hellwig struct bio_vec bv; 382d6d48196SJens Axboe 383e9cd19c0SChristoph Hellwig if (!rq->bio) 3841e428079SJens Axboe return 0; 385d6d48196SJens Axboe 386e9cd19c0SChristoph Hellwig switch (bio_op(rq->bio)) { 387a6f0788eSChaitanya Kulkarni case REQ_OP_DISCARD: 388a6f0788eSChaitanya Kulkarni case REQ_OP_SECURE_ERASE: 389a958937fSDavid Jeffery if (queue_max_discard_segments(rq->q) > 1) { 390a958937fSDavid Jeffery struct bio *bio = rq->bio; 391a958937fSDavid Jeffery 392a958937fSDavid Jeffery for_each_bio(bio) 393a958937fSDavid Jeffery nr_phys_segs++; 394a958937fSDavid Jeffery return nr_phys_segs; 395a958937fSDavid Jeffery } 396a958937fSDavid Jeffery return 1; 397a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 398f9d03f96SChristoph Hellwig return 0; 399a6f0788eSChaitanya Kulkarni } 4005cb8850cSKent Overstreet 401e9cd19c0SChristoph Hellwig rq_for_each_bvec(bv, rq, iter) 402ff9811b3SBart Van Assche bvec_split_segs(rq->q, &bv, &nr_phys_segs, &nr_sectors, 403708b25b3SBart Van Assche UINT_MAX, UINT_MAX); 4041e428079SJens Axboe return nr_phys_segs; 4051e428079SJens Axboe } 4061e428079SJens Axboe 40748d7727cSMing Lei static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, 408862e5a5eSMing Lei struct scatterlist *sglist) 409862e5a5eSMing Lei { 410862e5a5eSMing Lei if (!*sg) 411862e5a5eSMing Lei return sglist; 412862e5a5eSMing Lei 413862e5a5eSMing Lei /* 414862e5a5eSMing Lei * If the driver previously mapped a shorter list, we could see a 415862e5a5eSMing Lei * termination bit prematurely unless it fully inits the sg table 416862e5a5eSMing Lei * on each mapping. We KNOW that there must be more entries here 417862e5a5eSMing Lei * or the driver would be buggy, so force clear the termination bit 418862e5a5eSMing Lei * to avoid doing a full sg_init_table() in drivers for each command. 419862e5a5eSMing Lei */ 420862e5a5eSMing Lei sg_unmark_end(*sg); 421862e5a5eSMing Lei return sg_next(*sg); 422862e5a5eSMing Lei } 423862e5a5eSMing Lei 424862e5a5eSMing Lei static unsigned blk_bvec_map_sg(struct request_queue *q, 425862e5a5eSMing Lei struct bio_vec *bvec, struct scatterlist *sglist, 426862e5a5eSMing Lei struct scatterlist **sg) 427862e5a5eSMing Lei { 428862e5a5eSMing Lei unsigned nbytes = bvec->bv_len; 4298a96a0e4SChristoph Hellwig unsigned nsegs = 0, total = 0; 430862e5a5eSMing Lei 431862e5a5eSMing Lei while (nbytes > 0) { 4328a96a0e4SChristoph Hellwig unsigned offset = bvec->bv_offset + total; 433429120f3SMing Lei unsigned len = min(get_max_segment_size(q, bvec->bv_page, 434429120f3SMing Lei offset), nbytes); 435f9f76879SChristoph Hellwig struct page *page = bvec->bv_page; 436f9f76879SChristoph Hellwig 437f9f76879SChristoph Hellwig /* 438f9f76879SChristoph Hellwig * Unfortunately a fair number of drivers barf on scatterlists 439f9f76879SChristoph Hellwig * that have an offset larger than PAGE_SIZE, despite other 440f9f76879SChristoph Hellwig * subsystems dealing with that invariant just fine. For now 441f9f76879SChristoph Hellwig * stick to the legacy format where we never present those from 442f9f76879SChristoph Hellwig * the block layer, but the code below should be removed once 443f9f76879SChristoph Hellwig * these offenders (mostly MMC/SD drivers) are fixed. 444f9f76879SChristoph Hellwig */ 445f9f76879SChristoph Hellwig page += (offset >> PAGE_SHIFT); 446f9f76879SChristoph Hellwig offset &= ~PAGE_MASK; 447862e5a5eSMing Lei 448862e5a5eSMing Lei *sg = blk_next_sg(sg, sglist); 449f9f76879SChristoph Hellwig sg_set_page(*sg, page, len, offset); 450862e5a5eSMing Lei 4518a96a0e4SChristoph Hellwig total += len; 4528a96a0e4SChristoph Hellwig nbytes -= len; 453862e5a5eSMing Lei nsegs++; 454862e5a5eSMing Lei } 455862e5a5eSMing Lei 456862e5a5eSMing Lei return nsegs; 457862e5a5eSMing Lei } 458862e5a5eSMing Lei 45916e3e418SMing Lei static inline int __blk_bvec_map_sg(struct bio_vec bv, 46016e3e418SMing Lei struct scatterlist *sglist, struct scatterlist **sg) 46116e3e418SMing Lei { 46216e3e418SMing Lei *sg = blk_next_sg(sg, sglist); 46316e3e418SMing Lei sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); 46416e3e418SMing Lei return 1; 46516e3e418SMing Lei } 46616e3e418SMing Lei 467f6970f83SMing Lei /* only try to merge bvecs into one sg if they are from two bios */ 468f6970f83SMing Lei static inline bool 469f6970f83SMing Lei __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec, 470f6970f83SMing Lei struct bio_vec *bvprv, struct scatterlist **sg) 471963ab9e5SAsias He { 472963ab9e5SAsias He 473963ab9e5SAsias He int nbytes = bvec->bv_len; 474963ab9e5SAsias He 475f6970f83SMing Lei if (!*sg) 476f6970f83SMing Lei return false; 477f6970f83SMing Lei 478b4b6cb61SMing Lei if ((*sg)->length + nbytes > queue_max_segment_size(q)) 479f6970f83SMing Lei return false; 480f6970f83SMing Lei 4813dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, bvprv, bvec)) 482f6970f83SMing Lei return false; 483963ab9e5SAsias He 484963ab9e5SAsias He (*sg)->length += nbytes; 485f6970f83SMing Lei 486f6970f83SMing Lei return true; 487963ab9e5SAsias He } 488963ab9e5SAsias He 4895cb8850cSKent Overstreet static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, 4905cb8850cSKent Overstreet struct scatterlist *sglist, 4915cb8850cSKent Overstreet struct scatterlist **sg) 4925cb8850cSKent Overstreet { 4933f649ab7SKees Cook struct bio_vec bvec, bvprv = { NULL }; 4945cb8850cSKent Overstreet struct bvec_iter iter; 49538417468SChristoph Hellwig int nsegs = 0; 496f6970f83SMing Lei bool new_bio = false; 4975cb8850cSKent Overstreet 498f6970f83SMing Lei for_each_bio(bio) { 499f6970f83SMing Lei bio_for_each_bvec(bvec, bio, iter) { 500f6970f83SMing Lei /* 501f6970f83SMing Lei * Only try to merge bvecs from two bios given we 502f6970f83SMing Lei * have done bio internal merge when adding pages 503f6970f83SMing Lei * to bio 504f6970f83SMing Lei */ 505f6970f83SMing Lei if (new_bio && 506f6970f83SMing Lei __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg)) 507f6970f83SMing Lei goto next_bvec; 508f6970f83SMing Lei 509f6970f83SMing Lei if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE) 510f6970f83SMing Lei nsegs += __blk_bvec_map_sg(bvec, sglist, sg); 511f6970f83SMing Lei else 512f6970f83SMing Lei nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg); 513f6970f83SMing Lei next_bvec: 514f6970f83SMing Lei new_bio = false; 515f6970f83SMing Lei } 516b21e11c5SMing Lei if (likely(bio->bi_iter.bi_size)) { 517f6970f83SMing Lei bvprv = bvec; 518f6970f83SMing Lei new_bio = true; 519f6970f83SMing Lei } 520b21e11c5SMing Lei } 5215cb8850cSKent Overstreet 5225cb8850cSKent Overstreet return nsegs; 5235cb8850cSKent Overstreet } 5245cb8850cSKent Overstreet 525d6d48196SJens Axboe /* 526d6d48196SJens Axboe * map a request to scatterlist, return number of sg entries setup. Caller 527d6d48196SJens Axboe * must make sure sg can hold rq->nr_phys_segments entries 528d6d48196SJens Axboe */ 52989de1504SChristoph Hellwig int __blk_rq_map_sg(struct request_queue *q, struct request *rq, 53089de1504SChristoph Hellwig struct scatterlist *sglist, struct scatterlist **last_sg) 531d6d48196SJens Axboe { 5325cb8850cSKent Overstreet int nsegs = 0; 533d6d48196SJens Axboe 534f9d03f96SChristoph Hellwig if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) 53589de1504SChristoph Hellwig nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, last_sg); 536f9d03f96SChristoph Hellwig else if (rq->bio) 53789de1504SChristoph Hellwig nsegs = __blk_bios_map_sg(q, rq->bio, sglist, last_sg); 538f18573abSFUJITA Tomonori 53989de1504SChristoph Hellwig if (*last_sg) 54089de1504SChristoph Hellwig sg_mark_end(*last_sg); 541d6d48196SJens Axboe 54212e57f59SMing Lei /* 54312e57f59SMing Lei * Something must have been wrong if the figured number of 54412e57f59SMing Lei * segment is bigger than number of req's physical segments 54512e57f59SMing Lei */ 546f9d03f96SChristoph Hellwig WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); 54712e57f59SMing Lei 548d6d48196SJens Axboe return nsegs; 549d6d48196SJens Axboe } 55089de1504SChristoph Hellwig EXPORT_SYMBOL(__blk_rq_map_sg); 551d6d48196SJens Axboe 552943b40c8SMing Lei static inline unsigned int blk_rq_get_max_segments(struct request *rq) 553943b40c8SMing Lei { 554943b40c8SMing Lei if (req_op(rq) == REQ_OP_DISCARD) 555943b40c8SMing Lei return queue_max_discard_segments(rq->q); 556943b40c8SMing Lei return queue_max_segments(rq->q); 557943b40c8SMing Lei } 558943b40c8SMing Lei 559badf7f64SChristoph Hellwig static inline unsigned int blk_rq_get_max_sectors(struct request *rq, 560badf7f64SChristoph Hellwig sector_t offset) 561badf7f64SChristoph Hellwig { 562badf7f64SChristoph Hellwig struct request_queue *q = rq->q; 563badf7f64SChristoph Hellwig 564badf7f64SChristoph Hellwig if (blk_rq_is_passthrough(rq)) 565badf7f64SChristoph Hellwig return q->limits.max_hw_sectors; 566badf7f64SChristoph Hellwig 567badf7f64SChristoph Hellwig if (!q->limits.chunk_sectors || 568badf7f64SChristoph Hellwig req_op(rq) == REQ_OP_DISCARD || 569badf7f64SChristoph Hellwig req_op(rq) == REQ_OP_SECURE_ERASE) 570badf7f64SChristoph Hellwig return blk_queue_get_max_sectors(q, req_op(rq)); 571badf7f64SChristoph Hellwig 572badf7f64SChristoph Hellwig return min(blk_max_size_offset(q, offset, 0), 573badf7f64SChristoph Hellwig blk_queue_get_max_sectors(q, req_op(rq))); 574badf7f64SChristoph Hellwig } 575badf7f64SChristoph Hellwig 57614ccb66bSChristoph Hellwig static inline int ll_new_hw_segment(struct request *req, struct bio *bio, 57714ccb66bSChristoph Hellwig unsigned int nr_phys_segs) 578d6d48196SJens Axboe { 5796b2b0459STejun Heo if (!blk_cgroup_mergeable(req, bio)) 5806b2b0459STejun Heo goto no_merge; 5816b2b0459STejun Heo 5822705dfb2SMing Lei if (blk_integrity_merge_bio(req->q, req, bio) == false) 58313f05c8dSMartin K. Petersen goto no_merge; 58413f05c8dSMartin K. Petersen 5852705dfb2SMing Lei /* discard request merge won't add new segment */ 5862705dfb2SMing Lei if (req_op(req) == REQ_OP_DISCARD) 5872705dfb2SMing Lei return 1; 5882705dfb2SMing Lei 5892705dfb2SMing Lei if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) 59013f05c8dSMartin K. Petersen goto no_merge; 591d6d48196SJens Axboe 592d6d48196SJens Axboe /* 593d6d48196SJens Axboe * This will form the start of a new hw segment. Bump both 594d6d48196SJens Axboe * counters. 595d6d48196SJens Axboe */ 596d6d48196SJens Axboe req->nr_phys_segments += nr_phys_segs; 597d6d48196SJens Axboe return 1; 59813f05c8dSMartin K. Petersen 59913f05c8dSMartin K. Petersen no_merge: 60014ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 60113f05c8dSMartin K. Petersen return 0; 602d6d48196SJens Axboe } 603d6d48196SJens Axboe 60414ccb66bSChristoph Hellwig int ll_back_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs) 605d6d48196SJens Axboe { 6065e7c4274SJens Axboe if (req_gap_back_merge(req, bio)) 6075e7c4274SJens Axboe return 0; 6087f39add3SSagi Grimberg if (blk_integrity_rq(req) && 6097f39add3SSagi Grimberg integrity_req_gap_back_merge(req, bio)) 6107f39add3SSagi Grimberg return 0; 611a892c8d5SSatya Tangirala if (!bio_crypt_ctx_back_mergeable(req, bio)) 612a892c8d5SSatya Tangirala return 0; 613f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 61417007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) { 61514ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 616d6d48196SJens Axboe return 0; 617d6d48196SJens Axboe } 618d6d48196SJens Axboe 61914ccb66bSChristoph Hellwig return ll_new_hw_segment(req, bio, nr_segs); 620d6d48196SJens Axboe } 621d6d48196SJens Axboe 622eda5cc99SChristoph Hellwig static int ll_front_merge_fn(struct request *req, struct bio *bio, 623eda5cc99SChristoph Hellwig unsigned int nr_segs) 624d6d48196SJens Axboe { 6255e7c4274SJens Axboe if (req_gap_front_merge(req, bio)) 6265e7c4274SJens Axboe return 0; 6277f39add3SSagi Grimberg if (blk_integrity_rq(req) && 6287f39add3SSagi Grimberg integrity_req_gap_front_merge(req, bio)) 6297f39add3SSagi Grimberg return 0; 630a892c8d5SSatya Tangirala if (!bio_crypt_ctx_front_mergeable(req, bio)) 631a892c8d5SSatya Tangirala return 0; 632f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 63317007f39SDamien Le Moal blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { 63414ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 635d6d48196SJens Axboe return 0; 636d6d48196SJens Axboe } 637d6d48196SJens Axboe 63814ccb66bSChristoph Hellwig return ll_new_hw_segment(req, bio, nr_segs); 639d6d48196SJens Axboe } 640d6d48196SJens Axboe 641445251d0SJens Axboe static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, 642445251d0SJens Axboe struct request *next) 643445251d0SJens Axboe { 644445251d0SJens Axboe unsigned short segments = blk_rq_nr_discard_segments(req); 645445251d0SJens Axboe 646445251d0SJens Axboe if (segments >= queue_max_discard_segments(q)) 647445251d0SJens Axboe goto no_merge; 648445251d0SJens Axboe if (blk_rq_sectors(req) + bio_sectors(next->bio) > 649445251d0SJens Axboe blk_rq_get_max_sectors(req, blk_rq_pos(req))) 650445251d0SJens Axboe goto no_merge; 651445251d0SJens Axboe 652445251d0SJens Axboe req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); 653445251d0SJens Axboe return true; 654445251d0SJens Axboe no_merge: 655445251d0SJens Axboe req_set_nomerge(q, req); 656445251d0SJens Axboe return false; 657445251d0SJens Axboe } 658445251d0SJens Axboe 659d6d48196SJens Axboe static int ll_merge_requests_fn(struct request_queue *q, struct request *req, 660d6d48196SJens Axboe struct request *next) 661d6d48196SJens Axboe { 662d6d48196SJens Axboe int total_phys_segments; 663d6d48196SJens Axboe 6645e7c4274SJens Axboe if (req_gap_back_merge(req, next->bio)) 665854fbb9cSKeith Busch return 0; 666854fbb9cSKeith Busch 667d6d48196SJens Axboe /* 668d6d48196SJens Axboe * Will it become too large? 669d6d48196SJens Axboe */ 670f31dc1cdSMartin K. Petersen if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > 67117007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) 672d6d48196SJens Axboe return 0; 673d6d48196SJens Axboe 674d6d48196SJens Axboe total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; 675943b40c8SMing Lei if (total_phys_segments > blk_rq_get_max_segments(req)) 676d6d48196SJens Axboe return 0; 677d6d48196SJens Axboe 6786b2b0459STejun Heo if (!blk_cgroup_mergeable(req, next->bio)) 6796b2b0459STejun Heo return 0; 6806b2b0459STejun Heo 6814eaf99beSMartin K. Petersen if (blk_integrity_merge_rq(q, req, next) == false) 68213f05c8dSMartin K. Petersen return 0; 68313f05c8dSMartin K. Petersen 684a892c8d5SSatya Tangirala if (!bio_crypt_ctx_merge_rq(req, next)) 685a892c8d5SSatya Tangirala return 0; 686a892c8d5SSatya Tangirala 687d6d48196SJens Axboe /* Merge is OK... */ 688d6d48196SJens Axboe req->nr_phys_segments = total_phys_segments; 689d6d48196SJens Axboe return 1; 690d6d48196SJens Axboe } 691d6d48196SJens Axboe 69280a761fdSTejun Heo /** 69380a761fdSTejun Heo * blk_rq_set_mixed_merge - mark a request as mixed merge 69480a761fdSTejun Heo * @rq: request to mark as mixed merge 69580a761fdSTejun Heo * 69680a761fdSTejun Heo * Description: 69780a761fdSTejun Heo * @rq is about to be mixed merged. Make sure the attributes 69880a761fdSTejun Heo * which can be mixed are set in each bio and mark @rq as mixed 69980a761fdSTejun Heo * merged. 70080a761fdSTejun Heo */ 70180a761fdSTejun Heo void blk_rq_set_mixed_merge(struct request *rq) 70280a761fdSTejun Heo { 70380a761fdSTejun Heo unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 70480a761fdSTejun Heo struct bio *bio; 70580a761fdSTejun Heo 706e8064021SChristoph Hellwig if (rq->rq_flags & RQF_MIXED_MERGE) 70780a761fdSTejun Heo return; 70880a761fdSTejun Heo 70980a761fdSTejun Heo /* 71080a761fdSTejun Heo * @rq will no longer represent mixable attributes for all the 71180a761fdSTejun Heo * contained bios. It will just track those of the first one. 71280a761fdSTejun Heo * Distributes the attributs to each bio. 71380a761fdSTejun Heo */ 71480a761fdSTejun Heo for (bio = rq->bio; bio; bio = bio->bi_next) { 7151eff9d32SJens Axboe WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && 7161eff9d32SJens Axboe (bio->bi_opf & REQ_FAILFAST_MASK) != ff); 7171eff9d32SJens Axboe bio->bi_opf |= ff; 71880a761fdSTejun Heo } 719e8064021SChristoph Hellwig rq->rq_flags |= RQF_MIXED_MERGE; 72080a761fdSTejun Heo } 72180a761fdSTejun Heo 722b9c54f56SKonstantin Khlebnikov static void blk_account_io_merge_request(struct request *req) 72326308eabSJerome Marchand { 72426308eabSJerome Marchand if (blk_do_io_stat(req)) { 725112f158fSMike Snitzer part_stat_lock(); 726b9c54f56SKonstantin Khlebnikov part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); 72726308eabSJerome Marchand part_stat_unlock(); 72826308eabSJerome Marchand } 72926308eabSJerome Marchand } 730b9c54f56SKonstantin Khlebnikov 731e96c0d83SEric Biggers static enum elv_merge blk_try_req_merge(struct request *req, 732e96c0d83SEric Biggers struct request *next) 73369840466SJianchao Wang { 73469840466SJianchao Wang if (blk_discard_mergable(req)) 73569840466SJianchao Wang return ELEVATOR_DISCARD_MERGE; 73669840466SJianchao Wang else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) 73769840466SJianchao Wang return ELEVATOR_BACK_MERGE; 73869840466SJianchao Wang 73969840466SJianchao Wang return ELEVATOR_NO_MERGE; 74069840466SJianchao Wang } 74126308eabSJerome Marchand 742d6d48196SJens Axboe /* 743b973cb7eSJens Axboe * For non-mq, this has to be called with the request spinlock acquired. 744b973cb7eSJens Axboe * For mq with scheduling, the appropriate queue wide lock should be held. 745d6d48196SJens Axboe */ 746b973cb7eSJens Axboe static struct request *attempt_merge(struct request_queue *q, 747b973cb7eSJens Axboe struct request *req, struct request *next) 748d6d48196SJens Axboe { 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 75579bb1dbdSChristoph Hellwig if (rq_data_dir(req) != rq_data_dir(next)) 756b973cb7eSJens Axboe return NULL; 757d6d48196SJens Axboe 758668ffc03SDamien Le Moal if (req->ioprio != next->ioprio) 759668ffc03SDamien Le Moal return NULL; 760668ffc03SDamien Le Moal 761cb6934f8SJens Axboe /* 762d6d48196SJens Axboe * If we are allowed to merge, then append bio list 763d6d48196SJens Axboe * from next to rq and release next. merge_requests_fn 764d6d48196SJens Axboe * will have updated segment counts, update sector 765445251d0SJens Axboe * counts here. Handle DISCARDs separately, as they 766445251d0SJens Axboe * have separate settings. 767d6d48196SJens Axboe */ 76869840466SJianchao Wang 76969840466SJianchao Wang switch (blk_try_req_merge(req, next)) { 77069840466SJianchao Wang case ELEVATOR_DISCARD_MERGE: 771445251d0SJens Axboe if (!req_attempt_discard_merge(q, req, next)) 772445251d0SJens Axboe return NULL; 77369840466SJianchao Wang break; 77469840466SJianchao Wang case ELEVATOR_BACK_MERGE: 77569840466SJianchao Wang if (!ll_merge_requests_fn(q, req, next)) 776b973cb7eSJens Axboe return NULL; 77769840466SJianchao Wang break; 77869840466SJianchao Wang default: 77969840466SJianchao Wang return NULL; 78069840466SJianchao Wang } 781d6d48196SJens Axboe 782d6d48196SJens Axboe /* 78380a761fdSTejun Heo * If failfast settings disagree or any of the two is already 78480a761fdSTejun Heo * a mixed merge, mark both as mixed before proceeding. This 78580a761fdSTejun Heo * makes sure that all involved bios have mixable attributes 78680a761fdSTejun Heo * set properly. 78780a761fdSTejun Heo */ 788e8064021SChristoph Hellwig if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || 78980a761fdSTejun Heo (req->cmd_flags & REQ_FAILFAST_MASK) != 79080a761fdSTejun Heo (next->cmd_flags & REQ_FAILFAST_MASK)) { 79180a761fdSTejun Heo blk_rq_set_mixed_merge(req); 79280a761fdSTejun Heo blk_rq_set_mixed_merge(next); 79380a761fdSTejun Heo } 79480a761fdSTejun Heo 79580a761fdSTejun Heo /* 796522a7775SOmar Sandoval * At this point we have either done a back merge or front merge. We 797522a7775SOmar Sandoval * need the smaller start_time_ns of the merged requests to be the 798522a7775SOmar Sandoval * current request for accounting purposes. 799d6d48196SJens Axboe */ 800522a7775SOmar Sandoval if (next->start_time_ns < req->start_time_ns) 801522a7775SOmar Sandoval req->start_time_ns = next->start_time_ns; 802d6d48196SJens Axboe 803d6d48196SJens Axboe req->biotail->bi_next = next->bio; 804d6d48196SJens Axboe req->biotail = next->biotail; 805d6d48196SJens Axboe 806a2dec7b3STejun Heo req->__data_len += blk_rq_bytes(next); 807d6d48196SJens Axboe 8082a5cf35cSMing Lei if (!blk_discard_mergable(req)) 809d6d48196SJens Axboe elv_merge_requests(q, req, next); 810d6d48196SJens Axboe 81142dad764SJerome Marchand /* 81242dad764SJerome Marchand * 'next' is going away, so update stats accordingly 81342dad764SJerome Marchand */ 814b9c54f56SKonstantin Khlebnikov blk_account_io_merge_request(next); 815d6d48196SJens Axboe 816a54895faSChristoph Hellwig trace_block_rq_merge(next); 817f3bdc62fSJan Kara 818e4d750c9SJens Axboe /* 819e4d750c9SJens Axboe * ownership of bio passed from next to req, return 'next' for 820e4d750c9SJens Axboe * the caller to free 821e4d750c9SJens Axboe */ 8221cd96c24SBoaz Harrosh next->bio = NULL; 823b973cb7eSJens Axboe return next; 824d6d48196SJens Axboe } 825d6d48196SJens Axboe 826eda5cc99SChristoph Hellwig static struct request *attempt_back_merge(struct request_queue *q, 827eda5cc99SChristoph Hellwig struct request *rq) 828d6d48196SJens Axboe { 829d6d48196SJens Axboe struct request *next = elv_latter_request(q, rq); 830d6d48196SJens Axboe 831d6d48196SJens Axboe if (next) 832d6d48196SJens Axboe return attempt_merge(q, rq, next); 833d6d48196SJens Axboe 834b973cb7eSJens Axboe return NULL; 835d6d48196SJens Axboe } 836d6d48196SJens Axboe 837eda5cc99SChristoph Hellwig static struct request *attempt_front_merge(struct request_queue *q, 838eda5cc99SChristoph Hellwig struct request *rq) 839d6d48196SJens Axboe { 840d6d48196SJens Axboe struct request *prev = elv_former_request(q, rq); 841d6d48196SJens Axboe 842d6d48196SJens Axboe if (prev) 843d6d48196SJens Axboe return attempt_merge(q, prev, rq); 844d6d48196SJens Axboe 845b973cb7eSJens Axboe return NULL; 846d6d48196SJens Axboe } 8475e84ea3aSJens Axboe 848fd2ef39cSJan Kara /* 849fd2ef39cSJan Kara * Try to merge 'next' into 'rq'. Return true if the merge happened, false 850fd2ef39cSJan Kara * otherwise. The caller is responsible for freeing 'next' if the merge 851fd2ef39cSJan Kara * happened. 852fd2ef39cSJan Kara */ 853fd2ef39cSJan Kara bool blk_attempt_req_merge(struct request_queue *q, struct request *rq, 8545e84ea3aSJens Axboe struct request *next) 8555e84ea3aSJens Axboe { 856fd2ef39cSJan Kara return attempt_merge(q, rq, next); 8575e84ea3aSJens Axboe } 858050c8ea8STejun Heo 859050c8ea8STejun Heo bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 860050c8ea8STejun Heo { 861e2a60da7SMartin K. Petersen if (!rq_mergeable(rq) || !bio_mergeable(bio)) 862050c8ea8STejun Heo return false; 863050c8ea8STejun Heo 864288dab8aSChristoph Hellwig if (req_op(rq) != bio_op(bio)) 865f31dc1cdSMartin K. Petersen return false; 866f31dc1cdSMartin K. Petersen 867050c8ea8STejun Heo /* different data direction or already started, don't merge */ 868050c8ea8STejun Heo if (bio_data_dir(bio) != rq_data_dir(rq)) 869050c8ea8STejun Heo return false; 870050c8ea8STejun Heo 8716b2b0459STejun Heo /* don't merge across cgroup boundaries */ 8726b2b0459STejun Heo if (!blk_cgroup_mergeable(rq, bio)) 8736b2b0459STejun Heo return false; 8746b2b0459STejun Heo 875050c8ea8STejun Heo /* only merge integrity protected bio into ditto rq */ 8764eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(rq->q, rq, bio) == false) 877050c8ea8STejun Heo return false; 878050c8ea8STejun Heo 879a892c8d5SSatya Tangirala /* Only merge if the crypt contexts are compatible */ 880a892c8d5SSatya Tangirala if (!bio_crypt_rq_ctx_compatible(rq, bio)) 881a892c8d5SSatya Tangirala return false; 882a892c8d5SSatya Tangirala 883668ffc03SDamien Le Moal if (rq->ioprio != bio_prio(bio)) 884668ffc03SDamien Le Moal return false; 885668ffc03SDamien Le Moal 886050c8ea8STejun Heo return true; 887050c8ea8STejun Heo } 888050c8ea8STejun Heo 88934fe7c05SChristoph Hellwig enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) 890050c8ea8STejun Heo { 89169840466SJianchao Wang if (blk_discard_mergable(rq)) 8921e739730SChristoph Hellwig return ELEVATOR_DISCARD_MERGE; 8931e739730SChristoph Hellwig else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) 894050c8ea8STejun Heo return ELEVATOR_BACK_MERGE; 8954f024f37SKent Overstreet else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) 896050c8ea8STejun Heo return ELEVATOR_FRONT_MERGE; 897050c8ea8STejun Heo return ELEVATOR_NO_MERGE; 898050c8ea8STejun Heo } 8998e756373SBaolin Wang 9008e756373SBaolin Wang static void blk_account_io_merge_bio(struct request *req) 9018e756373SBaolin Wang { 9028e756373SBaolin Wang if (!blk_do_io_stat(req)) 9038e756373SBaolin Wang return; 9048e756373SBaolin Wang 9058e756373SBaolin Wang part_stat_lock(); 9068e756373SBaolin Wang part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); 9078e756373SBaolin Wang part_stat_unlock(); 9088e756373SBaolin Wang } 9098e756373SBaolin Wang 910eda5cc99SChristoph Hellwig enum bio_merge_status { 911eda5cc99SChristoph Hellwig BIO_MERGE_OK, 912eda5cc99SChristoph Hellwig BIO_MERGE_NONE, 913eda5cc99SChristoph Hellwig BIO_MERGE_FAILED, 914eda5cc99SChristoph Hellwig }; 915eda5cc99SChristoph Hellwig 916eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_back_merge(struct request *req, 917eda5cc99SChristoph Hellwig struct bio *bio, unsigned int nr_segs) 9188e756373SBaolin Wang { 9198e756373SBaolin Wang const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 9208e756373SBaolin Wang 9218e756373SBaolin Wang if (!ll_back_merge_fn(req, bio, nr_segs)) 9227d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 9238e756373SBaolin Wang 924e8a676d6SChristoph Hellwig trace_block_bio_backmerge(bio); 9258e756373SBaolin Wang rq_qos_merge(req->q, req, bio); 9268e756373SBaolin Wang 9278e756373SBaolin Wang if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 9288e756373SBaolin Wang blk_rq_set_mixed_merge(req); 9298e756373SBaolin Wang 9308e756373SBaolin Wang req->biotail->bi_next = bio; 9318e756373SBaolin Wang req->biotail = bio; 9328e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 9338e756373SBaolin Wang 9348e756373SBaolin Wang bio_crypt_free_ctx(bio); 9358e756373SBaolin Wang 9368e756373SBaolin Wang blk_account_io_merge_bio(req); 9377d7ca7c5SBaolin Wang return BIO_MERGE_OK; 9388e756373SBaolin Wang } 9398e756373SBaolin Wang 940eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_front_merge(struct request *req, 941eda5cc99SChristoph Hellwig struct bio *bio, unsigned int nr_segs) 9428e756373SBaolin Wang { 9438e756373SBaolin Wang const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 9448e756373SBaolin Wang 9458e756373SBaolin Wang if (!ll_front_merge_fn(req, bio, nr_segs)) 9467d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 9478e756373SBaolin Wang 948e8a676d6SChristoph Hellwig trace_block_bio_frontmerge(bio); 9498e756373SBaolin Wang rq_qos_merge(req->q, req, bio); 9508e756373SBaolin Wang 9518e756373SBaolin Wang if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 9528e756373SBaolin Wang blk_rq_set_mixed_merge(req); 9538e756373SBaolin Wang 9548e756373SBaolin Wang bio->bi_next = req->bio; 9558e756373SBaolin Wang req->bio = bio; 9568e756373SBaolin Wang 9578e756373SBaolin Wang req->__sector = bio->bi_iter.bi_sector; 9588e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 9598e756373SBaolin Wang 9608e756373SBaolin Wang bio_crypt_do_front_merge(req, bio); 9618e756373SBaolin Wang 9628e756373SBaolin Wang blk_account_io_merge_bio(req); 9637d7ca7c5SBaolin Wang return BIO_MERGE_OK; 9648e756373SBaolin Wang } 9658e756373SBaolin Wang 966eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q, 967eda5cc99SChristoph Hellwig struct request *req, struct bio *bio) 9688e756373SBaolin Wang { 9698e756373SBaolin Wang unsigned short segments = blk_rq_nr_discard_segments(req); 9708e756373SBaolin Wang 9718e756373SBaolin Wang if (segments >= queue_max_discard_segments(q)) 9728e756373SBaolin Wang goto no_merge; 9738e756373SBaolin Wang if (blk_rq_sectors(req) + bio_sectors(bio) > 9748e756373SBaolin Wang blk_rq_get_max_sectors(req, blk_rq_pos(req))) 9758e756373SBaolin Wang goto no_merge; 9768e756373SBaolin Wang 9778e756373SBaolin Wang rq_qos_merge(q, req, bio); 9788e756373SBaolin Wang 9798e756373SBaolin Wang req->biotail->bi_next = bio; 9808e756373SBaolin Wang req->biotail = bio; 9818e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 9828e756373SBaolin Wang req->nr_phys_segments = segments + 1; 9838e756373SBaolin Wang 9848e756373SBaolin Wang blk_account_io_merge_bio(req); 9857d7ca7c5SBaolin Wang return BIO_MERGE_OK; 9868e756373SBaolin Wang no_merge: 9878e756373SBaolin Wang req_set_nomerge(q, req); 9887d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 9897d7ca7c5SBaolin Wang } 9907d7ca7c5SBaolin Wang 9917d7ca7c5SBaolin Wang static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q, 9927d7ca7c5SBaolin Wang struct request *rq, 9937d7ca7c5SBaolin Wang struct bio *bio, 9947d7ca7c5SBaolin Wang unsigned int nr_segs, 9957d7ca7c5SBaolin Wang bool sched_allow_merge) 9967d7ca7c5SBaolin Wang { 9977d7ca7c5SBaolin Wang if (!blk_rq_merge_ok(rq, bio)) 9987d7ca7c5SBaolin Wang return BIO_MERGE_NONE; 9997d7ca7c5SBaolin Wang 10007d7ca7c5SBaolin Wang switch (blk_try_merge(rq, bio)) { 10017d7ca7c5SBaolin Wang case ELEVATOR_BACK_MERGE: 1002265600b7SBaolin Wang if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) 10037d7ca7c5SBaolin Wang return bio_attempt_back_merge(rq, bio, nr_segs); 10047d7ca7c5SBaolin Wang break; 10057d7ca7c5SBaolin Wang case ELEVATOR_FRONT_MERGE: 1006265600b7SBaolin Wang if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) 10077d7ca7c5SBaolin Wang return bio_attempt_front_merge(rq, bio, nr_segs); 10087d7ca7c5SBaolin Wang break; 10097d7ca7c5SBaolin Wang case ELEVATOR_DISCARD_MERGE: 10107d7ca7c5SBaolin Wang return bio_attempt_discard_merge(q, rq, bio); 10117d7ca7c5SBaolin Wang default: 10127d7ca7c5SBaolin Wang return BIO_MERGE_NONE; 10137d7ca7c5SBaolin Wang } 10147d7ca7c5SBaolin Wang 10157d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 10168e756373SBaolin Wang } 10178e756373SBaolin Wang 10188e756373SBaolin Wang /** 10198e756373SBaolin Wang * blk_attempt_plug_merge - try to merge with %current's plugged list 10208e756373SBaolin Wang * @q: request_queue new bio is being queued at 10218e756373SBaolin Wang * @bio: new bio being queued 10228e756373SBaolin Wang * @nr_segs: number of segments in @bio 102387c037d1SJens Axboe * from the passed in @q already in the plug list 10248e756373SBaolin Wang * 1025d38a9c04SJens Axboe * Determine whether @bio being queued on @q can be merged with the previous 1026d38a9c04SJens Axboe * request on %current's plugged list. Returns %true if merge was successful, 10278e756373SBaolin Wang * otherwise %false. 10288e756373SBaolin Wang * 10298e756373SBaolin Wang * Plugging coalesces IOs from the same issuer for the same purpose without 10308e756373SBaolin Wang * going through @q->queue_lock. As such it's more of an issuing mechanism 10318e756373SBaolin Wang * than scheduling, and the request, while may have elvpriv data, is not 10328e756373SBaolin Wang * added on the elevator at this point. In addition, we don't have 10338e756373SBaolin Wang * reliable access to the elevator outside queue lock. Only check basic 10348e756373SBaolin Wang * merging parameters without querying the elevator. 10358e756373SBaolin Wang * 10368e756373SBaolin Wang * Caller must ensure !blk_queue_nomerges(q) beforehand. 10378e756373SBaolin Wang */ 10388e756373SBaolin Wang bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 10390c5bcc92SChristoph Hellwig unsigned int nr_segs) 10408e756373SBaolin Wang { 10418e756373SBaolin Wang struct blk_plug *plug; 10428e756373SBaolin Wang struct request *rq; 10438e756373SBaolin Wang 10448e756373SBaolin Wang plug = blk_mq_plug(q, bio); 1045bc490f81SJens Axboe if (!plug || rq_list_empty(plug->mq_list)) 10468e756373SBaolin Wang return false; 10478e756373SBaolin Wang 10485b205071SJens Axboe rq_list_for_each(&plug->mq_list, rq) { 104987c037d1SJens Axboe if (rq->q == q) { 1050a1cb6537SMing Lei if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) == 1051a1cb6537SMing Lei BIO_MERGE_OK) 10528e756373SBaolin Wang return true; 10535b205071SJens Axboe break; 10545b205071SJens Axboe } 10555b205071SJens Axboe 10565b205071SJens Axboe /* 10575b205071SJens Axboe * Only keep iterating plug list for merges if we have multiple 10585b205071SJens Axboe * queues 10595b205071SJens Axboe */ 10605b205071SJens Axboe if (!plug->multiple_queues) 10615b205071SJens Axboe break; 1062a1cb6537SMing Lei } 10638e756373SBaolin Wang return false; 10648e756373SBaolin Wang } 1065bdc6a287SBaolin Wang 1066bdc6a287SBaolin Wang /* 1067bdc6a287SBaolin Wang * Iterate list of requests and see if we can merge this bio with any 1068bdc6a287SBaolin Wang * of them. 1069bdc6a287SBaolin Wang */ 1070bdc6a287SBaolin Wang bool blk_bio_list_merge(struct request_queue *q, struct list_head *list, 1071bdc6a287SBaolin Wang struct bio *bio, unsigned int nr_segs) 1072bdc6a287SBaolin Wang { 1073bdc6a287SBaolin Wang struct request *rq; 1074bdc6a287SBaolin Wang int checked = 8; 1075bdc6a287SBaolin Wang 1076bdc6a287SBaolin Wang list_for_each_entry_reverse(rq, list, queuelist) { 1077bdc6a287SBaolin Wang if (!checked--) 1078bdc6a287SBaolin Wang break; 1079bdc6a287SBaolin Wang 10807d7ca7c5SBaolin Wang switch (blk_attempt_bio_merge(q, rq, bio, nr_segs, true)) { 10817d7ca7c5SBaolin Wang case BIO_MERGE_NONE: 1082bdc6a287SBaolin Wang continue; 10837d7ca7c5SBaolin Wang case BIO_MERGE_OK: 10847d7ca7c5SBaolin Wang return true; 10857d7ca7c5SBaolin Wang case BIO_MERGE_FAILED: 10867d7ca7c5SBaolin Wang return false; 1087bdc6a287SBaolin Wang } 1088bdc6a287SBaolin Wang 1089bdc6a287SBaolin Wang } 1090bdc6a287SBaolin Wang 1091bdc6a287SBaolin Wang return false; 1092bdc6a287SBaolin Wang } 1093bdc6a287SBaolin Wang EXPORT_SYMBOL_GPL(blk_bio_list_merge); 1094eda5cc99SChristoph Hellwig 1095eda5cc99SChristoph Hellwig bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio, 1096eda5cc99SChristoph Hellwig unsigned int nr_segs, struct request **merged_request) 1097eda5cc99SChristoph Hellwig { 1098eda5cc99SChristoph Hellwig struct request *rq; 1099eda5cc99SChristoph Hellwig 1100eda5cc99SChristoph Hellwig switch (elv_merge(q, &rq, bio)) { 1101eda5cc99SChristoph Hellwig case ELEVATOR_BACK_MERGE: 1102eda5cc99SChristoph Hellwig if (!blk_mq_sched_allow_merge(q, rq, bio)) 1103eda5cc99SChristoph Hellwig return false; 1104eda5cc99SChristoph Hellwig if (bio_attempt_back_merge(rq, bio, nr_segs) != BIO_MERGE_OK) 1105eda5cc99SChristoph Hellwig return false; 1106eda5cc99SChristoph Hellwig *merged_request = attempt_back_merge(q, rq); 1107eda5cc99SChristoph Hellwig if (!*merged_request) 1108eda5cc99SChristoph Hellwig elv_merged_request(q, rq, ELEVATOR_BACK_MERGE); 1109eda5cc99SChristoph Hellwig return true; 1110eda5cc99SChristoph Hellwig case ELEVATOR_FRONT_MERGE: 1111eda5cc99SChristoph Hellwig if (!blk_mq_sched_allow_merge(q, rq, bio)) 1112eda5cc99SChristoph Hellwig return false; 1113eda5cc99SChristoph Hellwig if (bio_attempt_front_merge(rq, bio, nr_segs) != BIO_MERGE_OK) 1114eda5cc99SChristoph Hellwig return false; 1115eda5cc99SChristoph Hellwig *merged_request = attempt_front_merge(q, rq); 1116eda5cc99SChristoph Hellwig if (!*merged_request) 1117eda5cc99SChristoph Hellwig elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE); 1118eda5cc99SChristoph Hellwig return true; 1119eda5cc99SChristoph Hellwig case ELEVATOR_DISCARD_MERGE: 1120eda5cc99SChristoph Hellwig return bio_attempt_discard_merge(q, rq, bio) == BIO_MERGE_OK; 1121eda5cc99SChristoph Hellwig default: 1122eda5cc99SChristoph Hellwig return false; 1123eda5cc99SChristoph Hellwig } 1124eda5cc99SChristoph Hellwig } 1125eda5cc99SChristoph Hellwig EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge); 1126