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> 12*6b2b0459STejun 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 15654efd50bSKent Overstreet static struct bio *blk_bio_write_same_split(struct request_queue *q, 15754efd50bSKent Overstreet struct bio *bio, 158bdced438SMing Lei struct bio_set *bs, 159bdced438SMing Lei unsigned *nsegs) 16054efd50bSKent Overstreet { 161bdced438SMing Lei *nsegs = 1; 162bdced438SMing Lei 16354efd50bSKent Overstreet if (!q->limits.max_write_same_sectors) 16454efd50bSKent Overstreet return NULL; 16554efd50bSKent Overstreet 16654efd50bSKent Overstreet if (bio_sectors(bio) <= q->limits.max_write_same_sectors) 16754efd50bSKent Overstreet return NULL; 16854efd50bSKent Overstreet 16954efd50bSKent Overstreet return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); 17054efd50bSKent Overstreet } 17154efd50bSKent Overstreet 1729cc5169cSBart Van Assche /* 1739cc5169cSBart Van Assche * Return the maximum number of sectors from the start of a bio that may be 1749cc5169cSBart Van Assche * submitted as a single request to a block device. If enough sectors remain, 1759cc5169cSBart Van Assche * align the end to the physical block size. Otherwise align the end to the 1769cc5169cSBart Van Assche * logical block size. This approach minimizes the number of non-aligned 1779cc5169cSBart Van Assche * requests that are submitted to a block device if the start of a bio is not 1789cc5169cSBart Van Assche * aligned to a physical block boundary. 1799cc5169cSBart Van Assche */ 180d0e5fbb0SMing Lei static inline unsigned get_max_io_size(struct request_queue *q, 181d0e5fbb0SMing Lei struct bio *bio) 182d0e5fbb0SMing Lei { 1833ee16db3SMike Snitzer unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector, 0); 1849cc5169cSBart Van Assche unsigned max_sectors = sectors; 1859cc5169cSBart Van Assche unsigned pbs = queue_physical_block_size(q) >> SECTOR_SHIFT; 1869cc5169cSBart Van Assche unsigned lbs = queue_logical_block_size(q) >> SECTOR_SHIFT; 1879cc5169cSBart Van Assche unsigned start_offset = bio->bi_iter.bi_sector & (pbs - 1); 188d0e5fbb0SMing Lei 1899cc5169cSBart Van Assche max_sectors += start_offset; 1909cc5169cSBart Van Assche max_sectors &= ~(pbs - 1); 1919cc5169cSBart Van Assche if (max_sectors > start_offset) 1929cc5169cSBart Van Assche return max_sectors - start_offset; 193d0e5fbb0SMing Lei 194e4b469c6SKeith Busch return sectors & ~(lbs - 1); 195d0e5fbb0SMing Lei } 196d0e5fbb0SMing Lei 197429120f3SMing Lei static inline unsigned get_max_segment_size(const struct request_queue *q, 198429120f3SMing Lei struct page *start_page, 199429120f3SMing Lei unsigned long offset) 200dcebd755SMing Lei { 201dcebd755SMing Lei unsigned long mask = queue_segment_boundary(q); 202dcebd755SMing Lei 203429120f3SMing Lei offset = mask & (page_to_phys(start_page) + offset); 2044a2f704eSMing Lei 2054a2f704eSMing Lei /* 2064a2f704eSMing Lei * overflow may be triggered in case of zero page physical address 2074a2f704eSMing Lei * on 32bit arch, use queue's max segment size when that happens. 2084a2f704eSMing Lei */ 2094a2f704eSMing Lei return min_not_zero(mask - offset + 1, 2104a2f704eSMing Lei (unsigned long)queue_max_segment_size(q)); 211dcebd755SMing Lei } 212dcebd755SMing Lei 213708b25b3SBart Van Assche /** 214708b25b3SBart Van Assche * bvec_split_segs - verify whether or not a bvec should be split in the middle 215708b25b3SBart Van Assche * @q: [in] request queue associated with the bio associated with @bv 216708b25b3SBart Van Assche * @bv: [in] bvec to examine 217708b25b3SBart Van Assche * @nsegs: [in,out] Number of segments in the bio being built. Incremented 218708b25b3SBart Van Assche * by the number of segments from @bv that may be appended to that 219708b25b3SBart Van Assche * bio without exceeding @max_segs 220708b25b3SBart Van Assche * @sectors: [in,out] Number of sectors in the bio being built. Incremented 221708b25b3SBart Van Assche * by the number of sectors from @bv that may be appended to that 222708b25b3SBart Van Assche * bio without exceeding @max_sectors 223708b25b3SBart Van Assche * @max_segs: [in] upper bound for *@nsegs 224708b25b3SBart Van Assche * @max_sectors: [in] upper bound for *@sectors 225708b25b3SBart Van Assche * 226708b25b3SBart Van Assche * When splitting a bio, it can happen that a bvec is encountered that is too 227708b25b3SBart Van Assche * big to fit in a single segment and hence that it has to be split in the 228708b25b3SBart Van Assche * middle. This function verifies whether or not that should happen. The value 229708b25b3SBart Van Assche * %true is returned if and only if appending the entire @bv to a bio with 230708b25b3SBart Van Assche * *@nsegs segments and *@sectors sectors would make that bio unacceptable for 231708b25b3SBart Van Assche * the block driver. 232dcebd755SMing Lei */ 233af2c68feSBart Van Assche static bool bvec_split_segs(const struct request_queue *q, 234af2c68feSBart Van Assche const struct bio_vec *bv, unsigned *nsegs, 235708b25b3SBart Van Assche unsigned *sectors, unsigned max_segs, 236708b25b3SBart Van Assche unsigned max_sectors) 237dcebd755SMing Lei { 238708b25b3SBart Van Assche unsigned max_len = (min(max_sectors, UINT_MAX >> 9) - *sectors) << 9; 239708b25b3SBart Van Assche unsigned len = min(bv->bv_len, max_len); 240dcebd755SMing Lei unsigned total_len = 0; 241ff9811b3SBart Van Assche unsigned seg_size = 0; 242dcebd755SMing Lei 243ff9811b3SBart Van Assche while (len && *nsegs < max_segs) { 244429120f3SMing Lei seg_size = get_max_segment_size(q, bv->bv_page, 245429120f3SMing Lei bv->bv_offset + total_len); 246dcebd755SMing Lei seg_size = min(seg_size, len); 247dcebd755SMing Lei 248ff9811b3SBart Van Assche (*nsegs)++; 249dcebd755SMing Lei total_len += seg_size; 250dcebd755SMing Lei len -= seg_size; 251dcebd755SMing Lei 252dcebd755SMing Lei if ((bv->bv_offset + total_len) & queue_virt_boundary(q)) 253dcebd755SMing Lei break; 254dcebd755SMing Lei } 255dcebd755SMing Lei 256dcebd755SMing Lei *sectors += total_len >> 9; 257dcebd755SMing Lei 258708b25b3SBart Van Assche /* tell the caller to split the bvec if it is too big to fit */ 259708b25b3SBart Van Assche return len > 0 || bv->bv_len > max_len; 260dcebd755SMing Lei } 261dcebd755SMing Lei 262dad77584SBart Van Assche /** 263dad77584SBart Van Assche * blk_bio_segment_split - split a bio in two bios 264dad77584SBart Van Assche * @q: [in] request queue pointer 265dad77584SBart Van Assche * @bio: [in] bio to be split 266dad77584SBart Van Assche * @bs: [in] bio set to allocate the clone from 267dad77584SBart Van Assche * @segs: [out] number of segments in the bio with the first half of the sectors 268dad77584SBart Van Assche * 269dad77584SBart Van Assche * Clone @bio, update the bi_iter of the clone to represent the first sectors 270dad77584SBart Van Assche * of @bio and update @bio->bi_iter to represent the remaining sectors. The 271dad77584SBart Van Assche * following is guaranteed for the cloned bio: 272dad77584SBart Van Assche * - That it has at most get_max_io_size(@q, @bio) sectors. 273dad77584SBart Van Assche * - That it has at most queue_max_segments(@q) segments. 274dad77584SBart Van Assche * 275dad77584SBart Van Assche * Except for discard requests the cloned bio will point at the bi_io_vec of 276dad77584SBart Van Assche * the original bio. It is the responsibility of the caller to ensure that the 277dad77584SBart Van Assche * original bio is not freed before the cloned bio. The caller is also 278dad77584SBart Van Assche * responsible for ensuring that @bs is only destroyed after processing of the 279dad77584SBart Van Assche * split bio has finished. 280dad77584SBart Van Assche */ 28154efd50bSKent Overstreet static struct bio *blk_bio_segment_split(struct request_queue *q, 28254efd50bSKent Overstreet struct bio *bio, 283bdced438SMing Lei struct bio_set *bs, 284bdced438SMing Lei unsigned *segs) 28554efd50bSKent Overstreet { 2865014c311SJens Axboe struct bio_vec bv, bvprv, *bvprvp = NULL; 28754efd50bSKent Overstreet struct bvec_iter iter; 2886869875fSChristoph Hellwig unsigned nsegs = 0, sectors = 0; 289d0e5fbb0SMing Lei const unsigned max_sectors = get_max_io_size(q, bio); 29005b700baSMing Lei const unsigned max_segs = queue_max_segments(q); 29154efd50bSKent Overstreet 292dcebd755SMing Lei bio_for_each_bvec(bv, bio, iter) { 29354efd50bSKent Overstreet /* 29454efd50bSKent Overstreet * If the queue doesn't support SG gaps and adding this 29554efd50bSKent Overstreet * offset would create a gap, disallow it. 29654efd50bSKent Overstreet */ 2975014c311SJens Axboe if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) 29854efd50bSKent Overstreet goto split; 29954efd50bSKent Overstreet 30005b700baSMing Lei if (nsegs < max_segs && 301708b25b3SBart Van Assche sectors + (bv.bv_len >> 9) <= max_sectors && 302708b25b3SBart Van Assche bv.bv_offset + bv.bv_len <= PAGE_SIZE) { 303708b25b3SBart Van Assche nsegs++; 304708b25b3SBart Van Assche sectors += bv.bv_len >> 9; 305708b25b3SBart Van Assche } else if (bvec_split_segs(q, &bv, &nsegs, §ors, max_segs, 306708b25b3SBart Van Assche max_sectors)) { 307e36f6204SKeith Busch goto split; 308e36f6204SKeith Busch } 309e36f6204SKeith Busch 31054efd50bSKent Overstreet bvprv = bv; 311578270bfSMing Lei bvprvp = &bvprv; 31254efd50bSKent Overstreet } 31354efd50bSKent Overstreet 314d627065dSChristoph Hellwig *segs = nsegs; 315d627065dSChristoph Hellwig return NULL; 31654efd50bSKent Overstreet split: 317bdced438SMing Lei *segs = nsegs; 318cc29e1bfSJeffle Xu 319cc29e1bfSJeffle Xu /* 320cc29e1bfSJeffle Xu * Bio splitting may cause subtle trouble such as hang when doing sync 321cc29e1bfSJeffle Xu * iopoll in direct IO routine. Given performance gain of iopoll for 322cc29e1bfSJeffle Xu * big IO can be trival, disable iopoll when split needed. 323cc29e1bfSJeffle Xu */ 3246ce913feSChristoph Hellwig bio_clear_polled(bio); 325d627065dSChristoph Hellwig return bio_split(bio, sectors, GFP_NOIO, bs); 32654efd50bSKent Overstreet } 32754efd50bSKent Overstreet 328dad77584SBart Van Assche /** 329dad77584SBart Van Assche * __blk_queue_split - split a bio and submit the second half 330abd45c15SJens Axboe * @q: [in] request_queue new bio is being queued at 331dad77584SBart Van Assche * @bio: [in, out] bio to be split 332dad77584SBart Van Assche * @nr_segs: [out] number of segments in the first bio 333dad77584SBart Van Assche * 334dad77584SBart Van Assche * Split a bio into two bios, chain the two bios, submit the second half and 335dad77584SBart Van Assche * store a pointer to the first half in *@bio. If the second bio is still too 336dad77584SBart Van Assche * big it will be split by a recursive call to this function. Since this 337309dca30SChristoph Hellwig * function may allocate a new bio from q->bio_split, it is the responsibility 338309dca30SChristoph Hellwig * of the caller to ensure that q->bio_split is only released after processing 339309dca30SChristoph Hellwig * of the split bio has finished. 340dad77584SBart Van Assche */ 341abd45c15SJens Axboe void __blk_queue_split(struct request_queue *q, struct bio **bio, 342abd45c15SJens Axboe unsigned int *nr_segs) 34354efd50bSKent Overstreet { 344fa532287SChristoph Hellwig struct bio *split = NULL; 34554efd50bSKent Overstreet 3467afafc8aSAdrian Hunter switch (bio_op(*bio)) { 3477afafc8aSAdrian Hunter case REQ_OP_DISCARD: 3487afafc8aSAdrian Hunter case REQ_OP_SECURE_ERASE: 34914ccb66bSChristoph Hellwig split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs); 3507afafc8aSAdrian Hunter break; 351a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 35214ccb66bSChristoph Hellwig split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split, 35314ccb66bSChristoph Hellwig nr_segs); 354a6f0788eSChaitanya Kulkarni break; 3557afafc8aSAdrian Hunter case REQ_OP_WRITE_SAME: 35614ccb66bSChristoph Hellwig split = blk_bio_write_same_split(q, *bio, &q->bio_split, 35714ccb66bSChristoph Hellwig nr_segs); 3587afafc8aSAdrian Hunter break; 3597afafc8aSAdrian Hunter default: 36014ccb66bSChristoph Hellwig split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs); 3617afafc8aSAdrian Hunter break; 3627afafc8aSAdrian Hunter } 363bdced438SMing Lei 36454efd50bSKent Overstreet if (split) { 3656ac45aebSMing Lei /* there isn't chance to merge the splitted bio */ 3661eff9d32SJens Axboe split->bi_opf |= REQ_NOMERGE; 3676ac45aebSMing Lei 36854efd50bSKent Overstreet bio_chain(split, *bio); 369eb6f7f7cSChristoph Hellwig trace_block_split(split, (*bio)->bi_iter.bi_sector); 370ed00aabdSChristoph Hellwig submit_bio_noacct(*bio); 37154efd50bSKent Overstreet *bio = split; 37254efd50bSKent Overstreet } 37354efd50bSKent Overstreet } 37414ccb66bSChristoph Hellwig 375dad77584SBart Van Assche /** 376dad77584SBart Van Assche * blk_queue_split - split a bio and submit the second half 377dad77584SBart Van Assche * @bio: [in, out] bio to be split 378dad77584SBart Van Assche * 379dad77584SBart Van Assche * Split a bio into two bios, chains the two bios, submit the second half and 380dad77584SBart Van Assche * store a pointer to the first half in *@bio. Since this function may allocate 381309dca30SChristoph Hellwig * a new bio from q->bio_split, it is the responsibility of the caller to ensure 382309dca30SChristoph Hellwig * that q->bio_split is only released after processing of the split bio has 383309dca30SChristoph Hellwig * finished. 384dad77584SBart Van Assche */ 385f695ca38SChristoph Hellwig void blk_queue_split(struct bio **bio) 38614ccb66bSChristoph Hellwig { 387859897c3SPavel Begunkov struct request_queue *q = bdev_get_queue((*bio)->bi_bdev); 38814ccb66bSChristoph Hellwig unsigned int nr_segs; 38914ccb66bSChristoph Hellwig 390abd45c15SJens Axboe if (blk_may_split(q, *bio)) 391abd45c15SJens Axboe __blk_queue_split(q, bio, &nr_segs); 39214ccb66bSChristoph Hellwig } 39354efd50bSKent Overstreet EXPORT_SYMBOL(blk_queue_split); 39454efd50bSKent Overstreet 395e9cd19c0SChristoph Hellwig unsigned int blk_recalc_rq_segments(struct request *rq) 396d6d48196SJens Axboe { 3976869875fSChristoph Hellwig unsigned int nr_phys_segs = 0; 398ff9811b3SBart Van Assche unsigned int nr_sectors = 0; 399e9cd19c0SChristoph Hellwig struct req_iterator iter; 4006869875fSChristoph Hellwig struct bio_vec bv; 401d6d48196SJens Axboe 402e9cd19c0SChristoph Hellwig if (!rq->bio) 4031e428079SJens Axboe return 0; 404d6d48196SJens Axboe 405e9cd19c0SChristoph Hellwig switch (bio_op(rq->bio)) { 406a6f0788eSChaitanya Kulkarni case REQ_OP_DISCARD: 407a6f0788eSChaitanya Kulkarni case REQ_OP_SECURE_ERASE: 408a958937fSDavid Jeffery if (queue_max_discard_segments(rq->q) > 1) { 409a958937fSDavid Jeffery struct bio *bio = rq->bio; 410a958937fSDavid Jeffery 411a958937fSDavid Jeffery for_each_bio(bio) 412a958937fSDavid Jeffery nr_phys_segs++; 413a958937fSDavid Jeffery return nr_phys_segs; 414a958937fSDavid Jeffery } 415a958937fSDavid Jeffery return 1; 416a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 417f9d03f96SChristoph Hellwig return 0; 418f9d03f96SChristoph Hellwig case REQ_OP_WRITE_SAME: 4195cb8850cSKent Overstreet return 1; 420a6f0788eSChaitanya Kulkarni } 4215cb8850cSKent Overstreet 422e9cd19c0SChristoph Hellwig rq_for_each_bvec(bv, rq, iter) 423ff9811b3SBart Van Assche bvec_split_segs(rq->q, &bv, &nr_phys_segs, &nr_sectors, 424708b25b3SBart Van Assche UINT_MAX, UINT_MAX); 4251e428079SJens Axboe return nr_phys_segs; 4261e428079SJens Axboe } 4271e428079SJens Axboe 42848d7727cSMing Lei static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, 429862e5a5eSMing Lei struct scatterlist *sglist) 430862e5a5eSMing Lei { 431862e5a5eSMing Lei if (!*sg) 432862e5a5eSMing Lei return sglist; 433862e5a5eSMing Lei 434862e5a5eSMing Lei /* 435862e5a5eSMing Lei * If the driver previously mapped a shorter list, we could see a 436862e5a5eSMing Lei * termination bit prematurely unless it fully inits the sg table 437862e5a5eSMing Lei * on each mapping. We KNOW that there must be more entries here 438862e5a5eSMing Lei * or the driver would be buggy, so force clear the termination bit 439862e5a5eSMing Lei * to avoid doing a full sg_init_table() in drivers for each command. 440862e5a5eSMing Lei */ 441862e5a5eSMing Lei sg_unmark_end(*sg); 442862e5a5eSMing Lei return sg_next(*sg); 443862e5a5eSMing Lei } 444862e5a5eSMing Lei 445862e5a5eSMing Lei static unsigned blk_bvec_map_sg(struct request_queue *q, 446862e5a5eSMing Lei struct bio_vec *bvec, struct scatterlist *sglist, 447862e5a5eSMing Lei struct scatterlist **sg) 448862e5a5eSMing Lei { 449862e5a5eSMing Lei unsigned nbytes = bvec->bv_len; 4508a96a0e4SChristoph Hellwig unsigned nsegs = 0, total = 0; 451862e5a5eSMing Lei 452862e5a5eSMing Lei while (nbytes > 0) { 4538a96a0e4SChristoph Hellwig unsigned offset = bvec->bv_offset + total; 454429120f3SMing Lei unsigned len = min(get_max_segment_size(q, bvec->bv_page, 455429120f3SMing Lei offset), nbytes); 456f9f76879SChristoph Hellwig struct page *page = bvec->bv_page; 457f9f76879SChristoph Hellwig 458f9f76879SChristoph Hellwig /* 459f9f76879SChristoph Hellwig * Unfortunately a fair number of drivers barf on scatterlists 460f9f76879SChristoph Hellwig * that have an offset larger than PAGE_SIZE, despite other 461f9f76879SChristoph Hellwig * subsystems dealing with that invariant just fine. For now 462f9f76879SChristoph Hellwig * stick to the legacy format where we never present those from 463f9f76879SChristoph Hellwig * the block layer, but the code below should be removed once 464f9f76879SChristoph Hellwig * these offenders (mostly MMC/SD drivers) are fixed. 465f9f76879SChristoph Hellwig */ 466f9f76879SChristoph Hellwig page += (offset >> PAGE_SHIFT); 467f9f76879SChristoph Hellwig offset &= ~PAGE_MASK; 468862e5a5eSMing Lei 469862e5a5eSMing Lei *sg = blk_next_sg(sg, sglist); 470f9f76879SChristoph Hellwig sg_set_page(*sg, page, len, offset); 471862e5a5eSMing Lei 4728a96a0e4SChristoph Hellwig total += len; 4738a96a0e4SChristoph Hellwig nbytes -= len; 474862e5a5eSMing Lei nsegs++; 475862e5a5eSMing Lei } 476862e5a5eSMing Lei 477862e5a5eSMing Lei return nsegs; 478862e5a5eSMing Lei } 479862e5a5eSMing Lei 48016e3e418SMing Lei static inline int __blk_bvec_map_sg(struct bio_vec bv, 48116e3e418SMing Lei struct scatterlist *sglist, struct scatterlist **sg) 48216e3e418SMing Lei { 48316e3e418SMing Lei *sg = blk_next_sg(sg, sglist); 48416e3e418SMing Lei sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); 48516e3e418SMing Lei return 1; 48616e3e418SMing Lei } 48716e3e418SMing Lei 488f6970f83SMing Lei /* only try to merge bvecs into one sg if they are from two bios */ 489f6970f83SMing Lei static inline bool 490f6970f83SMing Lei __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec, 491f6970f83SMing Lei struct bio_vec *bvprv, struct scatterlist **sg) 492963ab9e5SAsias He { 493963ab9e5SAsias He 494963ab9e5SAsias He int nbytes = bvec->bv_len; 495963ab9e5SAsias He 496f6970f83SMing Lei if (!*sg) 497f6970f83SMing Lei return false; 498f6970f83SMing Lei 499b4b6cb61SMing Lei if ((*sg)->length + nbytes > queue_max_segment_size(q)) 500f6970f83SMing Lei return false; 501f6970f83SMing Lei 5023dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, bvprv, bvec)) 503f6970f83SMing Lei return false; 504963ab9e5SAsias He 505963ab9e5SAsias He (*sg)->length += nbytes; 506f6970f83SMing Lei 507f6970f83SMing Lei return true; 508963ab9e5SAsias He } 509963ab9e5SAsias He 5105cb8850cSKent Overstreet static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, 5115cb8850cSKent Overstreet struct scatterlist *sglist, 5125cb8850cSKent Overstreet struct scatterlist **sg) 5135cb8850cSKent Overstreet { 5143f649ab7SKees Cook struct bio_vec bvec, bvprv = { NULL }; 5155cb8850cSKent Overstreet struct bvec_iter iter; 51638417468SChristoph Hellwig int nsegs = 0; 517f6970f83SMing Lei bool new_bio = false; 5185cb8850cSKent Overstreet 519f6970f83SMing Lei for_each_bio(bio) { 520f6970f83SMing Lei bio_for_each_bvec(bvec, bio, iter) { 521f6970f83SMing Lei /* 522f6970f83SMing Lei * Only try to merge bvecs from two bios given we 523f6970f83SMing Lei * have done bio internal merge when adding pages 524f6970f83SMing Lei * to bio 525f6970f83SMing Lei */ 526f6970f83SMing Lei if (new_bio && 527f6970f83SMing Lei __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg)) 528f6970f83SMing Lei goto next_bvec; 529f6970f83SMing Lei 530f6970f83SMing Lei if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE) 531f6970f83SMing Lei nsegs += __blk_bvec_map_sg(bvec, sglist, sg); 532f6970f83SMing Lei else 533f6970f83SMing Lei nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg); 534f6970f83SMing Lei next_bvec: 535f6970f83SMing Lei new_bio = false; 536f6970f83SMing Lei } 537b21e11c5SMing Lei if (likely(bio->bi_iter.bi_size)) { 538f6970f83SMing Lei bvprv = bvec; 539f6970f83SMing Lei new_bio = true; 540f6970f83SMing Lei } 541b21e11c5SMing Lei } 5425cb8850cSKent Overstreet 5435cb8850cSKent Overstreet return nsegs; 5445cb8850cSKent Overstreet } 5455cb8850cSKent Overstreet 546d6d48196SJens Axboe /* 547d6d48196SJens Axboe * map a request to scatterlist, return number of sg entries setup. Caller 548d6d48196SJens Axboe * must make sure sg can hold rq->nr_phys_segments entries 549d6d48196SJens Axboe */ 55089de1504SChristoph Hellwig int __blk_rq_map_sg(struct request_queue *q, struct request *rq, 55189de1504SChristoph Hellwig struct scatterlist *sglist, struct scatterlist **last_sg) 552d6d48196SJens Axboe { 5535cb8850cSKent Overstreet int nsegs = 0; 554d6d48196SJens Axboe 555f9d03f96SChristoph Hellwig if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) 55689de1504SChristoph Hellwig nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, last_sg); 557f9d03f96SChristoph Hellwig else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME) 55889de1504SChristoph Hellwig nsegs = __blk_bvec_map_sg(bio_iovec(rq->bio), sglist, last_sg); 559f9d03f96SChristoph Hellwig else if (rq->bio) 56089de1504SChristoph Hellwig nsegs = __blk_bios_map_sg(q, rq->bio, sglist, last_sg); 561f18573abSFUJITA Tomonori 56289de1504SChristoph Hellwig if (*last_sg) 56389de1504SChristoph Hellwig sg_mark_end(*last_sg); 564d6d48196SJens Axboe 56512e57f59SMing Lei /* 56612e57f59SMing Lei * Something must have been wrong if the figured number of 56712e57f59SMing Lei * segment is bigger than number of req's physical segments 56812e57f59SMing Lei */ 569f9d03f96SChristoph Hellwig WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); 57012e57f59SMing Lei 571d6d48196SJens Axboe return nsegs; 572d6d48196SJens Axboe } 57389de1504SChristoph Hellwig EXPORT_SYMBOL(__blk_rq_map_sg); 574d6d48196SJens Axboe 575943b40c8SMing Lei static inline unsigned int blk_rq_get_max_segments(struct request *rq) 576943b40c8SMing Lei { 577943b40c8SMing Lei if (req_op(rq) == REQ_OP_DISCARD) 578943b40c8SMing Lei return queue_max_discard_segments(rq->q); 579943b40c8SMing Lei return queue_max_segments(rq->q); 580943b40c8SMing Lei } 581943b40c8SMing Lei 582badf7f64SChristoph Hellwig static inline unsigned int blk_rq_get_max_sectors(struct request *rq, 583badf7f64SChristoph Hellwig sector_t offset) 584badf7f64SChristoph Hellwig { 585badf7f64SChristoph Hellwig struct request_queue *q = rq->q; 586badf7f64SChristoph Hellwig 587badf7f64SChristoph Hellwig if (blk_rq_is_passthrough(rq)) 588badf7f64SChristoph Hellwig return q->limits.max_hw_sectors; 589badf7f64SChristoph Hellwig 590badf7f64SChristoph Hellwig if (!q->limits.chunk_sectors || 591badf7f64SChristoph Hellwig req_op(rq) == REQ_OP_DISCARD || 592badf7f64SChristoph Hellwig req_op(rq) == REQ_OP_SECURE_ERASE) 593badf7f64SChristoph Hellwig return blk_queue_get_max_sectors(q, req_op(rq)); 594badf7f64SChristoph Hellwig 595badf7f64SChristoph Hellwig return min(blk_max_size_offset(q, offset, 0), 596badf7f64SChristoph Hellwig blk_queue_get_max_sectors(q, req_op(rq))); 597badf7f64SChristoph Hellwig } 598badf7f64SChristoph Hellwig 59914ccb66bSChristoph Hellwig static inline int ll_new_hw_segment(struct request *req, struct bio *bio, 60014ccb66bSChristoph Hellwig unsigned int nr_phys_segs) 601d6d48196SJens Axboe { 602*6b2b0459STejun Heo if (!blk_cgroup_mergeable(req, bio)) 603*6b2b0459STejun Heo goto no_merge; 604*6b2b0459STejun Heo 6052705dfb2SMing Lei if (blk_integrity_merge_bio(req->q, req, bio) == false) 60613f05c8dSMartin K. Petersen goto no_merge; 60713f05c8dSMartin K. Petersen 6082705dfb2SMing Lei /* discard request merge won't add new segment */ 6092705dfb2SMing Lei if (req_op(req) == REQ_OP_DISCARD) 6102705dfb2SMing Lei return 1; 6112705dfb2SMing Lei 6122705dfb2SMing Lei if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) 61313f05c8dSMartin K. Petersen goto no_merge; 614d6d48196SJens Axboe 615d6d48196SJens Axboe /* 616d6d48196SJens Axboe * This will form the start of a new hw segment. Bump both 617d6d48196SJens Axboe * counters. 618d6d48196SJens Axboe */ 619d6d48196SJens Axboe req->nr_phys_segments += nr_phys_segs; 620d6d48196SJens Axboe return 1; 62113f05c8dSMartin K. Petersen 62213f05c8dSMartin K. Petersen no_merge: 62314ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 62413f05c8dSMartin K. Petersen return 0; 625d6d48196SJens Axboe } 626d6d48196SJens Axboe 62714ccb66bSChristoph Hellwig int ll_back_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs) 628d6d48196SJens Axboe { 6295e7c4274SJens Axboe if (req_gap_back_merge(req, bio)) 6305e7c4274SJens Axboe return 0; 6317f39add3SSagi Grimberg if (blk_integrity_rq(req) && 6327f39add3SSagi Grimberg integrity_req_gap_back_merge(req, bio)) 6337f39add3SSagi Grimberg return 0; 634a892c8d5SSatya Tangirala if (!bio_crypt_ctx_back_mergeable(req, bio)) 635a892c8d5SSatya Tangirala return 0; 636f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 63717007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) { 63814ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 639d6d48196SJens Axboe return 0; 640d6d48196SJens Axboe } 641d6d48196SJens Axboe 64214ccb66bSChristoph Hellwig return ll_new_hw_segment(req, bio, nr_segs); 643d6d48196SJens Axboe } 644d6d48196SJens Axboe 645eda5cc99SChristoph Hellwig static int ll_front_merge_fn(struct request *req, struct bio *bio, 646eda5cc99SChristoph Hellwig unsigned int nr_segs) 647d6d48196SJens Axboe { 6485e7c4274SJens Axboe if (req_gap_front_merge(req, bio)) 6495e7c4274SJens Axboe return 0; 6507f39add3SSagi Grimberg if (blk_integrity_rq(req) && 6517f39add3SSagi Grimberg integrity_req_gap_front_merge(req, bio)) 6527f39add3SSagi Grimberg return 0; 653a892c8d5SSatya Tangirala if (!bio_crypt_ctx_front_mergeable(req, bio)) 654a892c8d5SSatya Tangirala return 0; 655f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 65617007f39SDamien Le Moal blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { 65714ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 658d6d48196SJens Axboe return 0; 659d6d48196SJens Axboe } 660d6d48196SJens Axboe 66114ccb66bSChristoph Hellwig return ll_new_hw_segment(req, bio, nr_segs); 662d6d48196SJens Axboe } 663d6d48196SJens Axboe 664445251d0SJens Axboe static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, 665445251d0SJens Axboe struct request *next) 666445251d0SJens Axboe { 667445251d0SJens Axboe unsigned short segments = blk_rq_nr_discard_segments(req); 668445251d0SJens Axboe 669445251d0SJens Axboe if (segments >= queue_max_discard_segments(q)) 670445251d0SJens Axboe goto no_merge; 671445251d0SJens Axboe if (blk_rq_sectors(req) + bio_sectors(next->bio) > 672445251d0SJens Axboe blk_rq_get_max_sectors(req, blk_rq_pos(req))) 673445251d0SJens Axboe goto no_merge; 674445251d0SJens Axboe 675445251d0SJens Axboe req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); 676445251d0SJens Axboe return true; 677445251d0SJens Axboe no_merge: 678445251d0SJens Axboe req_set_nomerge(q, req); 679445251d0SJens Axboe return false; 680445251d0SJens Axboe } 681445251d0SJens Axboe 682d6d48196SJens Axboe static int ll_merge_requests_fn(struct request_queue *q, struct request *req, 683d6d48196SJens Axboe struct request *next) 684d6d48196SJens Axboe { 685d6d48196SJens Axboe int total_phys_segments; 686d6d48196SJens Axboe 6875e7c4274SJens Axboe if (req_gap_back_merge(req, next->bio)) 688854fbb9cSKeith Busch return 0; 689854fbb9cSKeith Busch 690d6d48196SJens Axboe /* 691d6d48196SJens Axboe * Will it become too large? 692d6d48196SJens Axboe */ 693f31dc1cdSMartin K. Petersen if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > 69417007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) 695d6d48196SJens Axboe return 0; 696d6d48196SJens Axboe 697d6d48196SJens Axboe total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; 698943b40c8SMing Lei if (total_phys_segments > blk_rq_get_max_segments(req)) 699d6d48196SJens Axboe return 0; 700d6d48196SJens Axboe 701*6b2b0459STejun Heo if (!blk_cgroup_mergeable(req, next->bio)) 702*6b2b0459STejun Heo return 0; 703*6b2b0459STejun Heo 7044eaf99beSMartin K. Petersen if (blk_integrity_merge_rq(q, req, next) == false) 70513f05c8dSMartin K. Petersen return 0; 70613f05c8dSMartin K. Petersen 707a892c8d5SSatya Tangirala if (!bio_crypt_ctx_merge_rq(req, next)) 708a892c8d5SSatya Tangirala return 0; 709a892c8d5SSatya Tangirala 710d6d48196SJens Axboe /* Merge is OK... */ 711d6d48196SJens Axboe req->nr_phys_segments = total_phys_segments; 712d6d48196SJens Axboe return 1; 713d6d48196SJens Axboe } 714d6d48196SJens Axboe 71580a761fdSTejun Heo /** 71680a761fdSTejun Heo * blk_rq_set_mixed_merge - mark a request as mixed merge 71780a761fdSTejun Heo * @rq: request to mark as mixed merge 71880a761fdSTejun Heo * 71980a761fdSTejun Heo * Description: 72080a761fdSTejun Heo * @rq is about to be mixed merged. Make sure the attributes 72180a761fdSTejun Heo * which can be mixed are set in each bio and mark @rq as mixed 72280a761fdSTejun Heo * merged. 72380a761fdSTejun Heo */ 72480a761fdSTejun Heo void blk_rq_set_mixed_merge(struct request *rq) 72580a761fdSTejun Heo { 72680a761fdSTejun Heo unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 72780a761fdSTejun Heo struct bio *bio; 72880a761fdSTejun Heo 729e8064021SChristoph Hellwig if (rq->rq_flags & RQF_MIXED_MERGE) 73080a761fdSTejun Heo return; 73180a761fdSTejun Heo 73280a761fdSTejun Heo /* 73380a761fdSTejun Heo * @rq will no longer represent mixable attributes for all the 73480a761fdSTejun Heo * contained bios. It will just track those of the first one. 73580a761fdSTejun Heo * Distributes the attributs to each bio. 73680a761fdSTejun Heo */ 73780a761fdSTejun Heo for (bio = rq->bio; bio; bio = bio->bi_next) { 7381eff9d32SJens Axboe WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && 7391eff9d32SJens Axboe (bio->bi_opf & REQ_FAILFAST_MASK) != ff); 7401eff9d32SJens Axboe bio->bi_opf |= ff; 74180a761fdSTejun Heo } 742e8064021SChristoph Hellwig rq->rq_flags |= RQF_MIXED_MERGE; 74380a761fdSTejun Heo } 74480a761fdSTejun Heo 745b9c54f56SKonstantin Khlebnikov static void blk_account_io_merge_request(struct request *req) 74626308eabSJerome Marchand { 74726308eabSJerome Marchand if (blk_do_io_stat(req)) { 748112f158fSMike Snitzer part_stat_lock(); 749b9c54f56SKonstantin Khlebnikov part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); 75026308eabSJerome Marchand part_stat_unlock(); 75126308eabSJerome Marchand } 75226308eabSJerome Marchand } 753b9c54f56SKonstantin Khlebnikov 754e96c0d83SEric Biggers static enum elv_merge blk_try_req_merge(struct request *req, 755e96c0d83SEric Biggers struct request *next) 75669840466SJianchao Wang { 75769840466SJianchao Wang if (blk_discard_mergable(req)) 75869840466SJianchao Wang return ELEVATOR_DISCARD_MERGE; 75969840466SJianchao Wang else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) 76069840466SJianchao Wang return ELEVATOR_BACK_MERGE; 76169840466SJianchao Wang 76269840466SJianchao Wang return ELEVATOR_NO_MERGE; 76369840466SJianchao Wang } 76426308eabSJerome Marchand 765badf7f64SChristoph Hellwig static inline bool blk_write_same_mergeable(struct bio *a, struct bio *b) 766badf7f64SChristoph Hellwig { 767badf7f64SChristoph Hellwig if (bio_page(a) == bio_page(b) && bio_offset(a) == bio_offset(b)) 768badf7f64SChristoph Hellwig return true; 769badf7f64SChristoph Hellwig return false; 770badf7f64SChristoph Hellwig } 771badf7f64SChristoph Hellwig 772d6d48196SJens Axboe /* 773b973cb7eSJens Axboe * For non-mq, this has to be called with the request spinlock acquired. 774b973cb7eSJens Axboe * For mq with scheduling, the appropriate queue wide lock should be held. 775d6d48196SJens Axboe */ 776b973cb7eSJens Axboe static struct request *attempt_merge(struct request_queue *q, 777b973cb7eSJens Axboe struct request *req, struct request *next) 778d6d48196SJens Axboe { 779d6d48196SJens Axboe if (!rq_mergeable(req) || !rq_mergeable(next)) 780b973cb7eSJens Axboe return NULL; 781d6d48196SJens Axboe 782288dab8aSChristoph Hellwig if (req_op(req) != req_op(next)) 783b973cb7eSJens Axboe return NULL; 784f31dc1cdSMartin K. Petersen 78579bb1dbdSChristoph Hellwig if (rq_data_dir(req) != rq_data_dir(next)) 786b973cb7eSJens Axboe return NULL; 787d6d48196SJens Axboe 7888fe0d473SMike Christie if (req_op(req) == REQ_OP_WRITE_SAME && 7894363ac7cSMartin K. Petersen !blk_write_same_mergeable(req->bio, next->bio)) 790b973cb7eSJens Axboe return NULL; 7914363ac7cSMartin K. Petersen 792d6d48196SJens Axboe /* 793cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 794cb6934f8SJens Axboe * non-hint IO. 795cb6934f8SJens Axboe */ 796cb6934f8SJens Axboe if (req->write_hint != next->write_hint) 797cb6934f8SJens Axboe return NULL; 798cb6934f8SJens Axboe 799668ffc03SDamien Le Moal if (req->ioprio != next->ioprio) 800668ffc03SDamien Le Moal return NULL; 801668ffc03SDamien Le Moal 802cb6934f8SJens Axboe /* 803d6d48196SJens Axboe * If we are allowed to merge, then append bio list 804d6d48196SJens Axboe * from next to rq and release next. merge_requests_fn 805d6d48196SJens Axboe * will have updated segment counts, update sector 806445251d0SJens Axboe * counts here. Handle DISCARDs separately, as they 807445251d0SJens Axboe * have separate settings. 808d6d48196SJens Axboe */ 80969840466SJianchao Wang 81069840466SJianchao Wang switch (blk_try_req_merge(req, next)) { 81169840466SJianchao Wang case ELEVATOR_DISCARD_MERGE: 812445251d0SJens Axboe if (!req_attempt_discard_merge(q, req, next)) 813445251d0SJens Axboe return NULL; 81469840466SJianchao Wang break; 81569840466SJianchao Wang case ELEVATOR_BACK_MERGE: 81669840466SJianchao Wang if (!ll_merge_requests_fn(q, req, next)) 817b973cb7eSJens Axboe return NULL; 81869840466SJianchao Wang break; 81969840466SJianchao Wang default: 82069840466SJianchao Wang return NULL; 82169840466SJianchao Wang } 822d6d48196SJens Axboe 823d6d48196SJens Axboe /* 82480a761fdSTejun Heo * If failfast settings disagree or any of the two is already 82580a761fdSTejun Heo * a mixed merge, mark both as mixed before proceeding. This 82680a761fdSTejun Heo * makes sure that all involved bios have mixable attributes 82780a761fdSTejun Heo * set properly. 82880a761fdSTejun Heo */ 829e8064021SChristoph Hellwig if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || 83080a761fdSTejun Heo (req->cmd_flags & REQ_FAILFAST_MASK) != 83180a761fdSTejun Heo (next->cmd_flags & REQ_FAILFAST_MASK)) { 83280a761fdSTejun Heo blk_rq_set_mixed_merge(req); 83380a761fdSTejun Heo blk_rq_set_mixed_merge(next); 83480a761fdSTejun Heo } 83580a761fdSTejun Heo 83680a761fdSTejun Heo /* 837522a7775SOmar Sandoval * At this point we have either done a back merge or front merge. We 838522a7775SOmar Sandoval * need the smaller start_time_ns of the merged requests to be the 839522a7775SOmar Sandoval * current request for accounting purposes. 840d6d48196SJens Axboe */ 841522a7775SOmar Sandoval if (next->start_time_ns < req->start_time_ns) 842522a7775SOmar Sandoval req->start_time_ns = next->start_time_ns; 843d6d48196SJens Axboe 844d6d48196SJens Axboe req->biotail->bi_next = next->bio; 845d6d48196SJens Axboe req->biotail = next->biotail; 846d6d48196SJens Axboe 847a2dec7b3STejun Heo req->__data_len += blk_rq_bytes(next); 848d6d48196SJens Axboe 8492a5cf35cSMing Lei if (!blk_discard_mergable(req)) 850d6d48196SJens Axboe elv_merge_requests(q, req, next); 851d6d48196SJens Axboe 85242dad764SJerome Marchand /* 85342dad764SJerome Marchand * 'next' is going away, so update stats accordingly 85442dad764SJerome Marchand */ 855b9c54f56SKonstantin Khlebnikov blk_account_io_merge_request(next); 856d6d48196SJens Axboe 857a54895faSChristoph Hellwig trace_block_rq_merge(next); 858f3bdc62fSJan Kara 859e4d750c9SJens Axboe /* 860e4d750c9SJens Axboe * ownership of bio passed from next to req, return 'next' for 861e4d750c9SJens Axboe * the caller to free 862e4d750c9SJens Axboe */ 8631cd96c24SBoaz Harrosh next->bio = NULL; 864b973cb7eSJens Axboe return next; 865d6d48196SJens Axboe } 866d6d48196SJens Axboe 867eda5cc99SChristoph Hellwig static struct request *attempt_back_merge(struct request_queue *q, 868eda5cc99SChristoph Hellwig struct request *rq) 869d6d48196SJens Axboe { 870d6d48196SJens Axboe struct request *next = elv_latter_request(q, rq); 871d6d48196SJens Axboe 872d6d48196SJens Axboe if (next) 873d6d48196SJens Axboe return attempt_merge(q, rq, next); 874d6d48196SJens Axboe 875b973cb7eSJens Axboe return NULL; 876d6d48196SJens Axboe } 877d6d48196SJens Axboe 878eda5cc99SChristoph Hellwig static struct request *attempt_front_merge(struct request_queue *q, 879eda5cc99SChristoph Hellwig 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 889fd2ef39cSJan Kara /* 890fd2ef39cSJan Kara * Try to merge 'next' into 'rq'. Return true if the merge happened, false 891fd2ef39cSJan Kara * otherwise. The caller is responsible for freeing 'next' if the merge 892fd2ef39cSJan Kara * happened. 893fd2ef39cSJan Kara */ 894fd2ef39cSJan Kara bool blk_attempt_req_merge(struct request_queue *q, struct request *rq, 8955e84ea3aSJens Axboe struct request *next) 8965e84ea3aSJens Axboe { 897fd2ef39cSJan Kara return attempt_merge(q, rq, next); 8985e84ea3aSJens Axboe } 899050c8ea8STejun Heo 900050c8ea8STejun Heo bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 901050c8ea8STejun Heo { 902e2a60da7SMartin K. Petersen if (!rq_mergeable(rq) || !bio_mergeable(bio)) 903050c8ea8STejun Heo return false; 904050c8ea8STejun Heo 905288dab8aSChristoph Hellwig if (req_op(rq) != bio_op(bio)) 906f31dc1cdSMartin K. Petersen return false; 907f31dc1cdSMartin K. Petersen 908050c8ea8STejun Heo /* different data direction or already started, don't merge */ 909050c8ea8STejun Heo if (bio_data_dir(bio) != rq_data_dir(rq)) 910050c8ea8STejun Heo return false; 911050c8ea8STejun Heo 912*6b2b0459STejun Heo /* don't merge across cgroup boundaries */ 913*6b2b0459STejun Heo if (!blk_cgroup_mergeable(rq, bio)) 914*6b2b0459STejun Heo return false; 915*6b2b0459STejun Heo 916050c8ea8STejun Heo /* only merge integrity protected bio into ditto rq */ 9174eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(rq->q, rq, bio) == false) 918050c8ea8STejun Heo return false; 919050c8ea8STejun Heo 920a892c8d5SSatya Tangirala /* Only merge if the crypt contexts are compatible */ 921a892c8d5SSatya Tangirala if (!bio_crypt_rq_ctx_compatible(rq, bio)) 922a892c8d5SSatya Tangirala return false; 923a892c8d5SSatya Tangirala 9244363ac7cSMartin K. Petersen /* must be using the same buffer */ 9258fe0d473SMike Christie if (req_op(rq) == REQ_OP_WRITE_SAME && 9264363ac7cSMartin K. Petersen !blk_write_same_mergeable(rq->bio, bio)) 9274363ac7cSMartin K. Petersen return false; 9284363ac7cSMartin K. Petersen 929cb6934f8SJens Axboe /* 930cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 931cb6934f8SJens Axboe * non-hint IO. 932cb6934f8SJens Axboe */ 933cb6934f8SJens Axboe if (rq->write_hint != bio->bi_write_hint) 934cb6934f8SJens Axboe return false; 935cb6934f8SJens Axboe 936668ffc03SDamien Le Moal if (rq->ioprio != bio_prio(bio)) 937668ffc03SDamien Le Moal return false; 938668ffc03SDamien Le Moal 939050c8ea8STejun Heo return true; 940050c8ea8STejun Heo } 941050c8ea8STejun Heo 94234fe7c05SChristoph Hellwig enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) 943050c8ea8STejun Heo { 94469840466SJianchao Wang if (blk_discard_mergable(rq)) 9451e739730SChristoph Hellwig return ELEVATOR_DISCARD_MERGE; 9461e739730SChristoph Hellwig else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) 947050c8ea8STejun Heo return ELEVATOR_BACK_MERGE; 9484f024f37SKent Overstreet else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) 949050c8ea8STejun Heo return ELEVATOR_FRONT_MERGE; 950050c8ea8STejun Heo return ELEVATOR_NO_MERGE; 951050c8ea8STejun Heo } 9528e756373SBaolin Wang 9538e756373SBaolin Wang static void blk_account_io_merge_bio(struct request *req) 9548e756373SBaolin Wang { 9558e756373SBaolin Wang if (!blk_do_io_stat(req)) 9568e756373SBaolin Wang return; 9578e756373SBaolin Wang 9588e756373SBaolin Wang part_stat_lock(); 9598e756373SBaolin Wang part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); 9608e756373SBaolin Wang part_stat_unlock(); 9618e756373SBaolin Wang } 9628e756373SBaolin Wang 963eda5cc99SChristoph Hellwig enum bio_merge_status { 964eda5cc99SChristoph Hellwig BIO_MERGE_OK, 965eda5cc99SChristoph Hellwig BIO_MERGE_NONE, 966eda5cc99SChristoph Hellwig BIO_MERGE_FAILED, 967eda5cc99SChristoph Hellwig }; 968eda5cc99SChristoph Hellwig 969eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_back_merge(struct request *req, 970eda5cc99SChristoph Hellwig struct bio *bio, unsigned int nr_segs) 9718e756373SBaolin Wang { 9728e756373SBaolin Wang const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 9738e756373SBaolin Wang 9748e756373SBaolin Wang if (!ll_back_merge_fn(req, bio, nr_segs)) 9757d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 9768e756373SBaolin Wang 977e8a676d6SChristoph Hellwig trace_block_bio_backmerge(bio); 9788e756373SBaolin Wang rq_qos_merge(req->q, req, bio); 9798e756373SBaolin Wang 9808e756373SBaolin Wang if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 9818e756373SBaolin Wang blk_rq_set_mixed_merge(req); 9828e756373SBaolin Wang 9838e756373SBaolin Wang req->biotail->bi_next = bio; 9848e756373SBaolin Wang req->biotail = bio; 9858e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 9868e756373SBaolin Wang 9878e756373SBaolin Wang bio_crypt_free_ctx(bio); 9888e756373SBaolin Wang 9898e756373SBaolin Wang blk_account_io_merge_bio(req); 9907d7ca7c5SBaolin Wang return BIO_MERGE_OK; 9918e756373SBaolin Wang } 9928e756373SBaolin Wang 993eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_front_merge(struct request *req, 994eda5cc99SChristoph Hellwig struct bio *bio, unsigned int nr_segs) 9958e756373SBaolin Wang { 9968e756373SBaolin Wang const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 9978e756373SBaolin Wang 9988e756373SBaolin Wang if (!ll_front_merge_fn(req, bio, nr_segs)) 9997d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 10008e756373SBaolin Wang 1001e8a676d6SChristoph Hellwig trace_block_bio_frontmerge(bio); 10028e756373SBaolin Wang rq_qos_merge(req->q, req, bio); 10038e756373SBaolin Wang 10048e756373SBaolin Wang if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 10058e756373SBaolin Wang blk_rq_set_mixed_merge(req); 10068e756373SBaolin Wang 10078e756373SBaolin Wang bio->bi_next = req->bio; 10088e756373SBaolin Wang req->bio = bio; 10098e756373SBaolin Wang 10108e756373SBaolin Wang req->__sector = bio->bi_iter.bi_sector; 10118e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 10128e756373SBaolin Wang 10138e756373SBaolin Wang bio_crypt_do_front_merge(req, bio); 10148e756373SBaolin Wang 10158e756373SBaolin Wang blk_account_io_merge_bio(req); 10167d7ca7c5SBaolin Wang return BIO_MERGE_OK; 10178e756373SBaolin Wang } 10188e756373SBaolin Wang 1019eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q, 1020eda5cc99SChristoph Hellwig struct request *req, struct bio *bio) 10218e756373SBaolin Wang { 10228e756373SBaolin Wang unsigned short segments = blk_rq_nr_discard_segments(req); 10238e756373SBaolin Wang 10248e756373SBaolin Wang if (segments >= queue_max_discard_segments(q)) 10258e756373SBaolin Wang goto no_merge; 10268e756373SBaolin Wang if (blk_rq_sectors(req) + bio_sectors(bio) > 10278e756373SBaolin Wang blk_rq_get_max_sectors(req, blk_rq_pos(req))) 10288e756373SBaolin Wang goto no_merge; 10298e756373SBaolin Wang 10308e756373SBaolin Wang rq_qos_merge(q, req, bio); 10318e756373SBaolin Wang 10328e756373SBaolin Wang req->biotail->bi_next = bio; 10338e756373SBaolin Wang req->biotail = bio; 10348e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 10358e756373SBaolin Wang req->nr_phys_segments = segments + 1; 10368e756373SBaolin Wang 10378e756373SBaolin Wang blk_account_io_merge_bio(req); 10387d7ca7c5SBaolin Wang return BIO_MERGE_OK; 10398e756373SBaolin Wang no_merge: 10408e756373SBaolin Wang req_set_nomerge(q, req); 10417d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 10427d7ca7c5SBaolin Wang } 10437d7ca7c5SBaolin Wang 10447d7ca7c5SBaolin Wang static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q, 10457d7ca7c5SBaolin Wang struct request *rq, 10467d7ca7c5SBaolin Wang struct bio *bio, 10477d7ca7c5SBaolin Wang unsigned int nr_segs, 10487d7ca7c5SBaolin Wang bool sched_allow_merge) 10497d7ca7c5SBaolin Wang { 10507d7ca7c5SBaolin Wang if (!blk_rq_merge_ok(rq, bio)) 10517d7ca7c5SBaolin Wang return BIO_MERGE_NONE; 10527d7ca7c5SBaolin Wang 10537d7ca7c5SBaolin Wang switch (blk_try_merge(rq, bio)) { 10547d7ca7c5SBaolin Wang case ELEVATOR_BACK_MERGE: 1055265600b7SBaolin Wang if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) 10567d7ca7c5SBaolin Wang return bio_attempt_back_merge(rq, bio, nr_segs); 10577d7ca7c5SBaolin Wang break; 10587d7ca7c5SBaolin Wang case ELEVATOR_FRONT_MERGE: 1059265600b7SBaolin Wang if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) 10607d7ca7c5SBaolin Wang return bio_attempt_front_merge(rq, bio, nr_segs); 10617d7ca7c5SBaolin Wang break; 10627d7ca7c5SBaolin Wang case ELEVATOR_DISCARD_MERGE: 10637d7ca7c5SBaolin Wang return bio_attempt_discard_merge(q, rq, bio); 10647d7ca7c5SBaolin Wang default: 10657d7ca7c5SBaolin Wang return BIO_MERGE_NONE; 10667d7ca7c5SBaolin Wang } 10677d7ca7c5SBaolin Wang 10687d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 10698e756373SBaolin Wang } 10708e756373SBaolin Wang 10718e756373SBaolin Wang /** 10728e756373SBaolin Wang * blk_attempt_plug_merge - try to merge with %current's plugged list 10738e756373SBaolin Wang * @q: request_queue new bio is being queued at 10748e756373SBaolin Wang * @bio: new bio being queued 10758e756373SBaolin Wang * @nr_segs: number of segments in @bio 107687c037d1SJens Axboe * from the passed in @q already in the plug list 10778e756373SBaolin Wang * 1078d38a9c04SJens Axboe * Determine whether @bio being queued on @q can be merged with the previous 1079d38a9c04SJens Axboe * request on %current's plugged list. Returns %true if merge was successful, 10808e756373SBaolin Wang * otherwise %false. 10818e756373SBaolin Wang * 10828e756373SBaolin Wang * Plugging coalesces IOs from the same issuer for the same purpose without 10838e756373SBaolin Wang * going through @q->queue_lock. As such it's more of an issuing mechanism 10848e756373SBaolin Wang * than scheduling, and the request, while may have elvpriv data, is not 10858e756373SBaolin Wang * added on the elevator at this point. In addition, we don't have 10868e756373SBaolin Wang * reliable access to the elevator outside queue lock. Only check basic 10878e756373SBaolin Wang * merging parameters without querying the elevator. 10888e756373SBaolin Wang * 10898e756373SBaolin Wang * Caller must ensure !blk_queue_nomerges(q) beforehand. 10908e756373SBaolin Wang */ 10918e756373SBaolin Wang bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 10920c5bcc92SChristoph Hellwig unsigned int nr_segs) 10938e756373SBaolin Wang { 10948e756373SBaolin Wang struct blk_plug *plug; 10958e756373SBaolin Wang struct request *rq; 10968e756373SBaolin Wang 10978e756373SBaolin Wang plug = blk_mq_plug(q, bio); 1098bc490f81SJens Axboe if (!plug || rq_list_empty(plug->mq_list)) 10998e756373SBaolin Wang return false; 11008e756373SBaolin Wang 11015b205071SJens Axboe rq_list_for_each(&plug->mq_list, rq) { 110287c037d1SJens Axboe if (rq->q == q) { 1103a1cb6537SMing Lei if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) == 1104a1cb6537SMing Lei BIO_MERGE_OK) 11058e756373SBaolin Wang return true; 11065b205071SJens Axboe break; 11075b205071SJens Axboe } 11085b205071SJens Axboe 11095b205071SJens Axboe /* 11105b205071SJens Axboe * Only keep iterating plug list for merges if we have multiple 11115b205071SJens Axboe * queues 11125b205071SJens Axboe */ 11135b205071SJens Axboe if (!plug->multiple_queues) 11145b205071SJens Axboe break; 1115a1cb6537SMing Lei } 11168e756373SBaolin Wang return false; 11178e756373SBaolin Wang } 1118bdc6a287SBaolin Wang 1119bdc6a287SBaolin Wang /* 1120bdc6a287SBaolin Wang * Iterate list of requests and see if we can merge this bio with any 1121bdc6a287SBaolin Wang * of them. 1122bdc6a287SBaolin Wang */ 1123bdc6a287SBaolin Wang bool blk_bio_list_merge(struct request_queue *q, struct list_head *list, 1124bdc6a287SBaolin Wang struct bio *bio, unsigned int nr_segs) 1125bdc6a287SBaolin Wang { 1126bdc6a287SBaolin Wang struct request *rq; 1127bdc6a287SBaolin Wang int checked = 8; 1128bdc6a287SBaolin Wang 1129bdc6a287SBaolin Wang list_for_each_entry_reverse(rq, list, queuelist) { 1130bdc6a287SBaolin Wang if (!checked--) 1131bdc6a287SBaolin Wang break; 1132bdc6a287SBaolin Wang 11337d7ca7c5SBaolin Wang switch (blk_attempt_bio_merge(q, rq, bio, nr_segs, true)) { 11347d7ca7c5SBaolin Wang case BIO_MERGE_NONE: 1135bdc6a287SBaolin Wang continue; 11367d7ca7c5SBaolin Wang case BIO_MERGE_OK: 11377d7ca7c5SBaolin Wang return true; 11387d7ca7c5SBaolin Wang case BIO_MERGE_FAILED: 11397d7ca7c5SBaolin Wang return false; 1140bdc6a287SBaolin Wang } 1141bdc6a287SBaolin Wang 1142bdc6a287SBaolin Wang } 1143bdc6a287SBaolin Wang 1144bdc6a287SBaolin Wang return false; 1145bdc6a287SBaolin Wang } 1146bdc6a287SBaolin Wang EXPORT_SYMBOL_GPL(blk_bio_list_merge); 1147eda5cc99SChristoph Hellwig 1148eda5cc99SChristoph Hellwig bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio, 1149eda5cc99SChristoph Hellwig unsigned int nr_segs, struct request **merged_request) 1150eda5cc99SChristoph Hellwig { 1151eda5cc99SChristoph Hellwig struct request *rq; 1152eda5cc99SChristoph Hellwig 1153eda5cc99SChristoph Hellwig switch (elv_merge(q, &rq, bio)) { 1154eda5cc99SChristoph Hellwig case ELEVATOR_BACK_MERGE: 1155eda5cc99SChristoph Hellwig if (!blk_mq_sched_allow_merge(q, rq, bio)) 1156eda5cc99SChristoph Hellwig return false; 1157eda5cc99SChristoph Hellwig if (bio_attempt_back_merge(rq, bio, nr_segs) != BIO_MERGE_OK) 1158eda5cc99SChristoph Hellwig return false; 1159eda5cc99SChristoph Hellwig *merged_request = attempt_back_merge(q, rq); 1160eda5cc99SChristoph Hellwig if (!*merged_request) 1161eda5cc99SChristoph Hellwig elv_merged_request(q, rq, ELEVATOR_BACK_MERGE); 1162eda5cc99SChristoph Hellwig return true; 1163eda5cc99SChristoph Hellwig case ELEVATOR_FRONT_MERGE: 1164eda5cc99SChristoph Hellwig if (!blk_mq_sched_allow_merge(q, rq, bio)) 1165eda5cc99SChristoph Hellwig return false; 1166eda5cc99SChristoph Hellwig if (bio_attempt_front_merge(rq, bio, nr_segs) != BIO_MERGE_OK) 1167eda5cc99SChristoph Hellwig return false; 1168eda5cc99SChristoph Hellwig *merged_request = attempt_front_merge(q, rq); 1169eda5cc99SChristoph Hellwig if (!*merged_request) 1170eda5cc99SChristoph Hellwig elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE); 1171eda5cc99SChristoph Hellwig return true; 1172eda5cc99SChristoph Hellwig case ELEVATOR_DISCARD_MERGE: 1173eda5cc99SChristoph Hellwig return bio_attempt_discard_merge(q, rq, bio) == BIO_MERGE_OK; 1174eda5cc99SChristoph Hellwig default: 1175eda5cc99SChristoph Hellwig return false; 1176eda5cc99SChristoph Hellwig } 1177eda5cc99SChristoph Hellwig } 1178eda5cc99SChristoph Hellwig EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge); 1179