1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 2d6d48196SJens Axboe /* 3d6d48196SJens Axboe * Functions related to segment and merge handling 4d6d48196SJens Axboe */ 5d6d48196SJens Axboe #include <linux/kernel.h> 6d6d48196SJens Axboe #include <linux/module.h> 7d6d48196SJens Axboe #include <linux/bio.h> 8d6d48196SJens Axboe #include <linux/blkdev.h> 9d6d48196SJens Axboe #include <linux/scatterlist.h> 10d6d48196SJens Axboe 11cda22646SMike Krinkin #include <trace/events/block.h> 12cda22646SMike Krinkin 13d6d48196SJens Axboe #include "blk.h" 148e756373SBaolin Wang #include "blk-rq-qos.h" 15d6d48196SJens Axboe 16e9907009SChristoph Hellwig static inline bool bio_will_gap(struct request_queue *q, 17e9907009SChristoph Hellwig struct request *prev_rq, struct bio *prev, struct bio *next) 18e9907009SChristoph Hellwig { 19e9907009SChristoph Hellwig struct bio_vec pb, nb; 20e9907009SChristoph Hellwig 21e9907009SChristoph Hellwig if (!bio_has_data(prev) || !queue_virt_boundary(q)) 22e9907009SChristoph Hellwig return false; 23e9907009SChristoph Hellwig 24e9907009SChristoph Hellwig /* 25e9907009SChristoph Hellwig * Don't merge if the 1st bio starts with non-zero offset, otherwise it 26e9907009SChristoph Hellwig * is quite difficult to respect the sg gap limit. We work hard to 27e9907009SChristoph Hellwig * merge a huge number of small single bios in case of mkfs. 28e9907009SChristoph Hellwig */ 29e9907009SChristoph Hellwig if (prev_rq) 30e9907009SChristoph Hellwig bio_get_first_bvec(prev_rq->bio, &pb); 31e9907009SChristoph Hellwig else 32e9907009SChristoph Hellwig bio_get_first_bvec(prev, &pb); 33df376b2eSJohannes Thumshirn if (pb.bv_offset & queue_virt_boundary(q)) 34e9907009SChristoph Hellwig return true; 35e9907009SChristoph Hellwig 36e9907009SChristoph Hellwig /* 37e9907009SChristoph Hellwig * We don't need to worry about the situation that the merged segment 38e9907009SChristoph Hellwig * ends in unaligned virt boundary: 39e9907009SChristoph Hellwig * 40e9907009SChristoph Hellwig * - if 'pb' ends aligned, the merged segment ends aligned 41e9907009SChristoph Hellwig * - if 'pb' ends unaligned, the next bio must include 42e9907009SChristoph Hellwig * one single bvec of 'nb', otherwise the 'nb' can't 43e9907009SChristoph Hellwig * merge with 'pb' 44e9907009SChristoph Hellwig */ 45e9907009SChristoph Hellwig bio_get_last_bvec(prev, &pb); 46e9907009SChristoph Hellwig bio_get_first_bvec(next, &nb); 47200a9affSChristoph Hellwig if (biovec_phys_mergeable(q, &pb, &nb)) 48e9907009SChristoph Hellwig return false; 49e9907009SChristoph Hellwig return __bvec_gap_to_prev(q, &pb, nb.bv_offset); 50e9907009SChristoph Hellwig } 51e9907009SChristoph Hellwig 52e9907009SChristoph Hellwig static inline bool req_gap_back_merge(struct request *req, struct bio *bio) 53e9907009SChristoph Hellwig { 54e9907009SChristoph Hellwig return bio_will_gap(req->q, req, req->biotail, bio); 55e9907009SChristoph Hellwig } 56e9907009SChristoph Hellwig 57e9907009SChristoph Hellwig static inline bool req_gap_front_merge(struct request *req, struct bio *bio) 58e9907009SChristoph Hellwig { 59e9907009SChristoph Hellwig return bio_will_gap(req->q, NULL, bio, req->bio); 60e9907009SChristoph Hellwig } 61e9907009SChristoph Hellwig 6254efd50bSKent Overstreet static struct bio *blk_bio_discard_split(struct request_queue *q, 6354efd50bSKent Overstreet struct bio *bio, 64bdced438SMing Lei struct bio_set *bs, 65bdced438SMing Lei unsigned *nsegs) 6654efd50bSKent Overstreet { 6754efd50bSKent Overstreet unsigned int max_discard_sectors, granularity; 6854efd50bSKent Overstreet int alignment; 6954efd50bSKent Overstreet sector_t tmp; 7054efd50bSKent Overstreet unsigned split_sectors; 7154efd50bSKent Overstreet 72bdced438SMing Lei *nsegs = 1; 73bdced438SMing Lei 7454efd50bSKent Overstreet /* Zero-sector (unknown) and one-sector granularities are the same. */ 7554efd50bSKent Overstreet granularity = max(q->limits.discard_granularity >> 9, 1U); 7654efd50bSKent Overstreet 771adfc5e4SMing Lei max_discard_sectors = min(q->limits.max_discard_sectors, 781adfc5e4SMing Lei bio_allowed_max_sectors(q)); 7954efd50bSKent Overstreet max_discard_sectors -= max_discard_sectors % granularity; 8054efd50bSKent Overstreet 8154efd50bSKent Overstreet if (unlikely(!max_discard_sectors)) { 8254efd50bSKent Overstreet /* XXX: warn */ 8354efd50bSKent Overstreet return NULL; 8454efd50bSKent Overstreet } 8554efd50bSKent Overstreet 8654efd50bSKent Overstreet if (bio_sectors(bio) <= max_discard_sectors) 8754efd50bSKent Overstreet return NULL; 8854efd50bSKent Overstreet 8954efd50bSKent Overstreet split_sectors = max_discard_sectors; 9054efd50bSKent Overstreet 9154efd50bSKent Overstreet /* 9254efd50bSKent Overstreet * If the next starting sector would be misaligned, stop the discard at 9354efd50bSKent Overstreet * the previous aligned sector. 9454efd50bSKent Overstreet */ 9554efd50bSKent Overstreet alignment = (q->limits.discard_alignment >> 9) % granularity; 9654efd50bSKent Overstreet 9754efd50bSKent Overstreet tmp = bio->bi_iter.bi_sector + split_sectors - alignment; 9854efd50bSKent Overstreet tmp = sector_div(tmp, granularity); 9954efd50bSKent Overstreet 10054efd50bSKent Overstreet if (split_sectors > tmp) 10154efd50bSKent Overstreet split_sectors -= tmp; 10254efd50bSKent Overstreet 10354efd50bSKent Overstreet return bio_split(bio, split_sectors, GFP_NOIO, bs); 10454efd50bSKent Overstreet } 10554efd50bSKent Overstreet 106885fa13fSChristoph Hellwig static struct bio *blk_bio_write_zeroes_split(struct request_queue *q, 107885fa13fSChristoph Hellwig struct bio *bio, struct bio_set *bs, unsigned *nsegs) 108885fa13fSChristoph Hellwig { 109d665e12aSChristoph Hellwig *nsegs = 0; 110885fa13fSChristoph Hellwig 111885fa13fSChristoph Hellwig if (!q->limits.max_write_zeroes_sectors) 112885fa13fSChristoph Hellwig return NULL; 113885fa13fSChristoph Hellwig 114885fa13fSChristoph Hellwig if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors) 115885fa13fSChristoph Hellwig return NULL; 116885fa13fSChristoph Hellwig 117885fa13fSChristoph Hellwig return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs); 118885fa13fSChristoph Hellwig } 119885fa13fSChristoph Hellwig 12054efd50bSKent Overstreet static struct bio *blk_bio_write_same_split(struct request_queue *q, 12154efd50bSKent Overstreet struct bio *bio, 122bdced438SMing Lei struct bio_set *bs, 123bdced438SMing Lei unsigned *nsegs) 12454efd50bSKent Overstreet { 125bdced438SMing Lei *nsegs = 1; 126bdced438SMing Lei 12754efd50bSKent Overstreet if (!q->limits.max_write_same_sectors) 12854efd50bSKent Overstreet return NULL; 12954efd50bSKent Overstreet 13054efd50bSKent Overstreet if (bio_sectors(bio) <= q->limits.max_write_same_sectors) 13154efd50bSKent Overstreet return NULL; 13254efd50bSKent Overstreet 13354efd50bSKent Overstreet return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); 13454efd50bSKent Overstreet } 13554efd50bSKent Overstreet 1369cc5169cSBart Van Assche /* 1379cc5169cSBart Van Assche * Return the maximum number of sectors from the start of a bio that may be 1389cc5169cSBart Van Assche * submitted as a single request to a block device. If enough sectors remain, 1399cc5169cSBart Van Assche * align the end to the physical block size. Otherwise align the end to the 1409cc5169cSBart Van Assche * logical block size. This approach minimizes the number of non-aligned 1419cc5169cSBart Van Assche * requests that are submitted to a block device if the start of a bio is not 1429cc5169cSBart Van Assche * aligned to a physical block boundary. 1439cc5169cSBart Van Assche */ 144d0e5fbb0SMing Lei static inline unsigned get_max_io_size(struct request_queue *q, 145d0e5fbb0SMing Lei struct bio *bio) 146d0e5fbb0SMing Lei { 147d0e5fbb0SMing Lei unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector); 1489cc5169cSBart Van Assche unsigned max_sectors = sectors; 1499cc5169cSBart Van Assche unsigned pbs = queue_physical_block_size(q) >> SECTOR_SHIFT; 1509cc5169cSBart Van Assche unsigned lbs = queue_logical_block_size(q) >> SECTOR_SHIFT; 1519cc5169cSBart Van Assche unsigned start_offset = bio->bi_iter.bi_sector & (pbs - 1); 152d0e5fbb0SMing Lei 1539cc5169cSBart Van Assche max_sectors += start_offset; 1549cc5169cSBart Van Assche max_sectors &= ~(pbs - 1); 1559cc5169cSBart Van Assche if (max_sectors > start_offset) 1569cc5169cSBart Van Assche return max_sectors - start_offset; 157d0e5fbb0SMing Lei 158e4b469c6SKeith Busch return sectors & ~(lbs - 1); 159d0e5fbb0SMing Lei } 160d0e5fbb0SMing Lei 161429120f3SMing Lei static inline unsigned get_max_segment_size(const struct request_queue *q, 162429120f3SMing Lei struct page *start_page, 163429120f3SMing Lei unsigned long offset) 164dcebd755SMing Lei { 165dcebd755SMing Lei unsigned long mask = queue_segment_boundary(q); 166dcebd755SMing Lei 167429120f3SMing Lei offset = mask & (page_to_phys(start_page) + offset); 1684a2f704eSMing Lei 1694a2f704eSMing Lei /* 1704a2f704eSMing Lei * overflow may be triggered in case of zero page physical address 1714a2f704eSMing Lei * on 32bit arch, use queue's max segment size when that happens. 1724a2f704eSMing Lei */ 1734a2f704eSMing Lei return min_not_zero(mask - offset + 1, 1744a2f704eSMing Lei (unsigned long)queue_max_segment_size(q)); 175dcebd755SMing Lei } 176dcebd755SMing Lei 177708b25b3SBart Van Assche /** 178708b25b3SBart Van Assche * bvec_split_segs - verify whether or not a bvec should be split in the middle 179708b25b3SBart Van Assche * @q: [in] request queue associated with the bio associated with @bv 180708b25b3SBart Van Assche * @bv: [in] bvec to examine 181708b25b3SBart Van Assche * @nsegs: [in,out] Number of segments in the bio being built. Incremented 182708b25b3SBart Van Assche * by the number of segments from @bv that may be appended to that 183708b25b3SBart Van Assche * bio without exceeding @max_segs 184708b25b3SBart Van Assche * @sectors: [in,out] Number of sectors in the bio being built. Incremented 185708b25b3SBart Van Assche * by the number of sectors from @bv that may be appended to that 186708b25b3SBart Van Assche * bio without exceeding @max_sectors 187708b25b3SBart Van Assche * @max_segs: [in] upper bound for *@nsegs 188708b25b3SBart Van Assche * @max_sectors: [in] upper bound for *@sectors 189708b25b3SBart Van Assche * 190708b25b3SBart Van Assche * When splitting a bio, it can happen that a bvec is encountered that is too 191708b25b3SBart Van Assche * big to fit in a single segment and hence that it has to be split in the 192708b25b3SBart Van Assche * middle. This function verifies whether or not that should happen. The value 193708b25b3SBart Van Assche * %true is returned if and only if appending the entire @bv to a bio with 194708b25b3SBart Van Assche * *@nsegs segments and *@sectors sectors would make that bio unacceptable for 195708b25b3SBart Van Assche * the block driver. 196dcebd755SMing Lei */ 197af2c68feSBart Van Assche static bool bvec_split_segs(const struct request_queue *q, 198af2c68feSBart Van Assche const struct bio_vec *bv, unsigned *nsegs, 199708b25b3SBart Van Assche unsigned *sectors, unsigned max_segs, 200708b25b3SBart Van Assche unsigned max_sectors) 201dcebd755SMing Lei { 202708b25b3SBart Van Assche unsigned max_len = (min(max_sectors, UINT_MAX >> 9) - *sectors) << 9; 203708b25b3SBart Van Assche unsigned len = min(bv->bv_len, max_len); 204dcebd755SMing Lei unsigned total_len = 0; 205ff9811b3SBart Van Assche unsigned seg_size = 0; 206dcebd755SMing Lei 207ff9811b3SBart Van Assche while (len && *nsegs < max_segs) { 208429120f3SMing Lei seg_size = get_max_segment_size(q, bv->bv_page, 209429120f3SMing Lei bv->bv_offset + total_len); 210dcebd755SMing Lei seg_size = min(seg_size, len); 211dcebd755SMing Lei 212ff9811b3SBart Van Assche (*nsegs)++; 213dcebd755SMing Lei total_len += seg_size; 214dcebd755SMing Lei len -= seg_size; 215dcebd755SMing Lei 216dcebd755SMing Lei if ((bv->bv_offset + total_len) & queue_virt_boundary(q)) 217dcebd755SMing Lei break; 218dcebd755SMing Lei } 219dcebd755SMing Lei 220dcebd755SMing Lei *sectors += total_len >> 9; 221dcebd755SMing Lei 222708b25b3SBart Van Assche /* tell the caller to split the bvec if it is too big to fit */ 223708b25b3SBart Van Assche return len > 0 || bv->bv_len > max_len; 224dcebd755SMing Lei } 225dcebd755SMing Lei 226dad77584SBart Van Assche /** 227dad77584SBart Van Assche * blk_bio_segment_split - split a bio in two bios 228dad77584SBart Van Assche * @q: [in] request queue pointer 229dad77584SBart Van Assche * @bio: [in] bio to be split 230dad77584SBart Van Assche * @bs: [in] bio set to allocate the clone from 231dad77584SBart Van Assche * @segs: [out] number of segments in the bio with the first half of the sectors 232dad77584SBart Van Assche * 233dad77584SBart Van Assche * Clone @bio, update the bi_iter of the clone to represent the first sectors 234dad77584SBart Van Assche * of @bio and update @bio->bi_iter to represent the remaining sectors. The 235dad77584SBart Van Assche * following is guaranteed for the cloned bio: 236dad77584SBart Van Assche * - That it has at most get_max_io_size(@q, @bio) sectors. 237dad77584SBart Van Assche * - That it has at most queue_max_segments(@q) segments. 238dad77584SBart Van Assche * 239dad77584SBart Van Assche * Except for discard requests the cloned bio will point at the bi_io_vec of 240dad77584SBart Van Assche * the original bio. It is the responsibility of the caller to ensure that the 241dad77584SBart Van Assche * original bio is not freed before the cloned bio. The caller is also 242dad77584SBart Van Assche * responsible for ensuring that @bs is only destroyed after processing of the 243dad77584SBart Van Assche * split bio has finished. 244dad77584SBart Van Assche */ 24554efd50bSKent Overstreet static struct bio *blk_bio_segment_split(struct request_queue *q, 24654efd50bSKent Overstreet struct bio *bio, 247bdced438SMing Lei struct bio_set *bs, 248bdced438SMing Lei unsigned *segs) 24954efd50bSKent Overstreet { 2505014c311SJens Axboe struct bio_vec bv, bvprv, *bvprvp = NULL; 25154efd50bSKent Overstreet struct bvec_iter iter; 2526869875fSChristoph Hellwig unsigned nsegs = 0, sectors = 0; 253d0e5fbb0SMing Lei const unsigned max_sectors = get_max_io_size(q, bio); 25405b700baSMing Lei const unsigned max_segs = queue_max_segments(q); 25554efd50bSKent Overstreet 256dcebd755SMing Lei bio_for_each_bvec(bv, bio, iter) { 25754efd50bSKent Overstreet /* 25854efd50bSKent Overstreet * If the queue doesn't support SG gaps and adding this 25954efd50bSKent Overstreet * offset would create a gap, disallow it. 26054efd50bSKent Overstreet */ 2615014c311SJens Axboe if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) 26254efd50bSKent Overstreet goto split; 26354efd50bSKent Overstreet 26405b700baSMing Lei if (nsegs < max_segs && 265708b25b3SBart Van Assche sectors + (bv.bv_len >> 9) <= max_sectors && 266708b25b3SBart Van Assche bv.bv_offset + bv.bv_len <= PAGE_SIZE) { 267708b25b3SBart Van Assche nsegs++; 268708b25b3SBart Van Assche sectors += bv.bv_len >> 9; 269708b25b3SBart Van Assche } else if (bvec_split_segs(q, &bv, &nsegs, §ors, max_segs, 270708b25b3SBart Van Assche max_sectors)) { 271e36f6204SKeith Busch goto split; 272e36f6204SKeith Busch } 273e36f6204SKeith Busch 27454efd50bSKent Overstreet bvprv = bv; 275578270bfSMing Lei bvprvp = &bvprv; 27654efd50bSKent Overstreet } 27754efd50bSKent Overstreet 278d627065dSChristoph Hellwig *segs = nsegs; 279d627065dSChristoph Hellwig return NULL; 28054efd50bSKent Overstreet split: 281bdced438SMing Lei *segs = nsegs; 282*cc29e1bfSJeffle Xu 283*cc29e1bfSJeffle Xu /* 284*cc29e1bfSJeffle Xu * Bio splitting may cause subtle trouble such as hang when doing sync 285*cc29e1bfSJeffle Xu * iopoll in direct IO routine. Given performance gain of iopoll for 286*cc29e1bfSJeffle Xu * big IO can be trival, disable iopoll when split needed. 287*cc29e1bfSJeffle Xu */ 288*cc29e1bfSJeffle Xu bio->bi_opf &= ~REQ_HIPRI; 289*cc29e1bfSJeffle Xu 290d627065dSChristoph Hellwig return bio_split(bio, sectors, GFP_NOIO, bs); 29154efd50bSKent Overstreet } 29254efd50bSKent Overstreet 293dad77584SBart Van Assche /** 294dad77584SBart Van Assche * __blk_queue_split - split a bio and submit the second half 295dad77584SBart Van Assche * @bio: [in, out] bio to be split 296dad77584SBart Van Assche * @nr_segs: [out] number of segments in the first bio 297dad77584SBart Van Assche * 298dad77584SBart Van Assche * Split a bio into two bios, chain the two bios, submit the second half and 299dad77584SBart Van Assche * store a pointer to the first half in *@bio. If the second bio is still too 300dad77584SBart Van Assche * big it will be split by a recursive call to this function. Since this 301f695ca38SChristoph Hellwig * function may allocate a new bio from @bio->bi_disk->queue->bio_split, it is 302f695ca38SChristoph Hellwig * the responsibility of the caller to ensure that 303f695ca38SChristoph Hellwig * @bio->bi_disk->queue->bio_split is only released after processing of the 304dad77584SBart Van Assche * split bio has finished. 305dad77584SBart Van Assche */ 306f695ca38SChristoph Hellwig void __blk_queue_split(struct bio **bio, unsigned int *nr_segs) 30754efd50bSKent Overstreet { 308f695ca38SChristoph Hellwig struct request_queue *q = (*bio)->bi_disk->queue; 309fa532287SChristoph Hellwig struct bio *split = NULL; 31054efd50bSKent Overstreet 3117afafc8aSAdrian Hunter switch (bio_op(*bio)) { 3127afafc8aSAdrian Hunter case REQ_OP_DISCARD: 3137afafc8aSAdrian Hunter case REQ_OP_SECURE_ERASE: 31414ccb66bSChristoph Hellwig split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs); 3157afafc8aSAdrian Hunter break; 316a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 31714ccb66bSChristoph Hellwig split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split, 31814ccb66bSChristoph Hellwig nr_segs); 319a6f0788eSChaitanya Kulkarni break; 3207afafc8aSAdrian Hunter case REQ_OP_WRITE_SAME: 32114ccb66bSChristoph Hellwig split = blk_bio_write_same_split(q, *bio, &q->bio_split, 32214ccb66bSChristoph Hellwig nr_segs); 3237afafc8aSAdrian Hunter break; 3247afafc8aSAdrian Hunter default: 325fa532287SChristoph Hellwig /* 326fa532287SChristoph Hellwig * All drivers must accept single-segments bios that are <= 327fa532287SChristoph Hellwig * PAGE_SIZE. This is a quick and dirty check that relies on 328fa532287SChristoph Hellwig * the fact that bi_io_vec[0] is always valid if a bio has data. 329fa532287SChristoph Hellwig * The check might lead to occasional false negatives when bios 330fa532287SChristoph Hellwig * are cloned, but compared to the performance impact of cloned 331fa532287SChristoph Hellwig * bios themselves the loop below doesn't matter anyway. 332fa532287SChristoph Hellwig */ 333fa532287SChristoph Hellwig if (!q->limits.chunk_sectors && 334fa532287SChristoph Hellwig (*bio)->bi_vcnt == 1 && 33559db8ba2SMing Lei ((*bio)->bi_io_vec[0].bv_len + 3361e279153SJens Axboe (*bio)->bi_io_vec[0].bv_offset) <= PAGE_SIZE) { 337fa532287SChristoph Hellwig *nr_segs = 1; 338fa532287SChristoph Hellwig break; 339fa532287SChristoph Hellwig } 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 34854efd50bSKent Overstreet bio_chain(split, *bio); 349eb6f7f7cSChristoph Hellwig trace_block_split(split, (*bio)->bi_iter.bi_sector); 350ed00aabdSChristoph Hellwig submit_bio_noacct(*bio); 35154efd50bSKent Overstreet *bio = split; 35254efd50bSKent Overstreet } 35354efd50bSKent Overstreet } 35414ccb66bSChristoph Hellwig 355dad77584SBart Van Assche /** 356dad77584SBart Van Assche * blk_queue_split - split a bio and submit the second half 357dad77584SBart Van Assche * @bio: [in, out] bio to be split 358dad77584SBart Van Assche * 359dad77584SBart Van Assche * Split a bio into two bios, chains the two bios, submit the second half and 360dad77584SBart Van Assche * store a pointer to the first half in *@bio. Since this function may allocate 361f695ca38SChristoph Hellwig * a new bio from @bio->bi_disk->queue->bio_split, it is the responsibility of 362f695ca38SChristoph Hellwig * the caller to ensure that @bio->bi_disk->queue->bio_split is only released 363f695ca38SChristoph Hellwig * after processing of the split bio has finished. 364dad77584SBart Van Assche */ 365f695ca38SChristoph Hellwig void blk_queue_split(struct bio **bio) 36614ccb66bSChristoph Hellwig { 36714ccb66bSChristoph Hellwig unsigned int nr_segs; 36814ccb66bSChristoph Hellwig 369f695ca38SChristoph Hellwig __blk_queue_split(bio, &nr_segs); 37014ccb66bSChristoph Hellwig } 37154efd50bSKent Overstreet EXPORT_SYMBOL(blk_queue_split); 37254efd50bSKent Overstreet 373e9cd19c0SChristoph Hellwig unsigned int blk_recalc_rq_segments(struct request *rq) 374d6d48196SJens Axboe { 3756869875fSChristoph Hellwig unsigned int nr_phys_segs = 0; 376ff9811b3SBart Van Assche unsigned int nr_sectors = 0; 377e9cd19c0SChristoph Hellwig struct req_iterator iter; 3786869875fSChristoph Hellwig struct bio_vec bv; 379d6d48196SJens Axboe 380e9cd19c0SChristoph Hellwig if (!rq->bio) 3811e428079SJens Axboe return 0; 382d6d48196SJens Axboe 383e9cd19c0SChristoph Hellwig switch (bio_op(rq->bio)) { 384a6f0788eSChaitanya Kulkarni case REQ_OP_DISCARD: 385a6f0788eSChaitanya Kulkarni case REQ_OP_SECURE_ERASE: 386a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 387f9d03f96SChristoph Hellwig return 0; 388f9d03f96SChristoph Hellwig case REQ_OP_WRITE_SAME: 3895cb8850cSKent Overstreet return 1; 390a6f0788eSChaitanya Kulkarni } 3915cb8850cSKent Overstreet 392e9cd19c0SChristoph Hellwig rq_for_each_bvec(bv, rq, iter) 393ff9811b3SBart Van Assche bvec_split_segs(rq->q, &bv, &nr_phys_segs, &nr_sectors, 394708b25b3SBart Van Assche UINT_MAX, UINT_MAX); 3951e428079SJens Axboe return nr_phys_segs; 3961e428079SJens Axboe } 3971e428079SJens Axboe 39848d7727cSMing Lei static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, 399862e5a5eSMing Lei struct scatterlist *sglist) 400862e5a5eSMing Lei { 401862e5a5eSMing Lei if (!*sg) 402862e5a5eSMing Lei return sglist; 403862e5a5eSMing Lei 404862e5a5eSMing Lei /* 405862e5a5eSMing Lei * If the driver previously mapped a shorter list, we could see a 406862e5a5eSMing Lei * termination bit prematurely unless it fully inits the sg table 407862e5a5eSMing Lei * on each mapping. We KNOW that there must be more entries here 408862e5a5eSMing Lei * or the driver would be buggy, so force clear the termination bit 409862e5a5eSMing Lei * to avoid doing a full sg_init_table() in drivers for each command. 410862e5a5eSMing Lei */ 411862e5a5eSMing Lei sg_unmark_end(*sg); 412862e5a5eSMing Lei return sg_next(*sg); 413862e5a5eSMing Lei } 414862e5a5eSMing Lei 415862e5a5eSMing Lei static unsigned blk_bvec_map_sg(struct request_queue *q, 416862e5a5eSMing Lei struct bio_vec *bvec, struct scatterlist *sglist, 417862e5a5eSMing Lei struct scatterlist **sg) 418862e5a5eSMing Lei { 419862e5a5eSMing Lei unsigned nbytes = bvec->bv_len; 4208a96a0e4SChristoph Hellwig unsigned nsegs = 0, total = 0; 421862e5a5eSMing Lei 422862e5a5eSMing Lei while (nbytes > 0) { 4238a96a0e4SChristoph Hellwig unsigned offset = bvec->bv_offset + total; 424429120f3SMing Lei unsigned len = min(get_max_segment_size(q, bvec->bv_page, 425429120f3SMing Lei offset), nbytes); 426f9f76879SChristoph Hellwig struct page *page = bvec->bv_page; 427f9f76879SChristoph Hellwig 428f9f76879SChristoph Hellwig /* 429f9f76879SChristoph Hellwig * Unfortunately a fair number of drivers barf on scatterlists 430f9f76879SChristoph Hellwig * that have an offset larger than PAGE_SIZE, despite other 431f9f76879SChristoph Hellwig * subsystems dealing with that invariant just fine. For now 432f9f76879SChristoph Hellwig * stick to the legacy format where we never present those from 433f9f76879SChristoph Hellwig * the block layer, but the code below should be removed once 434f9f76879SChristoph Hellwig * these offenders (mostly MMC/SD drivers) are fixed. 435f9f76879SChristoph Hellwig */ 436f9f76879SChristoph Hellwig page += (offset >> PAGE_SHIFT); 437f9f76879SChristoph Hellwig offset &= ~PAGE_MASK; 438862e5a5eSMing Lei 439862e5a5eSMing Lei *sg = blk_next_sg(sg, sglist); 440f9f76879SChristoph Hellwig sg_set_page(*sg, page, len, offset); 441862e5a5eSMing Lei 4428a96a0e4SChristoph Hellwig total += len; 4438a96a0e4SChristoph Hellwig nbytes -= len; 444862e5a5eSMing Lei nsegs++; 445862e5a5eSMing Lei } 446862e5a5eSMing Lei 447862e5a5eSMing Lei return nsegs; 448862e5a5eSMing Lei } 449862e5a5eSMing Lei 45016e3e418SMing Lei static inline int __blk_bvec_map_sg(struct bio_vec bv, 45116e3e418SMing Lei struct scatterlist *sglist, struct scatterlist **sg) 45216e3e418SMing Lei { 45316e3e418SMing Lei *sg = blk_next_sg(sg, sglist); 45416e3e418SMing Lei sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); 45516e3e418SMing Lei return 1; 45616e3e418SMing Lei } 45716e3e418SMing Lei 458f6970f83SMing Lei /* only try to merge bvecs into one sg if they are from two bios */ 459f6970f83SMing Lei static inline bool 460f6970f83SMing Lei __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec, 461f6970f83SMing Lei struct bio_vec *bvprv, struct scatterlist **sg) 462963ab9e5SAsias He { 463963ab9e5SAsias He 464963ab9e5SAsias He int nbytes = bvec->bv_len; 465963ab9e5SAsias He 466f6970f83SMing Lei if (!*sg) 467f6970f83SMing Lei return false; 468f6970f83SMing Lei 469b4b6cb61SMing Lei if ((*sg)->length + nbytes > queue_max_segment_size(q)) 470f6970f83SMing Lei return false; 471f6970f83SMing Lei 4723dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, bvprv, bvec)) 473f6970f83SMing Lei return false; 474963ab9e5SAsias He 475963ab9e5SAsias He (*sg)->length += nbytes; 476f6970f83SMing Lei 477f6970f83SMing Lei return true; 478963ab9e5SAsias He } 479963ab9e5SAsias He 4805cb8850cSKent Overstreet static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, 4815cb8850cSKent Overstreet struct scatterlist *sglist, 4825cb8850cSKent Overstreet struct scatterlist **sg) 4835cb8850cSKent Overstreet { 4843f649ab7SKees Cook struct bio_vec bvec, bvprv = { NULL }; 4855cb8850cSKent Overstreet struct bvec_iter iter; 48638417468SChristoph Hellwig int nsegs = 0; 487f6970f83SMing Lei bool new_bio = false; 4885cb8850cSKent Overstreet 489f6970f83SMing Lei for_each_bio(bio) { 490f6970f83SMing Lei bio_for_each_bvec(bvec, bio, iter) { 491f6970f83SMing Lei /* 492f6970f83SMing Lei * Only try to merge bvecs from two bios given we 493f6970f83SMing Lei * have done bio internal merge when adding pages 494f6970f83SMing Lei * to bio 495f6970f83SMing Lei */ 496f6970f83SMing Lei if (new_bio && 497f6970f83SMing Lei __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg)) 498f6970f83SMing Lei goto next_bvec; 499f6970f83SMing Lei 500f6970f83SMing Lei if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE) 501f6970f83SMing Lei nsegs += __blk_bvec_map_sg(bvec, sglist, sg); 502f6970f83SMing Lei else 503f6970f83SMing Lei nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg); 504f6970f83SMing Lei next_bvec: 505f6970f83SMing Lei new_bio = false; 506f6970f83SMing Lei } 507b21e11c5SMing Lei if (likely(bio->bi_iter.bi_size)) { 508f6970f83SMing Lei bvprv = bvec; 509f6970f83SMing Lei new_bio = true; 510f6970f83SMing Lei } 511b21e11c5SMing Lei } 5125cb8850cSKent Overstreet 5135cb8850cSKent Overstreet return nsegs; 5145cb8850cSKent Overstreet } 5155cb8850cSKent Overstreet 516d6d48196SJens Axboe /* 517d6d48196SJens Axboe * map a request to scatterlist, return number of sg entries setup. Caller 518d6d48196SJens Axboe * must make sure sg can hold rq->nr_phys_segments entries 519d6d48196SJens Axboe */ 52089de1504SChristoph Hellwig int __blk_rq_map_sg(struct request_queue *q, struct request *rq, 52189de1504SChristoph Hellwig struct scatterlist *sglist, struct scatterlist **last_sg) 522d6d48196SJens Axboe { 5235cb8850cSKent Overstreet int nsegs = 0; 524d6d48196SJens Axboe 525f9d03f96SChristoph Hellwig if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) 52689de1504SChristoph Hellwig nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, last_sg); 527f9d03f96SChristoph Hellwig else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME) 52889de1504SChristoph Hellwig nsegs = __blk_bvec_map_sg(bio_iovec(rq->bio), sglist, last_sg); 529f9d03f96SChristoph Hellwig else if (rq->bio) 53089de1504SChristoph Hellwig nsegs = __blk_bios_map_sg(q, rq->bio, sglist, last_sg); 531f18573abSFUJITA Tomonori 53289de1504SChristoph Hellwig if (*last_sg) 53389de1504SChristoph Hellwig sg_mark_end(*last_sg); 534d6d48196SJens Axboe 53512e57f59SMing Lei /* 53612e57f59SMing Lei * Something must have been wrong if the figured number of 53712e57f59SMing Lei * segment is bigger than number of req's physical segments 53812e57f59SMing Lei */ 539f9d03f96SChristoph Hellwig WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); 54012e57f59SMing Lei 541d6d48196SJens Axboe return nsegs; 542d6d48196SJens Axboe } 54389de1504SChristoph Hellwig EXPORT_SYMBOL(__blk_rq_map_sg); 544d6d48196SJens Axboe 545943b40c8SMing Lei static inline unsigned int blk_rq_get_max_segments(struct request *rq) 546943b40c8SMing Lei { 547943b40c8SMing Lei if (req_op(rq) == REQ_OP_DISCARD) 548943b40c8SMing Lei return queue_max_discard_segments(rq->q); 549943b40c8SMing Lei return queue_max_segments(rq->q); 550943b40c8SMing Lei } 551943b40c8SMing Lei 55214ccb66bSChristoph Hellwig static inline int ll_new_hw_segment(struct request *req, struct bio *bio, 55314ccb66bSChristoph Hellwig unsigned int nr_phys_segs) 554d6d48196SJens Axboe { 555943b40c8SMing Lei if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) 55613f05c8dSMartin K. Petersen goto no_merge; 55713f05c8dSMartin K. Petersen 55814ccb66bSChristoph Hellwig if (blk_integrity_merge_bio(req->q, req, bio) == false) 55913f05c8dSMartin K. Petersen goto no_merge; 560d6d48196SJens Axboe 561d6d48196SJens Axboe /* 562d6d48196SJens Axboe * This will form the start of a new hw segment. Bump both 563d6d48196SJens Axboe * counters. 564d6d48196SJens Axboe */ 565d6d48196SJens Axboe req->nr_phys_segments += nr_phys_segs; 566d6d48196SJens Axboe return 1; 56713f05c8dSMartin K. Petersen 56813f05c8dSMartin K. Petersen no_merge: 56914ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 57013f05c8dSMartin K. Petersen return 0; 571d6d48196SJens Axboe } 572d6d48196SJens Axboe 57314ccb66bSChristoph Hellwig int ll_back_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs) 574d6d48196SJens Axboe { 5755e7c4274SJens Axboe if (req_gap_back_merge(req, bio)) 5765e7c4274SJens Axboe return 0; 5777f39add3SSagi Grimberg if (blk_integrity_rq(req) && 5787f39add3SSagi Grimberg integrity_req_gap_back_merge(req, bio)) 5797f39add3SSagi Grimberg return 0; 580a892c8d5SSatya Tangirala if (!bio_crypt_ctx_back_mergeable(req, bio)) 581a892c8d5SSatya Tangirala return 0; 582f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 58317007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) { 58414ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 585d6d48196SJens Axboe return 0; 586d6d48196SJens Axboe } 587d6d48196SJens Axboe 58814ccb66bSChristoph Hellwig return ll_new_hw_segment(req, bio, nr_segs); 589d6d48196SJens Axboe } 590d6d48196SJens Axboe 591eda5cc99SChristoph Hellwig static int ll_front_merge_fn(struct request *req, struct bio *bio, 592eda5cc99SChristoph Hellwig unsigned int nr_segs) 593d6d48196SJens Axboe { 5945e7c4274SJens Axboe if (req_gap_front_merge(req, bio)) 5955e7c4274SJens Axboe return 0; 5967f39add3SSagi Grimberg if (blk_integrity_rq(req) && 5977f39add3SSagi Grimberg integrity_req_gap_front_merge(req, bio)) 5987f39add3SSagi Grimberg return 0; 599a892c8d5SSatya Tangirala if (!bio_crypt_ctx_front_mergeable(req, bio)) 600a892c8d5SSatya Tangirala return 0; 601f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 60217007f39SDamien Le Moal blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { 60314ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 604d6d48196SJens Axboe return 0; 605d6d48196SJens Axboe } 606d6d48196SJens Axboe 60714ccb66bSChristoph Hellwig return ll_new_hw_segment(req, bio, nr_segs); 608d6d48196SJens Axboe } 609d6d48196SJens Axboe 610445251d0SJens Axboe static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, 611445251d0SJens Axboe struct request *next) 612445251d0SJens Axboe { 613445251d0SJens Axboe unsigned short segments = blk_rq_nr_discard_segments(req); 614445251d0SJens Axboe 615445251d0SJens Axboe if (segments >= queue_max_discard_segments(q)) 616445251d0SJens Axboe goto no_merge; 617445251d0SJens Axboe if (blk_rq_sectors(req) + bio_sectors(next->bio) > 618445251d0SJens Axboe blk_rq_get_max_sectors(req, blk_rq_pos(req))) 619445251d0SJens Axboe goto no_merge; 620445251d0SJens Axboe 621445251d0SJens Axboe req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); 622445251d0SJens Axboe return true; 623445251d0SJens Axboe no_merge: 624445251d0SJens Axboe req_set_nomerge(q, req); 625445251d0SJens Axboe return false; 626445251d0SJens Axboe } 627445251d0SJens Axboe 628d6d48196SJens Axboe static int ll_merge_requests_fn(struct request_queue *q, struct request *req, 629d6d48196SJens Axboe struct request *next) 630d6d48196SJens Axboe { 631d6d48196SJens Axboe int total_phys_segments; 632d6d48196SJens Axboe 6335e7c4274SJens Axboe if (req_gap_back_merge(req, next->bio)) 634854fbb9cSKeith Busch return 0; 635854fbb9cSKeith Busch 636d6d48196SJens Axboe /* 637d6d48196SJens Axboe * Will it become too large? 638d6d48196SJens Axboe */ 639f31dc1cdSMartin K. Petersen if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > 64017007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) 641d6d48196SJens Axboe return 0; 642d6d48196SJens Axboe 643d6d48196SJens Axboe total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; 644943b40c8SMing Lei if (total_phys_segments > blk_rq_get_max_segments(req)) 645d6d48196SJens Axboe return 0; 646d6d48196SJens Axboe 6474eaf99beSMartin K. Petersen if (blk_integrity_merge_rq(q, req, next) == false) 64813f05c8dSMartin K. Petersen return 0; 64913f05c8dSMartin K. Petersen 650a892c8d5SSatya Tangirala if (!bio_crypt_ctx_merge_rq(req, next)) 651a892c8d5SSatya Tangirala return 0; 652a892c8d5SSatya Tangirala 653d6d48196SJens Axboe /* Merge is OK... */ 654d6d48196SJens Axboe req->nr_phys_segments = total_phys_segments; 655d6d48196SJens Axboe return 1; 656d6d48196SJens Axboe } 657d6d48196SJens Axboe 65880a761fdSTejun Heo /** 65980a761fdSTejun Heo * blk_rq_set_mixed_merge - mark a request as mixed merge 66080a761fdSTejun Heo * @rq: request to mark as mixed merge 66180a761fdSTejun Heo * 66280a761fdSTejun Heo * Description: 66380a761fdSTejun Heo * @rq is about to be mixed merged. Make sure the attributes 66480a761fdSTejun Heo * which can be mixed are set in each bio and mark @rq as mixed 66580a761fdSTejun Heo * merged. 66680a761fdSTejun Heo */ 66780a761fdSTejun Heo void blk_rq_set_mixed_merge(struct request *rq) 66880a761fdSTejun Heo { 66980a761fdSTejun Heo unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; 67080a761fdSTejun Heo struct bio *bio; 67180a761fdSTejun Heo 672e8064021SChristoph Hellwig if (rq->rq_flags & RQF_MIXED_MERGE) 67380a761fdSTejun Heo return; 67480a761fdSTejun Heo 67580a761fdSTejun Heo /* 67680a761fdSTejun Heo * @rq will no longer represent mixable attributes for all the 67780a761fdSTejun Heo * contained bios. It will just track those of the first one. 67880a761fdSTejun Heo * Distributes the attributs to each bio. 67980a761fdSTejun Heo */ 68080a761fdSTejun Heo for (bio = rq->bio; bio; bio = bio->bi_next) { 6811eff9d32SJens Axboe WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && 6821eff9d32SJens Axboe (bio->bi_opf & REQ_FAILFAST_MASK) != ff); 6831eff9d32SJens Axboe bio->bi_opf |= ff; 68480a761fdSTejun Heo } 685e8064021SChristoph Hellwig rq->rq_flags |= RQF_MIXED_MERGE; 68680a761fdSTejun Heo } 68780a761fdSTejun Heo 688b9c54f56SKonstantin Khlebnikov static void blk_account_io_merge_request(struct request *req) 68926308eabSJerome Marchand { 69026308eabSJerome Marchand if (blk_do_io_stat(req)) { 691112f158fSMike Snitzer part_stat_lock(); 692b9c54f56SKonstantin Khlebnikov part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); 69326308eabSJerome Marchand part_stat_unlock(); 69426308eabSJerome Marchand } 69526308eabSJerome Marchand } 696b9c54f56SKonstantin Khlebnikov 69769840466SJianchao Wang /* 69869840466SJianchao Wang * Two cases of handling DISCARD merge: 69969840466SJianchao Wang * If max_discard_segments > 1, the driver takes every bio 70069840466SJianchao Wang * as a range and send them to controller together. The ranges 70169840466SJianchao Wang * needn't to be contiguous. 70269840466SJianchao Wang * Otherwise, the bios/requests will be handled as same as 70369840466SJianchao Wang * others which should be contiguous. 70469840466SJianchao Wang */ 70569840466SJianchao Wang static inline bool blk_discard_mergable(struct request *req) 70669840466SJianchao Wang { 70769840466SJianchao Wang if (req_op(req) == REQ_OP_DISCARD && 70869840466SJianchao Wang queue_max_discard_segments(req->q) > 1) 70969840466SJianchao Wang return true; 71069840466SJianchao Wang return false; 71169840466SJianchao Wang } 71269840466SJianchao Wang 713e96c0d83SEric Biggers static enum elv_merge blk_try_req_merge(struct request *req, 714e96c0d83SEric Biggers struct request *next) 71569840466SJianchao Wang { 71669840466SJianchao Wang if (blk_discard_mergable(req)) 71769840466SJianchao Wang return ELEVATOR_DISCARD_MERGE; 71869840466SJianchao Wang else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) 71969840466SJianchao Wang return ELEVATOR_BACK_MERGE; 72069840466SJianchao Wang 72169840466SJianchao Wang return ELEVATOR_NO_MERGE; 72269840466SJianchao Wang } 72326308eabSJerome Marchand 724d6d48196SJens Axboe /* 725b973cb7eSJens Axboe * For non-mq, this has to be called with the request spinlock acquired. 726b973cb7eSJens Axboe * For mq with scheduling, the appropriate queue wide lock should be held. 727d6d48196SJens Axboe */ 728b973cb7eSJens Axboe static struct request *attempt_merge(struct request_queue *q, 729b973cb7eSJens Axboe struct request *req, struct request *next) 730d6d48196SJens Axboe { 731d6d48196SJens Axboe if (!rq_mergeable(req) || !rq_mergeable(next)) 732b973cb7eSJens Axboe return NULL; 733d6d48196SJens Axboe 734288dab8aSChristoph Hellwig if (req_op(req) != req_op(next)) 735b973cb7eSJens Axboe return NULL; 736f31dc1cdSMartin K. Petersen 737d6d48196SJens Axboe if (rq_data_dir(req) != rq_data_dir(next) 7382081a56bSJens Axboe || req->rq_disk != next->rq_disk) 739b973cb7eSJens Axboe return NULL; 740d6d48196SJens Axboe 7418fe0d473SMike Christie if (req_op(req) == REQ_OP_WRITE_SAME && 7424363ac7cSMartin K. Petersen !blk_write_same_mergeable(req->bio, next->bio)) 743b973cb7eSJens Axboe return NULL; 7444363ac7cSMartin K. Petersen 745d6d48196SJens Axboe /* 746cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 747cb6934f8SJens Axboe * non-hint IO. 748cb6934f8SJens Axboe */ 749cb6934f8SJens Axboe if (req->write_hint != next->write_hint) 750cb6934f8SJens Axboe return NULL; 751cb6934f8SJens Axboe 752668ffc03SDamien Le Moal if (req->ioprio != next->ioprio) 753668ffc03SDamien Le Moal return NULL; 754668ffc03SDamien Le Moal 755cb6934f8SJens Axboe /* 756d6d48196SJens Axboe * If we are allowed to merge, then append bio list 757d6d48196SJens Axboe * from next to rq and release next. merge_requests_fn 758d6d48196SJens Axboe * will have updated segment counts, update sector 759445251d0SJens Axboe * counts here. Handle DISCARDs separately, as they 760445251d0SJens Axboe * have separate settings. 761d6d48196SJens Axboe */ 76269840466SJianchao Wang 76369840466SJianchao Wang switch (blk_try_req_merge(req, next)) { 76469840466SJianchao Wang case ELEVATOR_DISCARD_MERGE: 765445251d0SJens Axboe if (!req_attempt_discard_merge(q, req, next)) 766445251d0SJens Axboe return NULL; 76769840466SJianchao Wang break; 76869840466SJianchao Wang case ELEVATOR_BACK_MERGE: 76969840466SJianchao Wang if (!ll_merge_requests_fn(q, req, next)) 770b973cb7eSJens Axboe return NULL; 77169840466SJianchao Wang break; 77269840466SJianchao Wang default: 77369840466SJianchao Wang return NULL; 77469840466SJianchao Wang } 775d6d48196SJens Axboe 776d6d48196SJens Axboe /* 77780a761fdSTejun Heo * If failfast settings disagree or any of the two is already 77880a761fdSTejun Heo * a mixed merge, mark both as mixed before proceeding. This 77980a761fdSTejun Heo * makes sure that all involved bios have mixable attributes 78080a761fdSTejun Heo * set properly. 78180a761fdSTejun Heo */ 782e8064021SChristoph Hellwig if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || 78380a761fdSTejun Heo (req->cmd_flags & REQ_FAILFAST_MASK) != 78480a761fdSTejun Heo (next->cmd_flags & REQ_FAILFAST_MASK)) { 78580a761fdSTejun Heo blk_rq_set_mixed_merge(req); 78680a761fdSTejun Heo blk_rq_set_mixed_merge(next); 78780a761fdSTejun Heo } 78880a761fdSTejun Heo 78980a761fdSTejun Heo /* 790522a7775SOmar Sandoval * At this point we have either done a back merge or front merge. We 791522a7775SOmar Sandoval * need the smaller start_time_ns of the merged requests to be the 792522a7775SOmar Sandoval * current request for accounting purposes. 793d6d48196SJens Axboe */ 794522a7775SOmar Sandoval if (next->start_time_ns < req->start_time_ns) 795522a7775SOmar Sandoval req->start_time_ns = next->start_time_ns; 796d6d48196SJens Axboe 797d6d48196SJens Axboe req->biotail->bi_next = next->bio; 798d6d48196SJens Axboe req->biotail = next->biotail; 799d6d48196SJens Axboe 800a2dec7b3STejun Heo req->__data_len += blk_rq_bytes(next); 801d6d48196SJens Axboe 8022a5cf35cSMing Lei if (!blk_discard_mergable(req)) 803d6d48196SJens Axboe elv_merge_requests(q, req, next); 804d6d48196SJens Axboe 80542dad764SJerome Marchand /* 80642dad764SJerome Marchand * 'next' is going away, so update stats accordingly 80742dad764SJerome Marchand */ 808b9c54f56SKonstantin Khlebnikov blk_account_io_merge_request(next); 809d6d48196SJens Axboe 810a54895faSChristoph Hellwig trace_block_rq_merge(next); 811f3bdc62fSJan Kara 812e4d750c9SJens Axboe /* 813e4d750c9SJens Axboe * ownership of bio passed from next to req, return 'next' for 814e4d750c9SJens Axboe * the caller to free 815e4d750c9SJens Axboe */ 8161cd96c24SBoaz Harrosh next->bio = NULL; 817b973cb7eSJens Axboe return next; 818d6d48196SJens Axboe } 819d6d48196SJens Axboe 820eda5cc99SChristoph Hellwig static struct request *attempt_back_merge(struct request_queue *q, 821eda5cc99SChristoph Hellwig struct request *rq) 822d6d48196SJens Axboe { 823d6d48196SJens Axboe struct request *next = elv_latter_request(q, rq); 824d6d48196SJens Axboe 825d6d48196SJens Axboe if (next) 826d6d48196SJens Axboe return attempt_merge(q, rq, next); 827d6d48196SJens Axboe 828b973cb7eSJens Axboe return NULL; 829d6d48196SJens Axboe } 830d6d48196SJens Axboe 831eda5cc99SChristoph Hellwig static struct request *attempt_front_merge(struct request_queue *q, 832eda5cc99SChristoph Hellwig struct request *rq) 833d6d48196SJens Axboe { 834d6d48196SJens Axboe struct request *prev = elv_former_request(q, rq); 835d6d48196SJens Axboe 836d6d48196SJens Axboe if (prev) 837d6d48196SJens Axboe return attempt_merge(q, prev, rq); 838d6d48196SJens Axboe 839b973cb7eSJens Axboe return NULL; 840d6d48196SJens Axboe } 8415e84ea3aSJens Axboe 8425e84ea3aSJens Axboe int blk_attempt_req_merge(struct request_queue *q, struct request *rq, 8435e84ea3aSJens Axboe struct request *next) 8445e84ea3aSJens Axboe { 845e4d750c9SJens Axboe struct request *free; 84672ef799bSTahsin Erdogan 847e4d750c9SJens Axboe free = attempt_merge(q, rq, next); 848e4d750c9SJens Axboe if (free) { 84992bc5a24SJens Axboe blk_put_request(free); 850e4d750c9SJens Axboe return 1; 851e4d750c9SJens Axboe } 852e4d750c9SJens Axboe 853e4d750c9SJens Axboe return 0; 8545e84ea3aSJens Axboe } 855050c8ea8STejun Heo 856050c8ea8STejun Heo bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 857050c8ea8STejun Heo { 858e2a60da7SMartin K. Petersen if (!rq_mergeable(rq) || !bio_mergeable(bio)) 859050c8ea8STejun Heo return false; 860050c8ea8STejun Heo 861288dab8aSChristoph Hellwig if (req_op(rq) != bio_op(bio)) 862f31dc1cdSMartin K. Petersen return false; 863f31dc1cdSMartin K. Petersen 864050c8ea8STejun Heo /* different data direction or already started, don't merge */ 865050c8ea8STejun Heo if (bio_data_dir(bio) != rq_data_dir(rq)) 866050c8ea8STejun Heo return false; 867050c8ea8STejun Heo 8682081a56bSJens Axboe /* must be same device */ 8692081a56bSJens Axboe if (rq->rq_disk != bio->bi_disk) 870050c8ea8STejun Heo return false; 871050c8ea8STejun Heo 872050c8ea8STejun Heo /* only merge integrity protected bio into ditto rq */ 8734eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(rq->q, rq, bio) == false) 874050c8ea8STejun Heo return false; 875050c8ea8STejun Heo 876a892c8d5SSatya Tangirala /* Only merge if the crypt contexts are compatible */ 877a892c8d5SSatya Tangirala if (!bio_crypt_rq_ctx_compatible(rq, bio)) 878a892c8d5SSatya Tangirala return false; 879a892c8d5SSatya Tangirala 8804363ac7cSMartin K. Petersen /* must be using the same buffer */ 8818fe0d473SMike Christie if (req_op(rq) == REQ_OP_WRITE_SAME && 8824363ac7cSMartin K. Petersen !blk_write_same_mergeable(rq->bio, bio)) 8834363ac7cSMartin K. Petersen return false; 8844363ac7cSMartin K. Petersen 885cb6934f8SJens Axboe /* 886cb6934f8SJens Axboe * Don't allow merge of different write hints, or for a hint with 887cb6934f8SJens Axboe * non-hint IO. 888cb6934f8SJens Axboe */ 889cb6934f8SJens Axboe if (rq->write_hint != bio->bi_write_hint) 890cb6934f8SJens Axboe return false; 891cb6934f8SJens Axboe 892668ffc03SDamien Le Moal if (rq->ioprio != bio_prio(bio)) 893668ffc03SDamien Le Moal return false; 894668ffc03SDamien Le Moal 895050c8ea8STejun Heo return true; 896050c8ea8STejun Heo } 897050c8ea8STejun Heo 89834fe7c05SChristoph Hellwig enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) 899050c8ea8STejun Heo { 90069840466SJianchao Wang if (blk_discard_mergable(rq)) 9011e739730SChristoph Hellwig return ELEVATOR_DISCARD_MERGE; 9021e739730SChristoph Hellwig else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) 903050c8ea8STejun Heo return ELEVATOR_BACK_MERGE; 9044f024f37SKent Overstreet else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) 905050c8ea8STejun Heo return ELEVATOR_FRONT_MERGE; 906050c8ea8STejun Heo return ELEVATOR_NO_MERGE; 907050c8ea8STejun Heo } 9088e756373SBaolin Wang 9098e756373SBaolin Wang static void blk_account_io_merge_bio(struct request *req) 9108e756373SBaolin Wang { 9118e756373SBaolin Wang if (!blk_do_io_stat(req)) 9128e756373SBaolin Wang return; 9138e756373SBaolin Wang 9148e756373SBaolin Wang part_stat_lock(); 9158e756373SBaolin Wang part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); 9168e756373SBaolin Wang part_stat_unlock(); 9178e756373SBaolin Wang } 9188e756373SBaolin Wang 919eda5cc99SChristoph Hellwig enum bio_merge_status { 920eda5cc99SChristoph Hellwig BIO_MERGE_OK, 921eda5cc99SChristoph Hellwig BIO_MERGE_NONE, 922eda5cc99SChristoph Hellwig BIO_MERGE_FAILED, 923eda5cc99SChristoph Hellwig }; 924eda5cc99SChristoph Hellwig 925eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_back_merge(struct request *req, 926eda5cc99SChristoph Hellwig struct bio *bio, unsigned int nr_segs) 9278e756373SBaolin Wang { 9288e756373SBaolin Wang const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 9298e756373SBaolin Wang 9308e756373SBaolin Wang if (!ll_back_merge_fn(req, bio, nr_segs)) 9317d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 9328e756373SBaolin Wang 933e8a676d6SChristoph Hellwig trace_block_bio_backmerge(bio); 9348e756373SBaolin Wang rq_qos_merge(req->q, req, bio); 9358e756373SBaolin Wang 9368e756373SBaolin Wang if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 9378e756373SBaolin Wang blk_rq_set_mixed_merge(req); 9388e756373SBaolin Wang 9398e756373SBaolin Wang req->biotail->bi_next = bio; 9408e756373SBaolin Wang req->biotail = bio; 9418e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 9428e756373SBaolin Wang 9438e756373SBaolin Wang bio_crypt_free_ctx(bio); 9448e756373SBaolin Wang 9458e756373SBaolin Wang blk_account_io_merge_bio(req); 9467d7ca7c5SBaolin Wang return BIO_MERGE_OK; 9478e756373SBaolin Wang } 9488e756373SBaolin Wang 949eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_front_merge(struct request *req, 950eda5cc99SChristoph Hellwig struct bio *bio, unsigned int nr_segs) 9518e756373SBaolin Wang { 9528e756373SBaolin Wang const int ff = bio->bi_opf & REQ_FAILFAST_MASK; 9538e756373SBaolin Wang 9548e756373SBaolin Wang if (!ll_front_merge_fn(req, bio, nr_segs)) 9557d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 9568e756373SBaolin Wang 957e8a676d6SChristoph Hellwig trace_block_bio_frontmerge(bio); 9588e756373SBaolin Wang rq_qos_merge(req->q, req, bio); 9598e756373SBaolin Wang 9608e756373SBaolin Wang if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 9618e756373SBaolin Wang blk_rq_set_mixed_merge(req); 9628e756373SBaolin Wang 9638e756373SBaolin Wang bio->bi_next = req->bio; 9648e756373SBaolin Wang req->bio = bio; 9658e756373SBaolin Wang 9668e756373SBaolin Wang req->__sector = bio->bi_iter.bi_sector; 9678e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 9688e756373SBaolin Wang 9698e756373SBaolin Wang bio_crypt_do_front_merge(req, bio); 9708e756373SBaolin Wang 9718e756373SBaolin Wang blk_account_io_merge_bio(req); 9727d7ca7c5SBaolin Wang return BIO_MERGE_OK; 9738e756373SBaolin Wang } 9748e756373SBaolin Wang 975eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q, 976eda5cc99SChristoph Hellwig struct request *req, struct bio *bio) 9778e756373SBaolin Wang { 9788e756373SBaolin Wang unsigned short segments = blk_rq_nr_discard_segments(req); 9798e756373SBaolin Wang 9808e756373SBaolin Wang if (segments >= queue_max_discard_segments(q)) 9818e756373SBaolin Wang goto no_merge; 9828e756373SBaolin Wang if (blk_rq_sectors(req) + bio_sectors(bio) > 9838e756373SBaolin Wang blk_rq_get_max_sectors(req, blk_rq_pos(req))) 9848e756373SBaolin Wang goto no_merge; 9858e756373SBaolin Wang 9868e756373SBaolin Wang rq_qos_merge(q, req, bio); 9878e756373SBaolin Wang 9888e756373SBaolin Wang req->biotail->bi_next = bio; 9898e756373SBaolin Wang req->biotail = bio; 9908e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 9918e756373SBaolin Wang req->nr_phys_segments = segments + 1; 9928e756373SBaolin Wang 9938e756373SBaolin Wang blk_account_io_merge_bio(req); 9947d7ca7c5SBaolin Wang return BIO_MERGE_OK; 9958e756373SBaolin Wang no_merge: 9968e756373SBaolin Wang req_set_nomerge(q, req); 9977d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 9987d7ca7c5SBaolin Wang } 9997d7ca7c5SBaolin Wang 10007d7ca7c5SBaolin Wang static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q, 10017d7ca7c5SBaolin Wang struct request *rq, 10027d7ca7c5SBaolin Wang struct bio *bio, 10037d7ca7c5SBaolin Wang unsigned int nr_segs, 10047d7ca7c5SBaolin Wang bool sched_allow_merge) 10057d7ca7c5SBaolin Wang { 10067d7ca7c5SBaolin Wang if (!blk_rq_merge_ok(rq, bio)) 10077d7ca7c5SBaolin Wang return BIO_MERGE_NONE; 10087d7ca7c5SBaolin Wang 10097d7ca7c5SBaolin Wang switch (blk_try_merge(rq, bio)) { 10107d7ca7c5SBaolin Wang case ELEVATOR_BACK_MERGE: 1011265600b7SBaolin Wang if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) 10127d7ca7c5SBaolin Wang return bio_attempt_back_merge(rq, bio, nr_segs); 10137d7ca7c5SBaolin Wang break; 10147d7ca7c5SBaolin Wang case ELEVATOR_FRONT_MERGE: 1015265600b7SBaolin Wang if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) 10167d7ca7c5SBaolin Wang return bio_attempt_front_merge(rq, bio, nr_segs); 10177d7ca7c5SBaolin Wang break; 10187d7ca7c5SBaolin Wang case ELEVATOR_DISCARD_MERGE: 10197d7ca7c5SBaolin Wang return bio_attempt_discard_merge(q, rq, bio); 10207d7ca7c5SBaolin Wang default: 10217d7ca7c5SBaolin Wang return BIO_MERGE_NONE; 10227d7ca7c5SBaolin Wang } 10237d7ca7c5SBaolin Wang 10247d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 10258e756373SBaolin Wang } 10268e756373SBaolin Wang 10278e756373SBaolin Wang /** 10288e756373SBaolin Wang * blk_attempt_plug_merge - try to merge with %current's plugged list 10298e756373SBaolin Wang * @q: request_queue new bio is being queued at 10308e756373SBaolin Wang * @bio: new bio being queued 10318e756373SBaolin Wang * @nr_segs: number of segments in @bio 10328e756373SBaolin Wang * @same_queue_rq: pointer to &struct request that gets filled in when 10338e756373SBaolin Wang * another request associated with @q is found on the plug list 10348e756373SBaolin Wang * (optional, may be %NULL) 10358e756373SBaolin Wang * 10368e756373SBaolin Wang * Determine whether @bio being queued on @q can be merged with a request 10378e756373SBaolin Wang * on %current's plugged list. Returns %true if merge was successful, 10388e756373SBaolin Wang * otherwise %false. 10398e756373SBaolin Wang * 10408e756373SBaolin Wang * Plugging coalesces IOs from the same issuer for the same purpose without 10418e756373SBaolin Wang * going through @q->queue_lock. As such it's more of an issuing mechanism 10428e756373SBaolin Wang * than scheduling, and the request, while may have elvpriv data, is not 10438e756373SBaolin Wang * added on the elevator at this point. In addition, we don't have 10448e756373SBaolin Wang * reliable access to the elevator outside queue lock. Only check basic 10458e756373SBaolin Wang * merging parameters without querying the elevator. 10468e756373SBaolin Wang * 10478e756373SBaolin Wang * Caller must ensure !blk_queue_nomerges(q) beforehand. 10488e756373SBaolin Wang */ 10498e756373SBaolin Wang bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 10508e756373SBaolin Wang unsigned int nr_segs, struct request **same_queue_rq) 10518e756373SBaolin Wang { 10528e756373SBaolin Wang struct blk_plug *plug; 10538e756373SBaolin Wang struct request *rq; 10548e756373SBaolin Wang struct list_head *plug_list; 10558e756373SBaolin Wang 10568e756373SBaolin Wang plug = blk_mq_plug(q, bio); 10578e756373SBaolin Wang if (!plug) 10588e756373SBaolin Wang return false; 10598e756373SBaolin Wang 10608e756373SBaolin Wang plug_list = &plug->mq_list; 10618e756373SBaolin Wang 10628e756373SBaolin Wang list_for_each_entry_reverse(rq, plug_list, queuelist) { 10638e756373SBaolin Wang if (rq->q == q && same_queue_rq) { 10648e756373SBaolin Wang /* 10658e756373SBaolin Wang * Only blk-mq multiple hardware queues case checks the 10668e756373SBaolin Wang * rq in the same queue, there should be only one such 10678e756373SBaolin Wang * rq in a queue 10688e756373SBaolin Wang **/ 10698e756373SBaolin Wang *same_queue_rq = rq; 10708e756373SBaolin Wang } 10718e756373SBaolin Wang 10727d7ca7c5SBaolin Wang if (rq->q != q) 10738e756373SBaolin Wang continue; 10748e756373SBaolin Wang 10757d7ca7c5SBaolin Wang if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) == 10767d7ca7c5SBaolin Wang BIO_MERGE_OK) 10778e756373SBaolin Wang return true; 10788e756373SBaolin Wang } 10798e756373SBaolin Wang 10808e756373SBaolin Wang return false; 10818e756373SBaolin Wang } 1082bdc6a287SBaolin Wang 1083bdc6a287SBaolin Wang /* 1084bdc6a287SBaolin Wang * Iterate list of requests and see if we can merge this bio with any 1085bdc6a287SBaolin Wang * of them. 1086bdc6a287SBaolin Wang */ 1087bdc6a287SBaolin Wang bool blk_bio_list_merge(struct request_queue *q, struct list_head *list, 1088bdc6a287SBaolin Wang struct bio *bio, unsigned int nr_segs) 1089bdc6a287SBaolin Wang { 1090bdc6a287SBaolin Wang struct request *rq; 1091bdc6a287SBaolin Wang int checked = 8; 1092bdc6a287SBaolin Wang 1093bdc6a287SBaolin Wang list_for_each_entry_reverse(rq, list, queuelist) { 1094bdc6a287SBaolin Wang if (!checked--) 1095bdc6a287SBaolin Wang break; 1096bdc6a287SBaolin Wang 10977d7ca7c5SBaolin Wang switch (blk_attempt_bio_merge(q, rq, bio, nr_segs, true)) { 10987d7ca7c5SBaolin Wang case BIO_MERGE_NONE: 1099bdc6a287SBaolin Wang continue; 11007d7ca7c5SBaolin Wang case BIO_MERGE_OK: 11017d7ca7c5SBaolin Wang return true; 11027d7ca7c5SBaolin Wang case BIO_MERGE_FAILED: 11037d7ca7c5SBaolin Wang return false; 1104bdc6a287SBaolin Wang } 1105bdc6a287SBaolin Wang 1106bdc6a287SBaolin Wang } 1107bdc6a287SBaolin Wang 1108bdc6a287SBaolin Wang return false; 1109bdc6a287SBaolin Wang } 1110bdc6a287SBaolin Wang EXPORT_SYMBOL_GPL(blk_bio_list_merge); 1111eda5cc99SChristoph Hellwig 1112eda5cc99SChristoph Hellwig bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio, 1113eda5cc99SChristoph Hellwig unsigned int nr_segs, struct request **merged_request) 1114eda5cc99SChristoph Hellwig { 1115eda5cc99SChristoph Hellwig struct request *rq; 1116eda5cc99SChristoph Hellwig 1117eda5cc99SChristoph Hellwig switch (elv_merge(q, &rq, bio)) { 1118eda5cc99SChristoph Hellwig case ELEVATOR_BACK_MERGE: 1119eda5cc99SChristoph Hellwig if (!blk_mq_sched_allow_merge(q, rq, bio)) 1120eda5cc99SChristoph Hellwig return false; 1121eda5cc99SChristoph Hellwig if (bio_attempt_back_merge(rq, bio, nr_segs) != BIO_MERGE_OK) 1122eda5cc99SChristoph Hellwig return false; 1123eda5cc99SChristoph Hellwig *merged_request = attempt_back_merge(q, rq); 1124eda5cc99SChristoph Hellwig if (!*merged_request) 1125eda5cc99SChristoph Hellwig elv_merged_request(q, rq, ELEVATOR_BACK_MERGE); 1126eda5cc99SChristoph Hellwig return true; 1127eda5cc99SChristoph Hellwig case ELEVATOR_FRONT_MERGE: 1128eda5cc99SChristoph Hellwig if (!blk_mq_sched_allow_merge(q, rq, bio)) 1129eda5cc99SChristoph Hellwig return false; 1130eda5cc99SChristoph Hellwig if (bio_attempt_front_merge(rq, bio, nr_segs) != BIO_MERGE_OK) 1131eda5cc99SChristoph Hellwig return false; 1132eda5cc99SChristoph Hellwig *merged_request = attempt_front_merge(q, rq); 1133eda5cc99SChristoph Hellwig if (!*merged_request) 1134eda5cc99SChristoph Hellwig elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE); 1135eda5cc99SChristoph Hellwig return true; 1136eda5cc99SChristoph Hellwig case ELEVATOR_DISCARD_MERGE: 1137eda5cc99SChristoph Hellwig return bio_attempt_discard_merge(q, rq, bio) == BIO_MERGE_OK; 1138eda5cc99SChristoph Hellwig default: 1139eda5cc99SChristoph Hellwig return false; 1140eda5cc99SChristoph Hellwig } 1141eda5cc99SChristoph Hellwig } 1142eda5cc99SChristoph Hellwig EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge); 1143