1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 2d6d48196SJens Axboe /* 3d6d48196SJens Axboe * Functions related to segment and merge handling 4d6d48196SJens Axboe */ 5d6d48196SJens Axboe #include <linux/kernel.h> 6d6d48196SJens Axboe #include <linux/module.h> 7d6d48196SJens Axboe #include <linux/bio.h> 8d6d48196SJens Axboe #include <linux/blkdev.h> 9fe45e630SChristoph Hellwig #include <linux/blk-integrity.h> 10d6d48196SJens Axboe #include <linux/scatterlist.h> 1182d981d4SChristoph Hellwig #include <linux/part_stat.h> 126b2b0459STejun Heo #include <linux/blk-cgroup.h> 13d6d48196SJens Axboe 14cda22646SMike Krinkin #include <trace/events/block.h> 15cda22646SMike Krinkin 16d6d48196SJens Axboe #include "blk.h" 172aa7745bSChristoph Hellwig #include "blk-mq-sched.h" 188e756373SBaolin Wang #include "blk-rq-qos.h" 19a7b36ee6SJens Axboe #include "blk-throttle.h" 20d6d48196SJens Axboe 21ff18d77bSChristoph Hellwig static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv) 22ff18d77bSChristoph Hellwig { 23ff18d77bSChristoph Hellwig *bv = mp_bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); 24ff18d77bSChristoph Hellwig } 25ff18d77bSChristoph Hellwig 26ff18d77bSChristoph Hellwig static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv) 27ff18d77bSChristoph Hellwig { 28ff18d77bSChristoph Hellwig struct bvec_iter iter = bio->bi_iter; 29ff18d77bSChristoph Hellwig int idx; 30ff18d77bSChristoph Hellwig 31ff18d77bSChristoph Hellwig bio_get_first_bvec(bio, bv); 32ff18d77bSChristoph Hellwig if (bv->bv_len == bio->bi_iter.bi_size) 33ff18d77bSChristoph Hellwig return; /* this bio only has a single bvec */ 34ff18d77bSChristoph Hellwig 35ff18d77bSChristoph Hellwig bio_advance_iter(bio, &iter, iter.bi_size); 36ff18d77bSChristoph Hellwig 37ff18d77bSChristoph Hellwig if (!iter.bi_bvec_done) 38ff18d77bSChristoph Hellwig idx = iter.bi_idx - 1; 39ff18d77bSChristoph Hellwig else /* in the middle of bvec */ 40ff18d77bSChristoph Hellwig idx = iter.bi_idx; 41ff18d77bSChristoph Hellwig 42ff18d77bSChristoph Hellwig *bv = bio->bi_io_vec[idx]; 43ff18d77bSChristoph Hellwig 44ff18d77bSChristoph Hellwig /* 45ff18d77bSChristoph Hellwig * iter.bi_bvec_done records actual length of the last bvec 46ff18d77bSChristoph Hellwig * if this bio ends in the middle of one io vector 47ff18d77bSChristoph Hellwig */ 48ff18d77bSChristoph Hellwig if (iter.bi_bvec_done) 49ff18d77bSChristoph Hellwig bv->bv_len = iter.bi_bvec_done; 50ff18d77bSChristoph Hellwig } 51ff18d77bSChristoph Hellwig 52e9907009SChristoph Hellwig static inline bool bio_will_gap(struct request_queue *q, 53e9907009SChristoph Hellwig struct request *prev_rq, struct bio *prev, struct bio *next) 54e9907009SChristoph Hellwig { 55e9907009SChristoph Hellwig struct bio_vec pb, nb; 56e9907009SChristoph Hellwig 57e9907009SChristoph Hellwig if (!bio_has_data(prev) || !queue_virt_boundary(q)) 58e9907009SChristoph Hellwig return false; 59e9907009SChristoph Hellwig 60e9907009SChristoph Hellwig /* 61e9907009SChristoph Hellwig * Don't merge if the 1st bio starts with non-zero offset, otherwise it 62e9907009SChristoph Hellwig * is quite difficult to respect the sg gap limit. We work hard to 63e9907009SChristoph Hellwig * merge a huge number of small single bios in case of mkfs. 64e9907009SChristoph Hellwig */ 65e9907009SChristoph Hellwig if (prev_rq) 66e9907009SChristoph Hellwig bio_get_first_bvec(prev_rq->bio, &pb); 67e9907009SChristoph Hellwig else 68e9907009SChristoph Hellwig bio_get_first_bvec(prev, &pb); 69df376b2eSJohannes Thumshirn if (pb.bv_offset & queue_virt_boundary(q)) 70e9907009SChristoph Hellwig return true; 71e9907009SChristoph Hellwig 72e9907009SChristoph Hellwig /* 73e9907009SChristoph Hellwig * We don't need to worry about the situation that the merged segment 74e9907009SChristoph Hellwig * ends in unaligned virt boundary: 75e9907009SChristoph Hellwig * 76e9907009SChristoph Hellwig * - if 'pb' ends aligned, the merged segment ends aligned 77e9907009SChristoph Hellwig * - if 'pb' ends unaligned, the next bio must include 78e9907009SChristoph Hellwig * one single bvec of 'nb', otherwise the 'nb' can't 79e9907009SChristoph Hellwig * merge with 'pb' 80e9907009SChristoph Hellwig */ 81e9907009SChristoph Hellwig bio_get_last_bvec(prev, &pb); 82e9907009SChristoph Hellwig bio_get_first_bvec(next, &nb); 83200a9affSChristoph Hellwig if (biovec_phys_mergeable(q, &pb, &nb)) 84e9907009SChristoph Hellwig return false; 85c55ddd90SChristoph Hellwig return __bvec_gap_to_prev(&q->limits, &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 98b6dc6198SChristoph Hellwig /* 99b6dc6198SChristoph Hellwig * The max size one bio can handle is UINT_MAX becasue bvec_iter.bi_size 100b6dc6198SChristoph Hellwig * is defined as 'unsigned int', meantime it has to be aligned to with the 101b6dc6198SChristoph Hellwig * logical block size, which is the minimum accepted unit by hardware. 102b6dc6198SChristoph Hellwig */ 103aa261f20SBart Van Assche static unsigned int bio_allowed_max_sectors(const struct queue_limits *lim) 104b6dc6198SChristoph Hellwig { 105c55ddd90SChristoph Hellwig return round_down(UINT_MAX, lim->logical_block_size) >> SECTOR_SHIFT; 106b6dc6198SChristoph Hellwig } 107b6dc6198SChristoph Hellwig 108aa261f20SBart Van Assche static struct bio *bio_split_discard(struct bio *bio, 109aa261f20SBart Van Assche const struct queue_limits *lim, 1105a97806fSChristoph Hellwig unsigned *nsegs, struct bio_set *bs) 11154efd50bSKent Overstreet { 11254efd50bSKent Overstreet unsigned int max_discard_sectors, granularity; 11354efd50bSKent Overstreet sector_t tmp; 11454efd50bSKent Overstreet unsigned split_sectors; 11554efd50bSKent Overstreet 116bdced438SMing Lei *nsegs = 1; 117bdced438SMing Lei 11854efd50bSKent Overstreet /* Zero-sector (unknown) and one-sector granularities are the same. */ 119c55ddd90SChristoph Hellwig granularity = max(lim->discard_granularity >> 9, 1U); 12054efd50bSKent Overstreet 121c55ddd90SChristoph Hellwig max_discard_sectors = 122c55ddd90SChristoph Hellwig min(lim->max_discard_sectors, bio_allowed_max_sectors(lim)); 12354efd50bSKent Overstreet max_discard_sectors -= max_discard_sectors % granularity; 12454efd50bSKent Overstreet 12554efd50bSKent Overstreet if (unlikely(!max_discard_sectors)) { 12654efd50bSKent Overstreet /* XXX: warn */ 12754efd50bSKent Overstreet return NULL; 12854efd50bSKent Overstreet } 12954efd50bSKent Overstreet 13054efd50bSKent Overstreet if (bio_sectors(bio) <= max_discard_sectors) 13154efd50bSKent Overstreet return NULL; 13254efd50bSKent Overstreet 13354efd50bSKent Overstreet split_sectors = max_discard_sectors; 13454efd50bSKent Overstreet 13554efd50bSKent Overstreet /* 13654efd50bSKent Overstreet * If the next starting sector would be misaligned, stop the discard at 13754efd50bSKent Overstreet * the previous aligned sector. 13854efd50bSKent Overstreet */ 139c55ddd90SChristoph Hellwig tmp = bio->bi_iter.bi_sector + split_sectors - 140c55ddd90SChristoph Hellwig ((lim->discard_alignment >> 9) % granularity); 14154efd50bSKent Overstreet tmp = sector_div(tmp, granularity); 14254efd50bSKent Overstreet 14354efd50bSKent Overstreet if (split_sectors > tmp) 14454efd50bSKent Overstreet split_sectors -= tmp; 14554efd50bSKent Overstreet 14654efd50bSKent Overstreet return bio_split(bio, split_sectors, GFP_NOIO, bs); 14754efd50bSKent Overstreet } 14854efd50bSKent Overstreet 1495a97806fSChristoph Hellwig static struct bio *bio_split_write_zeroes(struct bio *bio, 150aa261f20SBart Van Assche const struct queue_limits *lim, 151aa261f20SBart Van Assche unsigned *nsegs, struct bio_set *bs) 152885fa13fSChristoph Hellwig { 153d665e12aSChristoph Hellwig *nsegs = 0; 154c55ddd90SChristoph Hellwig if (!lim->max_write_zeroes_sectors) 155885fa13fSChristoph Hellwig return NULL; 156c55ddd90SChristoph Hellwig if (bio_sectors(bio) <= lim->max_write_zeroes_sectors) 157885fa13fSChristoph Hellwig return NULL; 158c55ddd90SChristoph Hellwig return bio_split(bio, lim->max_write_zeroes_sectors, GFP_NOIO, bs); 159885fa13fSChristoph Hellwig } 160885fa13fSChristoph Hellwig 1619cc5169cSBart Van Assche /* 1629cc5169cSBart Van Assche * Return the maximum number of sectors from the start of a bio that may be 1639cc5169cSBart Van Assche * submitted as a single request to a block device. If enough sectors remain, 1649cc5169cSBart Van Assche * align the end to the physical block size. Otherwise align the end to the 1659cc5169cSBart Van Assche * logical block size. This approach minimizes the number of non-aligned 1669cc5169cSBart Van Assche * requests that are submitted to a block device if the start of a bio is not 1679cc5169cSBart Van Assche * aligned to a physical block boundary. 1689cc5169cSBart Van Assche */ 1695a97806fSChristoph Hellwig static inline unsigned get_max_io_size(struct bio *bio, 170aa261f20SBart Van Assche const struct queue_limits *lim) 171d0e5fbb0SMing Lei { 172c55ddd90SChristoph Hellwig unsigned pbs = lim->physical_block_size >> SECTOR_SHIFT; 173c55ddd90SChristoph Hellwig unsigned lbs = lim->logical_block_size >> SECTOR_SHIFT; 174c55ddd90SChristoph Hellwig unsigned max_sectors = lim->max_sectors, start, end; 175d0e5fbb0SMing Lei 176c55ddd90SChristoph Hellwig if (lim->chunk_sectors) { 177efef739dSChristoph Hellwig max_sectors = min(max_sectors, 178efef739dSChristoph Hellwig blk_chunk_sectors_left(bio->bi_iter.bi_sector, 179c55ddd90SChristoph Hellwig lim->chunk_sectors)); 180efef739dSChristoph Hellwig } 181d0e5fbb0SMing Lei 18284613bedSChristoph Hellwig start = bio->bi_iter.bi_sector & (pbs - 1); 18384613bedSChristoph Hellwig end = (start + max_sectors) & ~(pbs - 1); 18484613bedSChristoph Hellwig if (end > start) 18584613bedSChristoph Hellwig return end - start; 18684613bedSChristoph Hellwig return max_sectors & ~(lbs - 1); 187d0e5fbb0SMing Lei } 188d0e5fbb0SMing Lei 18995465318SBart Van Assche /** 19095465318SBart Van Assche * get_max_segment_size() - maximum number of bytes to add as a single segment 19195465318SBart Van Assche * @lim: Request queue limits. 19295465318SBart Van Assche * @start_page: See below. 19395465318SBart Van Assche * @offset: Offset from @start_page where to add a segment. 19495465318SBart Van Assche * 19595465318SBart Van Assche * Returns the maximum number of bytes that can be added as a single segment. 19695465318SBart Van Assche */ 197aa261f20SBart Van Assche static inline unsigned get_max_segment_size(const struct queue_limits *lim, 198c55ddd90SChristoph Hellwig struct page *start_page, unsigned long offset) 199dcebd755SMing Lei { 200c55ddd90SChristoph Hellwig unsigned long mask = lim->seg_boundary_mask; 201dcebd755SMing Lei 202429120f3SMing Lei offset = mask & (page_to_phys(start_page) + offset); 2034a2f704eSMing Lei 2044a2f704eSMing Lei /* 20595465318SBart Van Assche * Prevent an overflow if mask = ULONG_MAX and offset = 0 by adding 1 20695465318SBart Van Assche * after having calculated the minimum. 2074a2f704eSMing Lei */ 20895465318SBart Van Assche return min(mask - offset, (unsigned long)lim->max_segment_size - 1) + 1; 209dcebd755SMing Lei } 210dcebd755SMing Lei 211708b25b3SBart Van Assche /** 212708b25b3SBart Van Assche * bvec_split_segs - verify whether or not a bvec should be split in the middle 213c55ddd90SChristoph Hellwig * @lim: [in] queue limits to split based on 214708b25b3SBart Van Assche * @bv: [in] bvec to examine 215708b25b3SBart Van Assche * @nsegs: [in,out] Number of segments in the bio being built. Incremented 216708b25b3SBart Van Assche * by the number of segments from @bv that may be appended to that 217708b25b3SBart Van Assche * bio without exceeding @max_segs 21867927d22SKeith Busch * @bytes: [in,out] Number of bytes in the bio being built. Incremented 21967927d22SKeith Busch * by the number of bytes from @bv that may be appended to that 22067927d22SKeith Busch * bio without exceeding @max_bytes 221708b25b3SBart Van Assche * @max_segs: [in] upper bound for *@nsegs 22267927d22SKeith Busch * @max_bytes: [in] upper bound for *@bytes 223708b25b3SBart Van Assche * 224708b25b3SBart Van Assche * When splitting a bio, it can happen that a bvec is encountered that is too 225708b25b3SBart Van Assche * big to fit in a single segment and hence that it has to be split in the 226708b25b3SBart Van Assche * middle. This function verifies whether or not that should happen. The value 227708b25b3SBart Van Assche * %true is returned if and only if appending the entire @bv to a bio with 228708b25b3SBart Van Assche * *@nsegs segments and *@sectors sectors would make that bio unacceptable for 229708b25b3SBart Van Assche * the block driver. 230dcebd755SMing Lei */ 231aa261f20SBart Van Assche static bool bvec_split_segs(const struct queue_limits *lim, 232aa261f20SBart Van Assche const struct bio_vec *bv, unsigned *nsegs, unsigned *bytes, 233aa261f20SBart Van Assche unsigned max_segs, unsigned max_bytes) 234dcebd755SMing Lei { 23567927d22SKeith Busch unsigned max_len = min(max_bytes, UINT_MAX) - *bytes; 236708b25b3SBart Van Assche unsigned len = min(bv->bv_len, max_len); 237dcebd755SMing Lei unsigned total_len = 0; 238ff9811b3SBart Van Assche unsigned seg_size = 0; 239dcebd755SMing Lei 240ff9811b3SBart Van Assche while (len && *nsegs < max_segs) { 241c55ddd90SChristoph Hellwig seg_size = get_max_segment_size(lim, bv->bv_page, 242429120f3SMing Lei bv->bv_offset + total_len); 243dcebd755SMing Lei seg_size = min(seg_size, len); 244dcebd755SMing Lei 245ff9811b3SBart Van Assche (*nsegs)++; 246dcebd755SMing Lei total_len += seg_size; 247dcebd755SMing Lei len -= seg_size; 248dcebd755SMing Lei 249c55ddd90SChristoph Hellwig if ((bv->bv_offset + total_len) & lim->virt_boundary_mask) 250dcebd755SMing Lei break; 251dcebd755SMing Lei } 252dcebd755SMing Lei 25367927d22SKeith Busch *bytes += total_len; 254dcebd755SMing Lei 255708b25b3SBart Van Assche /* tell the caller to split the bvec if it is too big to fit */ 256708b25b3SBart Van Assche return len > 0 || bv->bv_len > max_len; 257dcebd755SMing Lei } 258dcebd755SMing Lei 259dad77584SBart Van Assche /** 2605a97806fSChristoph Hellwig * bio_split_rw - split a bio in two bios 261dad77584SBart Van Assche * @bio: [in] bio to be split 262c55ddd90SChristoph Hellwig * @lim: [in] queue limits to split based on 263dad77584SBart Van Assche * @segs: [out] number of segments in the bio with the first half of the sectors 2645a97806fSChristoph Hellwig * @bs: [in] bio set to allocate the clone from 265a85b3637SChristoph Hellwig * @max_bytes: [in] maximum number of bytes per bio 266dad77584SBart Van Assche * 267dad77584SBart Van Assche * Clone @bio, update the bi_iter of the clone to represent the first sectors 268dad77584SBart Van Assche * of @bio and update @bio->bi_iter to represent the remaining sectors. The 269dad77584SBart Van Assche * following is guaranteed for the cloned bio: 270a85b3637SChristoph Hellwig * - That it has at most @max_bytes worth of data 271dad77584SBart Van Assche * - That it has at most queue_max_segments(@q) segments. 272dad77584SBart Van Assche * 273dad77584SBart Van Assche * Except for discard requests the cloned bio will point at the bi_io_vec of 274dad77584SBart Van Assche * the original bio. It is the responsibility of the caller to ensure that the 275dad77584SBart Van Assche * original bio is not freed before the cloned bio. The caller is also 276dad77584SBart Van Assche * responsible for ensuring that @bs is only destroyed after processing of the 277dad77584SBart Van Assche * split bio has finished. 278dad77584SBart Van Assche */ 279aa261f20SBart Van Assche static struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim, 280a85b3637SChristoph Hellwig unsigned *segs, struct bio_set *bs, unsigned max_bytes) 28154efd50bSKent Overstreet { 2825014c311SJens Axboe struct bio_vec bv, bvprv, *bvprvp = NULL; 28354efd50bSKent Overstreet struct bvec_iter iter; 28467927d22SKeith Busch unsigned nsegs = 0, bytes = 0; 28554efd50bSKent Overstreet 286dcebd755SMing Lei bio_for_each_bvec(bv, bio, iter) { 28754efd50bSKent Overstreet /* 28854efd50bSKent Overstreet * If the queue doesn't support SG gaps and adding this 28954efd50bSKent Overstreet * offset would create a gap, disallow it. 29054efd50bSKent Overstreet */ 291c55ddd90SChristoph Hellwig if (bvprvp && bvec_gap_to_prev(lim, bvprvp, bv.bv_offset)) 29254efd50bSKent Overstreet goto split; 29354efd50bSKent Overstreet 294c55ddd90SChristoph Hellwig if (nsegs < lim->max_segments && 29567927d22SKeith Busch bytes + bv.bv_len <= max_bytes && 296708b25b3SBart Van Assche bv.bv_offset + bv.bv_len <= PAGE_SIZE) { 297708b25b3SBart Van Assche nsegs++; 29867927d22SKeith Busch bytes += bv.bv_len; 299c55ddd90SChristoph Hellwig } else { 300c55ddd90SChristoph Hellwig if (bvec_split_segs(lim, &bv, &nsegs, &bytes, 301c55ddd90SChristoph Hellwig lim->max_segments, max_bytes)) 302e36f6204SKeith Busch goto split; 303e36f6204SKeith Busch } 304e36f6204SKeith Busch 30554efd50bSKent Overstreet bvprv = bv; 306578270bfSMing Lei bvprvp = &bvprv; 30754efd50bSKent Overstreet } 30854efd50bSKent Overstreet 309d627065dSChristoph Hellwig *segs = nsegs; 310d627065dSChristoph Hellwig return NULL; 31154efd50bSKent Overstreet split: 312bdced438SMing Lei *segs = nsegs; 313cc29e1bfSJeffle Xu 314cc29e1bfSJeffle Xu /* 31567927d22SKeith Busch * Individual bvecs might not be logical block aligned. Round down the 31667927d22SKeith Busch * split size so that each bio is properly block size aligned, even if 31767927d22SKeith Busch * we do not use the full hardware limits. 31867927d22SKeith Busch */ 319c55ddd90SChristoph Hellwig bytes = ALIGN_DOWN(bytes, lim->logical_block_size); 32067927d22SKeith Busch 32167927d22SKeith Busch /* 322cc29e1bfSJeffle Xu * Bio splitting may cause subtle trouble such as hang when doing sync 323cc29e1bfSJeffle Xu * iopoll in direct IO routine. Given performance gain of iopoll for 324cc29e1bfSJeffle Xu * big IO can be trival, disable iopoll when split needed. 325cc29e1bfSJeffle Xu */ 3266ce913feSChristoph Hellwig bio_clear_polled(bio); 32767927d22SKeith Busch return bio_split(bio, bytes >> SECTOR_SHIFT, GFP_NOIO, bs); 32854efd50bSKent Overstreet } 32954efd50bSKent Overstreet 330dad77584SBart Van Assche /** 3315a97806fSChristoph Hellwig * __bio_split_to_limits - split a bio to fit the queue limits 3325a97806fSChristoph Hellwig * @bio: bio to be split 333c55ddd90SChristoph Hellwig * @lim: queue limits to split based on 3345a97806fSChristoph Hellwig * @nr_segs: returns the number of segments in the returned bio 335dad77584SBart Van Assche * 3365a97806fSChristoph Hellwig * Check if @bio needs splitting based on the queue limits, and if so split off 3375a97806fSChristoph Hellwig * a bio fitting the limits from the beginning of @bio and return it. @bio is 3385a97806fSChristoph Hellwig * shortened to the remainder and re-submitted. 3395a97806fSChristoph Hellwig * 3405a97806fSChristoph Hellwig * The split bio is allocated from @q->bio_split, which is provided by the 3415a97806fSChristoph Hellwig * block layer. 342dad77584SBart Van Assche */ 343aa261f20SBart Van Assche struct bio *__bio_split_to_limits(struct bio *bio, 344aa261f20SBart Van Assche const struct queue_limits *lim, 345abd45c15SJens Axboe unsigned int *nr_segs) 34654efd50bSKent Overstreet { 34746754bd0SChristoph Hellwig struct bio_set *bs = &bio->bi_bdev->bd_disk->bio_split; 3485a97806fSChristoph Hellwig struct bio *split; 34954efd50bSKent Overstreet 3505a97806fSChristoph Hellwig switch (bio_op(bio)) { 3517afafc8aSAdrian Hunter case REQ_OP_DISCARD: 3527afafc8aSAdrian Hunter case REQ_OP_SECURE_ERASE: 353c55ddd90SChristoph Hellwig split = bio_split_discard(bio, lim, nr_segs, bs); 3547afafc8aSAdrian Hunter break; 355a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 356c55ddd90SChristoph Hellwig split = bio_split_write_zeroes(bio, lim, nr_segs, bs); 357a6f0788eSChaitanya Kulkarni break; 3587afafc8aSAdrian Hunter default: 359c55ddd90SChristoph Hellwig split = bio_split_rw(bio, lim, nr_segs, bs, 360c55ddd90SChristoph Hellwig get_max_io_size(bio, lim) << SECTOR_SHIFT); 361*613b1488SJens Axboe if (IS_ERR(split)) 362*613b1488SJens Axboe return NULL; 3637afafc8aSAdrian Hunter break; 3647afafc8aSAdrian Hunter } 365bdced438SMing Lei 36654efd50bSKent Overstreet if (split) { 367*613b1488SJens Axboe /* there isn't chance to merge the split bio */ 3681eff9d32SJens Axboe split->bi_opf |= REQ_NOMERGE; 3696ac45aebSMing Lei 370957a2b34SMuchun Song blkcg_bio_issue_init(split); 3715a97806fSChristoph Hellwig bio_chain(split, bio); 3725a97806fSChristoph Hellwig trace_block_split(split, bio->bi_iter.bi_sector); 3735a97806fSChristoph Hellwig submit_bio_noacct(bio); 3745a97806fSChristoph Hellwig return split; 37554efd50bSKent Overstreet } 3765a97806fSChristoph Hellwig return bio; 37754efd50bSKent Overstreet } 37814ccb66bSChristoph Hellwig 379dad77584SBart Van Assche /** 3805a97806fSChristoph Hellwig * bio_split_to_limits - split a bio to fit the queue limits 3815a97806fSChristoph Hellwig * @bio: bio to be split 382dad77584SBart Van Assche * 3835a97806fSChristoph Hellwig * Check if @bio needs splitting based on the queue limits of @bio->bi_bdev, and 3845a97806fSChristoph Hellwig * if so split off a bio fitting the limits from the beginning of @bio and 3855a97806fSChristoph Hellwig * return it. @bio is shortened to the remainder and re-submitted. 3865a97806fSChristoph Hellwig * 3875a97806fSChristoph Hellwig * The split bio is allocated from @q->bio_split, which is provided by the 3885a97806fSChristoph Hellwig * block layer. 389dad77584SBart Van Assche */ 3905a97806fSChristoph Hellwig struct bio *bio_split_to_limits(struct bio *bio) 39114ccb66bSChristoph Hellwig { 392aa261f20SBart Van Assche const struct queue_limits *lim = &bdev_get_queue(bio->bi_bdev)->limits; 39314ccb66bSChristoph Hellwig unsigned int nr_segs; 39414ccb66bSChristoph Hellwig 395c55ddd90SChristoph Hellwig if (bio_may_exceed_limits(bio, lim)) 396c55ddd90SChristoph Hellwig return __bio_split_to_limits(bio, lim, &nr_segs); 3975a97806fSChristoph Hellwig return bio; 39814ccb66bSChristoph Hellwig } 3995a97806fSChristoph Hellwig EXPORT_SYMBOL(bio_split_to_limits); 40054efd50bSKent Overstreet 401e9cd19c0SChristoph Hellwig unsigned int blk_recalc_rq_segments(struct request *rq) 402d6d48196SJens Axboe { 4036869875fSChristoph Hellwig unsigned int nr_phys_segs = 0; 40467927d22SKeith Busch unsigned int bytes = 0; 405e9cd19c0SChristoph Hellwig struct req_iterator iter; 4066869875fSChristoph Hellwig struct bio_vec bv; 407d6d48196SJens Axboe 408e9cd19c0SChristoph Hellwig if (!rq->bio) 4091e428079SJens Axboe return 0; 410d6d48196SJens Axboe 411e9cd19c0SChristoph Hellwig switch (bio_op(rq->bio)) { 412a6f0788eSChaitanya Kulkarni case REQ_OP_DISCARD: 413a6f0788eSChaitanya Kulkarni case REQ_OP_SECURE_ERASE: 414a958937fSDavid Jeffery if (queue_max_discard_segments(rq->q) > 1) { 415a958937fSDavid Jeffery struct bio *bio = rq->bio; 416a958937fSDavid Jeffery 417a958937fSDavid Jeffery for_each_bio(bio) 418a958937fSDavid Jeffery nr_phys_segs++; 419a958937fSDavid Jeffery return nr_phys_segs; 420a958937fSDavid Jeffery } 421a958937fSDavid Jeffery return 1; 422a6f0788eSChaitanya Kulkarni case REQ_OP_WRITE_ZEROES: 423f9d03f96SChristoph Hellwig return 0; 4242d9b02beSBart Van Assche default: 4252d9b02beSBart Van Assche break; 426a6f0788eSChaitanya Kulkarni } 4275cb8850cSKent Overstreet 428e9cd19c0SChristoph Hellwig rq_for_each_bvec(bv, rq, iter) 429c55ddd90SChristoph Hellwig bvec_split_segs(&rq->q->limits, &bv, &nr_phys_segs, &bytes, 430708b25b3SBart Van Assche UINT_MAX, UINT_MAX); 4311e428079SJens Axboe return nr_phys_segs; 4321e428079SJens Axboe } 4331e428079SJens Axboe 43448d7727cSMing Lei static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, 435862e5a5eSMing Lei struct scatterlist *sglist) 436862e5a5eSMing Lei { 437862e5a5eSMing Lei if (!*sg) 438862e5a5eSMing Lei return sglist; 439862e5a5eSMing Lei 440862e5a5eSMing Lei /* 441862e5a5eSMing Lei * If the driver previously mapped a shorter list, we could see a 442862e5a5eSMing Lei * termination bit prematurely unless it fully inits the sg table 443862e5a5eSMing Lei * on each mapping. We KNOW that there must be more entries here 444862e5a5eSMing Lei * or the driver would be buggy, so force clear the termination bit 445862e5a5eSMing Lei * to avoid doing a full sg_init_table() in drivers for each command. 446862e5a5eSMing Lei */ 447862e5a5eSMing Lei sg_unmark_end(*sg); 448862e5a5eSMing Lei return sg_next(*sg); 449862e5a5eSMing Lei } 450862e5a5eSMing Lei 451862e5a5eSMing Lei static unsigned blk_bvec_map_sg(struct request_queue *q, 452862e5a5eSMing Lei struct bio_vec *bvec, struct scatterlist *sglist, 453862e5a5eSMing Lei struct scatterlist **sg) 454862e5a5eSMing Lei { 455862e5a5eSMing Lei unsigned nbytes = bvec->bv_len; 4568a96a0e4SChristoph Hellwig unsigned nsegs = 0, total = 0; 457862e5a5eSMing Lei 458862e5a5eSMing Lei while (nbytes > 0) { 4598a96a0e4SChristoph Hellwig unsigned offset = bvec->bv_offset + total; 460c55ddd90SChristoph Hellwig unsigned len = min(get_max_segment_size(&q->limits, 461c55ddd90SChristoph Hellwig bvec->bv_page, offset), nbytes); 462f9f76879SChristoph Hellwig struct page *page = bvec->bv_page; 463f9f76879SChristoph Hellwig 464f9f76879SChristoph Hellwig /* 465f9f76879SChristoph Hellwig * Unfortunately a fair number of drivers barf on scatterlists 466f9f76879SChristoph Hellwig * that have an offset larger than PAGE_SIZE, despite other 467f9f76879SChristoph Hellwig * subsystems dealing with that invariant just fine. For now 468f9f76879SChristoph Hellwig * stick to the legacy format where we never present those from 469f9f76879SChristoph Hellwig * the block layer, but the code below should be removed once 470f9f76879SChristoph Hellwig * these offenders (mostly MMC/SD drivers) are fixed. 471f9f76879SChristoph Hellwig */ 472f9f76879SChristoph Hellwig page += (offset >> PAGE_SHIFT); 473f9f76879SChristoph Hellwig offset &= ~PAGE_MASK; 474862e5a5eSMing Lei 475862e5a5eSMing Lei *sg = blk_next_sg(sg, sglist); 476f9f76879SChristoph Hellwig sg_set_page(*sg, page, len, offset); 477862e5a5eSMing Lei 4788a96a0e4SChristoph Hellwig total += len; 4798a96a0e4SChristoph Hellwig nbytes -= len; 480862e5a5eSMing Lei nsegs++; 481862e5a5eSMing Lei } 482862e5a5eSMing Lei 483862e5a5eSMing Lei return nsegs; 484862e5a5eSMing Lei } 485862e5a5eSMing Lei 48616e3e418SMing Lei static inline int __blk_bvec_map_sg(struct bio_vec bv, 48716e3e418SMing Lei struct scatterlist *sglist, struct scatterlist **sg) 48816e3e418SMing Lei { 48916e3e418SMing Lei *sg = blk_next_sg(sg, sglist); 49016e3e418SMing Lei sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); 49116e3e418SMing Lei return 1; 49216e3e418SMing Lei } 49316e3e418SMing Lei 494f6970f83SMing Lei /* only try to merge bvecs into one sg if they are from two bios */ 495f6970f83SMing Lei static inline bool 496f6970f83SMing Lei __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec, 497f6970f83SMing Lei struct bio_vec *bvprv, struct scatterlist **sg) 498963ab9e5SAsias He { 499963ab9e5SAsias He 500963ab9e5SAsias He int nbytes = bvec->bv_len; 501963ab9e5SAsias He 502f6970f83SMing Lei if (!*sg) 503f6970f83SMing Lei return false; 504f6970f83SMing Lei 505b4b6cb61SMing Lei if ((*sg)->length + nbytes > queue_max_segment_size(q)) 506f6970f83SMing Lei return false; 507f6970f83SMing Lei 5083dccdae5SChristoph Hellwig if (!biovec_phys_mergeable(q, bvprv, bvec)) 509f6970f83SMing Lei return false; 510963ab9e5SAsias He 511963ab9e5SAsias He (*sg)->length += nbytes; 512f6970f83SMing Lei 513f6970f83SMing Lei return true; 514963ab9e5SAsias He } 515963ab9e5SAsias He 5165cb8850cSKent Overstreet static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, 5175cb8850cSKent Overstreet struct scatterlist *sglist, 5185cb8850cSKent Overstreet struct scatterlist **sg) 5195cb8850cSKent Overstreet { 5203f649ab7SKees Cook struct bio_vec bvec, bvprv = { NULL }; 5215cb8850cSKent Overstreet struct bvec_iter iter; 52238417468SChristoph Hellwig int nsegs = 0; 523f6970f83SMing Lei bool new_bio = false; 5245cb8850cSKent Overstreet 525f6970f83SMing Lei for_each_bio(bio) { 526f6970f83SMing Lei bio_for_each_bvec(bvec, bio, iter) { 527f6970f83SMing Lei /* 528f6970f83SMing Lei * Only try to merge bvecs from two bios given we 529f6970f83SMing Lei * have done bio internal merge when adding pages 530f6970f83SMing Lei * to bio 531f6970f83SMing Lei */ 532f6970f83SMing Lei if (new_bio && 533f6970f83SMing Lei __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg)) 534f6970f83SMing Lei goto next_bvec; 535f6970f83SMing Lei 536f6970f83SMing Lei if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE) 537f6970f83SMing Lei nsegs += __blk_bvec_map_sg(bvec, sglist, sg); 538f6970f83SMing Lei else 539f6970f83SMing Lei nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg); 540f6970f83SMing Lei next_bvec: 541f6970f83SMing Lei new_bio = false; 542f6970f83SMing Lei } 543b21e11c5SMing Lei if (likely(bio->bi_iter.bi_size)) { 544f6970f83SMing Lei bvprv = bvec; 545f6970f83SMing Lei new_bio = true; 546f6970f83SMing Lei } 547b21e11c5SMing Lei } 5485cb8850cSKent Overstreet 5495cb8850cSKent Overstreet return nsegs; 5505cb8850cSKent Overstreet } 5515cb8850cSKent Overstreet 552d6d48196SJens Axboe /* 553d6d48196SJens Axboe * map a request to scatterlist, return number of sg entries setup. Caller 554d6d48196SJens Axboe * must make sure sg can hold rq->nr_phys_segments entries 555d6d48196SJens Axboe */ 55689de1504SChristoph Hellwig int __blk_rq_map_sg(struct request_queue *q, struct request *rq, 55789de1504SChristoph Hellwig struct scatterlist *sglist, struct scatterlist **last_sg) 558d6d48196SJens Axboe { 5595cb8850cSKent Overstreet int nsegs = 0; 560d6d48196SJens Axboe 561f9d03f96SChristoph Hellwig if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) 56289de1504SChristoph Hellwig nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, last_sg); 563f9d03f96SChristoph Hellwig else if (rq->bio) 56489de1504SChristoph Hellwig nsegs = __blk_bios_map_sg(q, rq->bio, sglist, last_sg); 565f18573abSFUJITA Tomonori 56689de1504SChristoph Hellwig if (*last_sg) 56789de1504SChristoph Hellwig sg_mark_end(*last_sg); 568d6d48196SJens Axboe 56912e57f59SMing Lei /* 57012e57f59SMing Lei * Something must have been wrong if the figured number of 57112e57f59SMing Lei * segment is bigger than number of req's physical segments 57212e57f59SMing Lei */ 573f9d03f96SChristoph Hellwig WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); 57412e57f59SMing Lei 575d6d48196SJens Axboe return nsegs; 576d6d48196SJens Axboe } 57789de1504SChristoph Hellwig EXPORT_SYMBOL(__blk_rq_map_sg); 578d6d48196SJens Axboe 579943b40c8SMing Lei static inline unsigned int blk_rq_get_max_segments(struct request *rq) 580943b40c8SMing Lei { 581943b40c8SMing Lei if (req_op(rq) == REQ_OP_DISCARD) 582943b40c8SMing Lei return queue_max_discard_segments(rq->q); 583943b40c8SMing Lei return queue_max_segments(rq->q); 584943b40c8SMing Lei } 585943b40c8SMing Lei 586badf7f64SChristoph Hellwig static inline unsigned int blk_rq_get_max_sectors(struct request *rq, 587badf7f64SChristoph Hellwig sector_t offset) 588badf7f64SChristoph Hellwig { 589badf7f64SChristoph Hellwig struct request_queue *q = rq->q; 590c8875190SChristoph Hellwig unsigned int max_sectors; 591badf7f64SChristoph Hellwig 592badf7f64SChristoph Hellwig if (blk_rq_is_passthrough(rq)) 593badf7f64SChristoph Hellwig return q->limits.max_hw_sectors; 594badf7f64SChristoph Hellwig 595c8875190SChristoph Hellwig max_sectors = blk_queue_get_max_sectors(q, req_op(rq)); 596badf7f64SChristoph Hellwig if (!q->limits.chunk_sectors || 597badf7f64SChristoph Hellwig req_op(rq) == REQ_OP_DISCARD || 598badf7f64SChristoph Hellwig req_op(rq) == REQ_OP_SECURE_ERASE) 599c8875190SChristoph Hellwig return max_sectors; 600c8875190SChristoph Hellwig return min(max_sectors, 601c8875190SChristoph Hellwig blk_chunk_sectors_left(offset, q->limits.chunk_sectors)); 602badf7f64SChristoph Hellwig } 603badf7f64SChristoph Hellwig 60414ccb66bSChristoph Hellwig static inline int ll_new_hw_segment(struct request *req, struct bio *bio, 60514ccb66bSChristoph Hellwig unsigned int nr_phys_segs) 606d6d48196SJens Axboe { 6076b2b0459STejun Heo if (!blk_cgroup_mergeable(req, bio)) 6086b2b0459STejun Heo goto no_merge; 6096b2b0459STejun Heo 6102705dfb2SMing Lei if (blk_integrity_merge_bio(req->q, req, bio) == false) 61113f05c8dSMartin K. Petersen goto no_merge; 61213f05c8dSMartin K. Petersen 6132705dfb2SMing Lei /* discard request merge won't add new segment */ 6142705dfb2SMing Lei if (req_op(req) == REQ_OP_DISCARD) 6152705dfb2SMing Lei return 1; 6162705dfb2SMing Lei 6172705dfb2SMing Lei if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) 61813f05c8dSMartin K. Petersen goto no_merge; 619d6d48196SJens Axboe 620d6d48196SJens Axboe /* 621d6d48196SJens Axboe * This will form the start of a new hw segment. Bump both 622d6d48196SJens Axboe * counters. 623d6d48196SJens Axboe */ 624d6d48196SJens Axboe req->nr_phys_segments += nr_phys_segs; 625d6d48196SJens Axboe return 1; 62613f05c8dSMartin K. Petersen 62713f05c8dSMartin K. Petersen no_merge: 62814ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 62913f05c8dSMartin K. Petersen return 0; 630d6d48196SJens Axboe } 631d6d48196SJens Axboe 63214ccb66bSChristoph Hellwig int ll_back_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs) 633d6d48196SJens Axboe { 6345e7c4274SJens Axboe if (req_gap_back_merge(req, bio)) 6355e7c4274SJens Axboe return 0; 6367f39add3SSagi Grimberg if (blk_integrity_rq(req) && 6377f39add3SSagi Grimberg integrity_req_gap_back_merge(req, bio)) 6387f39add3SSagi Grimberg return 0; 639a892c8d5SSatya Tangirala if (!bio_crypt_ctx_back_mergeable(req, bio)) 640a892c8d5SSatya Tangirala return 0; 641f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 64217007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) { 64314ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 644d6d48196SJens Axboe return 0; 645d6d48196SJens Axboe } 646d6d48196SJens Axboe 64714ccb66bSChristoph Hellwig return ll_new_hw_segment(req, bio, nr_segs); 648d6d48196SJens Axboe } 649d6d48196SJens Axboe 650eda5cc99SChristoph Hellwig static int ll_front_merge_fn(struct request *req, struct bio *bio, 651eda5cc99SChristoph Hellwig unsigned int nr_segs) 652d6d48196SJens Axboe { 6535e7c4274SJens Axboe if (req_gap_front_merge(req, bio)) 6545e7c4274SJens Axboe return 0; 6557f39add3SSagi Grimberg if (blk_integrity_rq(req) && 6567f39add3SSagi Grimberg integrity_req_gap_front_merge(req, bio)) 6577f39add3SSagi Grimberg return 0; 658a892c8d5SSatya Tangirala if (!bio_crypt_ctx_front_mergeable(req, bio)) 659a892c8d5SSatya Tangirala return 0; 660f31dc1cdSMartin K. Petersen if (blk_rq_sectors(req) + bio_sectors(bio) > 66117007f39SDamien Le Moal blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { 66214ccb66bSChristoph Hellwig req_set_nomerge(req->q, req); 663d6d48196SJens Axboe return 0; 664d6d48196SJens Axboe } 665d6d48196SJens Axboe 66614ccb66bSChristoph Hellwig return ll_new_hw_segment(req, bio, nr_segs); 667d6d48196SJens Axboe } 668d6d48196SJens Axboe 669445251d0SJens Axboe static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, 670445251d0SJens Axboe struct request *next) 671445251d0SJens Axboe { 672445251d0SJens Axboe unsigned short segments = blk_rq_nr_discard_segments(req); 673445251d0SJens Axboe 674445251d0SJens Axboe if (segments >= queue_max_discard_segments(q)) 675445251d0SJens Axboe goto no_merge; 676445251d0SJens Axboe if (blk_rq_sectors(req) + bio_sectors(next->bio) > 677445251d0SJens Axboe blk_rq_get_max_sectors(req, blk_rq_pos(req))) 678445251d0SJens Axboe goto no_merge; 679445251d0SJens Axboe 680445251d0SJens Axboe req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); 681445251d0SJens Axboe return true; 682445251d0SJens Axboe no_merge: 683445251d0SJens Axboe req_set_nomerge(q, req); 684445251d0SJens Axboe return false; 685445251d0SJens Axboe } 686445251d0SJens Axboe 687d6d48196SJens Axboe static int ll_merge_requests_fn(struct request_queue *q, struct request *req, 688d6d48196SJens Axboe struct request *next) 689d6d48196SJens Axboe { 690d6d48196SJens Axboe int total_phys_segments; 691d6d48196SJens Axboe 6925e7c4274SJens Axboe if (req_gap_back_merge(req, next->bio)) 693854fbb9cSKeith Busch return 0; 694854fbb9cSKeith Busch 695d6d48196SJens Axboe /* 696d6d48196SJens Axboe * Will it become too large? 697d6d48196SJens Axboe */ 698f31dc1cdSMartin K. Petersen if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > 69917007f39SDamien Le Moal blk_rq_get_max_sectors(req, blk_rq_pos(req))) 700d6d48196SJens Axboe return 0; 701d6d48196SJens Axboe 702d6d48196SJens Axboe total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; 703943b40c8SMing Lei if (total_phys_segments > blk_rq_get_max_segments(req)) 704d6d48196SJens Axboe return 0; 705d6d48196SJens Axboe 7066b2b0459STejun Heo if (!blk_cgroup_mergeable(req, next->bio)) 7076b2b0459STejun Heo return 0; 7086b2b0459STejun Heo 7094eaf99beSMartin K. Petersen if (blk_integrity_merge_rq(q, req, next) == false) 71013f05c8dSMartin K. Petersen return 0; 71113f05c8dSMartin K. Petersen 712a892c8d5SSatya Tangirala if (!bio_crypt_ctx_merge_rq(req, next)) 713a892c8d5SSatya Tangirala return 0; 714a892c8d5SSatya Tangirala 715d6d48196SJens Axboe /* Merge is OK... */ 716d6d48196SJens Axboe req->nr_phys_segments = total_phys_segments; 717d6d48196SJens Axboe return 1; 718d6d48196SJens Axboe } 719d6d48196SJens Axboe 72080a761fdSTejun Heo /** 72180a761fdSTejun Heo * blk_rq_set_mixed_merge - mark a request as mixed merge 72280a761fdSTejun Heo * @rq: request to mark as mixed merge 72380a761fdSTejun Heo * 72480a761fdSTejun Heo * Description: 72580a761fdSTejun Heo * @rq is about to be mixed merged. Make sure the attributes 72680a761fdSTejun Heo * which can be mixed are set in each bio and mark @rq as mixed 72780a761fdSTejun Heo * merged. 72880a761fdSTejun Heo */ 72980a761fdSTejun Heo void blk_rq_set_mixed_merge(struct request *rq) 73080a761fdSTejun Heo { 73116458cf3SBart Van Assche blk_opf_t ff = rq->cmd_flags & REQ_FAILFAST_MASK; 73280a761fdSTejun Heo struct bio *bio; 73380a761fdSTejun Heo 734e8064021SChristoph Hellwig if (rq->rq_flags & RQF_MIXED_MERGE) 73580a761fdSTejun Heo return; 73680a761fdSTejun Heo 73780a761fdSTejun Heo /* 73880a761fdSTejun Heo * @rq will no longer represent mixable attributes for all the 73980a761fdSTejun Heo * contained bios. It will just track those of the first one. 74080a761fdSTejun Heo * Distributes the attributs to each bio. 74180a761fdSTejun Heo */ 74280a761fdSTejun Heo for (bio = rq->bio; bio; bio = bio->bi_next) { 7431eff9d32SJens Axboe WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && 7441eff9d32SJens Axboe (bio->bi_opf & REQ_FAILFAST_MASK) != ff); 7451eff9d32SJens Axboe bio->bi_opf |= ff; 74680a761fdSTejun Heo } 747e8064021SChristoph Hellwig rq->rq_flags |= RQF_MIXED_MERGE; 74880a761fdSTejun Heo } 74980a761fdSTejun Heo 750b9c54f56SKonstantin Khlebnikov static void blk_account_io_merge_request(struct request *req) 75126308eabSJerome Marchand { 75226308eabSJerome Marchand if (blk_do_io_stat(req)) { 753112f158fSMike Snitzer part_stat_lock(); 754b9c54f56SKonstantin Khlebnikov part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); 75526308eabSJerome Marchand part_stat_unlock(); 75626308eabSJerome Marchand } 75726308eabSJerome Marchand } 758b9c54f56SKonstantin Khlebnikov 759e96c0d83SEric Biggers static enum elv_merge blk_try_req_merge(struct request *req, 760e96c0d83SEric Biggers struct request *next) 76169840466SJianchao Wang { 76269840466SJianchao Wang if (blk_discard_mergable(req)) 76369840466SJianchao Wang return ELEVATOR_DISCARD_MERGE; 76469840466SJianchao Wang else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) 76569840466SJianchao Wang return ELEVATOR_BACK_MERGE; 76669840466SJianchao Wang 76769840466SJianchao Wang return ELEVATOR_NO_MERGE; 76869840466SJianchao Wang } 76926308eabSJerome Marchand 770d6d48196SJens Axboe /* 771b973cb7eSJens Axboe * For non-mq, this has to be called with the request spinlock acquired. 772b973cb7eSJens Axboe * For mq with scheduling, the appropriate queue wide lock should be held. 773d6d48196SJens Axboe */ 774b973cb7eSJens Axboe static struct request *attempt_merge(struct request_queue *q, 775b973cb7eSJens Axboe struct request *req, struct request *next) 776d6d48196SJens Axboe { 777d6d48196SJens Axboe if (!rq_mergeable(req) || !rq_mergeable(next)) 778b973cb7eSJens Axboe return NULL; 779d6d48196SJens Axboe 780288dab8aSChristoph Hellwig if (req_op(req) != req_op(next)) 781b973cb7eSJens Axboe return NULL; 782f31dc1cdSMartin K. Petersen 78379bb1dbdSChristoph Hellwig if (rq_data_dir(req) != rq_data_dir(next)) 784b973cb7eSJens Axboe return NULL; 785d6d48196SJens Axboe 786668ffc03SDamien Le Moal if (req->ioprio != next->ioprio) 787668ffc03SDamien Le Moal return NULL; 788668ffc03SDamien Le Moal 789cb6934f8SJens Axboe /* 790d6d48196SJens Axboe * If we are allowed to merge, then append bio list 791d6d48196SJens Axboe * from next to rq and release next. merge_requests_fn 792d6d48196SJens Axboe * will have updated segment counts, update sector 793445251d0SJens Axboe * counts here. Handle DISCARDs separately, as they 794445251d0SJens Axboe * have separate settings. 795d6d48196SJens Axboe */ 79669840466SJianchao Wang 79769840466SJianchao Wang switch (blk_try_req_merge(req, next)) { 79869840466SJianchao Wang case ELEVATOR_DISCARD_MERGE: 799445251d0SJens Axboe if (!req_attempt_discard_merge(q, req, next)) 800445251d0SJens Axboe return NULL; 80169840466SJianchao Wang break; 80269840466SJianchao Wang case ELEVATOR_BACK_MERGE: 80369840466SJianchao Wang if (!ll_merge_requests_fn(q, req, next)) 804b973cb7eSJens Axboe return NULL; 80569840466SJianchao Wang break; 80669840466SJianchao Wang default: 80769840466SJianchao Wang return NULL; 80869840466SJianchao Wang } 809d6d48196SJens Axboe 810d6d48196SJens Axboe /* 81180a761fdSTejun Heo * If failfast settings disagree or any of the two is already 81280a761fdSTejun Heo * a mixed merge, mark both as mixed before proceeding. This 81380a761fdSTejun Heo * makes sure that all involved bios have mixable attributes 81480a761fdSTejun Heo * set properly. 81580a761fdSTejun Heo */ 816e8064021SChristoph Hellwig if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || 81780a761fdSTejun Heo (req->cmd_flags & REQ_FAILFAST_MASK) != 81880a761fdSTejun Heo (next->cmd_flags & REQ_FAILFAST_MASK)) { 81980a761fdSTejun Heo blk_rq_set_mixed_merge(req); 82080a761fdSTejun Heo blk_rq_set_mixed_merge(next); 82180a761fdSTejun Heo } 82280a761fdSTejun Heo 82380a761fdSTejun Heo /* 824522a7775SOmar Sandoval * At this point we have either done a back merge or front merge. We 825522a7775SOmar Sandoval * need the smaller start_time_ns of the merged requests to be the 826522a7775SOmar Sandoval * current request for accounting purposes. 827d6d48196SJens Axboe */ 828522a7775SOmar Sandoval if (next->start_time_ns < req->start_time_ns) 829522a7775SOmar Sandoval req->start_time_ns = next->start_time_ns; 830d6d48196SJens Axboe 831d6d48196SJens Axboe req->biotail->bi_next = next->bio; 832d6d48196SJens Axboe req->biotail = next->biotail; 833d6d48196SJens Axboe 834a2dec7b3STejun Heo req->__data_len += blk_rq_bytes(next); 835d6d48196SJens Axboe 8362a5cf35cSMing Lei if (!blk_discard_mergable(req)) 837d6d48196SJens Axboe elv_merge_requests(q, req, next); 838d6d48196SJens Axboe 83942dad764SJerome Marchand /* 84042dad764SJerome Marchand * 'next' is going away, so update stats accordingly 84142dad764SJerome Marchand */ 842b9c54f56SKonstantin Khlebnikov blk_account_io_merge_request(next); 843d6d48196SJens Axboe 844a54895faSChristoph Hellwig trace_block_rq_merge(next); 845f3bdc62fSJan Kara 846e4d750c9SJens Axboe /* 847e4d750c9SJens Axboe * ownership of bio passed from next to req, return 'next' for 848e4d750c9SJens Axboe * the caller to free 849e4d750c9SJens Axboe */ 8501cd96c24SBoaz Harrosh next->bio = NULL; 851b973cb7eSJens Axboe return next; 852d6d48196SJens Axboe } 853d6d48196SJens Axboe 854eda5cc99SChristoph Hellwig static struct request *attempt_back_merge(struct request_queue *q, 855eda5cc99SChristoph Hellwig struct request *rq) 856d6d48196SJens Axboe { 857d6d48196SJens Axboe struct request *next = elv_latter_request(q, rq); 858d6d48196SJens Axboe 859d6d48196SJens Axboe if (next) 860d6d48196SJens Axboe return attempt_merge(q, rq, next); 861d6d48196SJens Axboe 862b973cb7eSJens Axboe return NULL; 863d6d48196SJens Axboe } 864d6d48196SJens Axboe 865eda5cc99SChristoph Hellwig static struct request *attempt_front_merge(struct request_queue *q, 866eda5cc99SChristoph Hellwig struct request *rq) 867d6d48196SJens Axboe { 868d6d48196SJens Axboe struct request *prev = elv_former_request(q, rq); 869d6d48196SJens Axboe 870d6d48196SJens Axboe if (prev) 871d6d48196SJens Axboe return attempt_merge(q, prev, rq); 872d6d48196SJens Axboe 873b973cb7eSJens Axboe return NULL; 874d6d48196SJens Axboe } 8755e84ea3aSJens Axboe 876fd2ef39cSJan Kara /* 877fd2ef39cSJan Kara * Try to merge 'next' into 'rq'. Return true if the merge happened, false 878fd2ef39cSJan Kara * otherwise. The caller is responsible for freeing 'next' if the merge 879fd2ef39cSJan Kara * happened. 880fd2ef39cSJan Kara */ 881fd2ef39cSJan Kara bool blk_attempt_req_merge(struct request_queue *q, struct request *rq, 8825e84ea3aSJens Axboe struct request *next) 8835e84ea3aSJens Axboe { 884fd2ef39cSJan Kara return attempt_merge(q, rq, next); 8855e84ea3aSJens Axboe } 886050c8ea8STejun Heo 887050c8ea8STejun Heo bool blk_rq_merge_ok(struct request *rq, struct bio *bio) 888050c8ea8STejun Heo { 889e2a60da7SMartin K. Petersen if (!rq_mergeable(rq) || !bio_mergeable(bio)) 890050c8ea8STejun Heo return false; 891050c8ea8STejun Heo 892288dab8aSChristoph Hellwig if (req_op(rq) != bio_op(bio)) 893f31dc1cdSMartin K. Petersen return false; 894f31dc1cdSMartin K. Petersen 895050c8ea8STejun Heo /* different data direction or already started, don't merge */ 896050c8ea8STejun Heo if (bio_data_dir(bio) != rq_data_dir(rq)) 897050c8ea8STejun Heo return false; 898050c8ea8STejun Heo 8996b2b0459STejun Heo /* don't merge across cgroup boundaries */ 9006b2b0459STejun Heo if (!blk_cgroup_mergeable(rq, bio)) 9016b2b0459STejun Heo return false; 9026b2b0459STejun Heo 903050c8ea8STejun Heo /* only merge integrity protected bio into ditto rq */ 9044eaf99beSMartin K. Petersen if (blk_integrity_merge_bio(rq->q, rq, bio) == false) 905050c8ea8STejun Heo return false; 906050c8ea8STejun Heo 907a892c8d5SSatya Tangirala /* Only merge if the crypt contexts are compatible */ 908a892c8d5SSatya Tangirala if (!bio_crypt_rq_ctx_compatible(rq, bio)) 909a892c8d5SSatya Tangirala return false; 910a892c8d5SSatya Tangirala 911668ffc03SDamien Le Moal if (rq->ioprio != bio_prio(bio)) 912668ffc03SDamien Le Moal return false; 913668ffc03SDamien Le Moal 914050c8ea8STejun Heo return true; 915050c8ea8STejun Heo } 916050c8ea8STejun Heo 91734fe7c05SChristoph Hellwig enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) 918050c8ea8STejun Heo { 91969840466SJianchao Wang if (blk_discard_mergable(rq)) 9201e739730SChristoph Hellwig return ELEVATOR_DISCARD_MERGE; 9211e739730SChristoph Hellwig else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) 922050c8ea8STejun Heo return ELEVATOR_BACK_MERGE; 9234f024f37SKent Overstreet else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) 924050c8ea8STejun Heo return ELEVATOR_FRONT_MERGE; 925050c8ea8STejun Heo return ELEVATOR_NO_MERGE; 926050c8ea8STejun Heo } 9278e756373SBaolin Wang 9288e756373SBaolin Wang static void blk_account_io_merge_bio(struct request *req) 9298e756373SBaolin Wang { 9308e756373SBaolin Wang if (!blk_do_io_stat(req)) 9318e756373SBaolin Wang return; 9328e756373SBaolin Wang 9338e756373SBaolin Wang part_stat_lock(); 9348e756373SBaolin Wang part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); 9358e756373SBaolin Wang part_stat_unlock(); 9368e756373SBaolin Wang } 9378e756373SBaolin Wang 938eda5cc99SChristoph Hellwig enum bio_merge_status { 939eda5cc99SChristoph Hellwig BIO_MERGE_OK, 940eda5cc99SChristoph Hellwig BIO_MERGE_NONE, 941eda5cc99SChristoph Hellwig BIO_MERGE_FAILED, 942eda5cc99SChristoph Hellwig }; 943eda5cc99SChristoph Hellwig 944eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_back_merge(struct request *req, 945eda5cc99SChristoph Hellwig struct bio *bio, unsigned int nr_segs) 9468e756373SBaolin Wang { 94716458cf3SBart Van Assche const blk_opf_t ff = bio->bi_opf & REQ_FAILFAST_MASK; 9488e756373SBaolin Wang 9498e756373SBaolin Wang if (!ll_back_merge_fn(req, bio, nr_segs)) 9507d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 9518e756373SBaolin Wang 952e8a676d6SChristoph Hellwig trace_block_bio_backmerge(bio); 9538e756373SBaolin Wang rq_qos_merge(req->q, req, bio); 9548e756373SBaolin Wang 9558e756373SBaolin Wang if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 9568e756373SBaolin Wang blk_rq_set_mixed_merge(req); 9578e756373SBaolin Wang 9588e756373SBaolin Wang req->biotail->bi_next = bio; 9598e756373SBaolin Wang req->biotail = bio; 9608e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 9618e756373SBaolin Wang 9628e756373SBaolin Wang bio_crypt_free_ctx(bio); 9638e756373SBaolin Wang 9648e756373SBaolin Wang blk_account_io_merge_bio(req); 9657d7ca7c5SBaolin Wang return BIO_MERGE_OK; 9668e756373SBaolin Wang } 9678e756373SBaolin Wang 968eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_front_merge(struct request *req, 969eda5cc99SChristoph Hellwig struct bio *bio, unsigned int nr_segs) 9708e756373SBaolin Wang { 97116458cf3SBart Van Assche const blk_opf_t ff = bio->bi_opf & REQ_FAILFAST_MASK; 9728e756373SBaolin Wang 9738e756373SBaolin Wang if (!ll_front_merge_fn(req, bio, nr_segs)) 9747d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 9758e756373SBaolin Wang 976e8a676d6SChristoph Hellwig trace_block_bio_frontmerge(bio); 9778e756373SBaolin Wang rq_qos_merge(req->q, req, bio); 9788e756373SBaolin Wang 9798e756373SBaolin Wang if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) 9808e756373SBaolin Wang blk_rq_set_mixed_merge(req); 9818e756373SBaolin Wang 9828e756373SBaolin Wang bio->bi_next = req->bio; 9838e756373SBaolin Wang req->bio = bio; 9848e756373SBaolin Wang 9858e756373SBaolin Wang req->__sector = bio->bi_iter.bi_sector; 9868e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 9878e756373SBaolin Wang 9888e756373SBaolin Wang bio_crypt_do_front_merge(req, bio); 9898e756373SBaolin Wang 9908e756373SBaolin Wang blk_account_io_merge_bio(req); 9917d7ca7c5SBaolin Wang return BIO_MERGE_OK; 9928e756373SBaolin Wang } 9938e756373SBaolin Wang 994eda5cc99SChristoph Hellwig static enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q, 995eda5cc99SChristoph Hellwig struct request *req, struct bio *bio) 9968e756373SBaolin Wang { 9978e756373SBaolin Wang unsigned short segments = blk_rq_nr_discard_segments(req); 9988e756373SBaolin Wang 9998e756373SBaolin Wang if (segments >= queue_max_discard_segments(q)) 10008e756373SBaolin Wang goto no_merge; 10018e756373SBaolin Wang if (blk_rq_sectors(req) + bio_sectors(bio) > 10028e756373SBaolin Wang blk_rq_get_max_sectors(req, blk_rq_pos(req))) 10038e756373SBaolin Wang goto no_merge; 10048e756373SBaolin Wang 10058e756373SBaolin Wang rq_qos_merge(q, req, bio); 10068e756373SBaolin Wang 10078e756373SBaolin Wang req->biotail->bi_next = bio; 10088e756373SBaolin Wang req->biotail = bio; 10098e756373SBaolin Wang req->__data_len += bio->bi_iter.bi_size; 10108e756373SBaolin Wang req->nr_phys_segments = segments + 1; 10118e756373SBaolin Wang 10128e756373SBaolin Wang blk_account_io_merge_bio(req); 10137d7ca7c5SBaolin Wang return BIO_MERGE_OK; 10148e756373SBaolin Wang no_merge: 10158e756373SBaolin Wang req_set_nomerge(q, req); 10167d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 10177d7ca7c5SBaolin Wang } 10187d7ca7c5SBaolin Wang 10197d7ca7c5SBaolin Wang static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q, 10207d7ca7c5SBaolin Wang struct request *rq, 10217d7ca7c5SBaolin Wang struct bio *bio, 10227d7ca7c5SBaolin Wang unsigned int nr_segs, 10237d7ca7c5SBaolin Wang bool sched_allow_merge) 10247d7ca7c5SBaolin Wang { 10257d7ca7c5SBaolin Wang if (!blk_rq_merge_ok(rq, bio)) 10267d7ca7c5SBaolin Wang return BIO_MERGE_NONE; 10277d7ca7c5SBaolin Wang 10287d7ca7c5SBaolin Wang switch (blk_try_merge(rq, bio)) { 10297d7ca7c5SBaolin Wang case ELEVATOR_BACK_MERGE: 1030265600b7SBaolin Wang if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) 10317d7ca7c5SBaolin Wang return bio_attempt_back_merge(rq, bio, nr_segs); 10327d7ca7c5SBaolin Wang break; 10337d7ca7c5SBaolin Wang case ELEVATOR_FRONT_MERGE: 1034265600b7SBaolin Wang if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) 10357d7ca7c5SBaolin Wang return bio_attempt_front_merge(rq, bio, nr_segs); 10367d7ca7c5SBaolin Wang break; 10377d7ca7c5SBaolin Wang case ELEVATOR_DISCARD_MERGE: 10387d7ca7c5SBaolin Wang return bio_attempt_discard_merge(q, rq, bio); 10397d7ca7c5SBaolin Wang default: 10407d7ca7c5SBaolin Wang return BIO_MERGE_NONE; 10417d7ca7c5SBaolin Wang } 10427d7ca7c5SBaolin Wang 10437d7ca7c5SBaolin Wang return BIO_MERGE_FAILED; 10448e756373SBaolin Wang } 10458e756373SBaolin Wang 10468e756373SBaolin Wang /** 10478e756373SBaolin Wang * blk_attempt_plug_merge - try to merge with %current's plugged list 10488e756373SBaolin Wang * @q: request_queue new bio is being queued at 10498e756373SBaolin Wang * @bio: new bio being queued 10508e756373SBaolin Wang * @nr_segs: number of segments in @bio 105187c037d1SJens Axboe * from the passed in @q already in the plug list 10528e756373SBaolin Wang * 1053d38a9c04SJens Axboe * Determine whether @bio being queued on @q can be merged with the previous 1054d38a9c04SJens Axboe * request on %current's plugged list. Returns %true if merge was successful, 10558e756373SBaolin Wang * otherwise %false. 10568e756373SBaolin Wang * 10578e756373SBaolin Wang * Plugging coalesces IOs from the same issuer for the same purpose without 10588e756373SBaolin Wang * going through @q->queue_lock. As such it's more of an issuing mechanism 10598e756373SBaolin Wang * than scheduling, and the request, while may have elvpriv data, is not 10608e756373SBaolin Wang * added on the elevator at this point. In addition, we don't have 10618e756373SBaolin Wang * reliable access to the elevator outside queue lock. Only check basic 10628e756373SBaolin Wang * merging parameters without querying the elevator. 10638e756373SBaolin Wang * 10648e756373SBaolin Wang * Caller must ensure !blk_queue_nomerges(q) beforehand. 10658e756373SBaolin Wang */ 10668e756373SBaolin Wang bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, 10670c5bcc92SChristoph Hellwig unsigned int nr_segs) 10688e756373SBaolin Wang { 10698e756373SBaolin Wang struct blk_plug *plug; 10708e756373SBaolin Wang struct request *rq; 10718e756373SBaolin Wang 10726deacb3bSChristoph Hellwig plug = blk_mq_plug(bio); 1073bc490f81SJens Axboe if (!plug || rq_list_empty(plug->mq_list)) 10748e756373SBaolin Wang return false; 10758e756373SBaolin Wang 10765b205071SJens Axboe rq_list_for_each(&plug->mq_list, rq) { 107787c037d1SJens Axboe if (rq->q == q) { 1078a1cb6537SMing Lei if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) == 1079a1cb6537SMing Lei BIO_MERGE_OK) 10808e756373SBaolin Wang return true; 10815b205071SJens Axboe break; 10825b205071SJens Axboe } 10835b205071SJens Axboe 10845b205071SJens Axboe /* 10855b205071SJens Axboe * Only keep iterating plug list for merges if we have multiple 10865b205071SJens Axboe * queues 10875b205071SJens Axboe */ 10885b205071SJens Axboe if (!plug->multiple_queues) 10895b205071SJens Axboe break; 1090a1cb6537SMing Lei } 10918e756373SBaolin Wang return false; 10928e756373SBaolin Wang } 1093bdc6a287SBaolin Wang 1094bdc6a287SBaolin Wang /* 1095bdc6a287SBaolin Wang * Iterate list of requests and see if we can merge this bio with any 1096bdc6a287SBaolin Wang * of them. 1097bdc6a287SBaolin Wang */ 1098bdc6a287SBaolin Wang bool blk_bio_list_merge(struct request_queue *q, struct list_head *list, 1099bdc6a287SBaolin Wang struct bio *bio, unsigned int nr_segs) 1100bdc6a287SBaolin Wang { 1101bdc6a287SBaolin Wang struct request *rq; 1102bdc6a287SBaolin Wang int checked = 8; 1103bdc6a287SBaolin Wang 1104bdc6a287SBaolin Wang list_for_each_entry_reverse(rq, list, queuelist) { 1105bdc6a287SBaolin Wang if (!checked--) 1106bdc6a287SBaolin Wang break; 1107bdc6a287SBaolin Wang 11087d7ca7c5SBaolin Wang switch (blk_attempt_bio_merge(q, rq, bio, nr_segs, true)) { 11097d7ca7c5SBaolin Wang case BIO_MERGE_NONE: 1110bdc6a287SBaolin Wang continue; 11117d7ca7c5SBaolin Wang case BIO_MERGE_OK: 11127d7ca7c5SBaolin Wang return true; 11137d7ca7c5SBaolin Wang case BIO_MERGE_FAILED: 11147d7ca7c5SBaolin Wang return false; 1115bdc6a287SBaolin Wang } 1116bdc6a287SBaolin Wang 1117bdc6a287SBaolin Wang } 1118bdc6a287SBaolin Wang 1119bdc6a287SBaolin Wang return false; 1120bdc6a287SBaolin Wang } 1121bdc6a287SBaolin Wang EXPORT_SYMBOL_GPL(blk_bio_list_merge); 1122eda5cc99SChristoph Hellwig 1123eda5cc99SChristoph Hellwig bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio, 1124eda5cc99SChristoph Hellwig unsigned int nr_segs, struct request **merged_request) 1125eda5cc99SChristoph Hellwig { 1126eda5cc99SChristoph Hellwig struct request *rq; 1127eda5cc99SChristoph Hellwig 1128eda5cc99SChristoph Hellwig switch (elv_merge(q, &rq, bio)) { 1129eda5cc99SChristoph Hellwig case ELEVATOR_BACK_MERGE: 1130eda5cc99SChristoph Hellwig if (!blk_mq_sched_allow_merge(q, rq, bio)) 1131eda5cc99SChristoph Hellwig return false; 1132eda5cc99SChristoph Hellwig if (bio_attempt_back_merge(rq, bio, nr_segs) != BIO_MERGE_OK) 1133eda5cc99SChristoph Hellwig return false; 1134eda5cc99SChristoph Hellwig *merged_request = attempt_back_merge(q, rq); 1135eda5cc99SChristoph Hellwig if (!*merged_request) 1136eda5cc99SChristoph Hellwig elv_merged_request(q, rq, ELEVATOR_BACK_MERGE); 1137eda5cc99SChristoph Hellwig return true; 1138eda5cc99SChristoph Hellwig case ELEVATOR_FRONT_MERGE: 1139eda5cc99SChristoph Hellwig if (!blk_mq_sched_allow_merge(q, rq, bio)) 1140eda5cc99SChristoph Hellwig return false; 1141eda5cc99SChristoph Hellwig if (bio_attempt_front_merge(rq, bio, nr_segs) != BIO_MERGE_OK) 1142eda5cc99SChristoph Hellwig return false; 1143eda5cc99SChristoph Hellwig *merged_request = attempt_front_merge(q, rq); 1144eda5cc99SChristoph Hellwig if (!*merged_request) 1145eda5cc99SChristoph Hellwig elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE); 1146eda5cc99SChristoph Hellwig return true; 1147eda5cc99SChristoph Hellwig case ELEVATOR_DISCARD_MERGE: 1148eda5cc99SChristoph Hellwig return bio_attempt_discard_merge(q, rq, bio) == BIO_MERGE_OK; 1149eda5cc99SChristoph Hellwig default: 1150eda5cc99SChristoph Hellwig return false; 1151eda5cc99SChristoph Hellwig } 1152eda5cc99SChristoph Hellwig } 1153eda5cc99SChristoph Hellwig EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge); 1154