// SPDX-License-Identifier: GPL-2.0 /* * Functions related to segment and merge handling */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/bio.h> #include <linux/blkdev.h> #include <linux/scatterlist.h> #include <trace/events/block.h> #include "blk.h" /* * Check if the two bvecs from two bios can be merged to one segment. If yes, * no need to check gap between the two bios since the 1st bio and the 1st bvec * in the 2nd bio can be handled in one segment. */ static inline bool bios_segs_mergeable(struct request_queue *q, struct bio *prev, struct bio_vec *prev_last_bv, struct bio_vec *next_first_bv) { if (!biovec_phys_mergeable(q, prev_last_bv, next_first_bv)) return false; if (prev->bi_seg_back_size + next_first_bv->bv_len > queue_max_segment_size(q)) return false; return true; } static inline bool bio_will_gap(struct request_queue *q, struct request *prev_rq, struct bio *prev, struct bio *next) { struct bio_vec pb, nb; if (!bio_has_data(prev) || !queue_virt_boundary(q)) return false; /* * Don't merge if the 1st bio starts with non-zero offset, otherwise it * is quite difficult to respect the sg gap limit. We work hard to * merge a huge number of small single bios in case of mkfs. */ if (prev_rq) bio_get_first_bvec(prev_rq->bio, &pb); else bio_get_first_bvec(prev, &pb); if (pb.bv_offset & queue_virt_boundary(q)) return true; /* * We don't need to worry about the situation that the merged segment * ends in unaligned virt boundary: * * - if 'pb' ends aligned, the merged segment ends aligned * - if 'pb' ends unaligned, the next bio must include * one single bvec of 'nb', otherwise the 'nb' can't * merge with 'pb' */ bio_get_last_bvec(prev, &pb); bio_get_first_bvec(next, &nb); if (bios_segs_mergeable(q, prev, &pb, &nb)) return false; return __bvec_gap_to_prev(q, &pb, nb.bv_offset); } static inline bool req_gap_back_merge(struct request *req, struct bio *bio) { return bio_will_gap(req->q, req, req->biotail, bio); } static inline bool req_gap_front_merge(struct request *req, struct bio *bio) { return bio_will_gap(req->q, NULL, bio, req->bio); } static struct bio *blk_bio_discard_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, unsigned *nsegs) { unsigned int max_discard_sectors, granularity; int alignment; sector_t tmp; unsigned split_sectors; *nsegs = 1; /* Zero-sector (unknown) and one-sector granularities are the same. */ granularity = max(q->limits.discard_granularity >> 9, 1U); max_discard_sectors = min(q->limits.max_discard_sectors, bio_allowed_max_sectors(q)); max_discard_sectors -= max_discard_sectors % granularity; if (unlikely(!max_discard_sectors)) { /* XXX: warn */ return NULL; } if (bio_sectors(bio) <= max_discard_sectors) return NULL; split_sectors = max_discard_sectors; /* * If the next starting sector would be misaligned, stop the discard at * the previous aligned sector. */ alignment = (q->limits.discard_alignment >> 9) % granularity; tmp = bio->bi_iter.bi_sector + split_sectors - alignment; tmp = sector_div(tmp, granularity); if (split_sectors > tmp) split_sectors -= tmp; return bio_split(bio, split_sectors, GFP_NOIO, bs); } static struct bio *blk_bio_write_zeroes_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, unsigned *nsegs) { *nsegs = 1; if (!q->limits.max_write_zeroes_sectors) return NULL; if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors) return NULL; return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs); } static struct bio *blk_bio_write_same_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, unsigned *nsegs) { *nsegs = 1; if (!q->limits.max_write_same_sectors) return NULL; if (bio_sectors(bio) <= q->limits.max_write_same_sectors) return NULL; return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); } static inline unsigned get_max_io_size(struct request_queue *q, struct bio *bio) { unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector); unsigned mask = queue_logical_block_size(q) - 1; /* aligned to logical block size */ sectors &= ~(mask >> 9); return sectors; } static unsigned get_max_segment_size(struct request_queue *q, unsigned offset) { unsigned long mask = queue_segment_boundary(q); /* default segment boundary mask means no boundary limit */ if (mask == BLK_SEG_BOUNDARY_MASK) return queue_max_segment_size(q); return min_t(unsigned long, mask - (mask & offset) + 1, queue_max_segment_size(q)); } /* * Split the bvec @bv into segments, and update all kinds of * variables. */ static bool bvec_split_segs(struct request_queue *q, struct bio_vec *bv, unsigned *nsegs, unsigned *last_seg_size, unsigned *front_seg_size, unsigned *sectors, unsigned max_segs) { unsigned len = bv->bv_len; unsigned total_len = 0; unsigned new_nsegs = 0, seg_size = 0; /* * Multi-page bvec may be too big to hold in one segment, so the * current bvec has to be splitted as multiple segments. */ while (len && new_nsegs + *nsegs < max_segs) { seg_size = get_max_segment_size(q, bv->bv_offset + total_len); seg_size = min(seg_size, len); new_nsegs++; total_len += seg_size; len -= seg_size; if ((bv->bv_offset + total_len) & queue_virt_boundary(q)) break; } if (!new_nsegs) return !!len; /* update front segment size */ if (!*nsegs) { unsigned first_seg_size; if (new_nsegs == 1) first_seg_size = get_max_segment_size(q, bv->bv_offset); else first_seg_size = queue_max_segment_size(q); if (*front_seg_size < first_seg_size) *front_seg_size = first_seg_size; } /* update other varibles */ *last_seg_size = seg_size; *nsegs += new_nsegs; if (sectors) *sectors += total_len >> 9; /* split in the middle of the bvec if len != 0 */ return !!len; } static struct bio *blk_bio_segment_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, unsigned *segs) { struct bio_vec bv, bvprv, *bvprvp = NULL; struct bvec_iter iter; unsigned seg_size = 0, nsegs = 0, sectors = 0; unsigned front_seg_size = bio->bi_seg_front_size; bool do_split = true; struct bio *new = NULL; const unsigned max_sectors = get_max_io_size(q, bio); const unsigned max_segs = queue_max_segments(q); bio_for_each_bvec(bv, bio, iter) { /* * If the queue doesn't support SG gaps and adding this * offset would create a gap, disallow it. */ if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) goto split; if (sectors + (bv.bv_len >> 9) > max_sectors) { /* * Consider this a new segment if we're splitting in * the middle of this vector. */ if (nsegs < max_segs && sectors < max_sectors) { /* split in the middle of bvec */ bv.bv_len = (max_sectors - sectors) << 9; bvec_split_segs(q, &bv, &nsegs, &seg_size, &front_seg_size, §ors, max_segs); } goto split; } if (bvprvp) { if (seg_size + bv.bv_len > queue_max_segment_size(q)) goto new_segment; if (!biovec_phys_mergeable(q, bvprvp, &bv)) goto new_segment; seg_size += bv.bv_len; bvprv = bv; bvprvp = &bvprv; sectors += bv.bv_len >> 9; if (nsegs == 1 && seg_size > front_seg_size) front_seg_size = seg_size; continue; } new_segment: if (nsegs == max_segs) goto split; bvprv = bv; bvprvp = &bvprv; if (bv.bv_offset + bv.bv_len <= PAGE_SIZE) { nsegs++; seg_size = bv.bv_len; sectors += bv.bv_len >> 9; if (nsegs == 1 && seg_size > front_seg_size) front_seg_size = seg_size; } else if (bvec_split_segs(q, &bv, &nsegs, &seg_size, &front_seg_size, §ors, max_segs)) { goto split; } } do_split = false; split: *segs = nsegs; if (do_split) { new = bio_split(bio, sectors, GFP_NOIO, bs); if (new) bio = new; } bio->bi_seg_front_size = front_seg_size; if (seg_size > bio->bi_seg_back_size) bio->bi_seg_back_size = seg_size; return do_split ? new : NULL; } void blk_queue_split(struct request_queue *q, struct bio **bio) { struct bio *split, *res; unsigned nsegs; switch (bio_op(*bio)) { case REQ_OP_DISCARD: case REQ_OP_SECURE_ERASE: split = blk_bio_discard_split(q, *bio, &q->bio_split, &nsegs); break; case REQ_OP_WRITE_ZEROES: split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split, &nsegs); break; case REQ_OP_WRITE_SAME: split = blk_bio_write_same_split(q, *bio, &q->bio_split, &nsegs); break; default: split = blk_bio_segment_split(q, *bio, &q->bio_split, &nsegs); break; } /* physical segments can be figured out during splitting */ res = split ? split : *bio; res->bi_phys_segments = nsegs; bio_set_flag(res, BIO_SEG_VALID); if (split) { /* there isn't chance to merge the splitted bio */ split->bi_opf |= REQ_NOMERGE; /* * Since we're recursing into make_request here, ensure * that we mark this bio as already having entered the queue. * If not, and the queue is going away, we can get stuck * forever on waiting for the queue reference to drop. But * that will never happen, as we're already holding a * reference to it. */ bio_set_flag(*bio, BIO_QUEUE_ENTERED); bio_chain(split, *bio); trace_block_split(q, split, (*bio)->bi_iter.bi_sector); generic_make_request(*bio); *bio = split; } } EXPORT_SYMBOL(blk_queue_split); static unsigned int __blk_recalc_rq_segments(struct request_queue *q, struct bio *bio) { struct bio_vec bv, bvprv = { NULL }; int prev = 0; unsigned int seg_size, nr_phys_segs; unsigned front_seg_size; struct bio *fbio, *bbio; struct bvec_iter iter; if (!bio) return 0; front_seg_size = bio->bi_seg_front_size; switch (bio_op(bio)) { case REQ_OP_DISCARD: case REQ_OP_SECURE_ERASE: case REQ_OP_WRITE_ZEROES: return 0; case REQ_OP_WRITE_SAME: return 1; } fbio = bio; seg_size = 0; nr_phys_segs = 0; for_each_bio(bio) { bio_for_each_bvec(bv, bio, iter) { if (prev) { if (seg_size + bv.bv_len > queue_max_segment_size(q)) goto new_segment; if (!biovec_phys_mergeable(q, &bvprv, &bv)) goto new_segment; seg_size += bv.bv_len; bvprv = bv; if (nr_phys_segs == 1 && seg_size > front_seg_size) front_seg_size = seg_size; continue; } new_segment: bvprv = bv; prev = 1; bvec_split_segs(q, &bv, &nr_phys_segs, &seg_size, &front_seg_size, NULL, UINT_MAX); } bbio = bio; } fbio->bi_seg_front_size = front_seg_size; if (seg_size > bbio->bi_seg_back_size) bbio->bi_seg_back_size = seg_size; return nr_phys_segs; } void blk_recalc_rq_segments(struct request *rq) { rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio); } void blk_recount_segments(struct request_queue *q, struct bio *bio) { struct bio *nxt = bio->bi_next; bio->bi_next = NULL; bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio); bio->bi_next = nxt; bio_set_flag(bio, BIO_SEG_VALID); } static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, struct bio *nxt) { struct bio_vec end_bv = { NULL }, nxt_bv; if (bio->bi_seg_back_size + nxt->bi_seg_front_size > queue_max_segment_size(q)) return 0; if (!bio_has_data(bio)) return 1; bio_get_last_bvec(bio, &end_bv); bio_get_first_bvec(nxt, &nxt_bv); return biovec_phys_mergeable(q, &end_bv, &nxt_bv); } static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, struct scatterlist *sglist) { if (!*sg) return sglist; /* * If the driver previously mapped a shorter list, we could see a * termination bit prematurely unless it fully inits the sg table * on each mapping. We KNOW that there must be more entries here * or the driver would be buggy, so force clear the termination bit * to avoid doing a full sg_init_table() in drivers for each command. */ sg_unmark_end(*sg); return sg_next(*sg); } static unsigned blk_bvec_map_sg(struct request_queue *q, struct bio_vec *bvec, struct scatterlist *sglist, struct scatterlist **sg) { unsigned nbytes = bvec->bv_len; unsigned nsegs = 0, total = 0, offset = 0; while (nbytes > 0) { unsigned seg_size; struct page *pg; unsigned idx; *sg = blk_next_sg(sg, sglist); seg_size = get_max_segment_size(q, bvec->bv_offset + total); seg_size = min(nbytes, seg_size); offset = (total + bvec->bv_offset) % PAGE_SIZE; idx = (total + bvec->bv_offset) / PAGE_SIZE; pg = bvec_nth_page(bvec->bv_page, idx); sg_set_page(*sg, pg, seg_size, offset); total += seg_size; nbytes -= seg_size; nsegs++; } return nsegs; } static inline void __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, struct scatterlist *sglist, struct bio_vec *bvprv, struct scatterlist **sg, int *nsegs) { int nbytes = bvec->bv_len; if (*sg) { if ((*sg)->length + nbytes > queue_max_segment_size(q)) goto new_segment; if (!biovec_phys_mergeable(q, bvprv, bvec)) goto new_segment; (*sg)->length += nbytes; } else { new_segment: if (bvec->bv_offset + bvec->bv_len <= PAGE_SIZE) { *sg = blk_next_sg(sg, sglist); sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); (*nsegs) += 1; } else (*nsegs) += blk_bvec_map_sg(q, bvec, sglist, sg); } *bvprv = *bvec; } static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, struct scatterlist *sglist, struct scatterlist **sg) { *sg = sglist; sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); return 1; } static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, struct scatterlist *sglist, struct scatterlist **sg) { struct bio_vec bvec, bvprv = { NULL }; struct bvec_iter iter; int nsegs = 0; for_each_bio(bio) bio_for_each_bvec(bvec, bio, iter) __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, &nsegs); return nsegs; } /* * map a request to scatterlist, return number of sg entries setup. Caller * must make sure sg can hold rq->nr_phys_segments entries */ int blk_rq_map_sg(struct request_queue *q, struct request *rq, struct scatterlist *sglist) { struct scatterlist *sg = NULL; int nsegs = 0; if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) nsegs = __blk_bvec_map_sg(q, rq->special_vec, sglist, &sg); else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME) nsegs = __blk_bvec_map_sg(q, bio_iovec(rq->bio), sglist, &sg); else if (rq->bio) nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); if (unlikely(rq->rq_flags & RQF_COPY_USER) && (blk_rq_bytes(rq) & q->dma_pad_mask)) { unsigned int pad_len = (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; sg->length += pad_len; rq->extra_len += pad_len; } if (q->dma_drain_size && q->dma_drain_needed(rq)) { if (op_is_write(req_op(rq))) memset(q->dma_drain_buffer, 0, q->dma_drain_size); sg_unmark_end(sg); sg = sg_next(sg); sg_set_page(sg, virt_to_page(q->dma_drain_buffer), q->dma_drain_size, ((unsigned long)q->dma_drain_buffer) & (PAGE_SIZE - 1)); nsegs++; rq->extra_len += q->dma_drain_size; } if (sg) sg_mark_end(sg); /* * Something must have been wrong if the figured number of * segment is bigger than number of req's physical segments */ WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); return nsegs; } EXPORT_SYMBOL(blk_rq_map_sg); static inline int ll_new_hw_segment(struct request_queue *q, struct request *req, struct bio *bio) { int nr_phys_segs = bio_phys_segments(q, bio); if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) goto no_merge; if (blk_integrity_merge_bio(q, req, bio) == false) goto no_merge; /* * This will form the start of a new hw segment. Bump both * counters. */ req->nr_phys_segments += nr_phys_segs; return 1; no_merge: req_set_nomerge(q, req); return 0; } int ll_back_merge_fn(struct request_queue *q, struct request *req, struct bio *bio) { if (req_gap_back_merge(req, bio)) return 0; if (blk_integrity_rq(req) && integrity_req_gap_back_merge(req, bio)) return 0; if (blk_rq_sectors(req) + bio_sectors(bio) > blk_rq_get_max_sectors(req, blk_rq_pos(req))) { req_set_nomerge(q, req); return 0; } if (!bio_flagged(req->biotail, BIO_SEG_VALID)) blk_recount_segments(q, req->biotail); if (!bio_flagged(bio, BIO_SEG_VALID)) blk_recount_segments(q, bio); return ll_new_hw_segment(q, req, bio); } int ll_front_merge_fn(struct request_queue *q, struct request *req, struct bio *bio) { if (req_gap_front_merge(req, bio)) return 0; if (blk_integrity_rq(req) && integrity_req_gap_front_merge(req, bio)) return 0; if (blk_rq_sectors(req) + bio_sectors(bio) > blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { req_set_nomerge(q, req); return 0; } if (!bio_flagged(bio, BIO_SEG_VALID)) blk_recount_segments(q, bio); if (!bio_flagged(req->bio, BIO_SEG_VALID)) blk_recount_segments(q, req->bio); return ll_new_hw_segment(q, req, bio); } static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, struct request *next) { unsigned short segments = blk_rq_nr_discard_segments(req); if (segments >= queue_max_discard_segments(q)) goto no_merge; if (blk_rq_sectors(req) + bio_sectors(next->bio) > blk_rq_get_max_sectors(req, blk_rq_pos(req))) goto no_merge; req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); return true; no_merge: req_set_nomerge(q, req); return false; } static int ll_merge_requests_fn(struct request_queue *q, struct request *req, struct request *next) { int total_phys_segments; unsigned int seg_size = req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; if (req_gap_back_merge(req, next->bio)) return 0; /* * Will it become too large? */ if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > blk_rq_get_max_sectors(req, blk_rq_pos(req))) return 0; total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; if (blk_phys_contig_segment(q, req->biotail, next->bio)) { if (req->nr_phys_segments == 1) req->bio->bi_seg_front_size = seg_size; if (next->nr_phys_segments == 1) next->biotail->bi_seg_back_size = seg_size; total_phys_segments--; } if (total_phys_segments > queue_max_segments(q)) return 0; if (blk_integrity_merge_rq(q, req, next) == false) return 0; /* Merge is OK... */ req->nr_phys_segments = total_phys_segments; return 1; } /** * blk_rq_set_mixed_merge - mark a request as mixed merge * @rq: request to mark as mixed merge * * Description: * @rq is about to be mixed merged. Make sure the attributes * which can be mixed are set in each bio and mark @rq as mixed * merged. */ void blk_rq_set_mixed_merge(struct request *rq) { unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; struct bio *bio; if (rq->rq_flags & RQF_MIXED_MERGE) return; /* * @rq will no longer represent mixable attributes for all the * contained bios. It will just track those of the first one. * Distributes the attributs to each bio. */ for (bio = rq->bio; bio; bio = bio->bi_next) { WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && (bio->bi_opf & REQ_FAILFAST_MASK) != ff); bio->bi_opf |= ff; } rq->rq_flags |= RQF_MIXED_MERGE; } static void blk_account_io_merge(struct request *req) { if (blk_do_io_stat(req)) { struct hd_struct *part; part_stat_lock(); part = req->part; part_dec_in_flight(req->q, part, rq_data_dir(req)); hd_struct_put(part); part_stat_unlock(); } } /* * Two cases of handling DISCARD merge: * If max_discard_segments > 1, the driver takes every bio * as a range and send them to controller together. The ranges * needn't to be contiguous. * Otherwise, the bios/requests will be handled as same as * others which should be contiguous. */ static inline bool blk_discard_mergable(struct request *req) { if (req_op(req) == REQ_OP_DISCARD && queue_max_discard_segments(req->q) > 1) return true; return false; } static enum elv_merge blk_try_req_merge(struct request *req, struct request *next) { if (blk_discard_mergable(req)) return ELEVATOR_DISCARD_MERGE; else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) return ELEVATOR_BACK_MERGE; return ELEVATOR_NO_MERGE; } /* * For non-mq, this has to be called with the request spinlock acquired. * For mq with scheduling, the appropriate queue wide lock should be held. */ static struct request *attempt_merge(struct request_queue *q, struct request *req, struct request *next) { if (!rq_mergeable(req) || !rq_mergeable(next)) return NULL; if (req_op(req) != req_op(next)) return NULL; if (rq_data_dir(req) != rq_data_dir(next) || req->rq_disk != next->rq_disk) return NULL; if (req_op(req) == REQ_OP_WRITE_SAME && !blk_write_same_mergeable(req->bio, next->bio)) return NULL; /* * Don't allow merge of different write hints, or for a hint with * non-hint IO. */ if (req->write_hint != next->write_hint) return NULL; if (req->ioprio != next->ioprio) return NULL; /* * If we are allowed to merge, then append bio list * from next to rq and release next. merge_requests_fn * will have updated segment counts, update sector * counts here. Handle DISCARDs separately, as they * have separate settings. */ switch (blk_try_req_merge(req, next)) { case ELEVATOR_DISCARD_MERGE: if (!req_attempt_discard_merge(q, req, next)) return NULL; break; case ELEVATOR_BACK_MERGE: if (!ll_merge_requests_fn(q, req, next)) return NULL; break; default: return NULL; } /* * If failfast settings disagree or any of the two is already * a mixed merge, mark both as mixed before proceeding. This * makes sure that all involved bios have mixable attributes * set properly. */ if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || (req->cmd_flags & REQ_FAILFAST_MASK) != (next->cmd_flags & REQ_FAILFAST_MASK)) { blk_rq_set_mixed_merge(req); blk_rq_set_mixed_merge(next); } /* * At this point we have either done a back merge or front merge. We * need the smaller start_time_ns of the merged requests to be the * current request for accounting purposes. */ if (next->start_time_ns < req->start_time_ns) req->start_time_ns = next->start_time_ns; req->biotail->bi_next = next->bio; req->biotail = next->biotail; req->__data_len += blk_rq_bytes(next); if (!blk_discard_mergable(req)) elv_merge_requests(q, req, next); /* * 'next' is going away, so update stats accordingly */ blk_account_io_merge(next); /* * ownership of bio passed from next to req, return 'next' for * the caller to free */ next->bio = NULL; return next; } struct request *attempt_back_merge(struct request_queue *q, struct request *rq) { struct request *next = elv_latter_request(q, rq); if (next) return attempt_merge(q, rq, next); return NULL; } struct request *attempt_front_merge(struct request_queue *q, struct request *rq) { struct request *prev = elv_former_request(q, rq); if (prev) return attempt_merge(q, prev, rq); return NULL; } int blk_attempt_req_merge(struct request_queue *q, struct request *rq, struct request *next) { struct request *free; free = attempt_merge(q, rq, next); if (free) { blk_put_request(free); return 1; } return 0; } bool blk_rq_merge_ok(struct request *rq, struct bio *bio) { if (!rq_mergeable(rq) || !bio_mergeable(bio)) return false; if (req_op(rq) != bio_op(bio)) return false; /* different data direction or already started, don't merge */ if (bio_data_dir(bio) != rq_data_dir(rq)) return false; /* must be same device */ if (rq->rq_disk != bio->bi_disk) return false; /* only merge integrity protected bio into ditto rq */ if (blk_integrity_merge_bio(rq->q, rq, bio) == false) return false; /* must be using the same buffer */ if (req_op(rq) == REQ_OP_WRITE_SAME && !blk_write_same_mergeable(rq->bio, bio)) return false; /* * Don't allow merge of different write hints, or for a hint with * non-hint IO. */ if (rq->write_hint != bio->bi_write_hint) return false; if (rq->ioprio != bio_prio(bio)) return false; return true; } enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) { if (blk_discard_mergable(rq)) return ELEVATOR_DISCARD_MERGE; else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) return ELEVATOR_BACK_MERGE; else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) return ELEVATOR_FRONT_MERGE; return ELEVATOR_NO_MERGE; }