[Feature]add MT2731_MP2_MR2_SVN388 baseline version
Change-Id: Ief04314834b31e27effab435d3ca8ba33b499059
diff --git a/src/kernel/linux/v4.14/block/blk-merge.c b/src/kernel/linux/v4.14/block/blk-merge.c
new file mode 100644
index 0000000..415b5da
--- /dev/null
+++ b/src/kernel/linux/v4.14/block/blk-merge.c
@@ -0,0 +1,865 @@
+// 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"
+
+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, UINT_MAX >> 9);
+ 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 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);
+
+ bio_for_each_segment(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 < queue_max_segments(q) &&
+ sectors < max_sectors) {
+ nsegs++;
+ sectors = max_sectors;
+ }
+ if (sectors)
+ goto split;
+ /* Make this single bvec as the 1st segment */
+ }
+
+ if (bvprvp && blk_queue_cluster(q)) {
+ if (seg_size + bv.bv_len > queue_max_segment_size(q))
+ goto new_segment;
+ if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv))
+ goto new_segment;
+ if (!BIOVEC_SEG_BOUNDARY(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 == queue_max_segments(q))
+ goto split;
+
+ nsegs++;
+ bvprv = bv;
+ bvprvp = &bvprv;
+ seg_size = bv.bv_len;
+ sectors += bv.bv_len >> 9;
+
+ if (nsegs == 1 && seg_size > front_seg_size)
+ front_seg_size = seg_size;
+ }
+
+ 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;
+
+ 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,
+ bool no_sg_merge)
+{
+ struct bio_vec bv, bvprv = { NULL };
+ int cluster, prev = 0;
+ unsigned int seg_size, nr_phys_segs;
+ struct bio *fbio, *bbio;
+ struct bvec_iter iter;
+
+ if (!bio)
+ return 0;
+
+ 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;
+ cluster = blk_queue_cluster(q);
+ seg_size = 0;
+ nr_phys_segs = 0;
+ for_each_bio(bio) {
+ bio_for_each_segment(bv, bio, iter) {
+ /*
+ * If SG merging is disabled, each bio vector is
+ * a segment
+ */
+ if (no_sg_merge)
+ goto new_segment;
+
+ if (prev && cluster) {
+ if (seg_size + bv.bv_len
+ > queue_max_segment_size(q))
+ goto new_segment;
+ if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv))
+ goto new_segment;
+ if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv))
+ goto new_segment;
+
+ seg_size += bv.bv_len;
+ bvprv = bv;
+ continue;
+ }
+new_segment:
+ if (nr_phys_segs == 1 && seg_size >
+ fbio->bi_seg_front_size)
+ fbio->bi_seg_front_size = seg_size;
+
+ nr_phys_segs++;
+ bvprv = bv;
+ prev = 1;
+ seg_size = bv.bv_len;
+ }
+ bbio = bio;
+ }
+
+ if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size)
+ fbio->bi_seg_front_size = 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)
+{
+ bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE,
+ &rq->q->queue_flags);
+
+ rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio,
+ no_sg_merge);
+}
+
+void blk_recount_segments(struct request_queue *q, struct bio *bio)
+{
+ unsigned short seg_cnt = bio_segments(bio);
+
+ if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) &&
+ (seg_cnt < queue_max_segments(q)))
+ bio->bi_phys_segments = seg_cnt;
+ else {
+ struct bio *nxt = bio->bi_next;
+
+ bio->bi_next = NULL;
+ bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false);
+ bio->bi_next = nxt;
+ }
+
+ bio_set_flag(bio, BIO_SEG_VALID);
+}
+EXPORT_SYMBOL(blk_recount_segments);
+
+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 (!blk_queue_cluster(q))
+ return 0;
+
+ 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);
+
+ if (!BIOVEC_PHYS_MERGEABLE(&end_bv, &nxt_bv))
+ return 0;
+
+ /*
+ * bio and nxt are contiguous in memory; check if the queue allows
+ * these two to be merged into one
+ */
+ if (BIOVEC_SEG_BOUNDARY(q, &end_bv, &nxt_bv))
+ return 1;
+
+ return 0;
+}
+
+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 *cluster)
+{
+
+ int nbytes = bvec->bv_len;
+
+ if (*sg && *cluster) {
+ if ((*sg)->length + nbytes > queue_max_segment_size(q))
+ goto new_segment;
+
+ if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
+ goto new_segment;
+ if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
+ goto new_segment;
+
+ (*sg)->length += nbytes;
+ } else {
+new_segment:
+ if (!*sg)
+ *sg = sglist;
+ else {
+ /*
+ * 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);
+ *sg = sg_next(*sg);
+ }
+
+ sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset);
+ (*nsegs)++;
+ }
+ *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 cluster = blk_queue_cluster(q), nsegs = 0;
+
+ for_each_bio(bio)
+ bio_for_each_segment(bvec, bio, iter)
+ __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg,
+ &nsegs, &cluster);
+
+ 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);
+}
+
+/*
+ * blk-mq uses req->special to carry normal driver per-request payload, it
+ * does not indicate a prepared command that we cannot merge with.
+ */
+static bool req_no_special_merge(struct request *req)
+{
+ struct request_queue *q = req->q;
+
+ return !q->mq_ops && req->special;
+}
+
+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;
+
+ /*
+ * First check if the either of the requests are re-queued
+ * requests. Can't merge them if they are.
+ */
+ if (req_no_special_merge(req) || req_no_special_merge(next))
+ return 0;
+
+ 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;
+ int cpu;
+
+ cpu = part_stat_lock();
+ part = req->part;
+
+ part_round_stats(req->q, cpu, 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;
+}
+
+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 (!q->mq_ops)
+ lockdep_assert_held(q->queue_lock);
+
+ 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
+ || req_no_special_merge(next))
+ 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 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 of
+ * the merged requests to be the current request
+ * for accounting purposes.
+ */
+ if (time_after(req->start_time, next->start_time))
+ req->start_time = next->start_time;
+
+ 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);
+
+ req->ioprio = ioprio_best(req->ioprio, next->ioprio);
+ if (blk_rq_cpu_valid(next))
+ req->cpu = next->cpu;
+
+ /*
+ * 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 elevator_queue *e = q->elevator;
+ struct request *free;
+
+ if (!e->uses_mq && e->type->ops.sq.elevator_allow_rq_merge_fn)
+ if (!e->type->ops.sq.elevator_allow_rq_merge_fn(q, rq, next))
+ return 0;
+
+ free = attempt_merge(q, rq, next);
+ if (free) {
+ __blk_put_request(q, 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 and not a special request */
+ if (rq->rq_disk != bio->bi_disk || req_no_special_merge(rq))
+ 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;
+
+ 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;
+}