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-rw-r--r--block/blk-merge.c368
1 files changed, 264 insertions, 104 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 99cb5cf1f44..54535831f1e 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -12,39 +12,56 @@
static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
struct bio *bio)
{
- unsigned int phys_size;
- struct bio_vec *bv, *bvprv = NULL;
- int cluster, i, high, highprv = 1;
+ struct bio_vec bv, bvprv = { NULL };
+ int cluster, high, highprv = 1, no_sg_merge;
unsigned int seg_size, nr_phys_segs;
struct bio *fbio, *bbio;
+ struct bvec_iter iter;
if (!bio)
return 0;
+ /*
+ * This should probably be returning 0, but blk_add_request_payload()
+ * (Christoph!!!!)
+ */
+ if (bio->bi_rw & REQ_DISCARD)
+ return 1;
+
+ if (bio->bi_rw & REQ_WRITE_SAME)
+ return 1;
+
fbio = bio;
- cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
+ cluster = blk_queue_cluster(q);
seg_size = 0;
- phys_size = nr_phys_segs = 0;
+ nr_phys_segs = 0;
+ no_sg_merge = test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags);
+ high = 0;
for_each_bio(bio) {
- bio_for_each_segment(bv, bio, i) {
+ bio_for_each_segment(bv, bio, iter) {
/*
- * the trick here is making sure that a high page is
- * never considered part of another segment, since that
- * might change with the bounce page.
+ * If SG merging is disabled, each bio vector is
+ * a segment
*/
- high = page_to_pfn(bv->bv_page) > queue_bounce_pfn(q);
- if (high || highprv)
+ if (no_sg_merge)
goto new_segment;
- if (cluster) {
- if (seg_size + bv->bv_len
+
+ /*
+ * the trick here is making sure that a high page is
+ * never considered part of another segment, since
+ * that might change with the bounce page.
+ */
+ high = page_to_pfn(bv.bv_page) > queue_bounce_pfn(q);
+ if (!high && !highprv && cluster) {
+ if (seg_size + bv.bv_len
> queue_max_segment_size(q))
goto new_segment;
- if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
+ if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv))
goto new_segment;
- if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
+ if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv))
goto new_segment;
- seg_size += bv->bv_len;
+ seg_size += bv.bv_len;
bvprv = bv;
continue;
}
@@ -55,7 +72,7 @@ new_segment:
nr_phys_segs++;
bvprv = bv;
- seg_size = bv->bv_len;
+ seg_size = bv.bv_len;
highprv = high;
}
bbio = bio;
@@ -76,11 +93,16 @@ void blk_recalc_rq_segments(struct request *rq)
void blk_recount_segments(struct request_queue *q, struct bio *bio)
{
- struct bio *nxt = bio->bi_next;
+ if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags))
+ bio->bi_phys_segments = bio->bi_vcnt;
+ else {
+ 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->bi_next = NULL;
- bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio);
- bio->bi_next = nxt;
bio->bi_flags |= (1 << BIO_SEG_VALID);
}
EXPORT_SYMBOL(blk_recount_segments);
@@ -88,7 +110,10 @@ EXPORT_SYMBOL(blk_recount_segments);
static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
struct bio *nxt)
{
- if (!test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags))
+ struct bio_vec end_bv = { NULL }, nxt_bv;
+ struct bvec_iter iter;
+
+ if (!blk_queue_cluster(q))
return 0;
if (bio->bi_seg_back_size + nxt->bi_seg_front_size >
@@ -98,77 +123,122 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
if (!bio_has_data(bio))
return 1;
- if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
+ bio_for_each_segment(end_bv, bio, iter)
+ if (end_bv.bv_len == iter.bi_size)
+ break;
+
+ nxt_bv = bio_iovec(nxt);
+
+ 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 (BIO_SEG_BOUNDARY(q, bio, nxt))
+ if (BIOVEC_SEG_BOUNDARY(q, &end_bv, &nxt_bv))
return 1;
return 0;
}
-/*
- * 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)
+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 int __blk_bios_map_sg(struct request_queue *q, struct bio *bio,
+ struct scatterlist *sglist,
+ struct scatterlist **sg)
{
- struct bio_vec *bvec, *bvprv;
- struct req_iterator iter;
- struct scatterlist *sg;
+ struct bio_vec bvec, bvprv = { NULL };
+ struct bvec_iter iter;
int nsegs, cluster;
nsegs = 0;
- cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
+ cluster = blk_queue_cluster(q);
- /*
- * for each bio in rq
- */
- bvprv = NULL;
- sg = NULL;
- rq_for_each_segment(bvec, rq, iter) {
- int nbytes = bvec->bv_len;
+ if (bio->bi_rw & REQ_DISCARD) {
+ /*
+ * This is a hack - drivers should be neither modifying the
+ * biovec, nor relying on bi_vcnt - but because of
+ * blk_add_request_payload(), a discard bio may or may not have
+ * a payload we need to set up here (thank you Christoph) and
+ * bi_vcnt is really the only way of telling if we need to.
+ */
- if (bvprv && cluster) {
- if (sg->length + nbytes > queue_max_segment_size(q))
- goto new_segment;
+ if (bio->bi_vcnt)
+ goto single_segment;
- if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
- goto new_segment;
- if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
- goto new_segment;
+ return 0;
+ }
- 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->page_link &= ~0x02;
- sg = sg_next(sg);
- }
+ if (bio->bi_rw & REQ_WRITE_SAME) {
+single_segment:
+ *sg = sglist;
+ bvec = bio_iovec(bio);
+ sg_set_page(*sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset);
+ return 1;
+ }
- sg_set_page(sg, bvec->bv_page, nbytes, bvec->bv_offset);
- nsegs++;
- }
- bvprv = bvec;
- } /* segments in rq */
+ 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->bio)
+ nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg);
if (unlikely(rq->cmd_flags & REQ_COPY_USER) &&
(blk_rq_bytes(rq) & q->dma_pad_mask)) {
@@ -180,7 +250,7 @@ new_segment:
}
if (q->dma_drain_size && q->dma_drain_needed(rq)) {
- if (rq->cmd_flags & REQ_RW)
+ if (rq->cmd_flags & REQ_WRITE)
memset(q->dma_drain_buffer, 0, q->dma_drain_size);
sg->page_link &= ~0x02;
@@ -200,19 +270,46 @@ new_segment:
}
EXPORT_SYMBOL(blk_rq_map_sg);
+/**
+ * blk_bio_map_sg - map a bio to a scatterlist
+ * @q: request_queue in question
+ * @bio: bio being mapped
+ * @sglist: scatterlist being mapped
+ *
+ * Note:
+ * Caller must make sure sg can hold bio->bi_phys_segments entries
+ *
+ * Will return the number of sg entries setup
+ */
+int blk_bio_map_sg(struct request_queue *q, struct bio *bio,
+ struct scatterlist *sglist)
+{
+ struct scatterlist *sg = NULL;
+ int nsegs;
+ struct bio *next = bio->bi_next;
+ bio->bi_next = NULL;
+
+ nsegs = __blk_bios_map_sg(q, bio, sglist, &sg);
+ bio->bi_next = next;
+ if (sg)
+ sg_mark_end(sg);
+
+ BUG_ON(bio->bi_phys_segments && nsegs > bio->bi_phys_segments);
+ return nsegs;
+}
+EXPORT_SYMBOL(blk_bio_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_hw_segments(q) ||
- req->nr_phys_segments + nr_phys_segs > queue_max_phys_segments(q)) {
- req->cmd_flags |= REQ_NOMERGE;
- if (req == q->last_merge)
- q->last_merge = NULL;
- return 0;
- }
+ if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q))
+ goto no_merge;
+
+ if (bio_integrity(bio) && blk_integrity_merge_bio(q, req, bio))
+ goto no_merge;
/*
* This will form the start of a new hw segment. Bump both
@@ -220,19 +317,19 @@ static inline int ll_new_hw_segment(struct request_queue *q,
*/
req->nr_phys_segments += nr_phys_segs;
return 1;
+
+no_merge:
+ req->cmd_flags |= REQ_NOMERGE;
+ if (req == q->last_merge)
+ q->last_merge = NULL;
+ return 0;
}
int ll_back_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio)
{
- unsigned short max_sectors;
-
- if (unlikely(blk_pc_request(req)))
- max_sectors = queue_max_hw_sectors(q);
- else
- max_sectors = queue_max_sectors(q);
-
- if (blk_rq_sectors(req) + bio_sectors(bio) > max_sectors) {
+ if (blk_rq_sectors(req) + bio_sectors(bio) >
+ blk_rq_get_max_sectors(req)) {
req->cmd_flags |= REQ_NOMERGE;
if (req == q->last_merge)
q->last_merge = NULL;
@@ -249,15 +346,8 @@ int ll_back_merge_fn(struct request_queue *q, struct request *req,
int ll_front_merge_fn(struct request_queue *q, struct request *req,
struct bio *bio)
{
- unsigned short max_sectors;
-
- if (unlikely(blk_pc_request(req)))
- max_sectors = queue_max_hw_sectors(q);
- else
- max_sectors = queue_max_sectors(q);
-
-
- if (blk_rq_sectors(req) + bio_sectors(bio) > max_sectors) {
+ if (blk_rq_sectors(req) + bio_sectors(bio) >
+ blk_rq_get_max_sectors(req)) {
req->cmd_flags |= REQ_NOMERGE;
if (req == q->last_merge)
q->last_merge = NULL;
@@ -271,6 +361,17 @@ int ll_front_merge_fn(struct request_queue *q, struct request *req,
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 int ll_merge_requests_fn(struct request_queue *q, struct request *req,
struct request *next)
{
@@ -282,13 +383,14 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
* First check if the either of the requests are re-queued
* requests. Can't merge them if they are.
*/
- if (req->special || next->special)
+ if (req_no_special_merge(req) || req_no_special_merge(next))
return 0;
/*
* Will it become too large?
*/
- if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > queue_max_sectors(q))
+ if ((blk_rq_sectors(req) + blk_rq_sectors(next)) >
+ blk_rq_get_max_sectors(req))
return 0;
total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
@@ -300,10 +402,10 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
total_phys_segments--;
}
- if (total_phys_segments > queue_max_phys_segments(q))
+ if (total_phys_segments > queue_max_segments(q))
return 0;
- if (total_phys_segments > queue_max_hw_segments(q))
+ if (blk_integrity_rq(req) && blk_integrity_merge_rq(q, req, next))
return 0;
/* Merge is OK... */
@@ -348,11 +450,12 @@ static void blk_account_io_merge(struct request *req)
int cpu;
cpu = part_stat_lock();
- part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req));
+ part = req->part;
part_round_stats(cpu, part);
part_dec_in_flight(part, rq_data_dir(req));
+ hd_struct_put(part);
part_stat_unlock();
}
}
@@ -366,6 +469,9 @@ static int attempt_merge(struct request_queue *q, struct request *req,
if (!rq_mergeable(req) || !rq_mergeable(next))
return 0;
+ if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags))
+ return 0;
+
/*
* not contiguous
*/
@@ -374,10 +480,11 @@ static int attempt_merge(struct request_queue *q, struct request *req,
if (rq_data_dir(req) != rq_data_dir(next)
|| req->rq_disk != next->rq_disk
- || next->special)
+ || req_no_special_merge(next))
return 0;
- if (blk_integrity_rq(req) != blk_integrity_rq(next))
+ if (req->cmd_flags & REQ_WRITE_SAME &&
+ !blk_write_same_mergeable(req->bio, next->bio))
return 0;
/*
@@ -452,3 +559,56 @@ int attempt_front_merge(struct request_queue *q, struct request *rq)
return 0;
}
+
+int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ return attempt_merge(q, rq, next);
+}
+
+bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
+{
+ struct request_queue *q = rq->q;
+
+ if (!rq_mergeable(rq) || !bio_mergeable(bio))
+ return false;
+
+ if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw))
+ 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_bdev->bd_disk || req_no_special_merge(rq))
+ return false;
+
+ /* only merge integrity protected bio into ditto rq */
+ if (bio_integrity(bio) != blk_integrity_rq(rq))
+ return false;
+
+ /* must be using the same buffer */
+ if (rq->cmd_flags & REQ_WRITE_SAME &&
+ !blk_write_same_mergeable(rq->bio, bio))
+ return false;
+
+ if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS)) {
+ struct bio_vec *bprev;
+
+ bprev = &rq->biotail->bi_io_vec[bio->bi_vcnt - 1];
+ if (bvec_gap_to_prev(bprev, bio->bi_io_vec[0].bv_offset))
+ return false;
+ }
+
+ return true;
+}
+
+int blk_try_merge(struct request *rq, struct bio *bio)
+{
+ 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;
+}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-12-21 00:18:26 +0000