The fast path is no splitting needed. Separate the handling into a
check part we can inline, and an out-of-line handling path if we do
need to split.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 9a55b5070829..20ec9f00801a 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -14,6 +14,7 @@
#include "blk.h"
#include "blk-rq-qos.h"
#include "blk-throttle.h"
+#include "blk-merge.h"
static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
{
@@ -92,10 +93,8 @@ 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)
+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;
@@ -136,8 +135,8 @@ static struct bio *blk_bio_discard_split(struct request_queue *q,
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)
+struct bio *blk_bio_write_zeroes_split(struct request_queue *q, struct bio *bio,
+ struct bio_set *bs, unsigned *nsegs)
{
*nsegs = 0;
@@ -150,10 +149,8 @@ static struct bio *blk_bio_write_zeroes_split(struct request_queue *q,
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)
+struct bio *blk_bio_write_same_split(struct request_queue *q, struct bio *bio,
+ struct bio_set *bs, unsigned *nsegs)
{
*nsegs = 1;
@@ -275,10 +272,8 @@ static bool bvec_split_segs(const struct request_queue *q,
* responsible for ensuring that @bs is only destroyed after processing of the
* split bio has finished.
*/
-static struct bio *blk_bio_segment_split(struct request_queue *q,
- struct bio *bio,
- struct bio_set *bs,
- unsigned *segs)
+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;
@@ -322,67 +317,17 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
return bio_split(bio, sectors, GFP_NOIO, bs);
}
-/**
- * __blk_queue_split - split a bio and submit the second half
- * @bio: [in, out] bio to be split
- * @nr_segs: [out] number of segments in the first bio
- *
- * Split a bio into two bios, chain the two bios, submit the second half and
- * store a pointer to the first half in *@bio. If the second bio is still too
- * big it will be split by a recursive call to this function. Since this
- * function may allocate a new bio from q->bio_split, it is the responsibility
- * of the caller to ensure that q->bio_split is only released after processing
- * of the split bio has finished.
- */
-void __blk_queue_split(struct bio **bio, unsigned int *nr_segs)
+void blk_bio_handle_split(struct bio **bio, struct bio *split)
{
- struct request_queue *q = (*bio)->bi_bdev->bd_disk->queue;
- struct bio *split = NULL;
-
- switch (bio_op(*bio)) {
- case REQ_OP_DISCARD:
- case REQ_OP_SECURE_ERASE:
- split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs);
- break;
- case REQ_OP_WRITE_ZEROES:
- split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split,
- nr_segs);
- break;
- case REQ_OP_WRITE_SAME:
- split = blk_bio_write_same_split(q, *bio, &q->bio_split,
- nr_segs);
- break;
- default:
- /*
- * All drivers must accept single-segments bios that are <=
- * PAGE_SIZE. This is a quick and dirty check that relies on
- * the fact that bi_io_vec[0] is always valid if a bio has data.
- * The check might lead to occasional false negatives when bios
- * are cloned, but compared to the performance impact of cloned
- * bios themselves the loop below doesn't matter anyway.
- */
- if (!q->limits.chunk_sectors &&
- (*bio)->bi_vcnt == 1 &&
- ((*bio)->bi_io_vec[0].bv_len +
- (*bio)->bi_io_vec[0].bv_offset) <= PAGE_SIZE) {
- *nr_segs = 1;
- break;
- }
- split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs);
- break;
- }
-
- if (split) {
- /* there isn't chance to merge the splitted bio */
- split->bi_opf |= REQ_NOMERGE;
+ /* there isn't chance to merge the splitted bio */
+ split->bi_opf |= REQ_NOMERGE;
- bio_chain(split, *bio);
- trace_block_split(split, (*bio)->bi_iter.bi_sector);
- submit_bio_noacct(*bio);
- *bio = split;
+ bio_chain(split, *bio);
+ trace_block_split(split, (*bio)->bi_iter.bi_sector);
+ submit_bio_noacct(*bio);
+ *bio = split;
- blk_throtl_charge_bio_split(*bio);
- }
+ blk_throtl_charge_bio_split(*bio);
}
/**
@@ -397,9 +342,10 @@ void __blk_queue_split(struct bio **bio, unsigned int *nr_segs)
*/
void blk_queue_split(struct bio **bio)
{
+ struct request_queue *q = (*bio)->bi_bdev->bd_disk->queue;
unsigned int nr_segs;
- __blk_queue_split(bio, &nr_segs);
+ __blk_queue_split(q, bio, &nr_segs);
}
EXPORT_SYMBOL(blk_queue_split);
diff --git a/block/blk-merge.h b/block/blk-merge.h
new file mode 100644
index 000000000000..8f0b7dec2dd2
--- /dev/null
+++ b/block/blk-merge.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef BLK_MERGE_H
+#define BLK_MERGE_H
+
+#include "blk-mq.h"
+
+struct bio *blk_bio_discard_split(struct request_queue *q, struct bio *bio,
+ struct bio_set *bs, unsigned *nsegs);
+struct bio *blk_bio_write_zeroes_split(struct request_queue *q, struct bio *bio,
+ struct bio_set *bs, unsigned *nsegs);
+struct bio *blk_bio_write_same_split(struct request_queue *q, struct bio *bio,
+ struct bio_set *bs, unsigned *nsegs);
+struct bio *blk_bio_segment_split(struct request_queue *q, struct bio *bio,
+ struct bio_set *bs, unsigned *segs);
+void blk_bio_handle_split(struct bio **bio, struct bio *split);
+
+/**
+ * blk_queue_split - split a bio and submit the second half
+ * @bio: [in, out] bio to be split
+ * @nr_segs: [out] number of segments in the first bio
+ *
+ * Split a bio into two bios, chain the two bios, submit the second half and
+ * store a pointer to the first half in *@bio. If the second bio is still too
+ * big it will be split by a recursive call to this function. Since this
+ * function may allocate a new bio from q->bio_split, it is the responsibility
+ * of the caller to ensure that q->bio_split is only released after processing
+ * of the split bio has finished.
+ */
+static inline void __blk_queue_split(struct request_queue *q, struct bio **bio,
+ unsigned int *nr_segs)
+{
+ struct bio *split = NULL;
+
+ switch (bio_op(*bio)) {
+ case REQ_OP_DISCARD:
+ case REQ_OP_SECURE_ERASE:
+ split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs);
+ break;
+ case REQ_OP_WRITE_ZEROES:
+ split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split,
+ nr_segs);
+ break;
+ case REQ_OP_WRITE_SAME:
+ split = blk_bio_write_same_split(q, *bio, &q->bio_split,
+ nr_segs);
+ break;
+ default:
+ /*
+ * All drivers must accept single-segments bios that are <=
+ * PAGE_SIZE. This is a quick and dirty check that relies on
+ * the fact that bi_io_vec[0] is always valid if a bio has data.
+ * The check might lead to occasional false negatives when bios
+ * are cloned, but compared to the performance impact of cloned
+ * bios themselves the loop below doesn't matter anyway.
+ */
+ if (!q->limits.chunk_sectors &&
+ (*bio)->bi_vcnt == 1 &&
+ ((*bio)->bi_io_vec[0].bv_len +
+ (*bio)->bi_io_vec[0].bv_offset) <= PAGE_SIZE) {
+ *nr_segs = 1;
+ break;
+ }
+ split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs);
+ break;
+ }
+
+ if (split)
+ blk_bio_handle_split(bio, split);
+}
+
+#endif
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 7dadfac5bad0..54c510c0f3ee 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -42,6 +42,7 @@
#include "blk-stat.h"
#include "blk-mq-sched.h"
#include "blk-rq-qos.h"
+#include "blk-merge.h"
static DEFINE_PER_CPU(struct llist_head, blk_cpu_done);
@@ -2514,7 +2515,7 @@ void blk_mq_submit_bio(struct bio *bio)
blk_status_t ret;
blk_queue_bounce(q, &bio);
- __blk_queue_split(&bio, &nr_segs);
+ __blk_queue_split(q, &bio, &nr_segs);
if (!bio_integrity_prep(bio))
goto queue_exit;
diff --git a/block/blk.h b/block/blk.h
index 0afee3e6a7c1..c0b59bc38a2e 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -262,7 +262,6 @@ ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);
ssize_t part_timeout_store(struct device *, struct device_attribute *,
const char *, size_t);
-void __blk_queue_split(struct bio **bio, unsigned int *nr_segs);
int ll_back_merge_fn(struct request *req, struct bio *bio,
unsigned int nr_segs);
bool blk_attempt_req_merge(struct request_queue *q, struct request *rq,
--
Jens Axboe
