[PATCH for-6.18/block 06/16] block: factor out a helper bio_submit_split_bioset()

Yu Kuai
2025-09-05T07:15:58Z

From: Yu Kuai <yukuai3@huawei.com>

No functional changes are intended, some drivers like mdraid will split
bio by internal processing, prepare to unify bio split codes.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
block/blk-merge.c | 59 ++++++++++++++++++++++++++++--------------
include/linux/blkdev.h | 2 ++
2 files changed, 42 insertions(+), 19 deletions(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 5538356770a4..51fe4ed5b7c0 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -104,33 +104,54 @@ static unsigned int bio_allowed_max_sectors(const struct queue_limits *lim)
return round_down(UINT_MAX, lim->logical_block_size) >> SECTOR_SHIFT;
}

+/*
+ * bio_submit_split_bioset - Submit a bio, splitting it at a designated sector
+ * @bio: the original bio to be submitted and split
+ * @split_sectors: the sector count at which to split
+ * @bs: the bio set used for allocating the new split bio
+ *
+ * The original bio is modified to contain the remaining sectors and submitted.
+ * The caller is responsible for submitting the returned bio.
+ *
+ * If succeed, the newly allocated bio representing the initial part will be
+ * returned, on failure NULL will be returned and original bio will fail.
+ */
+struct bio *bio_submit_split_bioset(struct bio *bio, unsigned int split_sectors,
+ struct bio_set *bs)
+{
+ struct bio *split = bio_split(bio, split_sectors, GFP_NOIO, bs);
+
+ if (IS_ERR(split)) {
+ bio->bi_status = errno_to_blk_status(PTR_ERR(split));
+ bio_endio(bio);
+ return NULL;
+ }
+
+ bio_chain(split, bio);
+ trace_block_split(split, bio->bi_iter.bi_sector);
+ WARN_ON_ONCE(bio_zone_write_plugging(bio));
+ submit_bio_noacct(bio);
+
+ return split;
+}
+EXPORT_SYMBOL_GPL(bio_submit_split_bioset);
+
static struct bio *bio_submit_split(struct bio *bio, int split_sectors)
{
- if (unlikely(split_sectors < 0))
- goto error;
+ if (unlikely(split_sectors < 0)) {
+ bio->bi_status = errno_to_blk_status(split_sectors);
+ bio_endio(bio);
+ return NULL;
+ }

if (split_sectors) {
- struct bio *split;
-
- split = bio_split(bio, split_sectors, GFP_NOIO,
+ bio = bio_submit_split_bioset(bio, split_sectors,
&bio->bi_bdev->bd_disk->bio_split);
- if (IS_ERR(split)) {
- split_sectors = PTR_ERR(split);
- goto error;
- }
- split->bi_opf |= REQ_NOMERGE;
- bio_chain(split, bio);
- trace_block_split(split, bio->bi_iter.bi_sector);
- WARN_ON_ONCE(bio_zone_write_plugging(bio));
- submit_bio_noacct(bio);
- return split;
+ if (bio)
+ bio->bi_opf |= REQ_NOMERGE;
}

return bio;
-error:
- bio->bi_status = errno_to_blk_status(split_sectors);
- bio_endio(bio);
- return NULL;
}

struct bio *bio_split_discard(struct bio *bio, const struct queue_limits *lim,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 3c3b64684d14..0982874b65fa 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1000,6 +1000,8 @@ extern int blk_register_queue(struct gendisk *disk);
extern void blk_unregister_queue(struct gendisk *disk);
void submit_bio_noacct(struct bio *bio);
struct bio *bio_split_to_limits(struct bio *bio);
+struct bio *bio_submit_split_bioset(struct bio *bio, unsigned int split_sectors,
+ struct bio_set *bs);

extern int blk_lld_busy(struct request_queue *q);
extern int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags);
--
2.39.2