Re: [PATCH 1/3] block: fix bio_may_need_split() by using bvec iterator way

[Nitesh Shetty <nj.shetty@samsung.com>]

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On 18/12/25 05:31PM, Ming Lei wrote:
>->bi_vcnt doesn't make sense for cloned bio, which is perfectly fine
>passed to bio_may_need_split().
>
>So fix bio_may_need_split() by not taking ->bi_vcnt directly, instead
>checking with help from bio size and bvec->len.
>
>Meantime retrieving the 1st bvec via __bvec_iter_bvec().
>
>Fixes: abd45c159df5 ("block: handle fast path of bio splitting inline")
>Signed-off-by: Ming Lei <ming.lei@redhat.com>
>---
> block/blk.h | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
>diff --git a/block/blk.h b/block/blk.h
>index e4c433f62dfc..a0b9cecba8fa 100644
>--- a/block/blk.h
>+++ b/block/blk.h
>@@ -371,12 +371,19 @@ struct bio *bio_split_zone_append(struct bio *bio,
> static inline bool bio_may_need_split(struct bio *bio,
> 		const struct queue_limits *lim)
> {
>+	const struct bio_vec *bv;
>+
> 	if (lim->chunk_sectors)
> 		return true;
>-	if (bio->bi_vcnt != 1)
>+
>+	if ((bio_op(bio) != REQ_OP_READ && bio_op(bio) != REQ_OP_WRITE) ||
>+			!bio->bi_io_vec)
REQ_OP_READ, REQ_OP_WRITE check is not necessary, since bio_may_need_split
is always called for READ/WRITE.

Thanks,
Nitesh

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