2021-06-03 18:48:19

by Long Li

[permalink] [raw]
Subject: [PATCH] block: return the correct first bvec when checking for gaps

From: Long Li <[email protected]>

After commit 07173c3ec276 ("block: enable multipage bvecs"), a bvec can
have multiple pages. But bio_will_gap() still assumes one page bvec while
checking for merging. This causes data corruption on drivers relying on
the correct merging on virt_boundary_mask.

Fix this by returning the bvec for multi-page bvec.

Cc: Jens Axboe <[email protected]>
Cc: Johannes Thumshirn <[email protected]>
Cc: Pavel Begunkov <[email protected]>
Cc: Ming Lei <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: Jeffle Xu <[email protected]>
Cc: [email protected]
Cc: [email protected]
Fixes: 07173c3ec276 ("block: enable multipage bvecs")
Signed-off-by: Long Li <[email protected]>
---
include/linux/bio.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index a0b4cfdf62a4..e89242a53bbc 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -271,7 +271,7 @@ static inline void bio_clear_flag(struct bio *bio, unsigned int bit)

static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv)
{
- *bv = bio_iovec(bio);
+ *bv = mp_bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
}

static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
--
2.17.1


2021-06-03 19:05:27

by Long Li

[permalink] [raw]
Subject: RE: [PATCH] block: return the correct first bvec when checking for gaps

Hi,

Please discard this patch as it's from a wrong work branch. The patch is not complete. I'll resubmit.

Long

> -----Original Message-----
> From: [email protected] <[email protected]>
> Sent: Thursday, June 3, 2021 11:47 AM
> To: [email protected]
> Cc: Long Li <[email protected]>; Jens Axboe <[email protected]>;
> Johannes Thumshirn <[email protected]>; Pavel Begunkov
> <[email protected]>; Ming Lei <[email protected]>; Tejun Heo
> <[email protected]>; Matthew Wilcox (Oracle) <[email protected]>; Jeffle Xu
> <[email protected]>; [email protected];
> [email protected]
> Subject: [PATCH] block: return the correct first bvec when checking for gaps
>
> From: Long Li <[email protected]>
>
> After commit 07173c3ec276 ("block: enable multipage bvecs"), a bvec can
> have multiple pages. But bio_will_gap() still assumes one page bvec while
> checking for merging. This causes data corruption on drivers relying on the
> correct merging on virt_boundary_mask.
>
> Fix this by returning the bvec for multi-page bvec.
>
> Cc: Jens Axboe <[email protected]>
> Cc: Johannes Thumshirn <[email protected]>
> Cc: Pavel Begunkov <[email protected]>
> Cc: Ming Lei <[email protected]>
> Cc: Tejun Heo <[email protected]>
> Cc: "Matthew Wilcox (Oracle)" <[email protected]>
> Cc: Jeffle Xu <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Fixes: 07173c3ec276 ("block: enable multipage bvecs")
> Signed-off-by: Long Li <[email protected]>
> ---
> include/linux/bio.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/bio.h b/include/linux/bio.h index
> a0b4cfdf62a4..e89242a53bbc 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -271,7 +271,7 @@ static inline void bio_clear_flag(struct bio *bio,
> unsigned int bit)
>
> static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv) {
> - *bv = bio_iovec(bio);
> + *bv = mp_bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
> }
>
> static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
> --
> 2.17.1