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: longli@linuxonhyperv.com longli@linuxonhyperv.com Sent: Thursday, June 3, 2021 11:47 AM To: linux-block@vger.kernel.org Cc: Long Li longli@microsoft.com; Jens Axboe axboe@kernel.dk; Johannes Thumshirn johannes.thumshirn@wdc.com; Pavel Begunkov asml.silence@gmail.com; Ming Lei ming.lei@redhat.com; Tejun Heo tj@kernel.org; Matthew Wilcox (Oracle) willy@infradead.org; Jeffle Xu jefflexu@linux.alibaba.com; linux-kernel@vger.kernel.org; stable@vger.kernel.org Subject: [PATCH] block: return the correct first bvec when checking for gaps

From: Long Li longli@microsoft.com

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 axboe@kernel.dk Cc: Johannes Thumshirn johannes.thumshirn@wdc.com Cc: Pavel Begunkov asml.silence@gmail.com Cc: Ming Lei ming.lei@redhat.com Cc: Tejun Heo tj@kernel.org Cc: "Matthew Wilcox (Oracle)" willy@infradead.org Cc: Jeffle Xu jefflexu@linux.alibaba.com Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org Fixes: 07173c3ec276 ("block: enable multipage bvecs") Signed-off-by: Long Li longli@microsoft.com

---

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