path: root/include
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authorMing Lei <ming.lei@redhat.com>2020-08-17 18:00:55 +0800
committerJens Axboe <axboe@kernel.dk>2020-09-02 20:59:40 -0600
commit7e24969022cbd61ddc586f14824fc205661bb124 (patch)
tree64854a523b26e7ae9f058097b5d0e5bbacaf4bd7 /include
parentblk-stat: make q->stats->lock irqsafe (diff)
block: allow for_each_bvec to support zero len bvec
Block layer usually doesn't support or allow zero-length bvec. Since commit 1bdc76aea115 ("iov_iter: use bvec iterator to implement iterate_bvec()"), iterate_bvec() switches to bvec iterator. However, Al mentioned that 'Zero-length segments are not disallowed' in iov_iter. Fixes for_each_bvec() so that it can move on after seeing one zero length bvec. Fixes: 1bdc76aea115 ("iov_iter: use bvec iterator to implement iterate_bvec()") Reported-by: syzbot <syzbot+61acc40a49a3e46e25ea@syzkaller.appspotmail.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Tested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> Link: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2262077.html Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include')
1 files changed, 8 insertions, 1 deletions
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index ac0c7299d5b8..dd74503f7e5e 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -117,11 +117,18 @@ static inline bool bvec_iter_advance(const struct bio_vec *bv,
return true;
+static inline void bvec_iter_skip_zero_bvec(struct bvec_iter *iter)
+ iter->bi_bvec_done = 0;
+ iter->bi_idx++;
#define for_each_bvec(bvl, bio_vec, iter, start) \
for (iter = (start); \
(iter).bi_size && \
((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
- bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
+ (bvl).bv_len ? (void)bvec_iter_advance((bio_vec), &(iter), \
+ (bvl).bv_len) : bvec_iter_skip_zero_bvec(&(iter)))
/* for iterating one bio from start to end */
#define BVEC_ITER_ALL_INIT (struct bvec_iter) \