[PATCH 4.4 48/50] block: dont optimize for non-cloned bio in bio_get_last_bvec()

Greg Kroah-Hartman
2016-03-14T17:54:36Z

From: Ming Lei <ming.lei@canonical.com>

commit 90d0f0f11588ec692c12f9009089b398be395184 upstream.

For !BIO_CLONED bio, we can use .bi_vcnt safely, but it
doesn't mean we can just simply return .bi_io_vec[.bi_vcnt - 1]
because the start postion may have been moved in the middle of
the bvec, such as splitting in the middle of bvec.

Fixes: 7bcd79ac50d9(block: bio: introduce helpers to get the 1st and last bvec)
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/linux/bio.h | 5 -----
1 file changed, 5 deletions(-)

--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -320,11 +320,6 @@ static inline void bio_get_last_bvec(str
struct bvec_iter iter = bio->bi_iter;
int idx;

- if (!bio_flagged(bio, BIO_CLONED)) {
- *bv = bio->bi_io_vec[bio->bi_vcnt - 1];
- return;
- }
-
if (unlikely(!bio_multiple_segments(bio))) {
*bv = bio_iovec(bio);
return;