From: Ming Lei <ming.lei@canonical.com>
Date: Sat, 12 Mar 2016 14:56:19 +0000 (+0800)
Subject: block: don't optimize for non-cloned bio in bio_get_last_bvec()
X-Git-Tag: v4.1.12-124.31.3~837
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=ed5c5ef39a7e85da8ff45d366a9602a4eb3b9128;p=users%2Fjedix%2Flinux-maple.git

block: don't optimize for non-cloned bio in bio_get_last_bvec()

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)
Cc: stable@vger.kernel.org
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>
(cherry picked from commit 90d0f0f11588ec692c12f9009089b398be395184)

Orabug: 27775588

Signed-off-by: Shan Hai <shan.hai@oracle.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>
---

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 9f7d4dd5eabf..cf588a60ddea 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -307,11 +307,6 @@ static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
 	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;