From: Wenbo Wang <wenbo.wang@memblaze.com>
Date: Fri, 20 Mar 2015 05:04:54 +0000 (-0400)
Subject: Fix bug in blk_rq_merge_ok
X-Git-Tag: v3.19.5~84
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f2a756bcb4678e804a5231f6c280dfd30270d663;p=thirdparty%2Fkernel%2Fstable.git

Fix bug in blk_rq_merge_ok

commit 7ee8e4f3983c4ff700958a6099c8fd212ea67b94 upstream.

Use the right array index to reference the last
element of rq->biotail->bi_io_vec[]

Signed-off-by: Wenbo Wang <wenbo.wang@memblaze.com>
Reviewed-by: Chong Yuan <chong.yuan@memblaze.com>
Fixes: 66cb45aa41315 ("block: add support for limiting gaps in SG lists")
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 89b97b5e08818..2be75ff7f171d 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -609,7 +609,7 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
 	if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS)) {
 		struct bio_vec *bprev;
 
-		bprev = &rq->biotail->bi_io_vec[bio->bi_vcnt - 1];
+		bprev = &rq->biotail->bi_io_vec[rq->biotail->bi_vcnt - 1];
 		if (bvec_gap_to_prev(bprev, bio->bi_io_vec[0].bv_offset))
 			return false;
 	}