linux-kernel - [PATCH v2 3/4] block: get the 1st and last bvec via helpers

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Date:	Fri, 26 Feb 2016 23:40:52 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org
Cc:	linux-block@...r.kernel.org, Christoph Hellwig <hch@...radead.org>,
	Sagi Grimberg <sagig@....mellanox.co.il>,
	Kent Overstreet <kent.overstreet@...il.com>,
	Keith Busch <keith.busch@...el.com>,
	Elliott Robert <elliott@....com>,
	Ming Lei <ming.lei@...onical.com>, stable@...r.kernel.org
Subject: [PATCH v2 3/4] block: get the 1st and last bvec via helpers

This patch applies the two introduced helpers to
figure out the 1st and last bvec, and fixes the
original way after bio splitting.

Cc: stable@...r.kernel.org
Reported-by: Sagi Grimberg <sagig@....mellanox.co.il>
Reviewed-by: Sagi Grimberg <sagig@...lanox.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Ming Lei <ming.lei@...onical.com>
---
 include/linux/blkdev.h | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index cd06a41..d7f6bca 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1394,11 +1394,16 @@ static inline bool bvec_gap_to_prev(struct request_queue *q,
 static inline bool bio_will_gap(struct request_queue *q, struct bio *prev,
 			 struct bio *next)
 {
-	if (!bio_has_data(prev) || !queue_virt_boundary(q))
-		return false;
+	if (bio_has_data(prev) && queue_virt_boundary(q)) {
+		struct bio_vec pb, nb;
+
+		bio_get_last_bvec(prev, &pb);
+		bio_get_first_bvec(next, &nb);
 
-	return __bvec_gap_to_prev(q, &prev->bi_io_vec[prev->bi_vcnt - 1],
-				  next->bi_io_vec[0].bv_offset);
+		return __bvec_gap_to_prev(q, &pb, nb.bv_offset);
+	}
+
+	return false;
 }
 
 static inline bool req_gap_back_merge(struct request *req, struct bio *bio)
-- 
1.9.1