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

[Ming Lei]

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@xxxxxxxxxxxxxxx # v4.3+
Reported-by: Sagi Grimberg <sagig@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
---
 include/linux/blkdev.h | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b8ff6a3..7152102 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1388,11 +1388,16 @@ 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))
+	if (!bio_has_data(prev) || !queue_virt_boundary(q)) {
 		return false;
+	} else {
+		struct bio_vec pb, nb;
 
-	return bvec_gap_to_prev(q, &prev->bi_io_vec[prev->bi_vcnt - 1],
-				next->bi_io_vec[0].bv_offset);
+		bio_get_last_bvec(prev, &pb);
+		bio_get_first_bvec(next, &nb);
+
+		return bvec_gap_to_prev(q, &pb, nb.bv_offset);
+	}
 }
 
 static inline bool req_gap_back_merge(struct request *req, struct bio *bio)
-- 
1.9.1