[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: sta...@vger.kernel.org # v4.3+
Reported-by: Sagi Grimberg <sa...@dev.mellanox.co.il>
Cc: Christoph Hellwig <h...@infradead.org>
Signed-off-by: Ming Lei <ming....@canonical.com>
---
 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