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@vger.kernel.org
Reported-by: Sagi Grimberg <sagig@dev.mellanox.co.il>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index cd06a41581b321094928569da4814cef74b3f0ae..d7f6bca707ef39101e2fad5e035c66d316eeb875 100644 (file)
--- 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)