[RESEND PATCH V5 30/33] block: enable multipage bvecs

[Ming Lei]

This patch pulls the trigger for multipage bvecs.

Now any request queue which supports queue cluster will see multipage
bvecs.

Signed-off-by: Ming Lei <ming....@redhat.com>
---
 block/bio.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/block/bio.c b/block/bio.c
index c160c143cc1b..bc3992f52fe8 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -876,6 +876,11 @@ int bio_add_page(struct bio *bio, struct page *page,
         * a consecutive offset.  Optimize this special case.
         */
        if (bio->bi_vcnt > 0) {
+               struct request_queue *q = NULL;
+
+               if (bio->bi_disk)
+                       q = bio->bi_disk->queue;
+
                bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
 
                if (page == bv->bv_page &&
@@ -883,6 +888,14 @@ int bio_add_page(struct bio *bio, struct page *page,
                        bv->bv_len += len;
                        goto done;
                }
+
+               /* disable multipage bvec too if cluster isn't enabled */
+               if (q && blk_queue_cluster(q) &&
+                   (bvec_to_phys(bv) + bv->bv_len ==
+                    page_to_phys(page) + offset)) {
+                       bv->bv_len += len;
+                       goto done;
+               }
        }
 
        if (bio->bi_vcnt >= bio->bi_max_vecs)
-- 
2.9.5