[PATCH V4 42/45] 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.lei@xxxxxxxxxx>
---
 block/bio.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/block/bio.c b/block/bio.c
index e82e4c815dbb..34af328681a8 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -845,6 +845,11 @@ 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 &&
@@ -852,6 +857,14 @@ 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