linux-kernel - [PATCH V6 28/30] block: enable multipage bvecs

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Date:   Sat,  9 Jun 2018 20:30:12 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Jens Axboe <axboe@...com>, Christoph Hellwig <hch@...radead.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Kent Overstreet <kent.overstreet@...il.com>
Cc:     David Sterba <dsterba@...e.cz>, Huang Ying <ying.huang@...el.com>,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        Theodore Ts'o <tytso@....edu>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        Coly Li <colyli@...e.de>, Filipe Manana <fdmanana@...il.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Ming Lei <ming.lei@...hat.com>
Subject: [PATCH V6 28/30] block: enable multipage bvecs

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@...hat.com>
---
 block/bio.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 276fc35ec559..284085ab97e7 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -870,12 +870,23 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page,
 
 	if (bio->bi_vcnt > 0) {
 		struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
-
-		if (page == bv->bv_page && off == bv->bv_offset + bv->bv_len) {
-			bv->bv_len += len;
-			bio->bi_iter.bi_size += len;
-			return true;
-		}
+		struct request_queue *q = NULL;
+
+		if (page == bv->bv_page && off == bv->bv_offset + bv->bv_len)
+			goto merge;
+
+		if (bio->bi_disk)
+			q = bio->bi_disk->queue;
+
+		/* 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) + off))
+			return false;
+ merge:
+		bv->bv_len += len;
+		bio->bi_iter.bi_size += len;
+		return true;
 	}
 	return false;
 }
-- 
2.9.5