linux-kernel - [PATCH V10 11/19] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc

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Date:   Thu, 15 Nov 2018 16:52:58 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Ming Lei <ming.lei@...hat.com>,
        Dave Chinner <dchinner@...hat.com>,
        Kent Overstreet <kent.overstreet@...il.com>,
        Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org, Shaohua Li <shli@...nel.org>,
        linux-raid@...r.kernel.org, linux-erofs@...ts.ozlabs.org,
        David Sterba <dsterba@...e.com>, linux-btrfs@...r.kernel.org,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        linux-xfs@...r.kernel.org, Gao Xiang <gaoxiang25@...wei.com>,
        Christoph Hellwig <hch@....de>, Theodore Ts'o <tytso@....edu>,
        linux-ext4@...r.kernel.org, Coly Li <colyli@...e.de>,
        linux-bcache@...r.kernel.org, Boaz Harrosh <ooo@...ctrozaur.com>,
        Bob Peterson <rpeterso@...hat.com>, cluster-devel@...hat.com
Subject: [PATCH V10 11/19] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages()

bch_bio_alloc_pages() is always called on one new bio, so it is safe
to access the bvec table directly. Given it is the only kind of this
case, open code the bvec table access since bio_for_each_segment_all()
will be changed to support for iterating over multipage bvec.

Cc: Dave Chinner <dchinner@...hat.com>
Cc: Kent Overstreet <kent.overstreet@...il.com>
Acked-by: Coly Li <colyli@...e.de>
Cc: Mike Snitzer <snitzer@...hat.com>
Cc: dm-devel@...hat.com
Cc: Alexander Viro <viro@...iv.linux.org.uk>
Cc: linux-fsdevel@...r.kernel.org
Cc: Shaohua Li <shli@...nel.org>
Cc: linux-raid@...r.kernel.org
Cc: linux-erofs@...ts.ozlabs.org
Cc: David Sterba <dsterba@...e.com>
Cc: linux-btrfs@...r.kernel.org
Cc: Darrick J. Wong <darrick.wong@...cle.com>
Cc: linux-xfs@...r.kernel.org
Cc: Gao Xiang <gaoxiang25@...wei.com>
Cc: Christoph Hellwig <hch@....de>
Cc: Theodore Ts'o <tytso@....edu>
Cc: linux-ext4@...r.kernel.org
Cc: Coly Li <colyli@...e.de>
Cc: linux-bcache@...r.kernel.org
Cc: Boaz Harrosh <ooo@...ctrozaur.com>
Cc: Bob Peterson <rpeterso@...hat.com>
Cc: cluster-devel@...hat.com
Signed-off-by: Ming Lei <ming.lei@...hat.com>
---
 drivers/md/bcache/util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/bcache/util.c b/drivers/md/bcache/util.c
index 20eddeac1531..8517aebcda2d 100644
--- a/drivers/md/bcache/util.c
+++ b/drivers/md/bcache/util.c
@@ -270,7 +270,7 @@ int bch_bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
 	int i;
 	struct bio_vec *bv;
 
-	bio_for_each_segment_all(bv, bio, i) {
+	for (i = 0, bv = bio->bi_io_vec; i < bio->bi_vcnt; bv++) {
 		bv->bv_page = alloc_page(gfp_mask);
 		if (!bv->bv_page) {
 			while (--bv >= bio->bi_io_vec)
-- 
2.9.5