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From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, Theodore Ts'o <tytso@mit.edu>,
	Omar Sandoval <osandov@fb.com>, Sagi Grimberg <sagi@grimberg.me>,
	Dave Chinner <dchinner@redhat.com>,
	Kent Overstreet <kent.overstreet@gmail.com>,
	Mike Snitzer <snitzer@redhat.com>,
	dm-devel@redhat.com, Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-raid@vger.kernel.org,
	David Sterba <dsterba@suse.com>,
	linux-btrfs@vger.kernel.org,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	linux-xfs@vger.kernel.org, Gao Xiang <gaoxiang25@huawei.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-ext4@vger.kernel.org, Coly Li <colyli@suse.de>,
	linux-bcache@vger.kernel.org, Boaz Harrosh <ooo@electrozaur.com>,
	Bob Peterson <rpeterso@redhat.com>,
	cluster-devel@redhat.com, Ming Lei <ming.lei@redhat.com>
Subject: [PATCH V14 12/18] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages()
Date: Mon, 21 Jan 2019 16:17:59 +0800
Message-ID: <20190121081805.32727-13-ming.lei@redhat.com> (raw)
In-Reply-To: <20190121081805.32727-1-ming.lei@redhat.com>

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.

Acked-by: Coly Li <colyli@suse.de>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/md/bcache/util.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/md/bcache/util.c b/drivers/md/bcache/util.c
index 20eddeac1531..62fb917f7a4f 100644
--- a/drivers/md/bcache/util.c
+++ b/drivers/md/bcache/util.c
@@ -270,7 +270,11 @@ 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) {
+	/*
+	 * This is called on freshly new bio, so it is safe to access the
+	 * bvec table directly.
+	 */
+	for (i = 0, bv = bio->bi_io_vec; i < bio->bi_vcnt; bv++, i++) {
 		bv->bv_page = alloc_page(gfp_mask);
 		if (!bv->bv_page) {
 			while (--bv >= bio->bi_io_vec)
-- 
2.9.5


  parent reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-21  8:17 [PATCH V14 00/18] block: support multi-page bvec Ming Lei
2019-01-21  8:17 ` [PATCH V14 01/18] btrfs: look at bi_size for repair decisions Ming Lei
2019-01-21  8:17 ` [PATCH V14 02/18] block: don't use bio->bi_vcnt to figure out segment number Ming Lei
2019-01-21  8:17 ` [PATCH V14 03/18] block: remove bvec_iter_rewind() Ming Lei
2019-01-21  8:17 ` [PATCH V14 04/18] block: introduce multi-page bvec helpers Ming Lei
2019-01-21  8:17 ` [PATCH V14 05/18] block: introduce bio_for_each_mp_bvec() and rq_for_each_mp_bvec() Ming Lei
2019-01-21  8:17 ` [PATCH V14 06/18] block: use bio_for_each_mp_bvec() to compute multi-page bvec count Ming Lei
2019-01-21  8:17 ` [PATCH V14 07/18] block: use bio_for_each_mp_bvec() to map sg Ming Lei
2019-01-21  8:17 ` [PATCH V14 08/18] block: introduce mp_bvec_last_segment() Ming Lei
2019-01-21  8:17 ` [PATCH V14 09/18] fs/buffer.c: use bvec iterator to truncate the bio Ming Lei
2019-01-21  8:17 ` [PATCH V14 10/18] btrfs: use mp_bvec_last_segment to get bio's last page Ming Lei
2019-01-21  8:17 ` [PATCH V14 11/18] block: loop: pass multi-page bvec to iov_iter Ming Lei
2019-01-21  8:17 ` Ming Lei [this message]
2019-01-21  8:18 ` [PATCH V14 13/18] block: allow bio_for_each_segment_all() to iterate over multi-page bvec Ming Lei
2019-01-21  8:18 ` [PATCH V14 14/18] block: enable multipage bvecs Ming Lei
2019-01-21  8:18 ` [PATCH V14 15/18] block: always define BIO_MAX_PAGES as 256 Ming Lei
2019-01-21  8:18 ` [PATCH V14 16/18] block: document usage of bio iterator helpers Ming Lei
2019-01-21  8:18 ` [PATCH V14 17/18] block: kill QUEUE_FLAG_NO_SG_MERGE Ming Lei
2019-01-21  8:18 ` [PATCH V14 18/18] block: kill BLK_MQ_F_SG_MERGE Ming Lei
2019-01-21  8:22 ` [PATCH V14 00/18] block: support multi-page bvec Christoph Hellwig
2019-01-21  8:37   ` Ming Lei
2019-01-21  8:38     ` Christoph Hellwig
2019-01-21  8:40       ` Ming Lei
2019-01-21  9:43 ` Sagi Grimberg
2019-01-22  2:01   ` Ming Lei

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