From: Ming Lei <ming.lei@redhat.com>
To: Omar Sandoval <osandov@osandov.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, 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, Shaohua Li <shli@kernel.org>,
linux-raid@vger.kernel.org, linux-erofs@lists.ozlabs.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>, Theodore Ts'o <tytso@mit.edu>,
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
Subject: Re: [PATCH V10 10/19] block: loop: pass multi-page bvec to iov_iter
Date: Mon, 19 Nov 2018 16:25:49 +0800 [thread overview]
Message-ID: <20181119082548.GD16736@ming.t460p> (raw)
In-Reply-To: <20181116004022.GE23828@vader>
On Thu, Nov 15, 2018 at 04:40:22PM -0800, Omar Sandoval wrote:
> On Thu, Nov 15, 2018 at 04:52:57PM +0800, Ming Lei wrote:
> > iov_iter is implemented with bvec itererator, so it is safe to pass
> > multipage bvec to it, and this way is much more efficient than
> > passing one page in each bvec.
> >
> > Cc: Dave Chinner <dchinner@redhat.com>
> > Cc: Kent Overstreet <kent.overstreet@gmail.com>
> > Cc: Mike Snitzer <snitzer@redhat.com>
> > Cc: dm-devel@redhat.com
> > Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> > Cc: linux-fsdevel@vger.kernel.org
> > Cc: Shaohua Li <shli@kernel.org>
> > Cc: linux-raid@vger.kernel.org
> > Cc: linux-erofs@lists.ozlabs.org
> > Cc: David Sterba <dsterba@suse.com>
> > Cc: linux-btrfs@vger.kernel.org
> > Cc: Darrick J. Wong <darrick.wong@oracle.com>
> > Cc: linux-xfs@vger.kernel.org
> > Cc: Gao Xiang <gaoxiang25@huawei.com>
> > Cc: Christoph Hellwig <hch@lst.de>
> > Cc: Theodore Ts'o <tytso@mit.edu>
> > Cc: linux-ext4@vger.kernel.org
> > Cc: Coly Li <colyli@suse.de>
> > Cc: linux-bcache@vger.kernel.org
> > Cc: Boaz Harrosh <ooo@electrozaur.com>
> > Cc: Bob Peterson <rpeterso@redhat.com>
> > Cc: cluster-devel@redhat.com
>
> Reviewed-by: Omar Sandoval <osandov@fb.com>
>
> Comments below.
>
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> > drivers/block/loop.c | 23 ++++++++++++-----------
> > 1 file changed, 12 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> > index bf6bc35aaf88..a3fd418ec637 100644
> > --- a/drivers/block/loop.c
> > +++ b/drivers/block/loop.c
> > @@ -515,16 +515,16 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
> > struct bio *bio = rq->bio;
> > struct file *file = lo->lo_backing_file;
> > unsigned int offset;
> > - int segments = 0;
> > + int nr_bvec = 0;
> > int ret;
> >
> > if (rq->bio != rq->biotail) {
> > - struct req_iterator iter;
> > + struct bvec_iter iter;
> > struct bio_vec tmp;
> >
> > __rq_for_each_bio(bio, rq)
> > - segments += bio_segments(bio);
> > - bvec = kmalloc_array(segments, sizeof(struct bio_vec),
> > + nr_bvec += bio_bvecs(bio);
> > + bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
> > GFP_NOIO);
> > if (!bvec)
> > return -EIO;
> > @@ -533,13 +533,14 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
> > /*
> > * The bios of the request may be started from the middle of
> > * the 'bvec' because of bio splitting, so we can't directly
> > - * copy bio->bi_iov_vec to new bvec. The rq_for_each_segment
> > + * copy bio->bi_iov_vec to new bvec. The bio_for_each_bvec
> > * API will take care of all details for us.
> > */
> > - rq_for_each_segment(tmp, rq, iter) {
> > - *bvec = tmp;
> > - bvec++;
> > - }
> > + __rq_for_each_bio(bio, rq)
> > + bio_for_each_bvec(tmp, bio, iter) {
> > + *bvec = tmp;
> > + bvec++;
> > + }
>
> Even if they're not strictly necessary, could you please include the
> curly braces for __rq_for_each_bio() here?
Sure, will do it.
>
> > bvec = cmd->bvec;
> > offset = 0;
> > } else {
> > @@ -550,11 +551,11 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
> > */
> > offset = bio->bi_iter.bi_bvec_done;
> > bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
> > - segments = bio_segments(bio);
> > + nr_bvec = bio_bvecs(bio);
>
> This scared me for a second, but it's fine to do here because we haven't
> actually enabled multipage bvecs yet, right?
Well, it is fine, all helpers supporting multi-page bvec actually works
well when it isn't enabled, cause single-page bvec is one special case in
which multi-page bevc helpers have to deal with.
Thanks,
Ming
next prev parent reply other threads:[~2018-11-19 8:26 UTC|newest]
Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-15 8:52 [PATCH V10 00/19] block: support multi-page bvec Ming Lei
2018-11-15 8:52 ` [PATCH V10 01/19] block: introduce multi-page page bvec helpers Ming Lei
2018-11-15 18:25 ` Omar Sandoval
2018-11-19 2:25 ` Ming Lei
2018-11-16 13:13 ` Christoph Hellwig
2018-11-19 2:23 ` Ming Lei
2018-11-19 3:10 ` Jens Axboe
2018-11-19 3:35 ` Ming Lei
2018-11-15 8:52 ` [PATCH V10 02/19] block: introduce bio_for_each_bvec() Ming Lei
2018-11-15 18:28 ` Omar Sandoval
2018-11-16 13:30 ` Christoph Hellwig
2018-11-19 3:31 ` Ming Lei
2018-11-15 8:52 ` [PATCH V10 03/19] block: use bio_for_each_bvec() to compute multi-page bvec count Ming Lei
2018-11-15 20:20 ` Omar Sandoval
2018-11-15 21:05 ` Mike Snitzer
2018-11-15 22:18 ` Omar Sandoval
2018-11-16 9:19 ` Christoph Hellwig
2018-11-16 9:41 ` Gao Xiang
2018-11-16 16:04 ` Omar Sandoval
2018-11-19 7:50 ` Ming Lei
2018-11-15 8:52 ` [PATCH V10 04/19] block: use bio_for_each_bvec() to map sg Ming Lei
2018-11-15 22:33 ` Omar Sandoval
2018-11-16 13:33 ` Christoph Hellwig
2018-11-19 7:51 ` Ming Lei
2018-11-15 8:52 ` [PATCH V10 05/19] block: introduce bvec_last_segment() Ming Lei
2018-11-15 23:23 ` Omar Sandoval
2018-11-19 7:57 ` Ming Lei
2018-11-16 13:34 ` Christoph Hellwig
2018-11-15 8:52 ` [PATCH V10 06/19] fs/buffer.c: use bvec iterator to truncate the bio Ming Lei
2018-11-16 0:20 ` Omar Sandoval
2018-11-16 13:36 ` Christoph Hellwig
2018-11-15 8:52 ` [PATCH V10 07/19] btrfs: use bvec_last_segment to get bio's last page Ming Lei
2018-11-16 0:21 ` Omar Sandoval
2018-11-16 13:37 ` Christoph Hellwig
2018-11-19 8:09 ` Ming Lei
2018-11-15 8:52 ` [PATCH V10 08/19] btrfs: move bio_pages_all() to btrfs Ming Lei
2018-11-16 0:23 ` Omar Sandoval
2018-11-19 8:15 ` Ming Lei
2018-11-16 13:38 ` Christoph Hellwig
2018-11-19 8:19 ` Ming Lei
2018-11-19 8:24 ` Christoph Hellwig
2018-11-15 8:52 ` [PATCH V10 09/19] block: introduce bio_bvecs() Ming Lei
2018-11-16 0:26 ` Omar Sandoval
2018-11-16 13:45 ` Christoph Hellwig
2018-11-19 8:21 ` Ming Lei
2018-11-20 0:49 ` Sagi Grimberg
2018-11-20 16:16 ` Christoph Hellwig
2018-11-20 20:11 ` Sagi Grimberg
2018-11-21 0:59 ` Ming Lei
2018-11-21 3:20 ` Sagi Grimberg
2018-11-21 3:44 ` Ming Lei
2018-11-21 4:25 ` Sagi Grimberg
2018-11-21 4:42 ` Sagi Grimberg
2018-11-21 5:04 ` Ming Lei
2018-11-21 5:35 ` Sagi Grimberg
2018-11-21 8:46 ` Christoph Hellwig
2018-11-21 10:19 ` Ming Lei
2018-11-15 8:52 ` [PATCH V10 10/19] block: loop: pass multi-page bvec to iov_iter Ming Lei
2018-11-16 0:40 ` Omar Sandoval
2018-11-19 8:25 ` Ming Lei [this message]
2018-11-15 8:52 ` [PATCH V10 11/19] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages() Ming Lei
2018-11-16 0:44 ` Omar Sandoval
2018-11-19 8:27 ` Ming Lei
2018-11-16 13:46 ` Christoph Hellwig
2018-11-19 8:28 ` Ming Lei
2018-11-15 8:52 ` [PATCH V10 12/19] block: allow bio_for_each_segment_all() to iterate over multi-page bvec Ming Lei
2018-11-15 12:42 ` David Sterba
2018-11-19 8:29 ` Ming Lei
2018-11-16 1:22 ` Omar Sandoval
2018-11-19 8:32 ` Ming Lei
2018-11-15 8:53 ` [PATCH V10 13/19] iomap & xfs: only account for new added page Ming Lei
2018-11-16 1:46 ` Omar Sandoval
2018-11-19 8:35 ` Ming Lei
2018-11-16 13:49 ` Christoph Hellwig
2018-11-19 8:39 ` Ming Lei
2018-11-15 8:53 ` [PATCH V10 14/19] block: enable multipage bvecs Ming Lei
2018-11-16 1:56 ` Omar Sandoval
2018-11-19 8:45 ` Ming Lei
2018-11-16 13:53 ` Christoph Hellwig
2018-11-19 9:00 ` Ming Lei
2018-11-15 8:53 ` [PATCH V10 15/19] block: always define BIO_MAX_PAGES as 256 Ming Lei
2018-11-16 1:59 ` Omar Sandoval
2018-11-19 9:04 ` Ming Lei
2018-11-20 2:45 ` Huang, Ying
2018-11-16 13:53 ` Christoph Hellwig
2018-11-15 8:53 ` [PATCH V10 16/19] block: document usage of bio iterator helpers Ming Lei
2018-11-16 2:05 ` Omar Sandoval
2018-11-15 8:53 ` [PATCH V10 17/19] block: don't use bio->bi_vcnt to figure out segment number Ming Lei
2018-11-16 2:11 ` Omar Sandoval
2018-11-19 9:06 ` Ming Lei
2018-11-16 13:55 ` Christoph Hellwig
2018-11-15 8:53 ` [PATCH V10 18/19] block: kill QUEUE_FLAG_NO_SG_MERGE Ming Lei
2018-11-16 2:18 ` Omar Sandoval
2018-11-16 13:59 ` Christoph Hellwig
2018-11-16 16:40 ` Omar Sandoval
2018-11-19 9:17 ` Ming Lei
2018-11-16 13:58 ` Christoph Hellwig
2018-11-19 9:20 ` Ming Lei
2018-11-15 8:53 ` [PATCH V10 19/19] block: kill BLK_MQ_F_SG_MERGE Ming Lei
2018-11-16 13:59 ` Christoph Hellwig
2018-11-16 16:40 ` Omar Sandoval
2018-11-16 14:03 ` [PATCH V10 00/19] block: support multi-page bvec Christoph Hellwig
2018-11-17 2:42 ` Ming Lei
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181119082548.GD16736@ming.t460p \
--to=ming.lei@redhat.com \
--cc=axboe@kernel.dk \
--cc=cluster-devel@redhat.com \
--cc=colyli@suse.de \
--cc=darrick.wong@oracle.com \
--cc=dchinner@redhat.com \
--cc=dm-devel@redhat.com \
--cc=dsterba@suse.com \
--cc=gaoxiang25@huawei.com \
--cc=hch@lst.de \
--cc=kent.overstreet@gmail.com \
--cc=linux-bcache@vger.kernel.org \
--cc=linux-block@vger.kernel.org \
--cc=linux-btrfs@vger.kernel.org \
--cc=linux-erofs@lists.ozlabs.org \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-raid@vger.kernel.org \
--cc=linux-xfs@vger.kernel.org \
--cc=ooo@electrozaur.com \
--cc=osandov@osandov.com \
--cc=rpeterso@redhat.com \
--cc=shli@kernel.org \
--cc=snitzer@redhat.com \
--cc=tytso@mit.edu \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).