From: Omar Sandoval <osandov@osandov.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
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, Shaohua Li <shli@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
Subject: Re: [PATCH V12 13/20] block: loop: pass multi-page bvec to iov_iter
Date: Mon, 26 Nov 2018 14:39:38 -0800 [thread overview]
Message-ID: <20181126223938.GJ30411@vader> (raw)
In-Reply-To: <20181126021720.19471-14-ming.lei@redhat.com>
On Mon, Nov 26, 2018 at 10:17:13AM +0800, Ming Lei wrote:
> iov_iter is implemented on bvec itererator helpers, so it is safe to pass
> multi-page bvec to it, and this way is much more efficient than passing one
> page in each bvec.
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Omar Sandoval <osandov@fb.com>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> drivers/block/loop.c | 20 ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 176ab1f28eca..e3683211f12d 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -510,21 +510,22 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
> loff_t pos, bool rw)
> {
> struct iov_iter iter;
> + struct req_iterator rq_iter;
> struct bio_vec *bvec;
> struct request *rq = blk_mq_rq_from_pdu(cmd);
> struct bio *bio = rq->bio;
> struct file *file = lo->lo_backing_file;
> + struct bio_vec tmp;
> unsigned int offset;
> - int segments = 0;
> + int nr_bvec = 0;
> int ret;
>
> + rq_for_each_bvec(tmp, rq, rq_iter)
> + nr_bvec++;
> +
> if (rq->bio != rq->biotail) {
> - struct req_iterator iter;
> - struct bio_vec tmp;
>
> - __rq_for_each_bio(bio, rq)
> - segments += bio_segments(bio);
> - bvec = kmalloc_array(segments, sizeof(struct bio_vec),
> + bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
> GFP_NOIO);
> if (!bvec)
> return -EIO;
> @@ -533,10 +534,10 @@ 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 rq_for_each_bvec
> * API will take care of all details for us.
> */
> - rq_for_each_segment(tmp, rq, iter) {
> + rq_for_each_bvec(tmp, rq, rq_iter) {
> *bvec = tmp;
> bvec++;
> }
> @@ -550,11 +551,10 @@ 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);
> }
> atomic_set(&cmd->ref, 2);
>
> - iov_iter_bvec(&iter, rw, bvec, segments, blk_rq_bytes(rq));
> + iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
> iter.iov_offset = offset;
>
> cmd->iocb.ki_pos = pos;
> --
> 2.9.5
>
next prev parent reply other threads:[~2018-11-26 22:39 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-26 2:17 [PATCH V12 00/20] block: support multi-page bvec Ming Lei
2018-11-26 2:17 ` [PATCH V12 01/20] btrfs: remove various bio_offset arguments Ming Lei
2018-11-26 22:28 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 02/20] btrfs: look at bi_size for repair decisions Ming Lei
2018-11-26 22:46 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 03/20] block: remove the "cluster" flag Ming Lei
2018-11-26 22:12 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 04/20] block: don't use bio->bi_vcnt to figure out segment number Ming Lei
2018-11-26 22:14 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 05/20] block: remove bvec_iter_rewind() Ming Lei
2018-11-26 12:53 ` Christoph Hellwig
2018-11-26 22:16 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 06/20] block: rename bvec helpers Ming Lei
2018-11-26 8:17 ` Miguel Ojeda
2018-11-26 12:54 ` Christoph Hellwig
2018-11-26 22:18 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 07/20] block: introduce multi-page " Ming Lei
2018-11-26 12:55 ` Christoph Hellwig
2018-11-26 2:17 ` [PATCH V12 08/20] block: introduce bio_for_each_bvec() and rq_for_each_bvec() Ming Lei
2018-11-26 12:55 ` Christoph Hellwig
2018-11-26 2:17 ` [PATCH V12 09/20] block: use bio_for_each_bvec() to compute multi-page bvec count Ming Lei
2018-11-26 13:11 ` Christoph Hellwig
2018-11-26 22:37 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 10/20] block: use bio_for_each_bvec() to map sg Ming Lei
2018-11-26 13:11 ` Christoph Hellwig
2018-11-26 2:17 ` [PATCH V12 11/20] block: introduce bvec_last_segment() Ming Lei
2018-11-26 2:17 ` [PATCH V12 12/20] fs/buffer.c: use bvec iterator to truncate the bio Ming Lei
2018-11-26 2:17 ` [PATCH V12 13/20] block: loop: pass multi-page bvec to iov_iter Ming Lei
2018-11-26 22:39 ` Omar Sandoval [this message]
2018-11-26 2:17 ` [PATCH V12 14/20] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages() Ming Lei
2018-11-26 22:40 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 15/20] block: allow bio_for_each_segment_all() to iterate over multi-page bvec Ming Lei
2018-11-26 22:42 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 16/20] block: enable multipage bvecs Ming Lei
2018-11-26 12:58 ` Christoph Hellwig
2018-11-27 2:25 ` Ming Lei
2018-11-26 22:56 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 17/20] block: always define BIO_MAX_PAGES as 256 Ming Lei
2018-11-26 22:44 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 18/20] block: document usage of bio iterator helpers Ming Lei
2018-11-26 12:59 ` Christoph Hellwig
2018-11-26 22:43 ` Omar Sandoval
2018-11-26 2:17 ` [PATCH V12 19/20] block: kill QUEUE_FLAG_NO_SG_MERGE Ming Lei
2018-11-26 2:17 ` [PATCH V12 20/20] block: kill BLK_MQ_F_SG_MERGE Ming Lei
2018-11-28 13:44 ` [PATCH V12 00/20] block: support multi-page bvec Jens Axboe
2018-11-29 1:30 ` Ming Lei
2018-11-29 2:20 ` Jens Axboe
2018-11-29 3:30 ` Ming Lei
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