From: Randy Dunlap <rdunlap@infradead.org>
To: Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@fb.com>,
Christoph Hellwig <hch@infradead.org>,
Kent Overstreet <kent.overstreet@gmail.com>
Cc: David Sterba <dsterba@suse.cz>, Huang Ying <ying.huang@intel.com>,
Mike Snitzer <snitzer@redhat.com>,
linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
Theodore Ts'o <tytso@mit.edu>,
"Darrick J . Wong" <darrick.wong@oracle.com>,
Coly Li <colyli@suse.de>, Filipe Manana <fdmanana@gmail.com>
Subject: Re: [PATCH V7 24/24] block: document usage of bio iterator helpers
Date: Wed, 27 Jun 2018 11:13:45 -0700 [thread overview]
Message-ID: <98d6ba9d-ec7a-b05b-94bb-e798ad0e0ea7@infradead.org> (raw)
In-Reply-To: <20180627124548.3456-25-ming.lei@redhat.com>
On 06/27/2018 05:45 AM, Ming Lei wrote:
> Now multipage bvec is supported, and some helpers may return page by
> page, and some may return segment by segment, this patch documents the
> usage for helping us use them correctly.
>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> Documentation/block/biovecs.txt | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/Documentation/block/biovecs.txt b/Documentation/block/biovecs.txt
> index 25689584e6e0..f63af564ae89 100644
> --- a/Documentation/block/biovecs.txt
> +++ b/Documentation/block/biovecs.txt
> @@ -117,3 +117,30 @@ Other implications:
> size limitations and the limitations of the underlying devices. Thus
> there's no need to define ->merge_bvec_fn() callbacks for individual block
> drivers.
> +
> +Usage of helpers:
> +=================
> +
> +* The following helpers which name has suffix of "_all" can only be used on
helpers whose names have the suffix of "_all" can only be used on
> +non-BIO_CLONED bio, and ususally they are used by filesystem code, and driver
usually
> +shouldn't use them becasue bio may have been splitted before they got to the
because split
> +driver:
> +
> + bio_for_each_segment_all()
> + bio_first_bvec_all()
> + bio_first_page_all()
> + bio_last_bvec_all()
> +
> +* The following helpers iterate over singlepage bvec, and the local
preferably: single-page
> +variable of 'struct bio_vec' or the reference records single page io
IO or I/O
> +vector during the itearation:
> +
> + bio_for_each_segment()
> + bio_for_each_segment_all()
> +
> +* The following helper iterates over multipage bvec, and each bvec may
preferably: multi-page
> +include multiple physically contiguous pages, and the local variable of
> +'struct bio_vec' or the reference records multi page io vector during the
multi-page IO or I/O
> +itearation:
> +
> + bio_for_each_bvec()
>
--
~Randy
prev parent reply other threads:[~2018-06-27 18:13 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-27 12:45 [PATCH V7 00/24] block: support multipage bvec Ming Lei
2018-06-27 12:45 ` [PATCH V7 01/24] dm: use bio_split() when splitting out the already processed bio Ming Lei
2018-06-27 13:17 ` Mike Snitzer
2018-06-27 12:45 ` [PATCH V7 02/24] bcache: don't clone bio in bch_data_verify Ming Lei
2018-06-27 12:45 ` [PATCH V7 03/24] exofs: use bio_clone_fast in _write_mirror Ming Lei
2018-06-27 12:45 ` [PATCH V7 04/24] block: remove bio_clone_kmalloc Ming Lei
2018-06-27 12:45 ` [PATCH V7 05/24] md: remove a bogus comment Ming Lei
2018-06-27 12:45 ` [PATCH V7 06/24] block: unexport bio_clone_bioset Ming Lei
2018-06-27 12:45 ` [PATCH V7 07/24] block: simplify bio_check_pages_dirty Ming Lei
2018-06-27 12:45 ` [PATCH V7 08/24] block: bio_set_pages_dirty can't see NULL bv_page in a valid bio_vec Ming Lei
2018-06-27 12:45 ` [PATCH V7 09/24] block: use bio_add_page in bio_iov_iter_get_pages Ming Lei
2018-06-27 12:45 ` [PATCH V7 10/24] block: introduce multipage page bvec helpers Ming Lei
2018-06-27 15:59 ` kbuild test robot
2018-11-09 11:15 ` Ming Lei
2018-06-27 12:45 ` [PATCH V7 11/24] block: introduce bio_for_each_bvec() Ming Lei
2018-06-27 12:45 ` [PATCH V7 12/24] block: use bio_for_each_bvec() to compute multipage bvec count Ming Lei
2018-06-27 12:45 ` [PATCH V7 13/24] block: use bio_for_each_bvec() to map sg Ming Lei
2018-06-27 12:45 ` [PATCH V7 14/24] block: introduce bvec_last_segment() Ming Lei
2018-06-27 12:45 ` [PATCH V7 15/24] fs/buffer.c: use bvec iterator to truncate the bio Ming Lei
2018-06-27 12:45 ` [PATCH V7 16/24] btrfs: use bvec_last_segment to get bio's last page Ming Lei
2018-06-27 12:45 ` [PATCH V7 17/24] btrfs: move bio_pages_all() to btrfs Ming Lei
2018-06-27 12:45 ` [PATCH V7 18/24] block: introduce bio_bvecs() Ming Lei
2018-06-27 12:45 ` [PATCH V7 19/24] block: loop: pass multipage bvec to iov_iter Ming Lei
2018-06-27 12:45 ` [PATCH V7 20/24] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages() Ming Lei
2018-06-27 15:55 ` Coly Li
2018-06-28 1:28 ` Ming Lei
2018-06-28 2:01 ` Coly Li
2018-06-27 12:45 ` [PATCH V7 21/24] block: allow bio_for_each_segment_all() to iterate over multipage bvec Ming Lei
2018-06-27 12:45 ` [PATCH V7 22/24] block: enable multipage bvecs Ming Lei
2018-06-27 12:45 ` [PATCH V7 23/24] block: always define BIO_MAX_PAGES as 256 Ming Lei
2018-06-27 12:45 ` [PATCH V7 24/24] block: document usage of bio iterator helpers Ming Lei
2018-06-27 18:13 ` Randy Dunlap [this message]
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