From: Ming Lin <mlin@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Kent Overstreet <kent.overstreet@gmail.com>,
Dongsu Park <dpark@posteo.net>, Mike Snitzer <snitzer@redhat.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Ming Lin <mlin@kernel.org>, Christoph Hellwig <hch@infradead.org>,
Jonathan Corbet <corbet@lwn.net>,
linux-doc@vger.kernel.org, Ming Lin <ming.l@ssi.samsung.com>
Subject: [PATCH v6 11/11] Documentation: update notes in biovecs about arbitrarily sized bios
Date: Wed, 12 Aug 2015 00:07:21 -0700 [thread overview]
Message-ID: <1439363241-31772-12-git-send-email-mlin@kernel.org> (raw)
In-Reply-To: <1439363241-31772-1-git-send-email-mlin@kernel.org>
From: Dongsu Park <dpark@posteo.net>
Update block/biovecs.txt so that it includes a note on what kind of
effects arbitrarily sized bios would bring to the block layer.
Also fix a trivial typo, bio_iter_iovec.
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Dongsu Park <dpark@posteo.net>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
---
Documentation/block/biovecs.txt | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/Documentation/block/biovecs.txt b/Documentation/block/biovecs.txt
index 74a32ad..2568958 100644
--- a/Documentation/block/biovecs.txt
+++ b/Documentation/block/biovecs.txt
@@ -24,7 +24,7 @@ particular, presenting the illusion of partially completed biovecs so that
normal code doesn't have to deal with bi_bvec_done.
* Driver code should no longer refer to biovecs directly; we now have
- bio_iovec() and bio_iovec_iter() macros that return literal struct biovecs,
+ bio_iovec() and bio_iter_iovec() macros that return literal struct biovecs,
constructed from the raw biovecs but taking into account bi_bvec_done and
bi_size.
@@ -109,3 +109,11 @@ Other implications:
over all the biovecs in the new bio - which is silly as it's not needed.
So, don't use bi_vcnt anymore.
+
+ * The current interface allows the block layer to split bios as needed, so we
+ could eliminate a lot of complexity particularly in stacked drivers. Code
+ that creates bios can then create whatever size bios are convenient, and
+ more importantly stacked drivers don't have to deal with both their own bio
+ size limitations and the limitations of the underlying devices. Thus
+ there's no need to define ->merge_bvec_fn() callbacks for individual block
+ drivers.
--
2.1.4
next prev parent reply other threads:[~2015-08-12 7:08 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-12 7:07 [PATCH v6 00/11] simplify block layer based on immutable biovecs Ming Lin
2015-08-12 7:07 ` [PATCH v6 01/11] block: make generic_make_request handle arbitrarily sized bios Ming Lin
2015-08-12 7:07 ` [PATCH v6 02/11] block: simplify bio_add_page() Ming Lin
2015-08-12 7:07 ` [PATCH v6 03/11] bcache: remove driver private bio splitting code Ming Lin
2016-01-08 1:53 ` Eric Wheeler
2015-08-12 7:07 ` [PATCH v6 04/11] btrfs: remove bio splitting and merge_bvec_fn() calls Ming Lin
2015-08-12 7:07 ` [PATCH v6 05/11] block: remove split code in blkdev_issue_{discard,write_same} Ming Lin
2015-10-13 11:50 ` Christoph Hellwig
2015-10-13 17:44 ` Ming Lin
2015-10-14 13:27 ` Christoph Hellwig
2015-10-14 16:38 ` [PATCH v6 05/11] block: remove split code in blkdev_issue_{discard,write_same}B Keith Busch
2015-10-14 16:50 ` Christoph Hellwig
2015-10-21 16:02 ` [PATCH v6 05/11] block: remove split code in blkdev_issue_{discard,write_same} Mike Snitzer
2015-10-21 16:19 ` Mike Snitzer
2015-10-21 16:33 ` Martin K. Petersen
2015-10-21 17:33 ` Ming Lin
2015-10-21 18:18 ` Mike Snitzer
2015-10-21 20:13 ` Ming Lin
2015-10-22 10:24 ` Christoph Hellwig
2015-10-22 11:22 ` Christoph Hellwig
2015-10-21 7:21 ` Christoph Hellwig
2015-10-21 13:39 ` Jeff Moyer
2015-10-21 15:01 ` Ming Lin
2015-10-21 15:33 ` Mike Snitzer
2015-10-21 17:18 ` Ming Lin
2015-08-12 7:07 ` [PATCH v6 06/11] md/raid5: split bio for chunk_aligned_read Ming Lin
2015-08-12 7:07 ` [PATCH v6 07/11] md/raid5: get rid of bio_fits_rdev() Ming Lin
2015-08-12 7:07 ` [PATCH v6 08/11] block: kill merge_bvec_fn() completely Ming Lin
2015-08-12 7:07 ` [PATCH v6 09/11] fs: use helper bio_add_page() instead of open coding on bi_io_vec Ming Lin
2015-08-12 7:07 ` [PATCH v6 10/11] block: remove bio_get_nr_vecs() Ming Lin
2015-08-12 7:07 ` Ming Lin [this message]
2015-08-13 16:51 ` [PATCH v6 00/11] simplify block layer based on immutable biovecs Jens Axboe
2015-08-13 17:03 ` Ming Lin
2015-08-13 17:07 ` Jens Axboe
2015-08-13 17:36 ` Ming Lin
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