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, 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, Ming Lei <ming.lei@redhat.com>
Subject: [PATCH V11 02/19] block: introduce multi-page bvec helpers
Date: Wed, 21 Nov 2018 11:23:10 +0800 [thread overview]
Message-ID: <20181121032327.8434-3-ming.lei@redhat.com> (raw)
In-Reply-To: <20181121032327.8434-1-ming.lei@redhat.com>
This patch introduces helpers of 'segment_iter_*' for multipage
bvec support.
The introduced helpers treate one bvec as real multi-page segment,
which may include more than one pages.
The existed helpers of bvec_iter_* are interfaces for supporting current
bvec iterator which is thought as single-page by drivers, fs, dm and
etc. These introduced helpers will build single-page bvec in flight, so
this way won't break current bio/bvec users, which needn't any change.
Follows some multi-page bvec background:
- bvecs stored in bio->bi_io_vec is always multi-page style
- bvec(struct bio_vec) represents one physically contiguous I/O
buffer, now the buffer may include more than one page after
multi-page bvec is supported, and all these pages represented
by one bvec is physically contiguous. Before multi-page bvec
support, at most one page is included in one bvec, we call it
single-page bvec.
- .bv_page of the bvec points to the 1st page in the multi-page bvec
- .bv_offset of the bvec is the offset of the buffer in the bvec
The effect on the current drivers/filesystem/dm/bcache/...:
- almost everyone supposes that one bvec only includes one single
page, so we keep the sp interface not changed, for example,
bio_for_each_segment() still returns single-page bvec
- bio_for_each_segment_all() will return single-page bvec too
- during iterating, iterator variable(struct bvec_iter) is always
updated in multi-page bvec style, and bvec_iter_advance() is kept
not changed
- returned(copied) single-page bvec is built in flight by bvec
helpers from the stored multi-page bvec
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
include/linux/bvec.h | 26 +++++++++++++++++++++++---
1 file changed, 23 insertions(+), 3 deletions(-)
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index 02c73c6aa805..ed90bbf4c9c9 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -23,6 +23,7 @@
#include <linux/kernel.h>
#include <linux/bug.h>
#include <linux/errno.h>
+#include <linux/mm.h>
/*
* was unsigned short, but we might as well be ready for > 64kB I/O pages
@@ -50,16 +51,35 @@ struct bvec_iter {
*/
#define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
-#define bvec_iter_page(bvec, iter) \
+#define segment_iter_page(bvec, iter) \
(__bvec_iter_bvec((bvec), (iter))->bv_page)
-#define bvec_iter_len(bvec, iter) \
+#define segment_iter_len(bvec, iter) \
min((iter).bi_size, \
__bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
-#define bvec_iter_offset(bvec, iter) \
+#define segment_iter_offset(bvec, iter) \
(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
+#define segment_iter_page_idx(bvec, iter) \
+ (segment_iter_offset((bvec), (iter)) / PAGE_SIZE)
+
+/*
+ * <page, offset,length> of single-page segment.
+ *
+ * This helpers are for building single-page bvec in flight.
+ */
+#define bvec_iter_offset(bvec, iter) \
+ (segment_iter_offset((bvec), (iter)) % PAGE_SIZE)
+
+#define bvec_iter_len(bvec, iter) \
+ min_t(unsigned, segment_iter_len((bvec), (iter)), \
+ PAGE_SIZE - bvec_iter_offset((bvec), (iter)))
+
+#define bvec_iter_page(bvec, iter) \
+ nth_page(segment_iter_page((bvec), (iter)), \
+ segment_iter_page_idx((bvec), (iter)))
+
#define bvec_iter_bvec(bvec, iter) \
((struct bio_vec) { \
.bv_page = bvec_iter_page((bvec), (iter)), \
--
2.9.5
next prev parent reply other threads:[~2018-11-21 3:25 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-21 3:23 [PATCH V11 00/19] block: support multi-page bvec Ming Lei
2018-11-21 3:23 ` [PATCH V11 01/19] block: don't use bio->bi_vcnt to figure out segment number Ming Lei
2018-11-21 3:23 ` Ming Lei [this message]
2018-11-21 13:19 ` [PATCH V11 02/19] block: introduce multi-page bvec helpers Christoph Hellwig
2018-11-21 15:06 ` Ming Lei
2018-11-21 16:08 ` Christoph Hellwig
2018-11-22 1:09 ` Ming Lei
2018-11-21 3:23 ` [PATCH V11 03/19] block: introduce bio_for_each_bvec() Ming Lei
2018-11-21 13:32 ` Christoph Hellwig
2018-11-21 15:31 ` Ming Lei
2018-11-21 16:10 ` Christoph Hellwig
2018-11-21 17:12 ` Christoph Hellwig
2018-11-22 10:15 ` Ming Lei
2018-11-22 10:23 ` Christoph Hellwig
2018-11-22 10:30 ` Christoph Hellwig
2018-11-22 14:57 ` Ming Lei
2018-11-22 1:17 ` Ming Lei
2018-11-21 3:23 ` [PATCH V11 04/19] block: use bio_for_each_bvec() to compute multi-page bvec count Ming Lei
2018-11-21 3:23 ` [PATCH V11 05/19] block: use bio_for_each_bvec() to map sg Ming Lei
2018-11-21 3:23 ` [PATCH V11 06/19] block: introduce bvec_last_segment() Ming Lei
2018-11-21 3:23 ` [PATCH V11 07/19] fs/buffer.c: use bvec iterator to truncate the bio Ming Lei
2018-11-22 10:58 ` Christoph Hellwig
2018-11-23 1:48 ` Ming Lei
2018-11-21 3:23 ` [PATCH V11 08/19] btrfs: use bvec_last_segment to get bio's last page Ming Lei
2018-11-21 3:23 ` [PATCH V11 09/19] btrfs: move bio_pages_all() to btrfs Ming Lei
2018-11-21 3:23 ` [PATCH V11 10/19] block: loop: pass multi-page bvec to iov_iter Ming Lei
2018-11-21 14:00 ` Christoph Hellwig
2018-11-21 3:23 ` [PATCH V11 11/19] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages() Ming Lei
2018-11-21 14:01 ` Christoph Hellwig
2018-11-21 3:23 ` [PATCH V11 12/19] block: allow bio_for_each_segment_all() to iterate over multi-page bvec Ming Lei
2018-11-21 14:02 ` Christoph Hellwig
2018-11-22 11:03 ` Christoph Hellwig
2018-11-23 2:19 ` Ming Lei
2018-11-21 3:23 ` [PATCH V11 13/19] block: move bounce_clone_bio into bio.c Ming Lei
2018-11-21 3:23 ` [PATCH V11 14/19] block: handle non-cluster bio out of blk_bio_segment_split Ming Lei
2018-11-21 14:33 ` Christoph Hellwig
2018-11-21 15:37 ` Ming Lei
2018-11-21 16:11 ` Christoph Hellwig
2018-11-21 17:46 ` Christoph Hellwig
2018-11-22 9:33 ` Ming Lei
2018-11-22 10:04 ` Christoph Hellwig
2018-11-22 10:26 ` Ming Lei
2018-11-22 10:40 ` Christoph Hellwig
2018-11-22 10:32 ` Ming Lei
2018-11-22 10:41 ` Christoph Hellwig
2018-11-22 10:46 ` Ming Lei
2018-11-22 10:47 ` Christoph Hellwig
2018-11-21 3:23 ` [PATCH V11 15/19] block: enable multipage bvecs Ming Lei
2018-11-21 14:55 ` Christoph Hellwig
2018-11-21 15:48 ` Ming Lei
2018-11-21 16:12 ` Christoph Hellwig
2018-11-23 10:50 ` Ming Lei
2018-11-21 3:23 ` [PATCH V11 16/19] block: always define BIO_MAX_PAGES as 256 Ming Lei
2018-11-21 3:23 ` [PATCH V11 17/19] block: document usage of bio iterator helpers Ming Lei
2018-11-21 7:45 ` Nikolay Borisov
2018-11-21 14:34 ` Christoph Hellwig
2018-11-21 3:23 ` [PATCH V11 18/19] block: kill QUEUE_FLAG_NO_SG_MERGE Ming Lei
2018-11-21 3:23 ` [PATCH V11 19/19] block: kill BLK_MQ_F_SG_MERGE Ming Lei
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