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, 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 V15 04/18] block: introduce multi-page bvec helpers
Date: Fri, 15 Feb 2019 19:13:10 +0800 [thread overview]
Message-ID: <20190215111324.30129-5-ming.lei@redhat.com> (raw)
In-Reply-To: <20190215111324.30129-1-ming.lei@redhat.com>
This patch introduces helpers of 'mp_bvec_iter_*' for multi-page 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: Christoph Hellwig <hch@lst.de>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
include/linux/bvec.h | 30 +++++++++++++++++++++++++++---
1 file changed, 27 insertions(+), 3 deletions(-)
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index ba0ae40e77c9..0ae729b1c9fe 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 +51,39 @@ struct bvec_iter {
*/
#define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
-#define bvec_iter_page(bvec, iter) \
+/* multi-page (mp_bvec) helpers */
+#define mp_bvec_iter_page(bvec, iter) \
(__bvec_iter_bvec((bvec), (iter))->bv_page)
-#define bvec_iter_len(bvec, iter) \
+#define mp_bvec_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 mp_bvec_iter_offset(bvec, iter) \
(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
+#define mp_bvec_iter_page_idx(bvec, iter) \
+ (mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE)
+
+#define mp_bvec_iter_bvec(bvec, iter) \
+((struct bio_vec) { \
+ .bv_page = mp_bvec_iter_page((bvec), (iter)), \
+ .bv_len = mp_bvec_iter_len((bvec), (iter)), \
+ .bv_offset = mp_bvec_iter_offset((bvec), (iter)), \
+})
+
+/* For building single-page bvec in flight */
+ #define bvec_iter_offset(bvec, iter) \
+ (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE)
+
+#define bvec_iter_len(bvec, iter) \
+ min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \
+ PAGE_SIZE - bvec_iter_offset((bvec), (iter)))
+
+#define bvec_iter_page(bvec, iter) \
+ nth_page(mp_bvec_iter_page((bvec), (iter)), \
+ mp_bvec_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:[~2019-02-15 11:14 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-15 11:13 [PATCH V15 00/18] block: support multi-page bvec Ming Lei
2019-02-15 11:13 ` [PATCH V15 01/18] btrfs: look at bi_size for repair decisions Ming Lei
2019-02-15 11:13 ` [PATCH V15 02/18] block: don't use bio->bi_vcnt to figure out segment number Ming Lei
2019-02-15 11:13 ` [PATCH V15 03/18] block: remove bvec_iter_rewind() Ming Lei
2019-02-15 11:13 ` Ming Lei [this message]
2019-02-15 11:13 ` [PATCH V15 05/18] block: introduce bio_for_each_bvec() and rq_for_each_bvec() Ming Lei
2019-02-15 11:13 ` [PATCH V15 06/18] block: use bio_for_each_bvec() to compute multi-page bvec count Ming Lei
2019-02-15 11:13 ` [PATCH V15 07/18] block: use bio_for_each_bvec() to map sg Ming Lei
2019-02-15 11:13 ` [PATCH V15 08/18] block: introduce mp_bvec_last_segment() Ming Lei
2019-02-15 11:13 ` [PATCH V15 09/18] fs/buffer.c: use bvec iterator to truncate the bio Ming Lei
2019-02-15 11:13 ` [PATCH V15 10/18] btrfs: use mp_bvec_last_segment to get bio's last page Ming Lei
2019-02-15 11:13 ` [PATCH V15 11/18] block: loop: pass multi-page bvec to iov_iter Ming Lei
2019-02-15 11:13 ` [PATCH V15 12/18] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages() Ming Lei
2019-02-15 11:13 ` [PATCH V15 13/18] block: allow bio_for_each_segment_all() to iterate over multi-page bvec Ming Lei
2019-02-15 11:13 ` [PATCH V15 14/18] block: enable multipage bvecs Ming Lei
[not found] ` <CGME20190221084301eucas1p11e8841a62b4b1da3cccca661b6f4c29d@eucas1p1.samsung.com>
2019-02-21 8:42 ` Marek Szyprowski
2019-02-21 9:57 ` Ming Lei
2019-02-21 10:08 ` Marek Szyprowski
2019-02-21 10:16 ` Ming Lei
2019-02-21 10:22 ` Marek Szyprowski
2019-02-21 10:38 ` Ming Lei
2019-02-21 11:42 ` Marek Szyprowski
2019-02-27 20:47 ` Jon Hunter
2019-02-27 23:29 ` Ming Lei
2019-02-28 7:51 ` Marek Szyprowski
2019-02-28 12:39 ` Jon Hunter
2019-02-15 11:13 ` [PATCH V15 15/18] block: always define BIO_MAX_PAGES as 256 Ming Lei
2019-02-15 11:13 ` [PATCH V15 16/18] block: document usage of bio iterator helpers Ming Lei
2019-02-15 11:13 ` [PATCH V15 17/18] block: kill QUEUE_FLAG_NO_SG_MERGE Ming Lei
2019-02-15 11:13 ` [PATCH V15 18/18] block: kill BLK_MQ_F_SG_MERGE Ming Lei
2019-02-15 14:51 ` [PATCH V15 00/18] block: support multi-page bvec Christoph Hellwig
2019-02-17 13:10 ` Ming Lei
2019-02-15 15:49 ` Jens Axboe
2019-02-15 17:14 ` [dm-devel] " Bart Van Assche
2019-02-15 17:59 ` Jens Axboe
2019-02-17 13:13 ` Ming Lei
2019-02-18 7:49 ` Ming Lei
2019-02-17 13:11 ` Ming Lei
2019-02-19 16:28 ` Bart Van Assche
2019-02-20 1:17 ` Ming Lei
2019-02-20 2:37 ` Bart Van Assche
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