From: Ming Lei <tom.leiming@gmail.com>
To: Jens Axboe <axboe@fb.com>, linux-kernel@vger.kernel.org
Cc: linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Ming Lei <tom.leiming@gmail.com>,
Johannes Berg <johannes.berg@intel.com>
Subject: [PATCH 31/60] block: introduce multipage/single page bvec helpers
Date: Sat, 29 Oct 2016 16:08:30 +0800 [thread overview]
Message-ID: <1477728600-12938-32-git-send-email-tom.leiming@gmail.com> (raw)
In-Reply-To: <1477728600-12938-1-git-send-email-tom.leiming@gmail.com>
This patch introduces helpers which are suffixed with _mp
and _sp for the multipage bvec/segment support.
The helpers with _mp suffix are the interfaces for treating
one bvec/segment as real multipage one, for example, .bv_len
is the total length of the multipage segment.
The helpers with _sp suffix are interfaces for supporting
current bvec iterator which is thought as singlepage only
by drivers, fs, dm and etc. These _sp helpers are introduced
to build singlepage bvec in flight, so users of bio/bvec
iterator still can work well and needn't change even though
we store multipage into bvec.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
---
include/linux/bvec.h | 57 +++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 54 insertions(+), 3 deletions(-)
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index 89b65b82d98f..da984fa171bc 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -24,6 +24,42 @@
#include <linux/bug.h>
/*
+ * What is multipage bvecs(segment)?
+ *
+ * - bvec stored in bio->bi_io_vec is always multipage style vector
+ *
+ * - bvec(struct bio_vec) represents one physically contiguous I/O
+ * buffer, now the buffer may include more than one pages since
+ * multipage(mp) bvec is supported, and all these pages represented
+ * by one bvec is physically contiguous. Before mp support, at most
+ * one page can be included in one bvec, we call it singlepage(sp)
+ * bvec.
+ *
+ * - .bv_page of th bvec represents the 1st page in the mp segment
+ *
+ * - .bv_offset of the bvec represents 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 bvec with single page
+ *
+ * - bio_for_each_segment_all() will be changed to return singlepage
+ * bvec too
+ *
+ * - during iterating, iterator variable(struct bvec_iter) is always
+ * updated in multipage bvec style and that means bvec_iter_advance()
+ * is kept not changed
+ *
+ * - returned(copied) singlepage bvec is generated in flight from bvec
+ * helpers
+ *
+ * - In case that some components(such as iov_iter) need to support mp
+ * segment, we introduce new helpers(suffixed with _mp) for them.
+ */
+
+/*
* was unsigned short, but we might as well be ready for > 64kB I/O pages
*/
struct bio_vec {
@@ -49,16 +85,31 @@ struct bvec_iter {
*/
#define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
-#define bvec_iter_page(bvec, iter) \
+#define bvec_iter_page_mp(bvec, iter) \
(__bvec_iter_bvec((bvec), (iter))->bv_page)
-#define bvec_iter_len(bvec, iter) \
+#define bvec_iter_len_mp(bvec, iter) \
min((iter).bi_size, \
__bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
-#define bvec_iter_offset(bvec, iter) \
+#define bvec_iter_offset_mp(bvec, iter) \
(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
+/*
+ * <page, offset,length> of sp segment.
+ *
+ * This helpers will be implemented for building sp bvec in flight.
+ *
+ */
+#define bvec_iter_offset_sp(bvec, iter) bvec_iter_offset_mp((bvec), (iter))
+#define bvec_iter_len_sp(bvec, iter) bvec_iter_len_mp((bvec), (iter))
+#define bvec_iter_page_sp(bvec, iter) bvec_iter_page_mp((bvec), (iter))
+
+/* current interfaces support sp style at default */
+#define bvec_iter_page(bvec, iter) bvec_iter_page_sp((bvec), (iter))
+#define bvec_iter_len(bvec, iter) bvec_iter_len_sp((bvec), (iter))
+#define bvec_iter_offset(bvec, iter) bvec_iter_offset_sp((bvec), (iter))
+
#define bvec_iter_bvec(bvec, iter) \
((struct bio_vec) { \
.bv_page = bvec_iter_page((bvec), (iter)), \
--
2.7.4
next prev parent reply other threads:[~2016-10-29 8:14 UTC|newest]
Thread overview: 107+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-29 8:07 [PATCH 00/60] block: support multipage bvec Ming Lei
2016-10-29 8:08 ` [PATCH 01/60] block: bio: introduce bio_init_with_vec_table() Ming Lei
2016-10-29 15:21 ` Christoph Hellwig
2016-10-29 8:08 ` [PATCH 02/60] block drivers: convert to bio_init_with_vec_table() Ming Lei
2016-10-29 8:08 ` [PATCH 03/60] block: drbd: remove impossible failure handling Ming Lei
2016-10-31 15:25 ` Christoph Hellwig
2016-10-29 8:08 ` [PATCH 04/60] block: floppy: use bio_add_page() Ming Lei
2016-10-31 15:26 ` Christoph Hellwig
2016-10-31 22:54 ` Ming Lei
2016-10-29 8:08 ` [PATCH 05/60] target: avoid to access .bi_vcnt directly Ming Lei
2016-10-31 15:26 ` Christoph Hellwig
2016-10-29 8:08 ` [PATCH 06/60] bcache: debug: avoid to access .bi_io_vec directly Ming Lei
2016-10-29 8:08 ` [PATCH 07/60] dm: crypt: use bio_add_page() Ming Lei
2016-10-29 8:08 ` [PATCH 08/60] dm: use bvec iterator helpers to implement .get_page and .next_page Ming Lei
2016-10-29 8:08 ` [PATCH 09/60] dm: dm.c: replace 'bio->bi_vcnt == 1' with !bio_multiple_segments Ming Lei
2016-10-31 15:29 ` Christoph Hellwig
2016-10-31 22:59 ` Ming Lei
2016-11-02 3:09 ` Kent Overstreet
2016-11-02 7:56 ` Ming Lei
2016-11-02 14:24 ` Mike Snitzer
2016-11-02 23:47 ` Ming Lei
2016-10-29 8:08 ` [PATCH 10/60] fs: logfs: convert to bio_add_page() in sync_request() Ming Lei
2016-10-29 8:08 ` [PATCH 11/60] fs: logfs: use bio_add_page() in __bdev_writeseg() Ming Lei
2016-10-31 15:29 ` Christoph Hellwig
2016-10-29 8:08 ` [PATCH 12/60] fs: logfs: use bio_add_page() in do_erase() Ming Lei
2016-10-31 15:29 ` Christoph Hellwig
2016-10-29 8:08 ` [PATCH 13/60] fs: logfs: remove unnecesary check Ming Lei
2016-10-31 15:29 ` Christoph Hellwig
2016-10-29 8:08 ` [PATCH 14/60] block: drbd: comment on direct access bvec table Ming Lei
2016-10-29 8:08 ` [PATCH 15/60] block: loop: comment on direct access to " Ming Lei
2016-10-31 15:31 ` Christoph Hellwig
2016-10-31 23:08 ` Ming Lei
2016-10-29 8:08 ` [PATCH 16/60] block: pktcdvd: " Ming Lei
2016-10-31 15:33 ` Christoph Hellwig
2016-10-31 23:08 ` Ming Lei
2016-10-29 8:08 ` [PATCH 17/60] kernel/power/swap.c: " Ming Lei
2016-10-29 8:08 ` [PATCH 18/60] mm: page_io.c: " Ming Lei
2016-10-29 8:08 ` [PATCH 19/60] fs/buffer: " Ming Lei
2016-10-31 15:35 ` Christoph Hellwig
2016-10-31 23:12 ` Ming Lei
2016-10-29 8:08 ` [PATCH 20/60] f2fs: f2fs_read_end_io: " Ming Lei
2016-10-29 8:08 ` [PATCH 21/60] bcache: " Ming Lei
2016-10-29 8:08 ` [PATCH 22/60] block: comment on bio_alloc_pages() Ming Lei
2016-10-29 8:08 ` [PATCH 23/60] block: introduce flag QUEUE_FLAG_NO_MP Ming Lei
2016-10-29 15:29 ` Christoph Hellwig
2016-10-29 22:20 ` Ming Lei
2016-10-29 8:08 ` [PATCH 24/60] md: set NO_MP for request queue of md Ming Lei
2016-10-29 8:08 ` [PATCH 25/60] block: pktcdvd: set NO_MP for pktcdvd request queue Ming Lei
2016-10-29 8:08 ` [PATCH 26/60] btrfs: set NO_MP for request queues behind BTRFS Ming Lei
2016-10-31 15:36 ` Christoph Hellwig
2016-10-31 17:58 ` Chris Mason
2016-10-31 18:00 ` Christoph Hellwig
2016-10-29 8:08 ` [PATCH 27/60] block: introduce BIO_SP_MAX_SECTORS Ming Lei
2016-10-29 8:08 ` [PATCH 28/60] block: introduce QUEUE_FLAG_SPLIT_MP Ming Lei
2016-10-31 15:39 ` Christoph Hellwig
2016-10-31 23:56 ` Ming Lei
2016-11-02 3:08 ` Kent Overstreet
2016-11-03 10:38 ` Ming Lei
2016-11-03 11:20 ` Kent Overstreet
2016-11-03 11:26 ` Ming Lei
2016-11-03 11:30 ` Kent Overstreet
2016-10-29 8:08 ` [PATCH 29/60] dm: limit the max bio size as BIO_SP_MAX_SECTORS << SECTOR_SHIFT Ming Lei
2016-10-29 8:08 ` [PATCH 30/60] bcache: set flag of QUEUE_FLAG_SPLIT_MP Ming Lei
2016-10-29 8:08 ` Ming Lei [this message]
2016-10-29 8:08 ` [PATCH 32/60] block: implement sp version of bvec iterator helpers Ming Lei
2016-10-29 11:06 ` kbuild test robot
2016-12-17 11:38 ` Ming Lei
2016-10-29 8:08 ` [PATCH 33/60] block: introduce bio_for_each_segment_mp() Ming Lei
2016-10-29 8:08 ` [PATCH 34/60] block: introduce bio_clone_sp() Ming Lei
2016-10-29 8:08 ` [PATCH 35/60] bvec_iter: introduce BVEC_ITER_ALL_INIT Ming Lei
2016-10-29 8:08 ` [PATCH 36/60] block: bounce: avoid direct access to bvec from bio->bi_io_vec Ming Lei
2016-10-29 8:08 ` [PATCH 37/60] block: bounce: don't access bio->bi_io_vec in copy_to_high_bio_irq Ming Lei
2016-10-29 8:08 ` [PATCH 38/60] block: bounce: convert multipage bvecs into singlepage Ming Lei
2016-10-29 8:08 ` [PATCH 39/60] bcache: debug: switch to bio_clone_sp() Ming Lei
2016-10-29 8:08 ` [PATCH 40/60] blk-merge: compute bio->bi_seg_front_size efficiently Ming Lei
2016-10-29 8:08 ` [PATCH 41/60] block: blk-merge: try to make front segments in full size Ming Lei
2016-10-29 8:08 ` [PATCH 42/60] block: use bio_for_each_segment_mp() to compute segments count Ming Lei
2016-10-29 8:08 ` [PATCH 43/60] block: use bio_for_each_segment_mp() to map sg Ming Lei
2016-10-29 8:08 ` [PATCH 44/60] block: introduce bvec_for_each_sp_bvec() Ming Lei
2016-10-29 8:08 ` [PATCH 45/60] block: bio: introduce bio_for_each_segment_all_rd() and its write pair Ming Lei
2016-10-31 13:59 ` Theodore Ts'o
2016-10-31 15:11 ` Christoph Hellwig
2016-10-31 22:50 ` Ming Lei
2016-11-02 3:01 ` Kent Overstreet
2016-10-31 22:46 ` Ming Lei
2016-10-31 23:51 ` Ming Lei
2016-11-01 14:17 ` Theodore Ts'o
2016-11-02 1:58 ` Ming Lei
2016-10-29 8:08 ` [PATCH 46/60] block: deal with dirtying pages for multipage bvec Ming Lei
2016-10-31 15:40 ` Christoph Hellwig
2016-11-01 0:19 ` Ming Lei
2016-10-29 8:08 ` [PATCH 47/60] block: convert to bio_for_each_segment_all_rd() Ming Lei
2016-10-29 8:08 ` [PATCH 48/60] fs/mpage: " Ming Lei
2016-10-29 8:08 ` [PATCH 49/60] fs/direct-io: " Ming Lei
2016-10-29 8:08 ` [PATCH 50/60] ext4: " Ming Lei
2016-10-29 8:08 ` [PATCH 51/60] xfs: " Ming Lei
2016-10-29 8:08 ` [PATCH 52/60] logfs: " Ming Lei
2016-10-29 8:08 ` [PATCH 53/60] gfs2: " Ming Lei
2016-10-29 8:08 ` [PATCH 54/60] f2fs: " Ming Lei
2016-10-29 8:08 ` [PATCH 55/60] exofs: " Ming Lei
2016-10-29 8:08 ` [PATCH 56/60] fs: crypto: " Ming Lei
2016-10-29 8:08 ` [PATCH 57/60] bcache: " Ming Lei
2016-10-29 8:08 ` [PATCH 58/60] dm-crypt: " Ming Lei
2016-10-29 8:08 ` [PATCH 59/60] fs/buffer.c: use bvec iterator to truncate the bio Ming Lei
2016-10-29 8:08 ` [PATCH 60/60] block: enable multipage bvecs Ming Lei
2016-10-31 15:25 ` [PATCH 00/60] block: support multipage bvec Christoph Hellwig
2016-10-31 22:52 ` Ming Lei
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