From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
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
Subject: Re: [PATCH V11 15/19] block: enable multipage bvecs
Date: Wed, 21 Nov 2018 15:55:02 +0100 [thread overview]
Message-ID: <20181121145502.GA3241@lst.de> (raw)
In-Reply-To: <20181121032327.8434-16-ming.lei@redhat.com>
On Wed, Nov 21, 2018 at 11:23:23AM +0800, Ming Lei wrote:
> if (bio->bi_vcnt > 0) {
> - struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
> + struct bio_vec bv;
> + struct bio_vec *seg = &bio->bi_io_vec[bio->bi_vcnt - 1];
>
> - if (page == bv->bv_page && off == bv->bv_offset + bv->bv_len) {
> - bv->bv_len += len;
> + bvec_last_segment(seg, &bv);
> +
> + if (page == bv.bv_page && off == bv.bv_offset + bv.bv_len) {
I think this we can simplify the try to merge into bio case a bit,
and also document it better with something like this:
diff --git a/block/bio.c b/block/bio.c
index 854676edc438..cc913281a723 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -822,54 +822,40 @@ EXPORT_SYMBOL(bio_add_pc_page);
* @page: page to add
* @len: length of the data to add
* @off: offset of the data in @page
+ * @same_page: if %true only merge if the new data is in the same physical
+ * page as the last segment of the bio.
*
- * Try to add the data at @page + @off to the last page of @bio. This is a
+ * Try to add the data at @page + @off to the last bvec of @bio. This is a
* a useful optimisation for file systems with a block size smaller than the
* page size.
*
* Return %true on success or %false on failure.
*/
bool __bio_try_merge_page(struct bio *bio, struct page *page,
- unsigned int len, unsigned int off)
+ unsigned int len, unsigned int off, bool same_page)
{
if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
return false;
if (bio->bi_vcnt > 0) {
- struct bio_vec bv;
- struct bio_vec *seg = &bio->bi_io_vec[bio->bi_vcnt - 1];
-
- bvec_last_segment(seg, &bv);
-
- if (page == bv.bv_page && off == bv.bv_offset + bv.bv_len) {
- seg->bv_len += len;
- bio->bi_iter.bi_size += len;
- return true;
- }
+ struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
+ phys_addr_t vec_addr = page_to_phys(bv->bv_page);
+ phys_addr_t page_addr = page_to_phys(page);
+
+ if (vec_addr + bv->bv_offset + bv->bv_len != page_addr + off)
+ return false;
+ if (same_page &&
+ (vec_addr & PAGE_SIZE) != (page_addr & PAGE_SIZE))
+ return false;
+
+ bv->bv_len += len;
+ bio->bi_iter.bi_size += len;
+ return true;
}
return false;
}
EXPORT_SYMBOL_GPL(__bio_try_merge_page);
-static bool bio_try_merge_segment(struct bio *bio, struct page *page,
- unsigned int len, unsigned int off)
-{
- if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
- return false;
-
- if (bio->bi_vcnt > 0) {
- struct bio_vec *seg = &bio->bi_io_vec[bio->bi_vcnt - 1];
-
- if (page_to_phys(seg->bv_page) + seg->bv_offset + seg->bv_len ==
- page_to_phys(page) + off) {
- seg->bv_len += len;
- bio->bi_iter.bi_size += len;
- return true;
- }
- }
- return false;
-}
-
/**
* __bio_add_page - add page to a bio in a new segment
* @bio: destination bio
@@ -910,7 +896,7 @@ EXPORT_SYMBOL_GPL(__bio_add_page);
int bio_add_page(struct bio *bio, struct page *page,
unsigned int len, unsigned int offset)
{
- if (!bio_try_merge_segment(bio, page, len, offset)) {
+ if (!__bio_try_merge_page(bio, page, len, offset, false)) {
if (bio_full(bio))
return 0;
__bio_add_page(bio, page, len, offset);
diff --git a/fs/iomap.c b/fs/iomap.c
index ccc2ba115f4d..d918acb9bfc9 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -313,7 +313,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
*/
sector = iomap_sector(iomap, pos);
if (ctx->bio && bio_end_sector(ctx->bio) == sector) {
- if (__bio_try_merge_page(ctx->bio, page, plen, poff))
+ if (__bio_try_merge_page(ctx->bio, page, plen, poff, true))
goto done;
is_contig = true;
}
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 5c2190216614..b9fd44168f61 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -616,7 +616,7 @@ xfs_add_to_ioend(
bdev, sector);
}
- if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff)) {
+ if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff, true)) {
if (iop)
atomic_inc(&iop->write_count);
if (bio_full(wpc->ioend->io_bio))
diff --git a/include/linux/bio.h b/include/linux/bio.h
index e5b975fa0558..f08e6940c1ab 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -442,7 +442,7 @@ extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
unsigned int, unsigned int);
bool __bio_try_merge_page(struct bio *bio, struct page *page,
- unsigned int len, unsigned int off);
+ unsigned int len, unsigned int off, bool same_page);
void __bio_add_page(struct bio *bio, struct page *page,
unsigned int len, unsigned int off);
int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
next prev parent reply other threads:[~2018-11-21 14:55 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 ` [PATCH V11 02/19] block: introduce multi-page bvec helpers Ming Lei
2018-11-21 13:19 ` 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 [this message]
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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