From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
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>,
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 23:48:13 +0800 [thread overview]
Message-ID: <20181121154812.GD19111@ming.t460p> (raw)
In-Reply-To: <20181121145502.GA3241@lst.de>
On Wed, Nov 21, 2018 at 03:55:02PM +0100, Christoph Hellwig wrote:
> 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;
I guess the correct check should be:
end_addr = vec_addr + bv->bv_offset + bv->bv_len;
if (same_page &&
(end_addr & PAGE_MASK) != (page_addr & PAGE_MASK))
return false;
And this approach is good, will take it in V12.
Thanks,
Ming
next prev parent reply other threads:[~2018-11-21 15:49 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
2018-11-21 15:48 ` Ming Lei [this message]
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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