From: Christoph Hellwig <hch@infradead.org>
To: Gao Xiang <hsiangkao@linux.alibaba.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Yifan Zhao <zhaoyifan28@huawei.com>,
linux-erofs@lists.ozlabs.org, linux-kernel@vger.kernel.org,
yekelu1@huawei.com, jingrui@huawei.com, zhukeqian1@huawei.com,
Ritesh Harjani <ritesh.list@gmail.com>,
"Darrick J. Wong" <djwong@kernel.org>,
linux-xfs@vger.kernel.org, Joanne Koong <joannelkoong@gmail.com>
Subject: Re: don't merge bios over iomap boundaries, was: Re: [PATCH] erofs: prevent buffered read bio merges across device chunks
Date: Fri, 12 Jun 2026 01:04:26 -0700 [thread overview]
Message-ID: <aiu9imWL_c1eyerw@infradead.org> (raw)
In-Reply-To: <befed994-02bc-42f8-945c-2aea3e3b10b2@linux.alibaba.com>
On Fri, Jun 12, 2026 at 03:35:38PM +0800, Gao Xiang wrote:
> btw, there may be be some edge cases like:
> written | hole | written | hole | written ...
>
> and if bios cannot across multiple iomaps, bios could be
> amplified according to the shuffle pattern even all written
> data is consecutive on disk (the block allocator may
> allocate written blocks consecutively.)
>
> Anyway, I never tried to argue with this cases (yet both
> previous buffer-head and mpage codebase will merge this
> except for some specific exceptions), maybe it's just a
> pure artificial pattern and I'm worried too much.
We actually just had something like this come for XFS even
with the current merging:
https://lore.kernel.org/linux-xfs/6csdtjn33va4ivyycr4uh2ogac22xput4kgzxzt3mczdkvwjaf@37audfdijskv/T/#t
although this involves REQ_NOWAIT and thus is a bit more complicated.
But the merging scheme discussed there should also help with your
above case in general.
next prev parent reply other threads:[~2026-06-12 8:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20260612033244.993507-1-zhaoyifan28@huawei.com>
[not found] ` <58bef9af-0926-4948-b917-e38c3793f596@linux.alibaba.com>
2026-06-12 6:25 ` don't merge bios over iomap boundaries, was: Re: [PATCH] erofs: prevent buffered read bio merges across device chunks Christoph Hellwig
2026-06-12 6:54 ` Gao Xiang
2026-06-12 7:10 ` Christoph Hellwig
2026-06-12 7:19 ` Gao Xiang
2026-06-12 7:35 ` Gao Xiang
2026-06-12 8:04 ` Christoph Hellwig [this message]
2026-06-12 8:01 ` Christoph Hellwig
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=aiu9imWL_c1eyerw@infradead.org \
--to=hch@infradead.org \
--cc=djwong@kernel.org \
--cc=hsiangkao@linux.alibaba.com \
--cc=jingrui@huawei.com \
--cc=joannelkoong@gmail.com \
--cc=linux-erofs@lists.ozlabs.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-xfs@vger.kernel.org \
--cc=ritesh.list@gmail.com \
--cc=yekelu1@huawei.com \
--cc=zhaoyifan28@huawei.com \
--cc=zhukeqian1@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox