From: Christoph Hellwig <hch@infradead.org>
To: Lin Jiapeng <ljp1205831794@gmail.com>
Cc: cem@kernel.org, linux-xfs@vger.kernel.org,
stable@vger.kernel.org, djwong@kernel.org,
jiapenglin@tencent.com
Subject: Re: [PATCH v2] xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN
Date: Mon, 27 Jul 2026 20:14:26 -0700 [thread overview]
Message-ID: <amgekiNKKoAdACnc@infradead.org> (raw)
In-Reply-To: <20260728022310.99955-1-jiapenglin@tencent.com>
On Tue, Jul 28, 2026 at 10:23:03AM +0800, Lin Jiapeng wrote:
> When exchanging two full-file ranges, xmi_can_exchange_reflink_flags()
> can move the reflink inode flag from the file that currently has it to
> the other file, as long as exactly one side is marked. This assumes
> that the file contents, and therefore all shared extents, are exchanged.
>
> That assumption is not true when XFS_EXCHMAPS_INO1_WRITTEN is set.
> xfs_exchmaps_can_skip_mapping() can skip hole and unwritten mappings
> from file1, so an exchange can complete without moving every mapping
> that the earlier flag-swap decision accounted for. In that case the
> post-operation cleanup can clear the reflink flag from an inode that
> still owns shared written extents. Later writes then take the
> non-reflink write path and may update blocks that should still have
> been protected by CoW, which shows up as data corruption between
> reflink-related files.
>
> Fix this by disabling the reflink flag exchange whenever
> XFS_EXCHMAPS_INO1_WRITTEN is requested. The contents exchange can still
> proceed; the conservative outcome is that both inodes keep the reflink
> flag. The regular reflink flag cleanup path can drop the extra flag
> later once the inode no longer has shared extents.
The fix looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
Can you add a test case to fstests for this?
next prev parent reply other threads:[~2026-07-28 3:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-28 2:23 [PATCH v2] xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN Lin Jiapeng
2026-07-28 3:14 ` Christoph Hellwig [this message]
2026-07-28 6:50 ` m00nb1rd lin
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=amgekiNKKoAdACnc@infradead.org \
--to=hch@infradead.org \
--cc=cem@kernel.org \
--cc=djwong@kernel.org \
--cc=jiapenglin@tencent.com \
--cc=linux-xfs@vger.kernel.org \
--cc=ljp1205831794@gmail.com \
--cc=stable@vger.kernel.org \
/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