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Date: Mon, 5 Oct 2026 15:14:53 +0200
From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Carlos Maiolino <cem@kernel.org>,
	Jens Axboe <axboe@kernel.dk>,
	Christian Brauner <brauner@kernel.org>, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 18/21] xfs: don't try to verify checksums on empty zones
Message-ID: <20261005131453.GF26805@lst.de>
References: <20260924100032.2733101-1-hch@lst.de> <20260924100032.2733101-19-hch@lst.de> <20260929012555.GZ2705364@frogsfrogsfrogs>
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On Mon, Sep 28, 2026 at 06:25:55PM -0700, Darrick J. Wong wrote:
> Just a general note -- if the csum update never makes it to disk, then
> the remap cannot have been written to disk either.  Therefore, fsmap
> will report that as unowned space, and xfs_scrub won't try to
> read-verify it, given the xfs_scrub patch you post later to only read rt
> blocks for which there are rmap records.
> 
> So I think this is only a theoretical concern, right?

At least earlier I could reproduce a case where scrub raced with
a zone reset and tries to verify the reset zone against the now
implicitly zeroed zone.