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Date: Thu, 3 Sep 2026 07:35:17 +0200
From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, cem@kernel.org, stable@vger.kernel.org,
	linux-xfs@vger.kernel.org
Subject: Re: [PATCH 3/5] xfs: compute dquot checksum after resetting dd_lsn
 in repair
Message-ID: <20260903053517.GC16469@lst.de>
References: <178832750681.3508131.6009513367948627110.stgit@frogsfrogsfrogs> <178832750773.3508131.8667220003399042973.stgit@frogsfrogsfrogs> <20260902072341.GC26173@lst.de> <20260902153703.GN1933798@frogsfrogsfrogs>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Wed, Sep 02, 2026 at 08:37:03AM -0700, Darrick J. Wong wrote:
> On Wed, Sep 02, 2026 at 09:23:41AM +0200, Christoph Hellwig wrote:
> > On Tue, Sep 01, 2026 at 10:49:16PM -0700, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <djwong@kernel.org>
> > > 
> > > LOLLM complains that xrep_quota_block updates dd_lsn after calculating
> > > the crc of the ondisk dquot.  That's clearly broken, so fix that.
> > 
> > Yeah:
> > 
> > Reviewed-by: Christoph Hellwig <hch@lst.de>
> > 
> > Also why do we set the lsn to 0, shouldn't that contain a valid value
> > (probably the current LSN, but I'd have to look deeper at what this
> > does in detail)
> 
> Hmm.  When I wrote this dquot repair code I was mirroring what
> xfs_qm_init_dquot_blk does (memsets the new dquot buffer to zeroes,
> doesn't explicitly touch dd_lsn).
> 
> It probably ought to be set to the current LSN but we don't really have
> a dquot log item for determining that, and assigning 0 here means that
> any subsequent logged dquot item will always be recovered into the
> ondisk dquot that xrep_quota_block writes.

Can we capture this for the future in comments somewhere?