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Date: Mon, 27 Nov 2023 13:55:33 -0800
From: "Darrick J. Wong" <djwong@kernel.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <dchinner@redhat.com>, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 1/1] xfs: make xchk_iget safer in the presence of corrupt
 inode btrees
Message-ID: <20231127215533.GF2766956@frogsfrogsfrogs>
References: <170086925757.2768713.18061984370448871279.stgit@frogsfrogsfrogs>
 <170086925774.2768713.17299783083709212096.stgit@frogsfrogsfrogs>
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On Fri, Nov 24, 2023 at 08:57:57PM -0800, Christoph Hellwig wrote:
> On Fri, Nov 24, 2023 at 03:46:54PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > When scrub is trying to iget an inode, ensure that it won't end up
> > deadlocked on a cycle in the inode btree by using an empty transaction
> > to store all the buffers.
> 
> My only concern here is how I'm suppsed to know when to use the _safe
> version or not.

For xchk_iget_safe, I'll amend the comment to read:

/*
 * Safe version of (untrusted) xchk_iget that uses an empty transaction to
 * avoid deadlocking on loops in the inobt.  This should only be used in a
 * scrub or repair setup routine, and only prior to grabbing a transaction.
 */

and add a comment for xchk_iget that reads:

/*
 * Grab the inode at @inum.  The caller must have created a scrub transaction
 * so that we can confirm the inumber by walking the inobt and not deadlock on
 * a loop in the inobt.
 */

> Otherwise looks good:
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Thanks!

--D