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From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Eric Sandeen <sandeen@redhat.com>,
	Brian Foster <bfoster@redhat.com>, xfs-oss <xfs@oss.sgi.com>
Subject: Re: [PATCH] xfs: fix buffer use after free on IO error
Date: Tue, 25 Mar 2014 11:13:55 -0700	[thread overview]
Message-ID: <20140325181355.GA18707@infradead.org> (raw)
In-Reply-To: <20140325180814.GF18572@destitution>

On Wed, Mar 26, 2014 at 05:08:14AM +1100, Dave Chinner wrote:
> > I think this should unconditionally avoid the schedule, and while we're
> > at it we should kill _xfs_buf_ioend and opencode it here and at the
> > other callsite.
> 
> I thought we schduled here because we can issue IO from IO
> completion and so we need to requeue the IO completion rather than
> run it inline in the current IO completion that hasn't fully
> completed it's processing yet..

Actually we get a recursive callchain there from the I/O error handling.
I switched from always 0 to always 1 here in:

commit 08023d6dbe840dc4271805a9ea376fcbdee9f744
Author: Christoph Hellwig <hch@infradead.org>
Date:   Mon Jul 2 06:00:04 2012 -0400

    xfs: prevent recursion in xfs_buf_iorequest

but I never got around fixing the root cause by cleaning up the way we
handle buffer I/O completions on a shut down filesystem.

So I guess Eric's fix is the best we can do for now.

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      reply	other threads:[~2014-03-25 18:13 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-22  2:48 [PATCH] xfs: fix buffer use after free on IO error Eric Sandeen
2014-03-25 12:58 ` Brian Foster
2014-03-25 13:17   ` Christoph Hellwig
2014-03-25 16:05     ` Eric Sandeen
2014-03-25 17:25       ` Christoph Hellwig
2014-03-25 17:39         ` Eric Sandeen
2014-03-25 17:44           ` Christoph Hellwig
2014-03-25 18:08     ` Dave Chinner
2014-03-25 18:13       ` Christoph Hellwig [this message]

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