linux-ext4 - Re: ext4: Fix data corruption with multi-block writepages support

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Message-ID: <20110207204419.GE3457@thunk.org>
Date:	Mon, 7 Feb 2011 15:44:19 -0500
From:	Ted Ts'o <tytso@....edu>
To:	Milan Broz <mbroz@...hat.com>
Cc:	Matt <jackdachef@...il.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	linux-ext4 <linux-ext4@...r.kernel.org>
Subject: Re: ext4: Fix data corruption with multi-block writepages support

On Mon, Feb 07, 2011 at 07:29:26PM +0100, Milan Broz wrote:
> 
> So it was ext4 only bug in ext4_end_bio(),
> dm-crypt per-cpu code was just trigger here, right?

There appeared to be two bugs that people were discussing on that
particular dm_crypt mail thread.  Some people were complaining about
issues with dm_crypt even when ext4 was not involved.

So I think it's fair to say that there was definitely _a_ ext4 bug
which was most easily seen when dm_crypt was in play, but which was
definitely not dm_crypt specific (it was possible to see it on an
hdd-only system, but the workload was much more severe).  In any case,
as soon as the problem was found, we disabled the ext4 optimization
in 2.6.37-rc5.

So the fact that we found and fixed an ext4 bug that was triggered by
dm_crypt should not be taken as a statement (one way or the other)
that dm_crypt is Bug-Free(tm).  :-)

					- Ted
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