From: Milan Broz <mbroz@redhat.com>
Subject: Re: hunt for 2.6.37 dm-crypt+ext4 corruption?
Date: Wed, 08 Dec 2010 09:03:51 +0100
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Cc: Chris Mason <chris.mason@oracle.com>,
	Mike Snitzer <snitzer@redhat.com>, Matt <jackdachef@gmail.com>,
	Andi Kleen <andi@firstfloor.org>,
	linux-btrfs <linux-btrfs@vger.kernel.org>,
	dm-devel <dm-devel@redhat.com>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	htd <htd@fancy-poultry.org>, htejun <htejun@gmail.com>,
	linux-ext4 <linux-ext4@vger.kernel.org>
To: Jon Nelson <jnelson@jamponi.net>
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On 12/08/2010 04:29 AM, Jon Nelson wrote:
> Maybe not so fantastic. I kept testing and had no more failures. At
> all. After 40+ iterations I gave up.
> I went back to trying ext4 on a LUKS volume. The 'hit' ratio went to
> something like 1 in 3, or better.

Encryption usually propagates bit corruption (not sure if it is
in this case). But in principle if there is one bit corrupted,
after decryption the whole sector is corrupted.
(That's why bit media errors have usually more serious impact
with FDE.)

Isn't there random noise instead of zeroes when reading
sparse files?
We should probably write some test focusing on sparse files
handling here...

Milan