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Date: Thu, 11 Oct 2001 07:47:03 -0400
From: Chris Mason <mason@suse.com>
To: Alexander Viro <viro@math.psu.edu>, Benjamin LaHaise <bcrl@redhat.com>
cc: Richard Gooch <rgooch@ras.ucalgary.ca>,
        Andreas Dilger <adilger@turbolabs.com>,
        Doug McNaught <doug@wireboard.com>,
        Lew Wolfgang <wolfgang@sweet-haven.com>, linux-kernel@vger.kernel.org
Subject: Re: Dump corrupts ext2?
Message-ID: <1223310000.1002800823@tiny>
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On Thursday, October 11, 2001 12:29:03 AM -0400 Alexander Viro <viro@math.psu.edu> wrote:
> On Thu, 11 Oct 2001, Benjamin LaHaise wrote:
> 
>> On Wed, Oct 10, 2001 at 09:48:41PM -0400, Chris Mason wrote:
>> > The bug where dump could corrupt things was when getblk and the
>> > block device both used the buffer cache.  That issue hasn't changed.
>> 
>> Let me emphasize this: 2.4.11+ will still exhibit filesystem corruption if 
>> the block device is accessed.  The only way to avoid this is to use raw io, 
> 
> What?  Details, please.  If you are talking about read access I would
> really like to know which filesystem it is.  ext2 used to have a bug
> in that area, but it had been fixed months ago.

Sorry, I wasn't very clear.  As far as I know, the specific ext2 bug
(race on up to date flag of newly allocated metadata) was found/fixed
by Al.  

The issues left are just dump getting inconsistent backups from
a rw mounted disk.  We'll have this bug regardless of page cache vs buffer
cache vs raw io in dump.

Now, what's interesting is the raw io dump + ext3 case.

-chris

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