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Message-ID: <20070409033134.GB13980@implementation>
Date: Mon, 9 Apr 2007 05:31:34 +0200
From: Samuel Thibault <samuel.thibault@...-lyon.org>
To: Eric Sandeen <sandeen@...hat.com>
Cc: linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Add a norecovery option to ext3/4?
Eric Sandeen, le Sun 08 Apr 2007 22:24:50 -0500, a écrit :
> Samuel Thibault wrote:
> >Distribution installers usually try to probe OSes for building a suited
> >grub menu. Unfortunately, mounting an ext3 partition, even in read-only
> >mode, does perform some operations on the filesystem (log recovery).
> >This is not a good idea since it may silently garbage data.
>
> Can you elaborate? Under what circumstances is log replay going to harm
> data? Do you mean that the installer mounts partitions, looking for
> what OS is installed? How is that harmful?
>
> Ohhh... this is http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=417407
> isn't it?
Yes.
> Hm, so the root cause there seems that the installer found 2 legs of a
> mirror and mounted them independently, recovering them independently...
> But why did that cause problems?
Because that thrashed his data (or at least it didn't help to keep data
safe).
> Other options you may have in the installer, though, is to check for
> md superblocks before mounting bare partitions, or maybe use the
> BLKROSET ioctl to set the block device to read-only prior to mount,
> for added insurance...
That's one the things proposed in the bugreport yes.
Samuel
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