linux-ext4 - Re: [ext3] Changes to block device after an ext3 mount point has been remounted readonly

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Message-id: <9F53CAF8-B6B4-40EB-89FA-CD6779D17DBE@sun.com>
Date:	Thu, 18 Feb 2010 14:41:45 -0700
From:	Andreas Dilger <adilger@....com>
To:	PiX <pix@...life.org>
Cc:	linux-fsdevel@...r.kernel.org,
	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [ext3] Changes to block device after an ext3 mount point has been
 remounted readonly

On 2010-02-18, at 09:45, PiX wrote:
> I'm experiencing a strange behavior. After having remounted / to
> readonly, I'm doing a sha1sum on /dev/sda1 (which is mounted on /)
> Then, I reboot, GRUB starts the kernel with the ro option, when I do a
> hash of /dev/sda1 the sum has changed.

Are you sure this isn't because e2fsck has been run at boot time and  
changed e.g. the "last checked" timestamp in the superblock?

> This only happen when the rootfs hash been mounted ro, then remounted
> rw to make some changes and remounted ro.
> On the next reboot the hash will change, but only one time. Next
> reboots will not alter the control sum, until of course I remount it
> RW.


Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.

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