linux-ext4 - EXT4 partition changes every time it's mounted. (How to stop this?)

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Date:	Sat, 21 May 2011 12:45:32 -0700 (PDT)
From:	Lee Davis <l.davis37@...il.com>
To:	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
Subject: EXT4 partition changes every time it's mounted. (How to stop this?)

Hi folks,

I'm setting up a Linux system with full disk encryption. I've written a script (to run on every boot) which will verify that neither the MBR or /boot partition (ext4) has been modified.

Problem is that every time I boot up the system, my /boot partition hashes differently.

Trying to solve this, I set the /boot partition to mount as read only in fstab. I then took individual hashes of every file on /boot. After I rebooted none of the files had changed (and there were no new files), yet the filesystem hashed as a whole had changed.

I'm guessing there is something behind the scenes which is changed/updated each time the filesystem is mounted? If so, can it be disabled?

Any advice would be greatly appreciated!

Cheers,
Lee

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