From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Davis Subject: Re: EXT4 partition changes every time it's mounted. (How to stop this?) Date: Wed, 25 May 2011 23:15:51 -0700 (PDT) Message-ID: <228119.28214.qm@web125215.mail.ne1.yahoo.com> References: <476510.14310.qm@web125206.mail.ne1.yahoo.com> <195291.47304.qm@web125204.mail.ne1.yahoo.com> Reply-To: Lee Davis Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: "linux-ext4@vger.kernel.org" To: Lee Davis , Theodore Tso Return-path: Received: from nm8-vm3.bullet.mail.ne1.yahoo.com ([98.138.91.138]:43206 "HELO nm8-vm3.bullet.mail.ne1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751754Ab1EZGPw convert rfc822-to-8bit (ORCPT ); Thu, 26 May 2011 02:15:52 -0400 In-Reply-To: <195291.47304.qm@web125204.mail.ne1.yahoo.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: I've just tested this on a clean Ubuntu installation without any crypto= -- exact same thing happens. Should I log this as an ext4 bug? Regards, Lee ----- Original Message ----- =46rom: Lee Davis To: Theodore Tso Cc: "linux-ext4@vger.kernel.org" Sent: Monday, 23 May 2011 2:39 PM Subject: Re: EXT4 partition changes every time it's mounted. (How to st= op this?) Hi Ted, I've checked again, and despite being mounted read-only, the filesystem= is definitely changing every time I reboot. The mount options are: ro,relatime,commit=3D0 I've taken three images of the filesystem (rebooting between each image= ), and with a bit of research I've managed to discover which fields in = the superblock are being changed. They are: s_wtime and s_kbytes_writte= n.=20 Here's how they're being changed: 0x430 (s_wtime): 06C8D94D -> 68D0D94D -> B9D7D94D 0x578 (s_kbytes_written): 42C8000000000000 -> 45C8000000000000 -> 48C80= 00000000000 These two fields are the only things that are changing in the entire fi= lesystem. Any ideas on what might be causing this and/or how to disable it? Much appreciated, Lee P.S. I just thought to test it after unmounting/re-mounting, and nothin= g was changed. So it appears to only get changed when I boot the system= =2E It's a fresh Ubuntu Natty installation, with GRUB on the MBR, an ext4 b= oot partition, and an encrypted ext4 root partition (which I set up thr= ough the installer). I can't think what might be writing to the boot pa= rtition. ----- Original Message ----- =46rom: Theodore Tso To: Lee Davis Cc: "linux-ext4@vger.kernel.org" Sent: Sunday, 22 May 2011 9:47 PM Subject: Re: EXT4 partition changes every time it's mounted. (How to st= op this?) On May 21, 2011, at 3:45 PM, Lee Davis wrote: > 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. >=20 > Problem is that every time I boot up the system, my /boot partition h= ashes differently. >=20 > I'm guessing there is something behind the scenes which is changed/up= dated each time the filesystem is mounted? If so, can it be disabled? Yes, there is a last mounted time in the superblock.=A0=A0 If you mount= the file system read-only, then not only will that field not be change= d, but you can guarantee that nothing else will change... -- Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at=A0 http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html