From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752596AbXDIDbj (ORCPT ); Sun, 8 Apr 2007 23:31:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752609AbXDIDbj (ORCPT ); Sun, 8 Apr 2007 23:31:39 -0400 Received: from iona.labri.fr ([147.210.8.143]:42711 "EHLO iona.labri.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752320AbXDIDbi (ORCPT ); Sun, 8 Apr 2007 23:31:38 -0400 Date: Mon, 9 Apr 2007 05:31:34 +0200 From: Samuel Thibault To: Eric Sandeen Cc: linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Add a norecovery option to ext3/4? Message-ID: <20070409033134.GB13980@implementation> Mail-Followup-To: Samuel Thibault , Eric Sandeen , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org References: <20070409000556.GA13980@implementation> <4619B202.3050601@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4619B202.3050601@redhat.com> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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