Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753415AbZAEDXf (ORCPT ); Sun, 4 Jan 2009 22:23:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753065AbZAEDXA (ORCPT ); Sun, 4 Jan 2009 22:23:00 -0500 Received: from static-71-162-243-5.phlapa.fios.verizon.net ([71.162.243.5]:43043 "EHLO grelber.thyrsus.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752992AbZAEDW5 (ORCPT ); Sun, 4 Jan 2009 22:22:57 -0500 From: Rob Landley Organization: Boundaries Unlimited To: Geert Uytterhoeven Subject: Re: document ext3 requirements Date: Sun, 4 Jan 2009 21:22:35 -0600 User-Agent: KMail/1.10.1 (Linux/2.6.27-7-generic; KDE/4.1.2; x86_64; ; ) Cc: Theodore Tso , Duane Griffin , Valdis.Kletnieks@vt.edu, Martin =?utf-8?q?MOKREJ=C5=A0?= , Pavel Machek , kernel list , Andrew Morton , mtk.manpages@gmail.com, rdunlap@xenotime.net, linux-doc@vger.kernel.org References: <20090104184040.GC17558@mit.edu> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200901042122.35828.rob@landley.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1093 Lines: 28 On Sunday 04 January 2009 13:21:06 Geert Uytterhoeven wrote: > I think most people get shocked when they discover that mounting something > read-only may actualy write to the media. This is a bit unexpected (hey, if > I mount `read-only', I expect that no writes will happen), as it behaved > differently before the introduction of journalling. Is this an unreasonable use case: kill -STOP $(pidof qemu) mount -o loop,ro hdb.img blah cp blah/thingy thingy umount blah kill -CONT $(pidof qemu) Currently, if your loopback mount is -t ext3 it'll write to the block device, and if your mount is -t ext2 it'll refuse to work on an unclean ext3 filesystem, even if it's read only. (But it _will_ work on an unclean ext2 filesystem.) My theory when I first found out about this was "the filesystem developers hate me personally". Rob -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/