From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935172AbXGTRcZ (ORCPT ); Fri, 20 Jul 2007 13:32:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764667AbXGTRbp (ORCPT ); Fri, 20 Jul 2007 13:31:45 -0400 Received: from alnrmhc11.comcast.net ([206.18.177.51]:50926 "EHLO alnrmhc11.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1764624AbXGTRbo (ORCPT ); Fri, 20 Jul 2007 13:31:44 -0400 From: Jeremy Maitin-Shepard To: Milton Miller Cc: "Rafael J. Wysocki" , Ying Huang , Alan Stern , LKML , David Lang , linux-pm Subject: Re: [linux-pm] Re: Hibernation considerations References: <200707192228.05136.rjw@sisk.pl> <200707201317.58025.rjw@sisk.pl> X-Habeas-SWE-9: mark in spam to . X-Habeas-SWE-8: Message (HCM) and not spam. Please report use of this X-Habeas-SWE-7: warrant mark warrants that this is a Habeas Compliant X-Habeas-SWE-6: email in exchange for a license for this Habeas X-Habeas-SWE-5: Sender Warranted Email (SWE) (tm). The sender of this X-Habeas-SWE-4: Copyright 2002 Habeas (tm) X-Habeas-SWE-3: like Habeas SWE (tm) X-Habeas-SWE-2: brightly anticipated X-Habeas-SWE-1: winter into spring Date: Fri, 20 Jul 2007 13:31:41 -0400 In-Reply-To: (Milton Miller's message of "Fri\, 20 Jul 2007 11\:56\:43 -0500") Message-ID: <87myxroubm.fsf@jbms.ath.cx> User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/22.0.990 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Milton Miller writes: [snip] >>>> (7) how to avoid corrupting filesystems mounted by the hibernated kernel >>> >>> I didn't realize this was a discussion item. I thought the options were >>> clear, for some filesystem types you can mount them read-only, but for >>> ext3 (and possilby other less common ones) you just plain cannot touch >>> them. >> >> That's correct. And since you cannot thouch ext3, you need either to assume >> that you won't touch filesystems at all, or to have a code to recognize the >> filesystem you're dealing with. > Or add a small bit of infrastructure that errors writes at make_request if you > don't have a magic "i am a direct block device write from userspace" flag on the > bio. I still don't understand why there is this fixation on accessing dirty filesystems in use by the hibernated system. Even if you avoid corrupting the filesystem by avoiding writing to the block device, there isn't any real guarantee about the state of the data, except for a filesystem that specifically makes guarantees about such data (and I don't believe any of the existing ones do). It isn't necessary to be able to access such filesystems: everything can be done from an initramfs/initrd. [snip] -- Jeremy Maitin-Shepard