From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [RFC][PATCH] PM / Sleep: Freeze filesystems during system suspend/hibernation Date: Wed, 1 Feb 2012 14:36:42 +0100 Message-ID: <20120201133642.GC3673@elf.ucw.cz> References: <201201281445.49377.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Linux PM list , LKML , Jan Kara , linux-fsdevel@vger.kernel.org, Dave Chinner , Nigel Cunningham , "Srivatsa S. Bhat" To: "Rafael J. Wysocki" Return-path: Content-Disposition: inline In-Reply-To: <201201281445.49377.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Hi! > From: Rafael J. Wysocki > > Freeze all filesystems during system suspend and (kernel-driven) > hibernation by calling freeze_supers() for all superblocks and thaw > them during the subsequent resume with the help of thaw_supers(). > > This makes filesystems stay in a consistent state in case something > goes wrong between system suspend (or hibernation) and the subsequent > resume (e.g. journal replays won't be necessary in those cases). In Good. > particular, this should help to solve a long-standing issue that, in > some cases, during resume from hibernation the boot loader causes the > journal to be replied for the filesystem containing the kernel image > and/or initrd causing it to become inconsistent with the information > stored in the hibernation image. Ungood. Why is bootloader/initrd doing that? If it mounts filesystem read/write, what is the guarantee that it will not change data on the filesystem, breaking stuff? Bootloaders should just not replay journals. > The user-space-driven hibernation (s2disk) is not covered by this > change, because the freezing of filesystems prevents s2disk from > accessing device special files it needs to do its job. ...so bootloaders need to be fixed, anyway. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html