From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751651Ab1HDGCY (ORCPT ); Thu, 4 Aug 2011 02:02:24 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:50640 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750773Ab1HDGCS (ORCPT ); Thu, 4 Aug 2011 02:02:18 -0400 Date: Wed, 3 Aug 2011 19:29:22 +0200 From: Pavel Machek To: "Rafael J. Wysocki" Cc: Nigel Cunningham , Christoph Hellwig , Dave Chinner , Christoph , Linux PM mailing list , xfs@oss.sgi.com, LKML Subject: Re: [RFC][PATCH] PM / Freezer: Freeze filesystems along with freezing processes (was: Re: PM / hibernate xfs lock up / xfs_reclaim_inodes_ag) Message-ID: <20110803172922.GA2126@ucw.cz> References: <4E1C70AD.1010101@u-club.de> <20110727103308.GA20805@infradead.org> <4E300317.7090108@tuxonice.net> <201108032315.06012.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201108032315.06012.rjw@sisk.pl> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! > Freeze all filesystems during the freezing of tasks by calling > freeze_bdev() for each of them and thaw them during the thawing > of tasks with the help of thaw_bdev(). > > This is needed by hibernation, because some filesystems (e.g. XFS) > deadlock with the preallocation of memory used by it if the memory > pressure caused by it is too heavy. > > The additional benefit of this change is that, if something goes > wrong after filesystems have been frozen, they will stay in a > consistent state and journal replays won't be necessary (e.g. after > a failing suspend or resume). In 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 initrd causing it to > become inconsistent with the information stored in the hibernation > image. > +/** > + * freeze_filesystems - Force all filesystems into a consistent state. > + */ > +void freeze_filesystems(void) > +{ > + struct super_block *sb; > + > + lockdep_off(); Ouch. So... why do we need to silence this? > + /* > + * Freeze in reverse order so filesystems dependant upon others are > + * frozen in the right order (eg. loopback on ext3). > + */ > + list_for_each_entry_reverse(sb, &super_blocks, s_list) { > + if (!sb->s_root || !sb->s_bdev || > + (sb->s_frozen == SB_FREEZE_TRANS) || > + (sb->s_flags & MS_RDONLY) || > + (sb->s_flags & MS_FROZEN)) > + continue; Should we stop NFS from modifying remote server, too? Plus... ext3 writes to read-only filesystems on mount; not sure if it does it later. But RDONLY means 'user cant write to it' not 'bdev will not be modified'. Should we freeze all? How can 'already frozen' happen? > + list_for_each_entry(sb, &super_blocks, s_list) > + if (sb->s_flags & MS_FROZEN) { > + sb->s_flags &= ~MS_FROZEN; > + thaw_bdev(sb->s_bdev, sb); > + } ...because we'll unfreeze it even if we did not freeze it... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html