From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id p749QPqj059496 for ; Thu, 4 Aug 2011 04:26:25 -0500 Received: from ogre.sisk.pl (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 3C2EA1E6FD47 for ; Thu, 4 Aug 2011 02:26:23 -0700 (PDT) Received: from ogre.sisk.pl (ogre.sisk.pl [217.79.144.158]) by cuda.sgi.com with ESMTP id jq9rMHYjg2BWlbSa for ; Thu, 04 Aug 2011 02:26:23 -0700 (PDT) From: "Rafael J. Wysocki" Subject: Re: [RFC][PATCH] PM / Freezer: Freeze filesystems along with freezing processes (was: Re: PM / hibernate xfs lock up / xfs_reclaim_inodes_ag) Date: Thu, 4 Aug 2011 11:27:30 +0200 References: <4E1C70AD.1010101@u-club.de> <201108032315.06012.rjw@sisk.pl> <20110803172922.GA2126@ucw.cz> In-Reply-To: <20110803172922.GA2126@ucw.cz> MIME-Version: 1.0 Message-Id: <201108041127.30944.rjw@sisk.pl> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Pavel Machek Cc: Christoph , LKML , xfs@oss.sgi.com, Christoph Hellwig , Nigel Cunningham , Linux PM mailing list On Wednesday, August 03, 2011, Pavel Machek wrote: > 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? So that it doesn't complain? :-) I'll need some time to get the exact details here. > > + /* > > + * 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? What do you mean exactly? > 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... So we need not check MS_FROZEN in freeze_filesystems(). OK Thanks, Rafael _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs