From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Tue, 24 Oct 2006 09:34:55 -0700 (PDT) Received: from larry.melbourne.sgi.com (larry.melbourne.sgi.com [134.14.52.130]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with SMTP id k9OGYfaG025798 for ; Tue, 24 Oct 2006 09:34:44 -0700 Date: Wed, 25 Oct 2006 02:33:45 +1000 From: David Chinner Subject: Re: [PATCH] Freeze bdevs when freezing processes. Message-ID: <20061024163345.GG11034@melbourne.sgi.com> References: <1161576735.3466.7.camel@nigel.suspend2.net> <200610231236.54317.rjw@sisk.pl> <20061024144446.GD11034@melbourne.sgi.com> <200610241730.00488.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200610241730.00488.rjw@sisk.pl> Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: "Rafael J. Wysocki" Cc: David Chinner , Nigel Cunningham , Andrew Morton , LKML , Pavel Machek , xfs@oss.sgi.com On Tue, Oct 24, 2006 at 05:29:59PM +0200, Rafael J. Wysocki wrote: > On Tuesday, 24 October 2006 16:44, David Chinner wrote: > > On Mon, Oct 23, 2006 at 12:36:53PM +0200, Rafael J. Wysocki wrote: > > > On Monday, 23 October 2006 06:12, Nigel Cunningham wrote: > > > > XFS can continue to submit I/O from a timer routine, even after > > > > freezeable kernel and userspace threads are frozen. This doesn't seem to > > > > be an issue for current swsusp code, > > > > > > So it doesn't look like we need the patch _now_. > > > > > > > but is definitely an issue for Suspend2, where the pages being written could > > > > be overwritten by Suspend2's atomic copy. > > > > > > And IMO that's a good reason why we shouldn't use RCU pages for storing the > > > image. XFS is one known example that breaks things if we do so and > > > there may be more such things that we don't know of. The fact that they > > > haven't appeared in testing so far doesn't mean they don't exist and > > > moreover some things like that may appear in the future. > > > > Could you please tell us which XFS bits are broken so we can get > > them fixed? The XFS daemons should all be checking if they are > > supposed to freeze (i.e. they call try_to_freeze() after they wake > > up due to timer expiry) so I thought they were doing the right > > thing. > > > > However, I have to say that I agree with freezing the filesystems > > before suspend - at least XFS will be in a consistent state that can > > be recovered from without corruption if your machine fails to > > resume.... > > Do you mean calling sys_sync() after the userspace has been frozen > may not be sufficient? In most cases it probably is, but sys_sync() doesn't provide any guarantees that the filesystem is not being used or written to after it completes. Given that every so often I hear about an XFS filesystem that was corrupted by suspend, I don't think this is sufficient... Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group