From: Nigel Cunningham <ncunningham@clear.net.nz>
To: Andreas Dilger <adilger@clusterfs.com>
Cc: Pavel Machek <pavel@ucw.cz>, Andrew Morton <akpm@digeo.com>,
cat@zip.com.au, mbligh@aracnet.com, gigerstyle@gmx.ch,
geert@linux-m68k.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Fix SWSUSP & !SWAP
Date: Fri, 25 Apr 2003 13:09:36 +1200 [thread overview]
Message-ID: <1051232975.1919.26.camel@laptop-linux> (raw)
In-Reply-To: <20030424154608.V26054@schatzie.adilger.int>
On Fri, 2003-04-25 at 09:46, Andreas Dilger wrote:
> On Apr 24, 2003 22:48 +0200, Pavel Machek wrote:
> OK, then why all of the talk earlier saying that journal recovery will
> corrupt a swapfile? That was the reason journaling was brought into the
> discussion in the first place:
>
> "And now you have kernel which expects data still in journal (that was
> state before suspend), but reality on disk is quite different (journal
> was replayed). Data corruption." -- Pavel
I don't believe Pavel was saying the image would be corrupted. Rather,
the rest of the disk contents are corrupted by replaying the journal and
then resuming back to a memory state that has been made inconsistent
with the disk state because of the journal replay.
> If the filesystem was not unmounted and remounted, then no replay will happen.
> End of story. If the suspend code is doing something like:
>
> 1) save memory contents to disk
> 2) suspend/power off
> 3) reboot kernel, mount filesystem(s), etc
This is just reboot kernel. Filesystems aren't mounted before (4).
> 4) check for presence of suspend image
> 5) replace currently-running kernel with suspended kernel
>
> Then you are in for a world of hurt regardless of whether the data is in a
> swap file or a swap partition. The data in the swapfile isn't touched by
> journal replay at all (so that is safe regardless), but the rest of the
> filesystem is, which could cause strange disk corruption since the in-memory
> data doesn't match the on-disk data.
On the second part, "Precisely."
> If that is the case, then the only way to avoid this would be to call
> sync_super_lockfs() on each filesystem before the suspend, which will
> force the journal to be empty when it returns. That API is supported
> by all of the journaling filesystems, and is probably a good thing to
> do anyways, as it will potentially free a lot of dirty data from RAM,
> and also ensure that the on-disk data is consistent in case the resume
> isn't handled gracefully.
Sounds like a good idea to me.
Regards,
Nigel
next prev parent reply other threads:[~2003-04-25 1:10 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-23 13:51 Fix SWSUSP & !SWAP Pavel Machek
2003-04-23 14:32 ` Geert Uytterhoeven
2003-04-23 14:47 ` Pavel Machek
2003-04-23 15:56 ` gigerstyle
2003-04-23 19:41 ` Nigel Cunningham
2003-04-23 20:36 ` Marc Giger
2003-04-23 22:25 ` Nigel Cunningham
2003-04-23 23:28 ` Martin J. Bligh
2003-04-23 23:58 ` Pavel Machek
2003-04-23 23:55 ` Martin J. Bligh
2003-04-24 0:07 ` Andrew Morton
2003-04-24 0:17 ` CaT
2003-04-24 0:16 ` Nigel Cunningham
2003-04-24 0:26 ` Randy.Dunlap
2003-04-24 0:31 ` CaT
2003-04-24 0:38 ` Andrew Morton
2003-04-24 0:54 ` CaT
2003-04-24 1:06 ` Andrew Morton
2003-04-24 8:48 ` John Bradford
2003-04-24 0:37 ` Andrew Morton
2003-04-24 9:12 ` Pavel Machek
2003-04-24 9:25 ` Andrew Morton
2003-04-24 9:35 ` Pavel Machek
2003-04-24 9:46 ` Andrew Morton
2003-04-24 11:13 ` Nigel Cunningham
2003-04-24 11:36 ` Andrew Morton
2003-04-24 14:26 ` Pavel Machek
2003-04-24 16:37 ` Andreas Dilger
2003-04-24 20:48 ` Pavel Machek
2003-04-24 21:46 ` Andreas Dilger
2003-04-25 1:09 ` Nigel Cunningham [this message]
2003-04-25 12:59 ` Pavel Machek
2003-04-25 16:20 ` Andreas Dilger
2003-04-25 18:28 ` Nigel Cunningham
2003-04-25 19:32 ` Jamie Lokier
2003-04-25 19:58 ` Andreas Dilger
2003-04-27 18:59 ` Pavel Machek
2003-04-24 11:36 ` Geert Uytterhoeven
2003-04-25 1:22 ` H. Peter Anvin
2003-04-25 1:19 ` Nigel Cunningham
2003-04-25 1:31 ` Hua Zhong
2003-04-25 19:41 ` H. Peter Anvin
2003-04-25 4:27 ` Andreas Dilger
2003-04-25 4:33 ` H. Peter Anvin
2003-04-24 0:25 ` Pavel Machek
2003-04-24 9:01 ` Andrew Morton
2003-04-24 9:14 ` Pavel Machek
2003-04-24 9:05 ` Jamie Lokier
2003-04-24 9:34 ` Pavel Machek
2003-04-24 15:22 ` Carl-Daniel Hailfinger
2003-04-24 8:00 ` Marc Giger
2003-04-23 23:47 Grover, Andrew
2003-04-24 0:03 ` Pavel Machek
2003-04-23 23:57 ` Martin J. Bligh
2003-04-24 0:25 ` Pavel Machek
2003-04-24 0:37 ` CaT
2003-04-24 0:49 ` Martin J. Bligh
2003-04-24 9:16 ` Pavel Machek
2003-04-24 0:02 ` Nigel Cunningham
2003-04-24 0:23 ` Pavel Machek
2003-04-24 0:45 ` Martin J. Bligh
2003-04-24 3:17 ` Nigel Cunningham
2003-04-24 4:37 ` Martin J. Bligh
2003-04-24 7:49 ` Marc Giger
2003-04-24 9:27 ` Pavel Machek
2003-04-24 3:49 ` David Ford
2003-04-24 6:54 ` Jörn Engel
2003-04-24 7:01 ` Elladan
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