safe resuming: automatically invalidating an outdated hibernate snapshot

safe resuming: automatically invalidating an outdated hibernate snapshot

[Martin Steigerwald]

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Cc to linux-kernel: This is mainly for tuxonice, but it might also be relevant 
for other hibernate implementations. Maybe some general mechanism for 
checking whether an on disk snapshot of the system is current would be good - 
as also the resume parameter could be missing or wrong or whatnot.


Hi!

Is there a way to automatically invalidate the tuxonice snapshot when a non 
tuxonice kernel is booted accidentally? I.e. could tuxonice recognize when 
the swap partition has been accessed *after* the snapshot has been written?

It happened here several times that someone booted the wrong kernel and then 
someone else booted the right one again. TuxOnIce would then resume from a 
snapshot that it not up-to-date anymore. This leads to filesystem breakage as 
the filesystem slab objects and other in memory structures would not 
represent the current state of the filesystem on disk. xfs_repair did a 
marvellous job on these occassions and I already changed menu.lst to hide the 
GRUB boot menu by default, but it would be better if this case of  
maloperation can be intercepted.

Ciao,
-- 
Martin Steigerwald - team(ix) GmbH - http://www.teamix.de
gpg: 19E3 8D42 896F D004 08AC A0CA 1E10 C593 0399 AE90

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Re: [TuxOnIce-devel] safe resuming: automatically invalidating an outdated hibernate snapshot

[Nigel Cunningham]

Hi Martin.

On Mon, 2008-10-13 at 12:13 +0200, Martin Steigerwald wrote:
> Cc to linux-kernel: This is mainly for tuxonice, but it might also be relevant 
> for other hibernate implementations. Maybe some general mechanism for 
> checking whether an on disk snapshot of the system is current would be good - 
> as also the resume parameter could be missing or wrong or whatnot.
> 
> 
> Hi!
> 
> Is there a way to automatically invalidate the tuxonice snapshot when a non 
> tuxonice kernel is booted accidentally? I.e. could tuxonice recognize when 
> the swap partition has been accessed *after* the snapshot has been written?
> 
> It happened here several times that someone booted the wrong kernel and then 
> someone else booted the right one again. TuxOnIce would then resume from a 
> snapshot that it not up-to-date anymore. This leads to filesystem breakage as 
> the filesystem slab objects and other in memory structures would not 
> represent the current state of the filesystem on disk. xfs_repair did a 
> marvellous job on these occassions and I already changed menu.lst to hide the 
> GRUB boot menu by default, but it would be better if this case of  
> maloperation can be intercepted.

The simplest way is to mkswap the appropriate partitions from a script
run when booting (after we check whether to resume, of course). I
believe the hibernate script already has support for this. Maybe
pm-utils or such like needs it too?

Nigel