From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pavel Machek <pavel@suse.cz>
Subject: Re: Re: standby to disk transition
Date: Tue, 14 Mar 2006 21:33:50 +0100
Message-ID: <20060314203350.GG1782@elf.ucw.cz>
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To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Nigel Cunningham <nigel@suspend2.net>, linux-pm@osdl.org, linux-pm@lists.osdl.org, "Victor Porton, , , " <porton@ex-code.com>
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Hi!

> > We need to be able to rollback the state of the filesystem in memory and on 
> > disk to the point where the last checkpoint was made. Memory would be 
> > straight forward if we want to do it dumbly and slowly - just reload the 
> > whole check pointed image. If we want to be more efficient, we'd want to just 
> > load the pages that had changed (Mark on (first) write?). But filesystems 
> > seem to be a whole different story. Do any of the commonly used fses have 
> > support for checkpointing and rollback back at the moment?
> 
> I'm not sure if we need a rollback as such.  What we need is to make sure
> the filesystems state will be consistent before as well as after we have
> "reloaded" the snapshot.

Even if you make sure *kernel* is consistent with changed filesystem,
userland is going to be badly confused. Imagine what will happen with
memory mapped files, for example. 

I'm not sure how it could work...
								Pavel
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