Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread freezer

[Rafael J. Wysocki]

On Tuesday, November 03, 2015 11:10:53 AM Dave Chinner wrote:
> On Mon, Nov 02, 2015 at 03:43:07AM +0100, Rafael J. Wysocki wrote:
> > I guess it may also helps to address the case when a device is removed from a
> > suspended system, written to on another system in the meantime and inserted
> > back into the (still suspended) original system which then is resumed.  Today
> > this is an almost guaranteed data corruption scenario, but if the filesystem in
> > question is properly frozen during suspend, the driver should be able to detect
> > superblock changes during unfreeze.
> 
> Never going to work. There is no guarantee that a write to a
> filesystem by a third party device is going to change the superblock
> (or any metadata in the rest of the filesystem) in any detectable
> way.  Hence freezing filesystems will not prevent Bad Things
> Happening if you do this while your system is suspended.

OK, thanks for the clarification.

Cheers,
Rafael

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