Re: [PATCH] mmc: add module parameter to set whether cards are assumed removable

[Maxim Levitsky <maximlevitsky@gmail.com>]

On Mon, 2009-11-30 at 13:51 +0000, Alan Cox wrote: 
> > Before we do suspend, pick few random sectors from the media, run that
> > through some hash function, thus creating some sort of watermark.
> 
> Statistically speaking the chances are you'll catch zero sectors and
> lose. You'll also not detect the suspend, move to other box, use, put
> back error. That is one users make and we need to be at least vaguely
> robust against.
> 
> Hence you need the fs checking here.
> 
> Alan
I have to agree with you about that one.
An FS checking is really only solution.

Then I think such check can be added gradually to existing filesystems
(starting with fat), and allow these filesystems to persist across low
power states regardsless of CONFIG_$system_UNSAFE_RESUME

For fat, simple checksum of the 'fat' table will catch most attempts.
Also directory modification times can be compared, at least for root
directory.

Best regards,
Maxim Levitsky