Re: [PATCH] Refuse to install on XFS destroying its superblock

[Vladimir 'phcoder' Serbinenko]

Robert Millan wrote:
> On Sun, Oct 18, 2009 at 06:30:11PM +0200, Vladimir 'phcoder' Serbinenko wrote:
>   
>> Robert Millan wrote:
>>     
>>> On Sat, Oct 17, 2009 at 02:09:31PM +0200, Vladimir 'phcoder' Serbinenko 
>>> wrote:
>>>   
>>>       
>>>>>> The danger is that fs_probe may reject filesystem as valid just because
>>>>>> it's newer than expected.
>>>>>>     
>>>>>>         
>>>>>>             
>>>>> What do you mean with "reject filesystem as valid"?
>>>>>
>>>>>   
>>>>>       
>>>>>           
>>>> Sorry for being unclear. I just meant that if some XFS structures are
>>>> updated then our xfs driver won't recognise it as xfs
>>>>     
>>>>         
>>> What do you mean with "updated"?  You mean a new implementation of XFS?  Or
>>> the same instance of XFS that has been modified after use?
>>>
>>>   
>>>       
>> I mean next version on XFS
>>     
>
> Sorry, but what did you expect?  You want to prevent PEBCAK using
> heuristic.  There's no way we can tell if those 512 bytes are valuable
> data, only the user can.  And even if you try to err on the safest side,
> there's no garantee that newer versions of XFS, or other filesystems that
> don't even exist yet will be detectable by us no matter what we do.
>
>   
I think best way is to have whitelist of OS which have first sector free
and possible manual override like it was suggested.
> Why don't we just take a backup like someone suggested a while ago?  I
> think there was even a patch.  This way if valuable data is lost, user can
> restore it (and while at it, learnt his lesson that filesystems and embedded
> code aren't really supposed to be mixed in the same place).
>
>   
The backup is inevitably stored on the filesystem itself which becomes
inaccessible once superblock is destroyed.


-- 
Regards
Vladimir 'phcoder' Serbinenko
Personal git repository: http://repo.or.cz/w/grub2/phcoder.git