Re: [PATCH 0/4] FS: userspace notification of errors

[Pavel Machek <pavel@ucw.cz>]

On Thu 2009-06-04 08:57:58, Artem Bityutskiy wrote:
> Andrew Morton wrote:
>> hm, I'm uncertain on the desirability or otherwise of the overall feature.
>>
>> Are there users or distros or device manufacturers asking for this?  
>> Where did the requirement come from?
>>
>> What downstream application will handle the uevent messages?  Do you
>> have some userspace design/plan in mind?
>>
>> IOW, it would be useful if we were told more about all of this, rather
>> than just staring at a kernel patch!
>
> As the original idea came from me, while whole implementation
> and design was done by Denis, I'll comment on this.
>
> Our use-case is about hand-held devices. We are particularly
> working with large FAT volumes on MMC. Do not question please
> why it is FAT and not something else :-) Anyway, FAT is very
> unreliable, and often hits errors, in which case it simply
> switches to read-only mode, and usually prints something to
> the printk ring buffer.

So fsck the mmc card on card insertion...? fsck.vfat on flash is
pretty fast operation (as it onl needs to read directories +
FATs). Android 1.5 implements this.

...otherwise you will loose data on two files sharing clusters, will
never recover lost clusters, etc.

Perhaps it would be feasible  to permit read-only mount of unclean
VFAT, run fsck in background, and buffer any changes in memory until
fsck finishes?

									Pavel

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