Re: UBI/UBIFS interrupted write page handling

[Matthieu CASTET <matthieu.castet@parrot.com>]

Hi Artem,

Artem Bityutskiy a écrit :
> On Thu, 2010-09-09 at 20:51 +0300, Artem Bityutskiy wrote:
>>> On one of our test, we are in case 3. Ubifs find a valid interrupt page 
>>> on mount and trust it. Latter the page become corrupted [1] because it 
>>> is unstable.
>> OK, I see.
>>
>>> To identify a interrupted write page we :
>>> - could use interrupted flags for static volume
>>> - handle with care data move (copy flags) : if sqnum of the copy is the 
>>> biggest, we should ignore it/copy it.
>>> - use upper layer for dynamic volume. For ubifs this could be a journal.
>> Actually, for UBIFS things are rather simple. In UBIFS every writes go
>> to the journal. Even GC writes to the journal. So when we are mounting
>> after an unclean reboot, we can simply refresh the last LEBs of all
>> journal heads using the 'ubi_leb_change()' call. This should handle all
>> the three cases you describe.
>>
>> I do not think it is very difficult to do.
> 
> Matthieu, I can try to do to make some patches for you, but when you
> come back on-line and start actively testing :-) I do want to help you
> and improve UBIFS, but I'm not very motivated to do this unless this is
> really needed. I think we have few other pending issues, and the ball is
> on your side. :-)
> 
Ok.

I will run some tests this weekend.

What I have to test ?

- 
http://git.infradead.org/users/dedekind/ubifs-v2.6.28.git/commit/7240a7396fa4b1998d0463123c6d1d192935f969
- UBI reliability improvements patch
- c->gc_lnum is -1 patch

thanks,

Matthieu