Re: [Lsf-pc] [LSF/MM TOPIC] Working towards better power fail testing

[Jan Kara <jack@suse.cz>]

On Mon 08-12-14 17:11:41, Josef Bacik wrote:
> Hello,
> 
> We have been doing pretty well at populating xfstests with loads of
> tests to catch regressions and validate we're all working properly.
> One thing that has been lacking is a good way to verify file system
> integrity after a power fail.  This is a core part of what file
> systems are supposed to provide but it is probably the least tested
> aspect.  We have dm-flakey tests in xfstests to test fsync
> correctness, but these tests do not catch the random horrible things
> that can go wrong.  We are still finding horrible scary things that
> go wrong in Btrfs because it is simply hard to reproduce and test
> for.
> 
> I have been working on an idea to do this better, some may have seen
> my dm-power-fail attempt, and I've got a new incarnation of the idea
> thanks to discussions with Zach Brown.  Obviously there will be a
> lot changing in this area in the time between now and March but it
> would be good to have everybody in the room talking about what they
> would need to build a good and deterministic test to make sure we're
> always giving a consistent file system and to make sure our fsync()
> handling is working properly.  Thanks,
  I agree we are lacking in testing this aspect. Just I don't see too much
material for discussion there, unless we have something more tangible -
when we have some implementation, we can talk about pros and cons of it,
what still needs doing etc.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR