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

[Josef Bacik <jbacik@fb.com>]

On 12/10/2014 06:27 AM, Jan Kara wrote:
> 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.
>

Right that's what I was getting at.  I have a solution and have sent it 
around but there doesn't seem to be too many people interested in 
commenting on it.  I figure one of two things will happen

1) My solution will go in before LSF, in which case YAY my job is done 
and this is more of an [ATTEND] than a [TOPIC], or

2) My solution hasn't gone in yet and I'd like to discuss my methodology 
and how we can integrate it into xfstests, future features, other areas 
we could test etc.

Maybe not a full blown slot but combined with a overall testing slot or 
hell just a quick lightening talk.  Thanks,

Josef