Re: [PATCH] fstest: CrashMonkey tests ported to xfstest

[Eryu Guan <guaneryu@gmail.com>]

On Fri, Nov 02, 2018 at 03:39:51PM -0500, Jayashree Mohan wrote:
> Hi Filipe,
> 
> Thanks for the feedback on the patch. Will fix the coding style as you
> suggested.
> 
> > For this type of tests, I think it's a good idea to let fsck run.
> >
> > Even if all of the links are persisted, the log/journal replay might
> > have caused metadata inconsistencies in the fs for example - this was
> > true for many cases I fixed over the years in btrfs.
> > Even if fsck doesn't report any problem now, it's still good to run
> > it, to help prevent future regressions.
> >
> > Plus this test creates a very small fs, it's not like fsck will take a
> > significant time to run.
> > So for all these reasons I would unmount and fsck after each test.

This looks reasonable to me.

> 
> Originally, there are 300 odd crash-consistency tests generated by
> CrashMonkey. To run fsck after each test, we will have to convert each
> of these tests into an equivalent xfstest test-case. We previously had
> a discussion about this, on the thread here (
> https://www.spinics.net/lists/fstests/msg10718.html ) and the
> suggestion was to batch similar tests together to reduce the external
> per-test overhead due to scrub/fsck.

You could batch similar tests together but still do fsck after each
sub-test by calling _check_scratch_fs manually, and call
_require_scratch_nocheck to indicate there's no need to do fsck at the
end of test.

> Additionally, batching similar tests will result in around 15 new test
> cases that could be added to the 'quick group', as opposed to adding
> 300 new tests.

I think we could batch similar tests and create relatively small fs
(e.g. 256M, as btrfs defaults to mixed mode if fs < 256M, and btrfs
folks wanted to test non-mixed mode by default) and run fsck after each
sub-test first, then see how long the tests take.

Thanks,
Eryu

> 
> However, if you still recommend that fsck be run after each test, I
> can submit patches for 300 individual test cases. Let me know which
> one is preferable.
> 
> Thanks,
> Jayashree.