Re: Is is possible to submit binary image as fstest test case?

[Dave Chinner <david@fromorbit.com>]

On Fri, Oct 07, 2016 at 05:26:27PM +0800, Qu Wenruo wrote:
> 
> 
> At 10/07/2016 05:18 PM, Dave Chinner wrote:
> >On Thu, Oct 06, 2016 at 04:12:56PM +0800, Qu Wenruo wrote:
> >>Hi,
> >>
> >>Just as the title says, for some case(OK, btrfs again) we need to
> >>catch a file system in special timing.
> >>
> >>In this specific case, we need to grab a btrfs image undergoing
> >>balancing, just before the balance finished.
> >>
> >>Although we can use flakey to drop all write, we still don't have
> >>method to catch the timing of the that transaction.
> >>
> >>
> >>On the other hand, we can tweak our local kernel, adding
> >>msleep()/message and dump the disk during the sleep.
> >>And the image I dumped can easily trigger btrfs kernel and user-space bug.
> >>
> >>So I'm wondering if I can just upload a zipped raw image as part of
> >>the test case?
> >
> >Preferably not. We've managed to avoid pre-built images in xfstests
> >for 15 years, so there'd have to be a really good reason to start
> >doing this, especially as once we open that floodgate we'll end up
> >with everyone wanting to do this and it will blow out the size of
> >the repository in now time.
> 
> Makes sense.
> For btrfs-progs, which includes test images, it already takes about
> 77M, even we have tried our best to reduce image size.
> 
> >
> >If the issue is just timing or being unable to trigger an error
> >at the right time, this is what error injection frameworks or
> >debug-only sysfs hooks are for. The XFS kernel code has both,
> >xfstests use both, and they pretty much do away with the need for
> >custom binary filesystem images for such testing...
> 
> So again, btrfs is lacking infrastructure for debug.
> It seems that we can only rely on images out of xfstest tree,

That's the /wrong answer/. Go and implement debug infrastructure
that btrfs needs - if you wait for someone else to do it, it will
never get done and btrfs will never stabilise....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com