Re: [PATCH] xfs: test log recovery for extent frees right after growfs

[Christoph Hellwig <hch@lst.de>]

On Tue, Sep 10, 2024 at 10:19:50AM -0400, Brian Foster wrote:
> No real issue with the test, but I wonder if we could do something more
> generic. Various XFS shutdown and log recovery issues went undetected
> for a while until we started adding more of the generic stress tests
> currently categorized in the recoveryloop group.
> 
> So for example, I'm wondering if you took something like generic/388 or
> 475 and modified it to start with a smallish fs, grew it in 1GB or
> whatever increments on each loop iteration, and then ran the same
> generic stress/timeout/shutdown/recovery sequence, would that eventually
> reproduce the issue you've fixed? I don't think reproducibility would
> need to be 100% for the test to be useful, fwiw.
> 
> Note that I'm assuming we don't have something like that already. I see
> growfs and shutdown tests in tests/xfs/group.list, but nothing in both
> groups and I haven't looked through the individual tests. Just a
> thought.

It turns out reproducing this bug was surprisingly complicated.
After a growfs we can now dip into reserves that made the test1
file start filling up the existing AGs first for a while, and thus
the error injection would hit on that and never even reach a new
AG.

So while agree with your sentiment and like the highlevel idea, I
suspect it will need a fair amount of work to actually be useful.
Right now I'm too busy with various projects to look into it
unfortunately.