Re: [PATCH 00/18 V2] Repair SWAP-over-NFS

[Christoph Hellwig]

On Mon, Dec 20, 2021 at 08:07:15AM +1100, NeilBrown wrote:
> > Thanks for fixing swap-over-NFS! Looks like it passes all the
> > swap-related xfstests except for generic/357 on NFS v4.2. This test
> > checks that we get -EINVAL on a reflinked swapfile, but I'm not sure
> > if there is a way to check for that on the client side but if you have
> > any ideas it would be nice to get that test passing while you're at
> > it!
> 
> Thanks for testing!.
> I think that testing that swap fails on a reflinked file is bogus.  This
> isn't an important part of the API, it is just an internal
> implementation detail.
> I certainly understand that it could be problematic implementing swap on
> a reflinked file within XFS and it is perfectly acceptable to fail such
> a request.  But if one day someone decided to implement it - should that
> be seen as a regression?

Yes, there is really no fundamental reason not to support swap to
reflinked files, especially for NFS.  We'll need some kind of opt-in/out
for this test.