How to VOP_RECLAIM on demand?

[Alan Somers]

It would be useful if I could trigger VOP_RECLAIM on demand for a
certain file or pathname.  There are some edge cases in fusefs that I
can't test otherwise.  But I don't see any way to do it.  Is such a
thing possible?  Would it be worth adding a special syscall for this
purpose?  It could be guarded with INVARIANTS so it wouldn't affect
production builds.
-Alan