Wrongly implemented InodeData refcounting can increase refcount from 0 to 1
The code at https://gitlab.com/virtio-fs/virtiofsd/-/blob/50ffd53962ffe10bc18760d91f21eae79bb7f42c/src/passthrough/mod.rs#L775 can increase the refcount from 0 to 1.
In this case, the consequence is that in self.do_lookup()
we return an InodeData that is no longer in the self.inodes
map. It probably doesn't violate any invariant we have, and hence it probably doesn't lead to a panic or the like. But it's nevertheless a behavior that's unexpected (and probably unintended by the programmer of that line).