Anonymous vnodes?

[Theodore Preduta <theo%pta.gg@localhost>]

Is it possible to create a vnode for a regular file in a file system
without linking the vnode to any directory, so that it disappears when
all open file descriptors to it are closed?  (As far as I can tell, this
isn't possible with any of the vn_* or VOP_* functions?)

If this idea is indeed not possible, should/could I implement something
like this?  (If so, how?)

For context, I'm currently working on implementing memfd_create(2), and
thought this might be a shortcut.  Otherwise, I'll have to implement it
in terms of uvm operations (which is fine, just more work).

Thanks,

Theo(dore)