Bill Studenmund <wrstuden@netbsd.org> writes:

> vnodes in general are expensive to build. I think it's good for us
> to keep them around.

I'm not sure nullfs is in the general case.  At least cost of building
vnode may differ between file systems.

> To fix it means changing the vnode interface (we need to add a way
> for upper vnodes to register themselves, and for lower ones to send
> info to upper ones).

Or, implement cache without keeping reference to lower vnode (as
commented in source).  Is keeping reference just for caching really
good?

> Oh, the problem with your proposed patch for 1555 is what happens when we
> have multiple layers.

Hm, I agree that the my patch was incomplete (or incorrect).

enami.