for VOP_GETATTR() and VOP_SETATTR(), reference VOP_NULL() to suggest
clearing all of *vap with it before setting specific values. Cross
reference VFS(9). Indicate that failure modes are possible from
VOP_GETATTR() and that an errno value is returned.
Submitted by: Hiten Pandya <hiten@uk.FreeBSD.org>
while the other half used `vap', and in one case resulted in code that
made no sense. Replaced all of them with `vap'.
(Typically, `vpp' is a pointer to a pointer to a struct vnode anyway).
incomplete and some are just placeholders but I wanted to try to get
something at least into 2.2 on the grounds that what I have is a lot
better than nothing. I also wanted to commit something which documents
the interfaces in 2.2 before I start updating the documentation for 3.0.
This is a definite 2.2 candidate and is also relavent to 2.1 if people
still care about that branch.
