vnode refcnt bug?

[Ian Dowse]

In message <200311252122.hAPLMRfE018534 at agora.fsl.cs.sunysb.edu>, Erez Zadok wr
ites:
>Hmmm, yes I think that could be a serious problem (esp. since fbsd doesn't
>have autofs yet).  And I think it deviates from "norms" where a cwd is
>essentially occupying a vnode within the mounted f/s and therefore the f/s
>shouldn't be unmounted!  This is rather bad for users who sit on an nfs mnt
>point, ls'ing files happily, and then the kernel unmounts the mnt pt, moves
>their cwd down to the covered (typically empty) vnode, and the poor user's
>next /bin/ls shows nothing.

Yes, I agree completely - however the question of what to do with
references to about-to-be-covered vnodes at mount time still remains.
I'll have to look in more detail at why the checkdirs() approach
was needed in the first place to see if simply removing it is an
option.

Any other approaches I can think of right now for solving this issue
appear to either extend the original checkdirs() hack, or else just
replace one kind of undesirable behaviour with another.

Ian