Conditional mounting from fstab

[Micha Feigin <michf@post.tau.ac.il>]

Is it possible to get conditional mounting from fstab?

I'm trying to setup an nfs server that exports it's root as read only for
nfsroot to other systems. For that to work I mount var,tmp,home etc from each
machines local disk by mounting the local disk to /local and then mounting them
using mount --bind (using the bind fstab option). This works, only it makes the
server do some circles by mounting /dev/sda1 as root, as /local and then again
double mounting home, etc, tmp,var etc.

Is there a simple way to avoid this on the server, and/or is there any overhead
to this (if there is no access overhead then I guess that there is also no
damage)

thanks