Todd Vierling writes:
> I proposed something like this a while ago, and now that I have a little
> time to get some pending ideas done, I'd like to propose a ffs (and related
> fs's) mount option that can turn on SVR4-style directory entry gid handling.
> That is, files created in a directory have the owner's default gid, not the
> gid of the directory, unless the directory itself is set-gid.
> 
> This would also involve adding appropriate set-gid bits to the base mtree
> files, so that the proper places would work as expected if the option were
> turned on for /.


I've actually filed a PR (kern/7731) about our NFS client not supporting
the opposite behaviour; i.e, files created on an NFS mount get your
base gid and not that of the parent directory *unless* g+s is set.

Solaris provides a `grpid' mount_nfs option. I'd like to see that in
our NFS code, and on by default (for consistency with ffs and BSD
semantics). I suppose that your proposal could then be implemented
with a `nogrpid' flag.