On Mon, Jun 29, 2009 at 04:38:50PM -0700, Glenn Faden wrote: > Nicolas Williams wrote: > >Well, it doesn't have to be possible. Instead it should be possible to > >have the mount(2) syscall detect the loopback NFS and convert it into a > >lofs mount if, say, a flag is set in the arguments, or even by default. > > I've thought about doing this in the past, but wasn't sure that it would > work. The automounter is has some special processing for NFS, and I > don't know what would happen if a requested NFS mount got turned into sa > LOFS mount. For example, the automounter attempts to unmount anything it > mounted that is no longer busy. So, it might also be necessary to modify > the umount syscall to translate NFS umounts to LOFS umounts. > > Then there is the issue of the automounter looking up entries in > /etc/mnttab. It might get confused when looking for NFS entries that > were turned into LOFS.
Perhaps there's the answer: > >That would work transparently for the automounter. Though it the > >automounter were not calling mount(2) directly, but instead passing back > >mount info to the autofs kernel module caller (which it does for some fs > >types), then the autofs module would need to know how to convert the > >mount to a lofs mount. > > > Note that cross-zone LOFS mounts have a fictitious value for "special" > when viewed in the zone's /etc/mnttab. Instead of the actaul global zone > pathname, the special is represented as a duplicate of the zone-relative > mountpoint. So it's not obvious how the automounter can do a useful > conversion. Do the NFS->lofs conversion on mount (and, if need be, umount), but pretend in mnttab that the mount was an NFS mount. This way the user-land automounter code would need no changes at all. > For this to work, the kernel would have to internally do a LOFS mount > but somehow make it appear externally that it is an NFS mount. Yup. Nico -- _______________________________________________ zones-discuss mailing list firstname.lastname@example.org