[nycbug-talk] nullfs, jails and quotas

[Ray Lai]

On Thu, Jan 12, 2006 at 02:14:22PM -0500, Okan Demirmen wrote:
> On Thu 2006.01.12 at 14:09 -0500, Isaac Levy wrote:
> > Hey Charles,  All,
> > 
> > Not a very timely response, but I feel I should weigh in on this issue.
> > 
> > On Jan 9, 2006, at 7:17 PM, Charles Sprickman wrote:
> > 
> > >Here's a quick tip:
> > >
> > >Don't try using nullfs to mount /usr/ports (or anything else) into  
> > >a jail and then enable quotas on the jail's partition.  Really bad  
> > >juju there.
> > >
> > >This is on 6-stable.  On running quotacheck after killing off all  
> > >jails, that process was hung, and anything else that touched that  
> > >partition went into a "disk wait" state that was unkillable.   
> > >Running a shutdown just left the machine hanging in a not-quite- 
> > >dead state.  It seems like the kernel will block forever on any  
> > >processes waiting for that partition.  A reboot alone did not clear  
> > >it, the background fsck also hung.
> > >
> > >Just a friendly warning for anyone doing that kind of tinkering  
> > >remotely - always unmount your nullfs mounts before screwing with  
> > >quotas...
> > 
> > Nullfs is outright unsuported, as I've said during the course of  
> > several lectures on jail(8).  The man page for mount_nullfs(8) states:
> > 
> > <snip>
> > BUGS
> >      THIS FILE SYSTEM TYPE IS NOT YET FULLY SUPPORTED (READ: IT  
> > DOESN'T WORK)
> >      AND USING IT MAY, IN FACT, DESTROY DATA ON YOUR SYSTEM.  USE AT  
> > YOUR OWN
> >      RISK.  BEWARE OF DOG.  SLIPPERY WHEN WET.
> > 
> >      This code also needs an owner in order to be less dangerous -  
> > serious
> >      hackers can apply by sending mail to <hackers at FreeBSD.org> and  
> > announcing
> >      their intent to take it over.
> > <snip>
> > 
> > Charles: I'm dreadfully empathetic if this cost you time and energy.
> 
> and as ray _almost_ eluded to a bit earlier, there's a reason why the
> layered filesystems were pulled from at least openbsd.

I should have been more explicit instead of assuming everyone was
in the know. =)

-Ray-