[nycbug-talk] nullfs, jails and quotas

[Isaac Levy]

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.

Rocket-
.ike