nullfs on 5.1

Tim Robbins tjr at
Fri Jan 9 01:35:52 PST 2004

Florian Weimer wrote:

>I'm trying to use nullfs on FreeBSD 5.1, and run into deadlocks in quite
>simple situations (chroot to tree that contains an alias mount, read
>access to the mounted tree -- no recursive/loop mounts).  Processes get
>stuck and hang forever in D state (holding a UFS log according to ps).
One major potential deadlock has been fixed since the release of 5.1. If 
you find a reproducible way of deadlocking nullfs on  5.2 or a -current 
snapshot less than 6 months old, submit a bug report.

>Is nullfs essentially unsuported, or is it just broken?  What's the
>status of unionfs (the manpage is rather discouraging).
Nullfs is unsupported, but works well except for a few outstanding bugs 
(e.g. accessing some kinds of special files on the lower layer through 
the upper layer causes a panic). Similarly for unionfs. Umapfs is broken 
and should be avoided.


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