is read-write nullfs safe?

[Kris Kennaway]

On Tue, Jun 19, 2007 at 02:39:22PM +0800, Rong-en Fan wrote:
> On 6/19/07, Josh Paetzel <josh at tcbug.org> wrote:
> >On Tuesday 19 June 2007, Rong-en Fan wrote:
> >> I'm running 6.2-RELEASE, and I am wondering
> >> if using nullfs w/ rw is safe in a production environment?
> >> My impression is that ro nullfs is ok, but not rw.
> >> Is this still the case?
> >>
> >> Regards,
> >> Rong-En Fan
> >
> >I've been using r/w nullfs in production for ages without issue...sure
> >you're not confusing nullfs with unionfs?
> 
> I'm aware that unionfs status and I think it's usable
> in 7.x, right?
> 
> I was asking about nullfs because the following lines
> in sys/conf/NOTES:
> 
> # NB: The NULL, PORTAL, UMAP and UNION filesystems are known to be
> # buggy, and WILL panic your system if you attempt to do anything with
> # them.  They are included here as an incentive for some enterprising
> # soul to sit down and fix them.

Yeah, that's almost completely stale for both 6.x and 7.x.  nullfs is
entirely stable, and unionfs is much better (i.e. not the instant
disaster it used to be), although it still has some serious issues.  I
think umap was actually disconnected entirely from the kernel and
module build, although the code was not removed (it should be, that's
what the attic is for).  portal probably has bugs since no-one uses
it.

Kris
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