Subject: re: phasing out mfs; make init(8) use tmpfs?
To: Christos Zoulas <>
From: matthew green <>
List: tech-kern
Date: 02/17/2007 05:29:38
   In article <>,
   David Young  <> wrote:
   >On Thu, Feb 15, 2007 at 11:55:51PM +0000, Geoff Wing wrote:
   >> David Young <> typed:
   >> : Is there anywhere TMPFS cannot replace MFS, and work at least as well?
   >> : If not, is it ok if we begin to phase MFS out?
   >> It doesn't have whitespace objects (so you can't do upper layer union mounts
   >> with it).
   >Do you use union mounts in this way on /dev/, today, or is this purely
   >hypothetical?  I ask because I have never been able to rely on union
   >mounts for anything, although it is my understanding that reliably may
   >have improved with recent changes by Chuck Silvers.
   fdesc is a union mount in /dev:
   fdesc          /dev                    fdesc   rw,union         0 0

note that "union mount" and "unionfs" are separate things.  one is
"mount -t union", one is "mount -o union".

a union mount (-o) has no requirement for whiteouts...  this
functionality has been stable since ~forever.  unionfs is the
problem child.