[Unionfs] Can't make branch read only

[Herton Ronaldo Krzesinski]

Em Thursday 25 October 2007 16:20:19 Erez Zadok escreveu:
> In message <200710251149.32474.herton at mandriva.com.br>, Herton Ronaldo 
Krzesinski writes:
> > > Strange, now I tried a stock kernel and still get this behaviour, it's
> > > a 2.6.22.9 kernel with just unionfs-2.1.7_for_2.6.22.10.diff.gz
> > > applied, config attached.
> >
> > Found some more time to debug this, and I discovered the following, with
> > "mount -t unionfs -o remount,mode=/live/foo=ro none /live/union" for some
> > reason it fails as I told, but doing:
> > "mount -o remount,mode=/live/foo=ro unionfs /live/union" I get the
> > expected behaviour. Note the slightly changes, I just don't use "-t"
> > anymore and none is replaced by unionfs. Can be a bug in our mount (from
> > util-linux-ng-2.13.0.1) or in kernel itself, I didn't found out yet (or
> > is just this way and we are using mount wrongly).
>
> Can you run strace on mount(8) and see if it's producing different output?
> I'm using /bin/mount from util-linux-2.13.  I'd say if utils-linux-ng
> changed the behavior of "none" or "mode=" then this could cause a lot of
> trouble to others as well.

yeah, the problem is with mount:
with mount -t...
25523 mount("none", "/live/union", 0x80660d0, MS_MGC_VAL|MS_REMOUNT, "") = 0

with the invocation that works...
25528 mount("unionfs", "/live/union", NULL, MS_MGC_VAL|MS_REMOUNT, "mode=/live/foo=ro") = 0

>
> Thanks,
> Erez.

--
[]'s
Herton