It looks like there are still some serious problems with this. I just
tried a similar thing on FreeBSD 4.4 and 4.5. I created a directory of
binaries to use for multiple jails, then null-mounted (read-only) the
binaries for each of the jails to use. To allow the /etc and other
parts of the jails to be written, I union-mounted a per-jail writeable
filesystem over each of the null mounts. It seemed to work well until
If I'm not mistaken, nullfs had been fixed significantly in -current, but
the changes were not MFC'd... I'm not entirely sure on this, you might
Boy, that was an old message I sent out...
Anyway, I didn't see any significant nullfs changes in -current (grabbing
updates as we speak in case something has come in the last day or two),
but a couple unionfs files seem to have been updated, though nothing is
blindingly obvious to me... I had buildworld failures both with -stable
and -current the last I tried, and possibly panics in -current that were
enough to scare me away from this way of doing things.
Oh, I remember what scared me away... Let's `ls' as a normal user my
mounted filesystem:
bash-2.05a$ ls -lart
ls: bin: Permission denied
ls: contrib: Permission denied
ls: crypto: Permission denied
ls: etc: Permission denied
ls: games: Permission denied
ls: gnu: Permission denied
ls: include: Permission denied
ls: kerberos5: Permission denied
ls: kerberosIV: Permission denied
ls: lib: Permission denied
ls: libexec: Permission denied
ls: release: Permission denied
ls: sbin: Permission denied
ls: secure: Permission denied
ls: share: Permission denied
ls: tools: Permission denied
ls: usr.bin: Permission denied
total 210
-rw-r--r--1 root wheel 9761 Aug 28 1999 Makefile.upgrade
-rw-r--r--1 root wheel 4735 Sep 5 1999 COPYRIGHT
-rw-r--r--1 root wheel 2678 Aug 31 2000 README
-rw-r--r--1 root wheel 7494 Mar 27 2001 Makefile
drwxr-xr-x 163 root wheel512 Dec 27 03:10 usr.sbin
drwxr-xr-x 163 root wheel512 Dec 27 03:10 usr.sbin
-rw-r--r--1 root wheel 25868 Dec 29 04:04 Makefile.inc1
drwxr-xr-x 51 root wheel512 Jan 2 03:07 sys
drwxr-xr-x 51 root wheel512 Jan 2 03:07 sys
-rw-r--r--1 root wheel 51200 Jan 25 10:19 UNHACKS.tar
-rw-r--r--1 root wheel 51200 Jan 25 10:23 HACKS.tar
-rw-r--r--1 root wheel 35654 Feb 6 18:44 UPDATING
drwxr-xr-x4 root wheel512 Feb 7 16:30 DIST
drwxr-xr-x 27 root wheel512 Feb 7 16:32 .
drwxr-xr-x 27 root wheel512 Feb 7 16:32 .
drwxr-xr-x4 root wheel512 Feb 7 16:33 HACKS
drwxr-xr-x 18 root wheel512 Feb 7 22:33 ..
drwxr-xr-x 18 root wheel512 Feb 7 22:33 ..
bash-2.05a$ ls /usr/local/system/src
(needless to say, this command on the orig nullfs mount, plus on the
original unionfs mount, work splendidly, and I don't see this problem
that I know of with -stable) Also, getcwd() still fails in -current too.
I've tried things like `truss'ing the failed `make' and such commands
on my union-atop-nullfs mount tree, to see if I can make sense of what
might be failing as the commands work their way up to the root of the
directory. Whatever I see, it's not enough for me to be able to say if
the problem is in nullfs or unionfs or elsewhere like getcwd() for my
failure. (My -stable failure. -current looks like more a nightmare.)
I do, however, have no problem with a simple nullfs mount, though I have
not yet tried a simple unionfs mount, which I guess I can do now...
(Not that my problem is related to Hr Helmer's)
thanks
barry bouwsma
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