Date: Mon, 16 May 2016 13:29:38 +0000 From: Grzegorz Junka <list1@gjunka.com> To: freebsd-jail@freebsd.org Subject: Jails and unionfs Message-ID: <63df6e06-ebac-fe44-ca70-5d2a9e78967b@gjunka.com>
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I have been using unionfs to host jails for quite a while now and in
general they work as expected, apart from three issues. The setup is as
below (example for one jail dev2):
_*jail.conf*_
exec.start = "/bin/sh /etc/rc";
exec.stop = "/bin/sh /etc/rc.shutdown";
exec.clean;
mount.devfs;
mount.fstab = "/usr/local/etc/fstab/$name";
devfs_ruleset = 4;
path = "/j/$name";
host.hostname = "$name.*myhost*.*mydomain*.com";
exec.consolelog = "/var/log/jail/$name";
dev2 {
ip4.addr = 192.168.1.71;
interface = lagg0;
}
_*/usr/local/etc/fstab/dev2*_
/j/_ro3 /j/dev2 nullfs ro 0 0
/j/_dev2 /j/dev2 unionfs rw,noatime 0 0
devfs /j/dev2/dev devfs rw,ruleset=4 0 0
_*df gives*_
tank1/j/_dev2 1198584120 131255 1198452864 0%
/j/_dev2
/j/_ro3 1198722545 269680 1198452864 0% /j/dev2
<above>:/j/_dev2 2397306665 1198853800 1198452864 50% /j/dev2
devfs 1 1 0 100% /j/dev2/dev
devfs 1 1 0 100% /j/dev2/dev
_*zfs list | grep dev2*_
tank1/j/_dev2 128M 1.12T 128M /j/_dev2
As can be seen I need to mount devfs twice, once in jail.conf and once
in the jail's fstab, otherwise it isn't mounted at all. That's the first
(smaller) issue.
The second issue is that the disks are not mounted/unmounted
automatically when I start/stop the jail. To make sure that all disks
are mounted properly after starting a jail I need to:
mount -F /usr/local/etc/fstab/dev2 -a
When stopping the jail sometimes the disks are unmounted but sometimes I
have to:
umount -F /usr/local/etc/fstab/dev2 -a
But the third, most annoying issue is that if I forget to unmount all
disks after stopping a jail and then I start the jail, the unionfs is
mounted twice. Once that happens and I need to stop the jail, unmounting
disks for that jail causes kernel panic.
Does anyone have experience with that setup? Are those issues known and
are there any possible fixes or workarounds?
Grzegorz
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