ufs on zvol "Filesystem is not clean..."

[Andrei Kolu]

Hello!

I am not sure I did everything correctly by creating UFS filesystem ontop of 
zpool. Should I make 10GB UFS on free space or like I did on following 
example?

# zfs create -V 10g tank/jails/ftpjail
# newfs /dev/zvol/tank/ftpjail
# mount /dev/zvol/tank/jails/ftpjail /usr/jails/ftpjail/

No complains from ZFS side- maybe it should say something like "You, stupid! 
You can't do that!"

I can create jail with ezjail:
# ezjail-admin create ftpjail 192.168.1.112
# jail /usr/jails/ftpjail ftpjail.example.com 192.168.1.112 /bin/csh
Everything works fine with jails so far until I reboot system....

Sep  5 12:18:45 freebsd7 kernel: ZFS filesystem version 6
Sep  5 12:18:45 freebsd7 kernel: ZFS storage pool version 6
Sep  5 12:18:45 freebsd7 savecore: no dumps found
Sep  5 12:18:46 freebsd7 root: /etc/rc.d/jail: WARNING: devfs_domount(): 
Unable to mount devfs on /usr/jails/ftpjail/dev
Sep  5 12:18:46 freebsd7 root: /etc/rc.d/jail: WARNING: devfs_mount_jail: 
devfs was not mounted on /usr/jails/ftpjail/dev
Sep  5 12:24:13 freebsd7 kernel: WARNING: R/W mount of /usr/jails/ftpjail 
denied.  Filesystem is not clean - run fsck

# mount /dev/zvol/tank/jails/ftpjail /usr/jails/ftpjail/
mount: /dev/zvol/tank/jails/ftpjail : Operation not permitted

# mount
/dev/ad4s1a on / (ufs, local)
devfs on /dev (devfs, local)
/dev/ad4s1e on /tmp (ufs, local, soft-updates)
/dev/ad4s1f on /usr (ufs, local, soft-updates)
/dev/ad4s1d on /var (ufs, local, soft-updates)
tank on /tank (zfs, local, noatime)
tank/usr on /tank/usr (zfs, local, noatime)
tank/jails on /usr/jails (zfs, local, noatime)
tank/usr/ports on /usr/ports (zfs, local, noatime)
tank/usr/ports/distfiles on /usr/ports/distfiles (zfs, local, noatime)
/usr/jails/basejail on /usr/jails/apachejail/basejail (nullfs, local, 
read-only)
devfs on /usr/jails/apachejail/dev (devfs, local)
fdescfs on /usr/jails/apachejail/dev/fd (fdescfs)
procfs on /usr/jails/apachejail/proc (procfs, local)

freebsd7# zpool status
  pool: tank
 state: ONLINE
 scrub: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        tank        ONLINE       0     0     0
          raidz1    ONLINE       0     0     0
            ad6     ONLINE       0     0     0
            ad8     ONLINE       0     0     0

errors: No known data errors