Ubuntu
zfs-linux package

  1. Bug #1837717
  2. Comment #0

Comment 0 for bug 1837717

Revision history for this message
Didier Roche-Tolomelli (didrocks) wrote :

# zpool create -o ashift=12 -O atime=off -O canmount=off -O normalization=formD -O mountpoint=/ -R /mnt rpool /dev/vda2
# zfs create rpool/ROOT -o canmount=off -o mountpoint=none
# zfs create rpool/ROOT/ubuntu_123456 -o mountpoint=/
# zfs create rpool/ROOT/ubuntu_123456/var
# zfs create rpool/ROOT/ubuntu_123456/var/lib -o canmount=off
# zfs create rpool/var -o canmount=off
# zfs create rpool/var/lib
# zfs create rpool/var/games
# zfs create rpool/ROOT/ubuntu_123456/var/lib/apt

Zfs mount is what we expect (5 datasets mounted):
# zfs mount
rpool/ROOT/ubuntu_123456 /mnt
rpool/ROOT/ubuntu_123456/var /mnt/var
rpool/var/games /mnt/var/games
rpool/var/lib /mnt/var/lib
rpool/ROOT/ubuntu_123456/var/lib/apt /mnt/var/lib/apt
# zfs umount -a

Everything unmounted as expected:
# find /mnt/
/mnt/

However, zfs mount -a doesn't mount everything in the correct order reliably:
# zfs mount -a
cannot mount '/mnt': directory is not empty
-> In that case, rpool/ROOT/ubuntu_123456 wasn't mounted:
# zfs mount
rpool/ROOT/ubuntu_123456/var /mnt/var
rpool/var/lib /mnt/var/lib
rpool/var/games /mnt/var/games
rpool/ROOT/ubuntu_123456/var/lib/apt /mnt/var/lib/apt
# find /mnt/
/mnt/
/mnt/var
/mnt/var/lib
/mnt/var/lib/apt
/mnt/var/games
# zfs umount -a
# find /mnt/
/mnt/
-> Everything was umounted, let's try to remount all again:

# zfs mount -a
cannot mount '/mnt/var/lib': failed to create mountpoint
# zfs mount
rpool/ROOT/ubuntu_123456 /mnt
rpool/ROOT/ubuntu_123456/var /mnt/var
rpool/var/games /mnt/var/games
rpool/ROOT/ubuntu_123456/var/lib/apt /mnt/var/lib/apt

-> This time, rpool/ROOT/ubuntu_123456 was mounted, but not rpool/var/lib (before rpool/ROOT/ubuntu_123456/var/lib/apt)

Tested as well with zfs 0.7: tried to zfs mount -a && zfs umount -a in loop, no issue: all datasets are mounted in the correct order reliably.

Note that it seems to be related to the version of zfs we created a pool with:
- Try zfs mount -a on zfs 0.7 with a pool/datasets created under zfs 0.8: the ordering issues occur
- Try zfs mount -a on zfs 0.8 with a pool/datasets created under zfs 0.7: no ordering issue.