Comment 0 for bug 1947568

I have a zvol containing a Windows image for a virtual machine. After restarting the system a node under /dev/zvol/... was not created for the virtual disk and no amount of prompting by `udevadm trigger` helped. Instead a create a snapshot from the most recent hourly backup:

# zfs clone rpool/vm/windows/windows10/hda@hourly07 rpool/vm/windows/windows10/hda-new
# zfs promote rpool/vm/windows/windows10/hda-new
cannot promote 'rpool/vm/windows/windows10/hda-new': not a cloned filesystem
(didn't work here but carried on assuming something can be sorted later)
# zfs rename rpool/vm/windows/windows10/hda rpool/vm/windows/windows10/hda-old
# zfs rename rpool/vm/windows/windows10/hda-new rpool/vm/windows/windows10/hda

Entries in /dev appeared and I could start the virtual machine. Trying to promote the clone gives 'not a cloned filesystem' message. I later renamed the old zvol and tried to cleanup:

# zfs rename rpool/vm/windows/windows10/hda-old rpool/to-be-deleted
# zfs destroy rpool/to-be-deleted@hourly07
cannot destroy 'rpool/to-be-deleted@hourly07': snapshot has dependent clones
use '-R' to destroy the following datasets:
rpool/vm/windows/windows10/hda@hourly09
rpool/vm/windows/windows10/hda@hourly10
rpool/vm/windows/windows10/hda
# zfs promote rpool/vm/windows/windows10/hda
cannot promote 'rpool/vm/windows/windows10/hda': not a cloned filesystem

# zfs get origin rpool/vm/windows/windows10/hda
NAME PROPERTY VALUE SOURCE
rpool/vm/windows/windows10/hda origin rpool/to-be-deleted@hourly07 -

# zfs get clones rpool/to-be-deleted@hourly07
NAME PROPERTY VALUE SOURCE
rpool/to-be-deleted@hourly07 clones rpool/vm/windows/windows10/hda -

The dependency between seems to be as expected. This small test fails in the same way:

# zfs create -V1G rpool/vm/test
# zfs snapshot rpool/vm/test@test2
# zfs clone rpool/vm/test@test2 rpool/vm/test3
# zfs promote rpool/vm/test3
cannot promote 'rpool/vm/test3': not a cloned filesystem
# zfs get origin rpool/vm/test3
NAME PROPERTY VALUE SOURCE
rpool/vm/test3 origin rpool/vm/test@test2 -
# zfs get clones rpool/vm/test@test2
NAME PROPERTY VALUE SOURCE
rpool/vm/test@test2 clones rpool/vm/test3 -

All the zpool members are ONLINE and no errors are reported.

# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.3 LTS
Release: 20.04
Codename: focal

# uname -r
5.11.0-37-generic

# modinfo zfs | grep -i version
version: 2.0.2-1ubuntu5.1
srcversion: F267DF7B3FFB43AFE76257D
vermagic: 5.11.0-37-generic SMP mod_unload modversions