ZFS-MOUNT-GENERATOR(8) System Manager's Manual ZFS-MOUNT-GENERATOR(8)

zfs-mount-generator — generate systemd mount units for ZFS filesystems

/lib/systemd/system-generators/zfs-mount-generator

zfs-mount-generator is a systemd.generator(7) that generates native systemd.mount(5) units for configured ZFS datasets.

=
or none.
=
off. Skipped if only noauto datasets exist for a given mountpoint and there's more than one. Datasets with take precedence over ones with noauto for the same mountpoint. Sets logical noauto flag if noauto. Encryption roots always generate zfs-load-key@root.service, even if off.
=, relatime=, =, =, =, =, =
Used to generate mount options equivalent to zfs mount.
=, keylocation=
If the dataset is an encryption root, its mount unit will bind to zfs-load-key@root.service, with additional dependencies as follows:
=
None, uses systemd-ask-password(1)
=URL (et al.)
=, After=: network-online.target
=<path>
=path
The service also uses the same Wants=, After=, Requires=, and RequiresMountsFor=, as the mount unit.
=path[ path]…
Requires= for the mount- and key-loading unit.
=path[ path]…
RequiresMountsFor= for the mount- and key-loading unit.
=unit[ unit]…
Before= for the mount unit.
=unit[ unit]…
After= for the mount unit.
=unit[ unit]…
Sets logical noauto flag (see below). If not none, sets WantedBy= for the mount unit.
=unit[ unit]…
Sets logical noauto flag (see below). If not none, sets RequiredBy= for the mount unit.
=(unset)|on|off
Waxes or wanes strength of default reverse dependencies of the mount unit, see below.
=on|off
on. Defaults to off.

Additionally, unless the pool the dataset resides on is imported at generation time, both units gain Wants=zfs-import.target and After=zfs-import.target.

Additionally, unless the logical noauto flag is set, the mount unit gains a reverse-dependency for local-fs.target of strength

(unset)
= + Before=
=
= + Before=

Because ZFS pools may not be available very early in the boot process, information on ZFS mountpoints must be stored separately. The output of

zfs list -Ho name,⟨every property above in order⟩
for datasets that should be mounted by systemd should be kept at /etc/zfs/zfs-list.cache/poolname, and, if writeable, will be kept synchronized for the entire pool by the history_event-zfs-list-cacher.sh ZEDLET, if enabled (see zed(8)).

The environment variable can either be (default), (print summary accounting information at the end), or at least 2 (print accounting information for each subprocess as it finishes). If not present, /proc/cmdline is additionally checked for "debug", in which case the debug level is set to 2.

To begin, enable tracking for the pool:

# touch /etc/zfs/zfs-list.cache/poolname
Then enable the tracking ZEDLET:
# ln -s /usr/lib/zfs-linux/zed.d/history_event-zfs-list-cacher.sh /etc/zfs/zed.d
# systemctl enable zfs-zed.service
# systemctl restart zfs-zed.service

If no history event is in the queue, inject one to ensure the ZEDLET runs to refresh the cache file by setting a monitored property somewhere on the pool:

# zfs set relatime=off poolname/dset
# zfs inherit relatime poolname/dset

To test the generator output:

$ mkdir /tmp/zfs-mount-generator
$ /lib/systemd/system-generators/zfs-mount-generator /tmp/zfs-mount-generator
If the generated units are satisfactory, instruct systemd to re-run all generators:
# systemctl daemon-reload

systemd.mount(5), systemd.target(5), zfs(5), systemd.generator(7), systemd.special(7), zed(8), zpool-events(8)

May 31, 2021 OpenZFS