zfs-mount-generator(8)

ZFS-MOUNT-GENERATOR(8)

System Manager's Manual

ZFS-MOUNT-GENERATOR(8)

NAME

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

SYNOPSIS

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

DESCRIPTION

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

Properties

mountpoint=

Skipped if legacy or none.

canmount=

Skipped if off. Skipped if only noauto datasets exist for a given mountpoint and there's more than one. Datasets with yes 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.

atime=, relatime=, devices=, exec=, readonly=, setuid=, nbmand=

Used to generate mount options equivalent to zfs mount.

encroot=, keylocation=

If the dataset is an encryption root, its mount unit will bind to zfs-load-key@root.service, with additional dependencies as follows:

keylocation=prompt: None, uses systemd-ask-password(1)
keylocation=https://URL (et al.): Wants=, After=: network-online.target
keylocation=file://<path>: RequiresMountsFor=path

The service also uses the same Wants=, After=, Requires=, and RequiresMountsFor=, as the mount unit.

org.openzfs.systemd:requires=path[ path]…

Sets Requires= for the mount- and key-loading unit.

org.openzfs.systemd:requires-mounts-for=path[ path]…

Sets RequiresMountsFor= for the mount- and key-loading unit.

org.openzfs.systemd:before=unit[ unit]…

Sets Before= for the mount unit.

org.openzfs.systemd:after=unit[ unit]…

Sets After= for the mount unit.

org.openzfs.systemd:wanted-by=unit[ unit]…

Sets logical noauto flag (see below). If not none, sets WantedBy= for the mount unit.

org.openzfs.systemd:required-by=unit[ unit]…

Sets logical noauto flag (see below). If not none, sets RequiredBy= for the mount unit.

org.openzfs.systemd:nofail=(unset)|on|off

Waxes or wanes strength of default reverse dependencies of the mount unit, see below.

org.openzfs.systemd:ignore=on|off

Skip if on. Defaults to off.

Unit Ordering And Dependencies

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): WantedBy= + Before=
on: WantedBy=
off: RequiredBy= + Before=

Cache File

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)).

ENVIRONMENT

If the ZFS_DEBUG environment variable is nonzero (or unset and /proc/cmdline contains "debug"), print summary accounting information at the end.

EXAMPLES

To begin, enable tracking for the pool:

# touch
  /etc/zfs/zfs-list.cache/poolname

Then enable the tracking ZEDLET:

# ln
  -s
  /usr/libexec/zfs/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