ecbbdac799
This commit refactors the systemd mount generators and makes the
following major changes:
- The generator now generates units for datasets marked canmount=noauto,
too. These units are NOT WantedBy local-fs.target.
If there are multiple noauto datasets for a path, no noauto unit will
be created. Datasets with canmount=on are prioritized.
- Introduces handling of new user properties which are now included in
the zfs-list.cache files:
- org.openzfs.systemd:requires:
List of units to require for this mount unit
- org.openzfs.systemd:requires-mounts-for:
List of mounts to require by this mount unit
- org.openzfs.systemd:before:
List of units to order after this mount unit
- org.openzfs.systemd:after:
List of units to order before this mount unit
- org.openzfs.systemd:wanted-by:
List of units to add a Wants dependency on this mount unit to
- org.openzfs.systemd:required-by:
List of units to add a Requires dependency on this mount unit to
- org.openzfs.systemd:nofail:
Toggles between a wants and a requires dependency.
- org.openzfs.systemd:ignore:
Do not generate a mount unit for this dataset.
Consult the updated man page for detailed documentation.
- Restructures and extends the zfs-mount-generator(8) man page with the
above properties, information on unit ordering and a license header.
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Antonio Russo <antonio.e.russo@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: InsanePrawn <insane.prawny@gmail.com>
Closes #9649
249 lines
6.7 KiB
Groff
249 lines
6.7 KiB
Groff
.\"
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.\" Copyright 2018 Antonio Russo <antonio.e.russo@gmail.com>
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.\" Copyright 2019 Kjeld Schouten-Lebbing <kjeld@schouten-lebbing.nl>
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.\" Copyright 2020 InsanePrawn <insane.prawny@gmail.com>
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.\"
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.\" Permission is hereby granted, free of charge, to any person obtaining
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.\" a copy of this software and associated documentation files (the
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.\" "Software"), to deal in the Software without restriction, including
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.\" without limitation the rights to use, copy, modify, merge, publish,
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.\" distribute, sublicense, and/or sell copies of the Software, and to
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.\" permit persons to whom the Software is furnished to do so, subject to
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.\" the following conditions:
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.\"
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.\" The above copyright notice and this permission notice shall be
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.\" included in all copies or substantial portions of the Software.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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.\" EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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.\" NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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.\" LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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.\" OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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.\" WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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.TH "ZFS\-MOUNT\-GENERATOR" "8" "2020-01-19" "ZFS" "zfs-mount-generator" "\""
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.SH "NAME"
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zfs\-mount\-generator \- generates systemd mount units for ZFS
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.SH SYNOPSIS
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.B @systemdgeneratordir@/zfs\-mount\-generator
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.sp
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.SH DESCRIPTION
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zfs\-mount\-generator implements the \fBGenerators Specification\fP
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of
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.BR systemd (1),
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and is called during early boot to generate
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.BR systemd.mount (5)
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units for automatically mounted datasets. Mount ordering and dependencies
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are created for all tracked pools (see below).
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.SS ENCRYPTION KEYS
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If the dataset is an encryption root, a service that loads the associated key (either from file or through a
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.BR systemd\-ask\-password (1)
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prompt) will be created. This service
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. BR RequiresMountsFor
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the path of the key (if file-based) and also copies the mount unit's
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.BR After ,
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.BR Before
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and
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.BR Requires .
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All mount units of encrypted datasets add the key\-load service for their encryption root to their
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.BR Wants
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and
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.BR After .
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The service will not be
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.BR Want ed
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or
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.BR Require d
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by
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.BR local-fs.target
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directly, and so will only be started manually or as a dependency of a started mount unit.
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.SS UNIT ORDERING AND DEPENDENCIES
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mount unit's
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.BR Before
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\->
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key\-load service (if any)
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\->
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mount unit
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\->
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mount unit's
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.BR After
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It is worth nothing that when a mount unit is activated, it activates all available mount units for parent paths to its mountpoint, i.e. activating the mount unit for /tmp/foo/1/2/3 automatically activates all available mount units for /tmp, /tmp/foo, /tmp/foo/1, and /tmp/foo/1/2. This is true for any combination of mount units from any sources, not just ZFS.
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.SS CACHE FILE
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Because ZFS pools may not be available very early in the boot process,
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information on ZFS mountpoints must be stored separately. The output of the command
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.PP
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.RS 4
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zfs list -H -o name,mountpoint,canmount,atime,relatime,devices,exec,readonly,setuid,nbmand,encroot,keylocation,org.openzfs.systemd:requires,org.openzfs.systemd:requires-mounts-for,org.openzfs.systemd:before,org.openzfs.systemd:after,org.openzfs.systemd:wanted-by,org.openzfs.systemd:required-by,org.openzfs.systemd:nofail,org.openzfs.systemd:ignore
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.RE
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.PP
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for datasets that should be mounted by systemd, should be kept
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separate from the pool, at
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.PP
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.RS 4
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.RI @sysconfdir@/zfs/zfs-list.cache/ POOLNAME
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.
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.RE
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.PP
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The cache file, if writeable, will be kept synchronized with the pool
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state by the ZEDLET
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.PP
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.RS 4
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history_event-zfs-list-cacher.sh .
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.RE
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.PP
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.sp
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.SS PROPERTIES
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The behavior of the generator script can be influenced by the following dataset properties:
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.sp
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.TP 4
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.BR canmount = on | off | noauto
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If a dataset has
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.BR mountpoint
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set and
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.BR canmount
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is not
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.BR off ,
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a mount unit will be generated.
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Additionally, if
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.BR canmount
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is
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.BR on ,
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.BR local-fs.target
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will gain a dependency on the mount unit.
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This behavior is equal to the
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.BR auto
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and
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.BR noauto
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legacy mount options, see
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.BR systemd.mount (5).
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Encryption roots always generate a key-load service, even for
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.BR canmount=off .
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.TP 4
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.BR org.openzfs.systemd:requires\-mounts\-for = \fIpath\fR...
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Space\-separated list of mountpoints to require to be mounted for this mount unit
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.TP 4
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.BR org.openzfs.systemd:before = \fIunit\fR...
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The mount unit and associated key\-load service will be ordered before this space\-separated list of units.
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.TP 4
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.BR org.openzfs.systemd:after = \fIunit\fR...
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The mount unit and associated key\-load service will be ordered after this space\-separated list of units.
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.TP 4
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.BR org.openzfs.systemd:wanted\-by = \fIunit\fR...
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Space-separated list of units that will gain a
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.BR Wants
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dependency on this mount unit.
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Setting this property implies
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.BR noauto .
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.TP 4
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.BR org.openzfs.systemd:required\-by = \fIunit\fR...
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Space-separated list of units that will gain a
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.BR Requires
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dependency on this mount unit.
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Setting this property implies
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.BR noauto .
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.TP 4
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.BR org.openzfs.systemd:nofail = unset | on | off
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Toggles between a
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.BR Wants
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and
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.BR Requires
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type of dependency between the mount unit and
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.BR local-fs.target ,
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if
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.BR noauto
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isn't set or implied.
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.BR on :
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Mount will be
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.BR WantedBy
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local-fs.target
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.BR off :
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Mount will be
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.BR Before
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and
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.BR RequiredBy
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local-fs.target
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.BR unset :
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Mount will be
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.BR Before
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and
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.BR WantedBy
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local-fs.target
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.TP 4
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.BR org.openzfs.systemd:ignore = on | off
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If set to
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.BR on ,
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do not generate a mount unit for this dataset.
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.RE
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See also
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.BR systemd.mount (5)
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.PP
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.SH EXAMPLE
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To begin, enable tracking for the pool:
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.PP
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.RS 4
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touch
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.RI @sysconfdir@/zfs/zfs-list.cache/ POOLNAME
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.RE
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.PP
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Then, enable the tracking ZEDLET:
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.PP
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.RS 4
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ln -s "@zfsexecdir@/zed.d/history_event-zfs-list-cacher.sh" "@sysconfdir@/zfs/zed.d"
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systemctl enable zfs-zed.service
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systemctl restart zfs-zed.service
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.RE
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.PP
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Force the running of the ZEDLET by setting a monitored property, e.g.
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.BR canmount ,
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for at least one dataset in the pool:
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.PP
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.RS 4
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zfs set canmount=on
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.I DATASET
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.RE
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.PP
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This forces an update to the stale cache file.
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To test the generator output, run
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.PP
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.RS 4
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@systemdgeneratordir@/zfs-mount-generator /tmp/zfs-mount-generator . .
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.RE
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.PP
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This will generate units and dependencies in
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.I /tmp/zfs-mount-generator
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for you to inspect them. The second and third argument are ignored.
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If you're satisfied with the generated units, instruct systemd to re-run all generators:
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.PP
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.RS 4
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systemctl daemon-reload
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.RE
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.PP
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.sp
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.SH SEE ALSO
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.BR zfs (5)
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.BR zfs-events (5)
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.BR zed (8)
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.BR zpool (5)
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.BR systemd (1)
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.BR systemd.target (5)
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.BR systemd.special (7)
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.BR systemd.mount (7)
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