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Systemd mount generator: Generate noauto units; add control properties

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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
This commit is contained in:
InsanePrawn
2020-02-12 18:01:15 +01:00
committed by Brian Behlendorf
parent 9d2f3b7f94
commit ecbbdac799
4 changed files with 386 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files
man/man8/Makefile.am
+1
View File
@@ -89,6 +89,7 @@ EXTRA_DIST = \
$(nodist_man_MANS): %: %.in
-$(SED) -e 's,@zfsexecdir\@,$(zfsexecdir),g' \
-e 's,@systemdgeneratordir\@,$(systemdgeneratordir),g' \
-e 's,@runstatedir\@,$(runstatedir),g' \
-e 's,@sysconfdir\@,$(sysconfdir),g' \
$< >'$@'
man/man8/zfs-mount-generator.8.in
+181 -16
View File
@@ -1,8 +1,33 @@
.TH "ZFS\-MOUNT\-GENERATOR" "8" "ZFS" "zfs-mount-generator" "\""
.\"
.\" Copyright 2018 Antonio Russo <antonio.e.russo@gmail.com>
.\" Copyright 2019 Kjeld Schouten-Lebbing <kjeld@schouten-lebbing.nl>
.\" Copyright 2020 InsanePrawn <insane.prawny@gmail.com>
.\"
.\" Permission is hereby granted, free of charge, to any person obtaining
.\" a copy of this software and associated documentation files (the
.\" "Software"), to deal in the Software without restriction, including
.\" without limitation the rights to use, copy, modify, merge, publish,
.\" distribute, sublicense, and/or sell copies of the Software, and to
.\" permit persons to whom the Software is furnished to do so, subject to
.\" the following conditions:
.\"
.\" The above copyright notice and this permission notice shall be
.\" included in all copies or substantial portions of the Software.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
.\" EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
.\" NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
.\" LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
.\" OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
.\" WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
.TH "ZFS\-MOUNT\-GENERATOR" "8" "2020-01-19" "ZFS" "zfs-mount-generator" "\""
.SH "NAME"
zfs\-mount\-generator \- generates systemd mount units for ZFS
.SH SYNOPSIS
.B /lib/systemd/system-generators/zfs\-mount\-generator
.B @systemdgeneratordir@/zfs\-mount\-generator
.sp
.SH DESCRIPTION
zfs\-mount\-generator implements the \fBGenerators Specification\fP
@@ -11,22 +36,50 @@ of
and is called during early boot to generate
.BR systemd.mount (5)
units for automatically mounted datasets. Mount ordering and dependencies
are created for all tracked pools (see below). If a dataset has
.BR canmount=on
and
.BR mountpoint
set, the
.BR auto
mount option will be set, and a dependency for
.BR local-fs.target
on the mount will be created.
are created for all tracked pools (see below).
Because zfs pools may not be available very early in the boot process,
information on ZFS mountpoints must be stored separately. The output
of the command
.SS ENCRYPTION KEYS
If the dataset is an encryption root, a service that loads the associated key (either from file or through a
.BR systemd\-ask\-password (1)
prompt) will be created. This service
. BR RequiresMountsFor
the path of the key (if file-based) and also copies the mount unit's
.BR After ,
.BR Before
and
.BR Requires .
All mount units of encrypted datasets add the key\-load service for their encryption root to their
.BR Wants
and
.BR After .
The service will not be
.BR Want ed
or
.BR Require d
by
.BR local-fs.target
directly, and so will only be started manually or as a dependency of a started mount unit.
.SS UNIT ORDERING AND DEPENDENCIES
mount unit's
.BR Before
\->
key\-load service (if any)
\->
mount unit
\->
mount unit's
.BR After
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.
.SS 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 the command
.PP
.RS 4
zfs list -H -o name,mountpoint,canmount,atime,relatime,devices,exec,readonly,setuid,nbmand,encroot,keylocation
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
.RE
.PP
for datasets that should be mounted by systemd, should be kept
@@ -45,6 +98,98 @@ history_event-zfs-list-cacher.sh .
.RE
.PP
.sp
.SS PROPERTIES
The behavior of the generator script can be influenced by the following dataset properties:
.sp
.TP 4
.BR canmount = on | off | noauto
If a dataset has
.BR mountpoint
set and
.BR canmount
is not
.BR off ,
a mount unit will be generated.
Additionally, if
.BR canmount
is
.BR on ,
.BR local-fs.target
will gain a dependency on the mount unit.
This behavior is equal to the
.BR auto
and
.BR noauto
legacy mount options, see
.BR systemd.mount (5).
Encryption roots always generate a key-load service, even for
.BR canmount=off .
.TP 4
.BR org.openzfs.systemd:requires\-mounts\-for = \fIpath\fR...
Space\-separated list of mountpoints to require to be mounted for this mount unit
.TP 4
.BR org.openzfs.systemd:before = \fIunit\fR...
The mount unit and associated key\-load service will be ordered before this space\-separated list of units.
.TP 4
.BR org.openzfs.systemd:after = \fIunit\fR...
The mount unit and associated key\-load service will be ordered after this space\-separated list of units.
.TP 4
.BR org.openzfs.systemd:wanted\-by = \fIunit\fR...
Space-separated list of units that will gain a
.BR Wants
dependency on this mount unit.
Setting this property implies
.BR noauto .
.TP 4
.BR org.openzfs.systemd:required\-by = \fIunit\fR...
Space-separated list of units that will gain a
.BR Requires
dependency on this mount unit.
Setting this property implies
.BR noauto .
.TP 4
.BR org.openzfs.systemd:nofail = unset | on | off
Toggles between a
.BR Wants
and
.BR Requires
type of dependency between the mount unit and
.BR local-fs.target ,
if
.BR noauto
isn't set or implied.
.BR on :
Mount will be
.BR WantedBy
local-fs.target
.BR off :
Mount will be
.BR Before
and
.BR RequiredBy
local-fs.target
.BR unset :
Mount will be
.BR Before
and
.BR WantedBy
local-fs.target
.TP 4
.BR org.openzfs.systemd:ignore = on | off
If set to
.BR on ,
do not generate a mount unit for this dataset.
.RE
See also
.BR systemd.mount (5)
.PP
.SH EXAMPLE
To begin, enable tracking for the pool:
.PP
@@ -63,7 +208,9 @@ systemctl enable zfs-zed.service
systemctl restart zfs-zed.service
.RE
.PP
Force the running of the ZEDLET by setting canmount=on for at least one dataset in the pool:
Force the running of the ZEDLET by setting a monitored property, e.g.
.BR canmount ,
for at least one dataset in the pool:
.PP
.RS 4
zfs set canmount=on
@@ -71,6 +218,24 @@ zfs set canmount=on
.RE
.PP
This forces an update to the stale cache file.
To test the generator output, run
.PP
.RS 4
@systemdgeneratordir@/zfs-mount-generator /tmp/zfs-mount-generator . .
.RE
.PP
This will generate units and dependencies in
.I /tmp/zfs-mount-generator
for you to inspect them. The second and third argument are ignored.
If you're satisfied with the generated units, instruct systemd to re-run all generators:
.PP
.RS 4
systemctl daemon-reload
.RE
.PP
.sp
.SH SEE ALSO
.BR zfs (5)