man: document automatic dependencies

For all units ensure there's an "Automatic Dependencies" section in the
man page, and explain which dependencies are automatically added in all
cases, and which ones are added on top if DefaultDependencies=yes is
set.

This is also done for systemd.exec(5), systemd.resource-control(5) and
systemd.unit(5) as these pages describe common behaviour of various unit
types.

1 files changed, 47 insertions, 5 deletions

diff --git a/man/systemd.mount.xml b/man/systemd.mount.xml
index dd6b7a51a8..67e96dc157 100644
--- a/man/systemd.mount.xml
+++ b/man/systemd.mount.xml
@@ -94,10 +94,6 @@
     unit, to allow on-demand or parallelized mounting. See
     <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 
-    <para>If a mount point is beneath another mount point in the file
-    system hierarchy, a dependency between both units is created
-    automatically.</para>
-
     <para>Mount points created at runtime (independently of unit files
     or <filename>/etc/fstab</filename>) will be monitored by systemd
     and appear like any other mount unit in systemd. See
@@ -114,6 +110,52 @@
   </refsect1>
 
   <refsect1>
+    <title>Automatic Dependencies</title>
+
+    <para>If a mount unit is beneath another mount unit in the file
+    system hierarchy, both a requirement dependency and an ordering
+    dependency between both units are created automatically.</para>
+
+    <para>Block device backed file systems automatically gain
+    <varname>BindsTo=</varname> and <varname>After=</varname> type
+    dependencies on the device unit encapsulating the block
+    device (see below).</para>
+
+    <para>If traditional file system quota is enabled for a mount
+    unit, automatic <varname>Wants=</varname> and
+    <varname>Before=</varname> dependencies on
+    <filename>systemd-quotacheck.service</filename> and
+    <filename>quotaon.service</filename> are added.</para>
+
+    <para>For mount units with
+    <varname>DefaultDependencies=yes</varname> (the default) a couple
+    additional dependencies are added. Mount units referring to local
+    file systems automatically gain an <varname>After=</varname>
+    dependency on <filename>local-fs-pre.target</filename>. Network
+    mount units automatically acquire <varname>After=</varname>
+    dependencies on <filename>remote-fs-pre.target</filename>,
+    <filename>network.target</filename> and
+    <filename>network-online.target</filename>. Towards the latter a
+    <varname>Wants=</varname> unit is added as well. Mount units
+    referring to local and network file systems are distinguished by
+    their file system type specification. In some cases this is not
+    sufficient (for example network block device based mounts, such as
+    iSCSI), in which case <option>_netdev</option> may be added to the
+    mount option string of the unit, which forces systemd to consider the
+    mount unit a network mount. Mount units (regardless if local or
+    network) also acquire automatic <varname>Before=</varname> and
+    <varname>Conflicts=</varname> on
+    <filename>umount.target</filename> in order to be stopped
+    during shutdown.</para>
+
+    <para>Additional implicit dependencies may be added as result of
+    execution and resource control parameters as documented in
+    <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+    and
+    <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+  </refsect1>
+
+  <refsect1>
     <title><filename>fstab</filename></title>
 
     <para>Mount units may either be configured via unit files, or via
@@ -130,7 +172,7 @@
     <para>When reading <filename>/etc/fstab</filename> a few special
     mount options are understood by systemd which influence how
     dependencies are created for mount points. systemd will create a
-    dependency of type <option>Wants</option> or
+    dependency of type <varname>Wants=</varname> or
     <option>Requires</option> (see option <option>nofail</option>
     below), from either <filename>local-fs.target</filename> or
     <filename>remote-fs.target</filename>, depending whether the file