units: add initrd-cryptsetup.target

For encrypted block devices that we need to unlock from the initramfs,
we currently rely on dracut shipping `cryptsetup.target`. This works,
but doesn't cover the case where the encrypted block device requires
networking (i.e. the `remote-cryptsetup.target` version). That target
however is traditionally dynamically enabled.

Instead, let's rework things here by adding a `initrd-cryptsetup.target`
specifically for initramfs encrypted block device setup. This plays the
role of both `cryptsetup.target` and `remote-cryptsetup.target` in the
initramfs.

Then, adapt `systemd-cryptsetup-generator` to hook all generated
services to this new unit when running from the initrd. This is
analogous to `systemd-fstab-generator` hooking all mounts to
`initrd-fs.target`, regardless of whether they're network-backed or not.

1 files changed, 17 insertions, 4 deletions

diff --git a/man/systemd.special.xml b/man/systemd.special.xml
index 1434ead7d5..fe40da7fbe 100644
--- a/man/systemd.special.xml
+++ b/man/systemd.special.xml
@@ -41,6 +41,7 @@
     <filename>hybrid-sleep.target</filename>,
     <filename>suspend-then-hibernate.target</filename>,
     <filename>initrd.target</filename>,
+    <filename>initrd-cryptsetup.target</filename>,
     <filename>initrd-fs.target</filename>,
     <filename>initrd-root-device.target</filename>,
     <filename>initrd-root-fs.target</filename>,
@@ -182,8 +183,10 @@
         <varlistentry>
           <term><filename>cryptsetup.target</filename></term>
           <listitem>
-            <para>A target that pulls in setup services for all
-            encrypted block devices.</para>
+            <para>A target that pulls in setup services for local encrypted block devices.
+            See <filename>remote-cryptsetup.target</filename> below for the equivalent target for remote
+            volumes, and <filename>initrd-cryptsetup.target</filename> below for the equivalent target in the
+            initrd.</para>
           </listitem>
         </varlistentry>
         <varlistentry>
@@ -352,13 +355,21 @@
         <varlistentry>
           <term><filename>initrd.target</filename></term>
           <listitem>
-            <para>This is the default target in the initramfs, similar to <filename>default.target</filename>
+            <para>This is the default target in the initrd, similar to <filename>default.target</filename>
             in the main system. It is used to mount the real root and transition to it. See
             <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
             more discussion.</para>
           </listitem>
         </varlistentry>
         <varlistentry>
+          <term><filename>initrd-cryptsetup.target</filename></term>
+          <listitem>
+            <para>A target that pulls in setup services for all encrypted block devices. See
+            <filename>cryptsetup.target</filename> and <filename>remote-cryptsetup.target</filename> for the
+            equivalent targets in the real root.</para>
+          </listitem>
+        </varlistentry>
+        <varlistentry>
           <term><filename>initrd-fs.target</filename></term>
           <listitem>
             <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
@@ -549,7 +560,9 @@
             <para>Similar to <filename>cryptsetup.target</filename>, but for encrypted
             devices which are accessed over the network. It is used for
             <citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>8</manvolnum></citerefentry>
-            entries marked with <option>_netdev</option>.</para>
+            entries marked with <option>_netdev</option>.
+            See <filename>cryptsetup.target</filename> for the equivalent target for local volumes, and
+            <filename>initrd-cryptsetup.target</filename> for the equivalent target in the initrd.</para>
           </listitem>
         </varlistentry>
         <varlistentry>