Move dracut specifics to dracut mount unit

Dracut depends on BOOTFS environment variable to be set after pool
import. This dracut specific systemd ExecStartPost command should not be
called for any non-dracut systems, so let's move it to a static systemd
unit that gets pulled in by the generated mount unit.

configure.ac

@@ -127,6 +127,7 @@ AC_CONFIG_FILES([
 	contrib/dracut/Makefile
 	contrib/dracut/02zfsexpandknowledge/Makefile
 	contrib/dracut/90zfs/Makefile
+	contrib/dracut/systemd/Makefile
 	contrib/initramfs/Makefile
 	contrib/initramfs/hooks/Makefile
 	contrib/initramfs/scripts/Makefile

contrib/dracut/90zfs/zfs-generator.sh.in

@@ -41,7 +41,8 @@ echo "zfs-generator: writing extension for sysroot.mount to $GENERATOR_DIR"/sysr
 {
     echo "[Unit]"
     echo "Before=initrd-root-fs.target"
-    echo "After=zfs-import.target"
+    echo "After=zfs-dracut-bootfs.service zfs-import.target"
+    echo "Requires=zfs-dracut-bootfs.service"
     echo "[Mount]"
     if [ "${root}" = "zfs:AUTO" ] ; then
       echo "PassEnvironment=BOOTFS"

contrib/dracut/Makefile.am

@@ -1,3 +1,3 @@
-SUBDIRS = 02zfsexpandknowledge 90zfs
+SUBDIRS = 02zfsexpandknowledge 90zfs systemd
 
 EXTRA_DIST = README.dracut.markdown

contrib/dracut/systemd/.gitignore

@@ -0,0 +1 @@
+zfs-dracut-bootfs.service

contrib/dracut/systemd/Makefile.am

@@ -0,0 +1,13 @@
+systemdunit_DATA = \
+	zfs-dracut-bootfs.service
+
+EXTRA_DIST = \
+	$(top_srcdir)/contrib/dracut/systemd/zfs-dracut-bootfs.service.in
+
+$(systemdunit_DATA):%:%.in
+	-$(SED) -e 's,@bindir\@,$(bindir),g' \
+		-e 's,@sbindir\@,$(sbindir),g' \
+		$< >'$@'
+
+distclean-local::
+	-$(RM) $(systemdunit_DATA)

contrib/dracut/systemd/zfs-dracut-bootfs.service.in

@@ -0,0 +1,10 @@
+[Unit]
+Description=Set BOOTFS environment for dracut
+Documentation=man:zfs(8)
+DefaultDependencies=no
+After=zfs-import.target
+Requires=zfs-import.target
+
+[Service]
+Type=oneshot
+ExecStart=/bin/sh -c "/bin/systemctl set-environment BOOTFS=$(@sbindir@/zpool list -H -o bootfs | egrep -v '^-$')"

etc/systemd/system/zfs-import-cache.service.in

@@ -13,7 +13,6 @@ ConditionPathExists=@sysconfdir@/zfs/zpool.cache
 Type=oneshot
 RemainAfterExit=yes
 ExecStart=@sbindir@/zpool import -c @sysconfdir@/zfs/zpool.cache -aN
-ExecStartPost=/bin/sh -c "/bin/systemctl set-environment BOOTFS=$(@sbindir@/zpool list -H -o bootfs | egrep -v '^-$')"
 
 [Install]
 WantedBy=zfs-import.target

etc/systemd/system/zfs-import-scan.service.in

@@ -12,7 +12,6 @@ ConditionPathExists=!@sysconfdir@/zfs/zpool.cache
 Type=oneshot
 RemainAfterExit=yes
 ExecStart=@sbindir@/zpool import -aN -o cachefile=none
-ExecStartPost=/bin/sh -c "/bin/systemctl set-environment BOOTFS=$(@sbindir@/zpool list -H -o bootfs | egrep -v '^-$')"
 
 [Install]
 WantedBy=zfs-import.target