Add systemd unit files for ZFS startup

This adds systemd unit files replacing the functionality offered by
the SysV init script found in etc/init.d.

It has been developed and tested on Fedora 19, Fedora 20
and openSuSE 13.1.

Four unit files and one target are offered.

zfs-import-cache.service:
    Import pools from /etc/zfs/zpool.cache. This unit will wait for
    udev to settle.
zfs-import-scan.service:
    Import pools by scanning /dev/disk/by-id for zvols. This unit will
    only run if /etc/zfs/zpool.cache is not present. This unit will wait
    for udev to settle
zfs-mount.service:
    Mount ZFS native filesystems. It contains a dependency to be loaded
    before local-fs.target.
zfs-share.service:
    Share NFS/SMB filesystems. This unit contains a dependency that
    will cause it to be restarted whenever the smb or nfs-server unit
    is restarted, restoring the shares added.
zfs.target:
    This target pulls in the other units in order to start ZFS. It's
    the only unit that can be enabled/disabled, all other services
    are static and pulled in by dependencies. It will honour zfs=off
    and zfs=no options on the kernel command line.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2108

etc/systemd/system/.gitignore

@@ -0,0 +1,3 @@
+*.service
+*.target
+*.preset

etc/systemd/system/50-zfs.preset.in

@@ -0,0 +1,2 @@
+# ZFS is enabled by default
+enable zfs.*

etc/systemd/system/Makefile.am

@@ -0,0 +1,31 @@
+systemdpreset_DATA = \
+	$(top_srcdir)/etc/systemd/system/50-zfs.preset
+systemdunit_DATA = \
+	$(top_srcdir)/etc/systemd/system/zfs-import-scan.service \
+	$(top_srcdir)/etc/systemd/system/zfs-import-cache.service \
+	$(top_srcdir)/etc/systemd/system/zfs-mount.service \
+	$(top_srcdir)/etc/systemd/system/zfs-share.service \
+	$(top_srcdir)/etc/systemd/system/zfs.target
+
+EXTRA_DIST = \
+	$(top_srcdir)/etc/systemd/system/zfs-import-scan.service.in \
+	$(top_srcdir)/etc/systemd/system/zfs-import-cache.service.in \
+	$(top_srcdir)/etc/systemd/system/zfs-mount.service.in \
+	$(top_srcdir)/etc/systemd/system/zfs-share.service.in \
+	$(top_srcdir)/etc/systemd/system/zfs.target.in \
+	$(top_srcdir)/etc/systemd/system/50-zfs.preset.in
+
+$(systemdunit_DATA):
+	-$(SED) -e 's,@bindir\@,$(bindir),g' \
+		-e 's,@sbindir\@,$(sbindir),g' \
+		-e 's,@sysconfdir\@,$(sysconfdir),g' \
+		'$@.in' >'$@'
+
+$(systemdpreset_DATA):
+	-$(SED) -e 's,@bindir\@,$(bindir),g' \
+		-e 's,@sbindir\@,$(sbindir),g' \
+		-e 's,@sysconfdir\@,$(sysconfdir),g' \
+		'$@.in' >'$@'
+
+distclean-local::
+	-$(RM) $(systemdunit_DATA) $(systemdpreset_DATA)

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

@@ -0,0 +1,11 @@
+[Unit]
+Description=Import ZFS pools by cache file
+DefaultDependencies=no
+Requires=systemd-udev-settle.service
+After=systemd-udev-settle.service
+ConditionPathExists=@sysconfdir@/zfs/zpool.cache
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=@sbindir@/zpool import -c @sysconfdir@/zfs/zpool.cache -aN

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

@@ -0,0 +1,11 @@
+[Unit]
+Description=Import ZFS pools by device scanning
+DefaultDependencies=no
+Requires=systemd-udev-settle.service
+After=systemd-udev-settle.service
+ConditionPathExists=!@sysconfdir@/zfs/zpool.cache
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=@sbindir@/zpool import -d /dev/disk/by-id -aN

etc/systemd/system/zfs-mount.service.in

@@ -0,0 +1,15 @@
+[Unit]
+Description=Mount ZFS filesystems
+DefaultDependencies=no
+Wants=zfs-import-cache.service
+Wants=zfs-import-scan.service
+Requires=systemd-udev-settle.service
+After=systemd-udev-settle.service
+After=zfs-import-cache.service
+After=zfs-import-scan.service
+Before=local-fs.target
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=@sbindir@/zfs mount -a

etc/systemd/system/zfs-share.service.in

@@ -0,0 +1,11 @@
+[Unit]
+Description=ZFS file system shares
+After=nfs-server.service
+After=smb.service
+PartOf=nfs-server.service
+PartOf=smb.service
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=@sbindir@/zfs share -a

etc/systemd/system/zfs.target.in

@@ -0,0 +1,7 @@
+[Unit]
+Description=ZFS startup target
+Requires=zfs-mount.service
+Requires=zfs-share.service
+
+[Install]
+WantedBy=multi-user.target