systemd.mount integration

cmd/zed/Makefile.am

@@ -4,7 +4,8 @@ DEFAULT_INCLUDES += \
 	-I$(top_srcdir)/include \
 	-I$(top_srcdir)/lib/libspl/include
 
-EXTRA_DIST = zed.d/README
+EXTRA_DIST = zed.d/README \
+	zed.d/history_event-zfs-list-cacher.sh.in
 
 sbin_PROGRAMS = zed
 
@@ -60,6 +61,7 @@ dist_zedexec_SCRIPTS = \
 	zed.d/all-syslog.sh \
 	zed.d/data-notify.sh \
 	zed.d/generic-notify.sh \
+	zed.d/history_event-zfs-list-cacher.sh \
 	zed.d/resilver_finish-notify.sh \
 	zed.d/scrub_finish-notify.sh \
 	zed.d/statechange-led.sh \
@@ -69,6 +71,13 @@ dist_zedexec_SCRIPTS = \
 	zed.d/pool_import-led.sh \
 	zed.d/resilver_finish-start-scrub.sh
 
+zed.d/history_event-zfs-list-cacher.sh: %: %.in
+	-$(SED) -e 's,@bindir\@,$(bindir),g' \
+		-e 's,@runstatedir\@,$(runstatedir),g' \
+		-e 's,@sbindir\@,$(sbindir),g' \
+		-e 's,@sysconfdir\@,$(sysconfdir),g' \
+		$< >'$@'
+
 zedconfdefaults = \
 	all-syslog.sh \
 	data-notify.sh \

cmd/zed/zed.d/.gitignore

@@ -0,0 +1 @@
+history_event-zfs-list-cacher.sh

cmd/zed/zed.d/history_event-zfs-list-cacher.sh.in

@@ -0,0 +1,73 @@
+#!/bin/sh
+#
+# Track changes to enumerated pools for use in early-boot
+set -ef
+
+FSLIST_DIR="@sysconfdir@/zfs/zfs-list.cache"
+FSLIST_TMP="@runstatedir@/zfs-list.cache.new"
+FSLIST="${FSLIST_DIR}/${ZEVENT_POOL}"
+
+# If the pool specific cache file is not writeable, abort
+[ -w "${FSLIST}" ] || exit 0
+
+[ -f "${ZED_ZEDLET_DIR}/zed.rc" ] && . "${ZED_ZEDLET_DIR}/zed.rc"
+. "${ZED_ZEDLET_DIR}/zed-functions.sh"
+
+zed_exit_if_ignoring_this_event
+zed_check_cmd "${ZFS}" sort diff grep
+
+# If we are acting on a snapshot, we have nothing to do
+printf '%s' "${ZEVENT_HISTORY_DSNAME}" | grep '@' && exit 0
+
+# We obtain a lock on zfs-list to avoid any simultaneous writes.
+# If we run into trouble, log and drop the lock
+abort_alter() {
+  zed_log_msg "Error updating zfs-list.cache!"
+  zed_unlock zfs-list
+}
+
+finished() {
+  zed_unlock zfs-list
+  trap - EXIT
+  exit 0
+}
+
+case "${ZEVENT_HISTORY_INTERNAL_NAME}" in
+    create|"finish receiving"|import|destroy|rename)
+      ;;
+
+    export)
+        zed_lock zfs-list
+        trap abort_alter EXIT
+        echo > "${FSLIST}"
+        finished
+      ;;
+
+    set|inherit)
+        # Only act if the mountpoint or canmount setting is altered.
+        case "${ZEVENT_HISTORY_INTERNAL_STR}" in
+            canmount=*|mountpoint=*) ;;
+            *) exit 0 ;;
+        esac
+      ;;
+
+    *)
+        # Ignore all other events.
+        exit 0
+      ;;
+esac
+
+zed_lock zfs-list
+trap abort_alter EXIT
+
+"${ZFS}" list -H -tfilesystem -oname,mountpoint,canmount -r "${ZEVENT_POOL}" \
+    >"${FSLIST_TMP}"
+
+# Sort the output so that it is stable
+sort "${FSLIST_TMP}" -o "${FSLIST_TMP}"
+
+# Don't modify the file if it hasn't changed
+diff -q "${FSLIST_TMP}" "${FSLIST}" || mv "${FSLIST_TMP}" "${FSLIST}"
+rm -f "${FSLIST_TMP}"
+
+finished

config/user-systemd.m4

@@ -20,6 +20,11 @@ AC_DEFUN([ZFS_AC_CONFIG_USER_SYSTEMD], [
 		[install systemd module load files into dir [[/usr/lib/modules-load.d]]]),
 		systemdmoduleloaddir=$withval,systemdmodulesloaddir=/usr/lib/modules-load.d)
 
+	AC_ARG_WITH(systemdgeneratordir,
+		AC_HELP_STRING([--with-systemdgeneratordir=DIR],
+		[install systemd generators in dir [[/usr/lib/systemd/system-generators]]]),
+		systemdgeneratordir=$withval,systemdgeneratordir=/usr/lib/systemd/system-generators)
+
 	AS_IF([test "x$enable_systemd" = xcheck], [
 		AS_IF([systemctl --version >/dev/null 2>&1],
 			[enable_systemd=yes],
@@ -32,7 +37,7 @@ AC_DEFUN([ZFS_AC_CONFIG_USER_SYSTEMD], [
 	AS_IF([test "x$enable_systemd" = xyes], [
 		ZFS_INIT_SYSTEMD=systemd
 		ZFS_MODULE_LOAD=modules-load.d
-		DEFINE_SYSTEMD='--with systemd --define "_unitdir $(systemdunitdir)" --define "_presetdir $(systemdpresetdir)"'
+		DEFINE_SYSTEMD='--with systemd --define "_unitdir $(systemdunitdir)" --define "_presetdir $(systemdpresetdir)" --define "_generatordir $(systemdgeneratordir)"'
 		modulesloaddir=$systemdmodulesloaddir
 	],[
 		DEFINE_SYSTEMD='--without systemd'
@@ -43,5 +48,6 @@ AC_DEFUN([ZFS_AC_CONFIG_USER_SYSTEMD], [
 	AC_SUBST(DEFINE_SYSTEMD)
 	AC_SUBST(systemdunitdir)
 	AC_SUBST(systemdpresetdir)
+	AC_SUBST(systemdgeneratordir)
 	AC_SUBST(modulesloaddir)
 ])

configure.ac

@@ -67,6 +67,7 @@ AC_CONFIG_FILES([
 	etc/zfs/Makefile
 	etc/systemd/Makefile
 	etc/systemd/system/Makefile
+	etc/systemd/system-generators/Makefile
 	etc/sudoers.d/Makefile
 	etc/modules-load.d/Makefile
 	man/Makefile

etc/systemd/Makefile.am

@@ -1 +1 @@
-SUBDIRS = system
+SUBDIRS = system system-generators

etc/systemd/system-generators/.gitignore

@@ -0,0 +1 @@
+zfs-mount-generator

etc/systemd/system-generators/Makefile.am

@@ -0,0 +1,15 @@
+systemdgenerator_SCRIPTS = \
+	zfs-mount-generator
+
+EXTRA_DIST = \
+	$(top_srcdir)/etc/systemd/system-generators/zfs-mount-generator.in
+
+$(systemdgenerator_SCRIPTS): %: %.in
+	-$(SED) -e 's,@bindir\@,$(bindir),g' \
+		-e 's,@runstatedir\@,$(runstatedir),g' \
+		-e 's,@sbindir\@,$(sbindir),g' \
+		-e 's,@sysconfdir\@,$(sysconfdir),g' \
+		$< >'$@'
+
+distclean-local::
+	-$(RM) $(systemdgenerator_SCRIPTS)

etc/systemd/system-generators/zfs-mount-generator.in

@@ -0,0 +1,115 @@
+#!/bin/sh
+
+# zfs-mount-generator - generates systemd mount units for zfs
+# Copyright (c) 2017 Antonio Russo <antonio.e.russo@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.
+
+set -ef
+
+FSLIST="@sysconfdir@/zfs/zfs-list.cache"
+
+[ -d "${FSLIST}" ] || exit 0
+
+do_fail() {
+  printf 'zfs-mount-generator.sh: %s\n' "$*" > /dev/kmsg
+  exit 1
+}
+
+# see systemd.generator
+if [ $# -eq 0 ] ; then
+  dest_norm="/tmp"
+elif [ $# -eq 3 ] ; then
+  dest_norm="${1}"
+else
+  do_fail "zero or three arguments required"
+fi
+
+# For ZFSs marked "auto", a dependency is created for local-fs.target. To
+# avoid regressions, this dependency is reduced to "wants" rather than
+# "requires". **THIS MAY CHANGE**
+req_dir="${dest_norm}/local-fs.target.wants/"
+mkdir -p "${req_dir}"
+
+# All needed information about each ZFS is available from
+# zfs list -H -t filesystem -oname,mountpoint,canmount
+# cached in $FSLIST, and each line is processed by the following function:
+
+process_line() {
+
+  # Check for canmount=off .
+  if [ "${3}" = "off" ] ; then
+    return
+  elif [ "${3}" = "noauto" ] ; then
+    # Don't let a noauto marked mountpoint block an "auto" market mountpoint
+    return
+  elif [ "${3}" = "on" ] ; then
+    : # This is OK
+  else
+    do_fail "invalid canmount"
+  fi
+
+  # Check for legacy and blank mountpoints.
+  if [ "${2}" = "legacy" ] ; then
+    return
+  elif [ "${2}" = "none" ] ; then
+    return
+  elif [ "${2%"${2#?}"}" != "/" ] ; then
+    do_fail "invalid mountpoint $*"
+  fi
+
+  # Escape the mountpoint per systemd policy.
+  mountfile="$(systemd-escape "${2#?}").mount"
+
+  # If the mountpoint has already been created, give it precedence.
+  if [ -e "${dest_norm}/${mountfile}" ] ; then
+    printf 'zfs-mount-generator.sh: %s.mount already exists\n' "${2}" \
+      >/dev/kmsg
+    return
+  fi
+
+  # By ordering before zfs-mount.service, we avoid race conditions.
+  cat > "${dest_norm}/${mountfile}" << EOF
+# Automatically generated by zfs-mount-generator
+
+[Unit]
+SourcePath=${FSLIST}/${cachefile}
+Documentation=man:zfs-mount-generator(8)
+Before=local-fs.target zfs-mount.service
+After=zfs-import.target
+Wants=zfs-import.target
+
+[Mount]
+Where=${2}
+What=${1}
+Type=zfs
+Options=zfsutil,auto
+EOF
+
+  # Finally, create the appropriate dependencies based on the ZFS properties.
+  [ "$3" = "on" ] & ln -s "../${mountfile}" "${req_dir}"
+}
+
+# Feed each line into process_line
+for cachefile in $(ls "${FSLIST}") ; do
+  while read -r fs ; do
+    process_line $fs
+  done < "${FSLIST}/${cachefile}"
+done

man/man8/Makefile.am

@@ -4,6 +4,7 @@ dist_man_MANS = \
 	vdev_id.8 \
 	zdb.8 \
 	zfs.8 \
+	zfs-mount-generator.8 \
 	zfs-program.8 \
 	zgenhostid.8 \
 	zinject.8 \

man/man8/zfs-mount-generator.8

@@ -0,0 +1,56 @@
+.TH "ZFS\-MOUNT\-GENERATOR" "8" "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
+.sp
+.SH DESCRIPTION
+The zfs\-mount\-generator implements the \fBGenerators Specification\fP
+of
+.BR systemd (1),
+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.
+
+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 -oname,mountpoint,canmount
+.RE
+.PP
+for datasets that should be mounted by systemd, should be kept
+separate from the pool, at
+.PP
+.RS 4
+.RI @sysconfdir@/zfs/zfs-list.cache/ POOLNAME
+.
+.RE
+.PP
+The cache file, if writeable, will be kept synchronized with the pool
+state by the ZEDLET
+.PP
+.RS 4
+history_event-zfs-list-cacher.sh .
+.RE
+.PP
+.sp
+.SH SEE ALSO
+.BR zfs (5)
+.BR zfs-events (5)
+.BR zed (8)
+.BR zpool (5)
+.BR systemd (1)
+.BR systemd.target (5)
+.BR systemd.special (7)
+.BR systemd.mount (7)

rpm/generic/zfs.spec.in

@@ -338,6 +338,7 @@ systemctl --system daemon-reload >/dev/null || true
 /usr/lib/modules-load.d/*
 %{_unitdir}/*
 %{_presetdir}/*
+%{_generatordir}/*
 %else
 %config(noreplace) %{_sysconfdir}/init.d/*
 %config(noreplace) %{_initconfdir}/zfs