--- zfs	2016-10-13 08:19:54.000000000 +0200
+++ zfs	2019-05-20 13:17:04.686796000 +0200
@@ -16,6 +16,20 @@ 
 stop_cmd="zfs_stop"
 required_modules="zfs"
 
+#
+# Add the following lines to /etc/rc.conf to enable ZFS ordered mount:
+# zfs_ordered_mount_enable (bool):                Mount ZFS in order (or NO).
+# zfs_ordered_mount_zpoolname_egrep_filter (str): Optional egrep(1) pattern for filtering unwanted filesystems, one per zpool.
+#                                                 Filesystems having canmount=off will be excluded automatically.
+#
+# Example:
+# zfs_ordered_mount_enable="YES"
+# zfs_ordered_mount_zroot_egrep_filter="zroot\$|zroot/ROOT|zroot/do-not-destroy"
+# zfs_ordered_mount_zdata_egrep_filter="zdata\$|zdata/do-not-destroy"
+#
+
+zfs_ordered_mount_enable=${zfs_ordered_mount_enable:-"NO"}
+
 zfs_start_jail()
 {
 	if [ `$SYSCTL_N security.jail.mount_allowed` -eq 1 ]; then
@@ -25,11 +39,43 @@ 
 
 zfs_start_main()
 {
-	zfs mount -va
+	if checkyesno zfs_ordered_mount_enable; then
+		local _zroot _zpool
+
+		_zroot=`df -t zfs / | tail -1 | awk '{print $1}' | cut -d / -f 1`
+
+		if [ -n "${_zroot}" ]; then
+			zfs_mount_pool ${_zroot}
+		fi
+
+		for _zpool in `zpool list -Ho name`; do
+			if [ "${_zpool}" != "${_zroot}"; then
+				zfs_mount_pool ${_zpool}
+			fi
+		done
+	else
+		zfs mount -va
+	fi
 	zfs share -a
 	if [ ! -r /etc/zfs/exports ]; then
 		touch /etc/zfs/exports
 	fi
+}
+
+zfs_mount_pool()
+{
+	local _zpool _egrep_filter_name _egrep_filter _fs
+	_zpool=${1}
+
+	_egrep_filter_name=zfs_ordered_mount_${_zpool}_egrep_filter
+	_egrep_filter=`eval echo \$\{${_egrep_filter_name}\}`
+	if [ -n "${_egrep_filter}" ]; then
+		# Need to separate our ^off from the user's specification.
+		_egrep_filter="|${_egrep_filter}"
+	fi
+	for _fs in `zfs list -Hro canmount,name -t filesystem ${_zpool} | egrep -ve "^off${_egrep_filter}" | awk '{print $2}'`; do
+		zfs mount -v ${_fs}
+	done
 }
 
 zfs_start()