rhel: Add support for "systemctl reload openvswitch"

The reload procedure will trigger a script that saves the flows and tlv
maps (using ovs-save) then it restarts ovsdb-server, it stops ovs-vswitchd,
it sets other_config:flow-restore-wait=true (to wait till flow restore is
finished), it starts ovs-vswitchd, it restore the backupped flows/tlv
maps and it removes other_config:flow-restore-wait=true (logic mostly ripped
from ovs-ctl).

It uses systemctl with --job-mode=ignore-dependencies to restart ovsdb-server
and stop and start ovs-vswitchd in order to avoid systemd to restart the other
components due to dependencies (as explained in rhel/README.RHEL.rst).

Signed-off-by: Timothy Redaelli <tredaelli@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Flavio Leitner <fbl@sysclose.org>

rhel/automake.mk

@@ -24,6 +24,7 @@ EXTRA_DIST += \
 	rhel/openvswitch.spec.in \
 	rhel/openvswitch-fedora.spec \
 	rhel/openvswitch-fedora.spec.in \
+	rhel/usr_share_openvswitch_scripts_ovs-systemd-reload \
 	rhel/usr_share_openvswitch_scripts_sysconfig.template \
 	rhel/usr_share_openvswitch_scripts_systemd_sysconfig.template \
 	rhel/usr_lib_udev_rules.d_91-vfio.rules \

rhel/openvswitch-fedora.spec.in

@@ -314,6 +314,10 @@ install -d -m 0755 $RPM_BUILD_ROOT%{_prefix}/lib/ocf/resource.d/ovn
 ln -s %{_datadir}/openvswitch/scripts/ovndb-servers.ocf \
       $RPM_BUILD_ROOT%{_prefix}/lib/ocf/resource.d/ovn/ovndb-servers
 
+install -p -D -m 0755 \
+        rhel/usr_share_openvswitch_scripts_ovs-systemd-reload \
+        $RPM_BUILD_ROOT%{_datadir}/openvswitch/scripts/ovs-systemd-reload
+
 # remove unpackaged files
 rm -f $RPM_BUILD_ROOT%{_bindir}/ovs-parse-backtrace \
         $RPM_BUILD_ROOT%{_sbindir}/ovs-vlan-bug-workaround \
@@ -539,6 +543,7 @@ fi
 %{_datadir}/openvswitch/scripts/ovs-save
 %{_datadir}/openvswitch/scripts/ovs-vtep
 %{_datadir}/openvswitch/scripts/ovs-ctl
+%{_datadir}/openvswitch/scripts/ovs-systemd-reload
 %config %{_datadir}/openvswitch/vswitch.ovsschema
 %config %{_datadir}/openvswitch/vtep.ovsschema
 %{_bindir}/ovs-appctl

rhel/usr_lib_systemd_system_openvswitch.service

@@ -9,7 +9,7 @@ Requires=ovs-vswitchd.service
 [Service]
 Type=oneshot
 ExecStart=/bin/true
-ExecReload=/bin/true
+ExecReload=/usr/share/openvswitch/scripts/ovs-systemd-reload
 ExecStop=/bin/true
 RemainAfterExit=yes
 

rhel/usr_lib_systemd_system_ovsdb-server.service

@@ -3,7 +3,6 @@ Description=Open vSwitch Database Unit
 After=syslog.target network-pre.target
 Before=network.target network.service
 Wants=ovs-delete-transient-ports.service
-ReloadPropagatedFrom=openvswitch.service
 PartOf=openvswitch.service
 
 [Service]

rhel/usr_share_openvswitch_scripts_ovs-systemd-reload

@@ -0,0 +1,36 @@
+#! /bin/sh
+
+# Copyright (c) 2017 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Save flows
+bridges=$(ovs-vsctl -- --real list-br)
+flows=$(/usr/share/openvswitch/scripts/ovs-save save-flows $bridges)
+
+# Restart the database first, since a large database may take a
+# while to load, and we want to minimize forwarding disruption.
+systemctl --job-mode=ignore-dependencies restart ovsdb-server
+
+# Stop ovs-vswitchd.
+systemctl --job-mode=ignore-dependencies stop ovs-vswitchd
+
+# Start vswitchd by asking it to wait till flow restore is finished.
+ovs-vsctl --no-wait set open_vswitch . other_config:flow-restore-wait=true
+systemctl --job-mode=ignore-dependencies start ovs-vswitchd
+
+# Restore saved flows and inform vswitchd that we are done.
+eval "$flows"
+ovs-vsctl --if-exists remove open_vswitch . other_config flow-restore-wait=true
+
+exit 0