[libvirt] [PATCH 4/5] network: set macvtap/hostdev networks active if their state file exists

[Laine Stump]

libvirt attempts to determine at startup time which networks are
already active, and set their active flags. Previously it has done
this by assuming that all networks are inactive, then setting the flag
if the network has a bridge device associated with it, and that bridge
device exists. This is not useful for macvtap and hostdev based
networks, since they do not use a bridge device.

Of course the reason that such a check had to be done was that the
presence of a status file in the network "stateDir" couldn't be
trusted as an indicator of whether or not a network was active. This
was due to the network driver mistakenly using
/var/lib/libvirt/network to store the status files, rather than
/var/run/libvirt/network (similar to what is done by every other
libirt driver that stores status xml for its objects). The difference
is that /var/run is cleared out when the host reboots, so you cvqan be
assured that the state file you are seeing isn't just left over from a
previous boot of the host.

Now that the network driver has been switched to using
/var/run/libvirt/network for status, we can also modify it to assume
that any network with an existing status file is by definition active
- we do this when reading the status file. To fine tune the results,
networkFindActiveConfigs() is changed to networkFindInactiveConfigs(),
and only sets active = 0 if the conditions for particular network
types are *not* met.

The result is that during the first run of libvirtd after the host
boots, there are no status files, so no networks are active. Any time
it is restarted, and network with a status file will be marked as
inactive (unless it uses a bridge device and that device for some
reason doesn't exist).
---
 src/conf/network_conf.c     |  1 +
 src/network/bridge_driver.c | 49 +++++++++++++++++++++++++++++++++------------
 2 files changed, 37 insertions(+), 13 deletions(-)

diff --git a/src/conf/network_conf.c b/src/conf/network_conf.c
index 56c4a09..69ad929 100644
--- a/src/conf/network_conf.c
+++ b/src/conf/network_conf.c
@@ -3060,6 +3060,7 @@ virNetworkLoadState(virNetworkObjListPtr nets,
         net->floor_sum = floor_sum_val;
 
     net->taint = taint;
+    net->active = 1; /* any network with a state file is by definition active */
 
  cleanup:
     VIR_FREE(configFile);
diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
index 98d10bd..7beab79 100644
--- a/src/network/bridge_driver.c
+++ b/src/network/bridge_driver.c
@@ -328,7 +328,7 @@ networkBridgeDummyNicName(const char *brname)
 }
 
 static void
-networkFindActiveConfigs(virNetworkDriverStatePtr driver)
+networkFindInactiveConfigs(virNetworkDriverStatePtr driver)
 {
     size_t i;
 
@@ -336,29 +336,51 @@ networkFindActiveConfigs(virNetworkDriverStatePtr driver)
         virNetworkObjPtr obj = driver->networks.objs[i];
 
         virNetworkObjLock(obj);
-
-        /* If bridge exists, then mark it active */
-        if (obj->def->bridge &&
-            virNetDevExists(obj->def->bridge) == 1) {
-            obj->active = 1;
+        switch (obj->def->forward.type) {
+        case VIR_NETWORK_FORWARD_NONE:
+        case VIR_NETWORK_FORWARD_NAT:
+        case VIR_NETWORK_FORWARD_ROUTE:
+            /* If bridge exists, then mark it active */
+            if (!(obj->def->bridge && virNetDevExists(obj->def->bridge) == 1)) {
+                obj->active = 0;
+                break;
+            }
 
             /* Try and read dnsmasq/radvd pids if any */
             if (obj->def->ips && (obj->def->nips > 0)) {
                 char *radvdpidbase;
 
-                ignore_value(virPidFileReadIfAlive(driverState->pidDir, obj->def->name,
+                ignore_value(virPidFileReadIfAlive(driverState->pidDir,
+                                                   obj->def->name,
                                                    &obj->dnsmasqPid,
                                                    dnsmasqCapsGetBinaryPath(driver->dnsmasqCaps)));
-
-                if (!(radvdpidbase = networkRadvdPidfileBasename(obj->def->name)))
-                    goto cleanup;
-                ignore_value(virPidFileReadIfAlive(driverState->pidDir, radvdpidbase,
+                radvdpidbase = networkRadvdPidfileBasename(obj->def->name);
+                if (!radvdpidbase)
+                    break;
+                ignore_value(virPidFileReadIfAlive(driverState->pidDir,
+                                                   radvdpidbase,
                                                    &obj->radvdPid, RADVD));
                 VIR_FREE(radvdpidbase);
             }
+            break;
+
+        case VIR_NETWORK_FORWARD_BRIDGE:
+            if (obj->def->bridge) {
+                if (virNetDevExists(obj->def->bridge) != 1)
+                    obj->active = 0;
+                break;
+            }
+            /* intentionally drop through to common case for all
+             * macvtap networks (forward='bridge' with no bridge
+             * device defined is macvtap using its 'bridge' mode)
+             */
+        case VIR_NETWORK_FORWARD_PRIVATE:
+        case VIR_NETWORK_FORWARD_VEPA:
+        case VIR_NETWORK_FORWARD_PASSTHROUGH:
+        case VIR_NETWORK_FORWARD_HOSTDEV:
+            break;
         }
 
-    cleanup:
         virNetworkObjUnlock(obj);
     }
 
@@ -542,12 +564,13 @@ networkStateInitialize(bool privileged,
                                driverState->stateDir) < 0)
         goto error;
 
+    networkFindInactiveConfigs(driverState);
+
     if (virNetworkLoadAllConfigs(&driverState->networks,
                                  driverState->networkConfigDir,
                                  driverState->networkAutostartDir) < 0)
         goto error;
 
-    networkFindActiveConfigs(driverState);
     networkReloadFirewallRules(driverState);
     networkRefreshDaemons(driverState);
 
-- 
1.9.0