fix plugin probe init race causing erroneous volume unmounts

Signed-off-by: Olga Shestopalova <oshestopalova1@gmail.com>

pkg/volume/plugins.go

@@ -627,6 +627,7 @@ func (pm *VolumePluginMgr) initProbedPlugin(probedPlugin VolumePlugin) error {
 // specification.  If no plugins can support or more than one plugin can
 // support it, return error.
 func (pm *VolumePluginMgr) FindPluginBySpec(spec *Spec) (VolumePlugin, error) {
+	pm.refreshProbedPlugins()
 	pm.mutex.RLock()
 	defer pm.mutex.RUnlock()
 
@@ -643,7 +644,6 @@ func (pm *VolumePluginMgr) FindPluginBySpec(spec *Spec) (VolumePlugin, error) {
 		}
 	}
 
-	pm.refreshProbedPlugins()
 	for _, plugin := range pm.probedPlugins {
 		if plugin.CanSupport(spec) {
 			match = plugin
@@ -663,6 +663,7 @@ func (pm *VolumePluginMgr) FindPluginBySpec(spec *Spec) (VolumePlugin, error) {
 
 // FindPluginByName fetches a plugin by name. If no plugin is found, returns error.
 func (pm *VolumePluginMgr) FindPluginByName(name string) (VolumePlugin, error) {
+	pm.refreshProbedPlugins()
 	pm.mutex.RLock()
 	defer pm.mutex.RUnlock()
 
@@ -671,7 +672,6 @@ func (pm *VolumePluginMgr) FindPluginByName(name string) (VolumePlugin, error) {
 		match = v
 	}
 
-	pm.refreshProbedPlugins()
 	if plugin, found := pm.probedPlugins[name]; found {
 		if match != nil {
 			return nil, fmt.Errorf("multiple volume plugins matched: %s and %s", match.GetPluginName(), plugin.GetPluginName())
@@ -694,6 +694,12 @@ func (pm *VolumePluginMgr) refreshProbedPlugins() {
 		klog.ErrorS(err, "Error dynamically probing plugins")
 	}
 
+	if len(events) == 0 {
+		return
+	}
+
+	pm.mutex.Lock()
+	defer pm.mutex.Unlock()
 	// because the probe function can return a list of valid plugins
 	// even when an error is present we still must add the plugins
 	// or they will be skipped because each event only fires once