Add path exist check in getPodVolumePathListFromDisk

Add the path exist check in the function. If the path does not exist,
return empty list and nil error.

Author: jingxu97

Diff for: pkg/kubelet/BUILD

@@ -113,6 +113,7 @@ go_library(
         "//pkg/util/wait:go_default_library",
         "//pkg/version:go_default_library",
         "//pkg/volume:go_default_library",
+        "//pkg/volume/util:go_default_library",
         "//pkg/volume/util/types:go_default_library",
         "//pkg/volume/util/volumehelper:go_default_library",
         "//plugin/pkg/scheduler/algorithm/predicates:go_default_library",

Diff for: pkg/kubelet/kubelet_getters.go

@@ -30,6 +30,7 @@ import (
 	"k8s.io/kubernetes/pkg/types"
 	"k8s.io/kubernetes/pkg/util"
 	nodeutil "k8s.io/kubernetes/pkg/util/node"
+	volumeutil "k8s.io/kubernetes/pkg/volume/util"
 )
 
 // getRootDir returns the full path to the directory under which kubelet can
@@ -244,6 +245,14 @@ func (kl *Kubelet) GetExtraSupplementalGroupsForPod(pod *v1.Pod) []int64 {
 func (kl *Kubelet) getPodVolumePathListFromDisk(podUID types.UID) ([]string, error) {
 	volumes := []string{}
 	podVolDir := kl.getPodVolumesDir(podUID)
+
+	if pathExists, pathErr := volumeutil.PathExists(podVolDir); pathErr != nil {
+		return volumes, fmt.Errorf("Error checking if path %q exists: %v", podVolDir, pathErr)
+	} else if !pathExists {
+		glog.Warningf("Warning: path %q does not exist: %q", podVolDir)
+		return volumes, nil
+	}
+
 	volumePluginDirs, err := ioutil.ReadDir(podVolDir)
 	if err != nil {
 		glog.Errorf("Could not read directory %s: %v", podVolDir, err)