Add more volume types in e2e and fix part of them.

- Add dir-link/dir-bindmounted/dir-link-bindmounted/blockfs volume types for e2e
tests.
- Return error if we cannot resolve volume path.
- Add GetFSGroup/GetMountRefs methods for mount.Interface.
- Fix fsGroup related e2e tests partially.

pkg/util/mount/exec_mount_test.go

@@ -19,6 +19,7 @@ limitations under the License.
 package mount
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"reflect"
@@ -163,3 +164,11 @@ func (fm *fakeMounter) CleanSubPaths(podDir string, volumeName string) error {
 func (fm *fakeMounter) SafeMakeDir(pathname string, base string, perm os.FileMode) error {
 	return nil
 }
+
+func (fm *fakeMounter) GetMountRefs(pathname string) ([]string, error) {
+	return nil, errors.New("not implemented")
+}
+
+func (fm *fakeMounter) GetFSGroup(pathname string) (int64, error) {
+	return -1, errors.New("not implemented")
+}