remove IsAbs validation on local volume

use MakeAbsolutePath to convert path in Windows

fix test error: allow relative path for local volume

fix comments

fix comments and add windows unit tests

pkg/volume/local/local_linux_test.go

@@ -0,0 +1,68 @@
+// +build linux darwin
+
+/*
+Copyright 2017 The Kubernetes Authors.
+
+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.
+*/
+
+package local
+
+import (
+	"os"
+	"syscall"
+	"testing"
+
+	"k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/types"
+)
+
+func TestFSGroupMount(t *testing.T) {
+	tmpDir, plug := getPlugin(t)
+	defer os.RemoveAll(tmpDir)
+	info, err := os.Stat(tmpDir)
+	if err != nil {
+		t.Errorf("Error getting stats for %s (%v)", tmpDir, err)
+	}
+	s := info.Sys().(*syscall.Stat_t)
+	if s == nil {
+		t.Errorf("Error getting stats for %s (%v)", tmpDir, err)
+	}
+	fsGroup1 := int64(s.Gid)
+	fsGroup2 := fsGroup1 + 1
+	pod1 := &v1.Pod{ObjectMeta: metav1.ObjectMeta{UID: types.UID("poduid")}}
+	pod1.Spec.SecurityContext = &v1.PodSecurityContext{
+		FSGroup: &fsGroup1,
+	}
+	pod2 := &v1.Pod{ObjectMeta: metav1.ObjectMeta{UID: types.UID("poduid")}}
+	pod2.Spec.SecurityContext = &v1.PodSecurityContext{
+		FSGroup: &fsGroup2,
+	}
+	err = testFSGroupMount(plug, pod1, tmpDir, fsGroup1)
+	if err != nil {
+		t.Errorf("Failed to make a new Mounter: %v", err)
+	}
+	err = testFSGroupMount(plug, pod2, tmpDir, fsGroup2)
+	if err != nil {
+		t.Errorf("Failed to make a new Mounter: %v", err)
+	}
+	//Checking if GID of tmpDir has not been changed by mounting it by second pod
+	s = info.Sys().(*syscall.Stat_t)
+	if s == nil {
+		t.Errorf("Error getting stats for %s (%v)", tmpDir, err)
+	}
+	if fsGroup1 != int64(s.Gid) {
+		t.Errorf("Old Gid %d for volume %s got overwritten by new Gid %d", fsGroup1, tmpDir, int64(s.Gid))
+	}
+}