@@ -29,8 +29,9 @@ func isremount(device string, flags uintptr) bool {

 func mount(device, target, mType string, flags uintptr, data string) error {

 	oflags := flags &^ ptypes

-	if !isremount(device, flags) {

-		// Initial call applying all non-propagation flags.

+	if !isremount(device, flags) || data != "" {

+		// Initial call applying all non-propagation flags for mount

+		// or remount with changed data

 		if err := unix.Mount(device, target, mType, oflags, data); err != nil {

 			return err

 		}

@@ -26,7 +26,7 @@ func TestMount(t *testing.T) {

 		t.Fatal(err)

 	}

 	defer ensureUnmount(t, source)

-	validateMount(t, source, "", "")

+	validateMount(t, source, "", "", "")

 	if t.Failed() {

 		t.FailNow()

 	}

@@ -43,27 +43,31 @@ func TestMount(t *testing.T) {

 		options          string

 		expectedOpts     string

 		expectedOptional string

+		expectedVFS      string

 	}{

 		// No options

-		{"tmpfs", "tmpfs", "", "", ""},

+		{"tmpfs", "tmpfs", "", "", "", ""},

 		// Default rw / ro test

-		{source, "", "bind", "", ""},

-		{source, "", "bind,private", "", ""},

-		{source, "", "bind,shared", "", "shared"},

-		{source, "", "bind,slave", "", "master"},

-		{source, "", "bind,unbindable", "", "unbindable"},

+		{source, "", "bind", "", "", ""},

+		{source, "", "bind,private", "", "", ""},

+		{source, "", "bind,shared", "", "shared", ""},

+		{source, "", "bind,slave", "", "master", ""},

+		{source, "", "bind,unbindable", "", "unbindable", ""},

 		// Read Write tests

-		{source, "", "bind,rw", "rw", ""},

-		{source, "", "bind,rw,private", "rw", ""},

-		{source, "", "bind,rw,shared", "rw", "shared"},

-		{source, "", "bind,rw,slave", "rw", "master"},

-		{source, "", "bind,rw,unbindable", "rw", "unbindable"},

+		{source, "", "bind,rw", "rw", "", ""},

+		{source, "", "bind,rw,private", "rw", "", ""},

+		{source, "", "bind,rw,shared", "rw", "shared", ""},

+		{source, "", "bind,rw,slave", "rw", "master", ""},

+		{source, "", "bind,rw,unbindable", "rw", "unbindable", ""},

 		// Read Only tests

-		{source, "", "bind,ro", "ro", ""},

-		{source, "", "bind,ro,private", "ro", ""},

-		{source, "", "bind,ro,shared", "ro", "shared"},

-		{source, "", "bind,ro,slave", "ro", "master"},

-		{source, "", "bind,ro,unbindable", "ro", "unbindable"},

+		{source, "", "bind,ro", "ro", "", ""},

+		{source, "", "bind,ro,private", "ro", "", ""},

+		{source, "", "bind,ro,shared", "ro", "shared", ""},

+		{source, "", "bind,ro,slave", "ro", "master", ""},

+		{source, "", "bind,ro,unbindable", "ro", "unbindable", ""},

+		// Remount tests to change per filesystem options

+		{"", "", "remount,size=128k", "rw", "", "rw,size=128k"},

+		{"", "", "remount,ro,size=128k", "ro", "", "ro,size=128k"},

 	}

 	for _, tc := range tests {

@@ -87,11 +91,17 @@ func TestMount(t *testing.T) {

 					}

 				}()

 			}

+			if strings.Contains(tc.options, "remount") {

+				// create a new mount to remount first

+				if err := Mount("tmpfs", target, "tmpfs", ""); err != nil {

+					t.Fatal(err)

+				}

+			}

 			if err := Mount(tc.source, target, tc.ftype, tc.options); err != nil {

 				t.Fatal(err)

 			}

 			defer ensureUnmount(t, target)

-			validateMount(t, target, tc.expectedOpts, tc.expectedOptional)

+			validateMount(t, target, tc.expectedOpts, tc.expectedOptional, tc.expectedVFS)

 		})

 	}

 }

@@ -104,7 +114,7 @@ func ensureUnmount(t *testing.T, mnt string) {

 }

 // validateMount checks that mnt has the given options

-func validateMount(t *testing.T, mnt string, opts, optional string) {

+func validateMount(t *testing.T, mnt string, opts, optional, vfs string) {

 	info, err := GetMounts()

 	if err != nil {

 		t.Fatal(err)

@@ -124,6 +134,13 @@ func validateMount(t *testing.T, mnt string, opts, optional string) {

 		}

 	}

+	wantedVFS := make(map[string]struct{})

+	if vfs != "" {

+		for _, opt := range strings.Split(vfs, ",") {

+			wantedVFS[opt] = struct{}{}

+		}

+	}

+

 	mnts := make(map[int]*Info, len(info))

 	for _, mi := range info {

 		mnts[mi.ID] = mi

@@ -177,6 +194,22 @@ func validateMount(t *testing.T, mnt string, opts, optional string) {

 			t.Errorf("missing optional field %q found %q", field, mi.Optional)

 		}

+		// Validate VFS if set

+		if vfs != "" {

+			if mi.VfsOpts != "" {

+				for _, opt := range strings.Split(mi.VfsOpts, ",") {

+					opt = clean(opt)

+					if !has(wantedVFS, opt) {

+						t.Errorf("unexpected mount option %q expected %q", opt, vfs)

+					}

+					delete(wantedVFS, opt)

+				}

+			}

+			for opt := range wantedVFS {

+				t.Errorf("missing mount option %q found %q", opt, mi.VfsOpts)

+			}

+		}

+

 		return

 	}