Use `blkid` to get fs type of device.

pkg/util/mount/mount_linux.go

@@ -542,9 +542,18 @@ func (mounter *SafeFormatAndMount) GetDiskFormat(disk string) (string, error) {
 	glog.V(4).Infof("Attempting to determine if disk %q is formatted using blkid with args: (%v)", disk, args)
 	dataOut, err := mounter.Exec.Run("blkid", args...)
 	output := string(dataOut)
-	glog.V(4).Infof("Output: %q", output)
+	glog.V(4).Infof("Output: %q, err: %v", output, err)
 
 	if err != nil {
+		if exit, ok := err.(utilexec.ExitError); ok {
+			if exit.ExitStatus() == 2 {
+				// Disk device is unformatted.
+				// For `blkid`, if the specified token (TYPE/PTTYPE, etc) was
+				// not found, or no (specified) devices could be identified, an
+				// exit code of 2 is returned.
+				return "", nil
+			}
+		}
 		glog.Errorf("Could not determine if disk %q is formatted (%v)", disk, err)
 		return "", err
 	}

pkg/util/mount/safe_format_and_mount_test.go

@@ -115,7 +115,7 @@ func TestSafeFormatAndMount(t *testing.T) {
 			mountErrs:   []error{fmt.Errorf("unknown filesystem type '(null)'")},
 			execScripts: []ExecArgs{
 				{"fsck", []string{"-a", "/dev/foo"}, "", nil},
-				{"blkid", []string{"-p", "-s", "TYPE", "-s", "PTTYPE", "-o", "export", "/dev/foo"}, "", nil},
+				{"blkid", []string{"-p", "-s", "TYPE", "-s", "PTTYPE", "-o", "export", "/dev/foo"}, "", &fakeexec.FakeExitError{Status: 2}},
 				{"mkfs.ext4", []string{"-F", "/dev/foo"}, "", fmt.Errorf("formatting failed")},
 			},
 			expectedError: fmt.Errorf("formatting failed"),
@@ -126,7 +126,7 @@ func TestSafeFormatAndMount(t *testing.T) {
 			mountErrs:   []error{fmt.Errorf("unknown filesystem type '(null)'"), fmt.Errorf("Still cannot mount")},
 			execScripts: []ExecArgs{
 				{"fsck", []string{"-a", "/dev/foo"}, "", nil},
-				{"blkid", []string{"-p", "-s", "TYPE", "-s", "PTTYPE", "-o", "export", "/dev/foo"}, "", nil},
+				{"blkid", []string{"-p", "-s", "TYPE", "-s", "PTTYPE", "-o", "export", "/dev/foo"}, "", &fakeexec.FakeExitError{Status: 2}},
 				{"mkfs.ext4", []string{"-F", "/dev/foo"}, "", nil},
 			},
 			expectedError: fmt.Errorf("Still cannot mount"),
@@ -137,7 +137,7 @@ func TestSafeFormatAndMount(t *testing.T) {
 			mountErrs:   []error{fmt.Errorf("unknown filesystem type '(null)'"), nil},
 			execScripts: []ExecArgs{
 				{"fsck", []string{"-a", "/dev/foo"}, "", nil},
-				{"blkid", []string{"-p", "-s", "TYPE", "-s", "PTTYPE", "-o", "export", "/dev/foo"}, "", nil},
+				{"blkid", []string{"-p", "-s", "TYPE", "-s", "PTTYPE", "-o", "export", "/dev/foo"}, "", &fakeexec.FakeExitError{Status: 2}},
 				{"mkfs.ext4", []string{"-F", "/dev/foo"}, "", nil},
 			},
 			expectedError: nil,
@@ -148,7 +148,7 @@ func TestSafeFormatAndMount(t *testing.T) {
 			mountErrs:   []error{fmt.Errorf("unknown filesystem type '(null)'"), nil},
 			execScripts: []ExecArgs{
 				{"fsck", []string{"-a", "/dev/foo"}, "", nil},
-				{"blkid", []string{"-p", "-s", "TYPE", "-s", "PTTYPE", "-o", "export", "/dev/foo"}, "", nil},
+				{"blkid", []string{"-p", "-s", "TYPE", "-s", "PTTYPE", "-o", "export", "/dev/foo"}, "", &fakeexec.FakeExitError{Status: 2}},
 				{"mkfs.ext3", []string{"-F", "/dev/foo"}, "", nil},
 			},
 			expectedError: nil,
@@ -159,7 +159,7 @@ func TestSafeFormatAndMount(t *testing.T) {
 			mountErrs:   []error{fmt.Errorf("unknown filesystem type '(null)'"), nil},
 			execScripts: []ExecArgs{
 				{"fsck", []string{"-a", "/dev/foo"}, "", nil},
-				{"blkid", []string{"-p", "-s", "TYPE", "-s", "PTTYPE", "-o", "export", "/dev/foo"}, "", nil},
+				{"blkid", []string{"-p", "-s", "TYPE", "-s", "PTTYPE", "-o", "export", "/dev/foo"}, "", &fakeexec.FakeExitError{Status: 2}},
 				{"mkfs.xfs", []string{"/dev/foo"}, "", nil},
 			},
 			expectedError: nil,
@@ -174,6 +174,17 @@ func TestSafeFormatAndMount(t *testing.T) {
 			},
 			expectedError: fmt.Errorf("failed to mount the volume as \"ext3\", it already contains unknown data, probably partitions. Mount error: unknown filesystem type '(null)'"),
 		},
+		{
+			description: "Test that 'blkid' is called but has some usage or other errors (an exit code of 4 is returned)",
+			fstype:      "xfs",
+			mountErrs:   []error{fmt.Errorf("unknown filesystem type '(null)'"), nil},
+			execScripts: []ExecArgs{
+				{"fsck", []string{"-a", "/dev/foo"}, "", nil},
+				{"blkid", []string{"-p", "-s", "TYPE", "-s", "PTTYPE", "-o", "export", "/dev/foo"}, "", &fakeexec.FakeExitError{Status: 4}},
+				{"mkfs.xfs", []string{"/dev/foo"}, "", nil},
+			},
+			expectedError: fmt.Errorf("exit 4"),
+		},
 	}
 
 	for _, test := range tests {