feat: add support for checking if device is already open

This allows to handle retries better on Talos volume management side.

Signed-off-by: Andrey Smirnov <[email protected]>

encryption/luks/luks.go

@@ -148,6 +148,22 @@ func (l *LUKS) Open(ctx context.Context, deviceName, mappedName string, key *enc
 	return filepath.Join("/dev/mapper", mappedName), nil
 }
 
+// IsOpen checks if the device is already opened.
+func (l *LUKS) IsOpen(ctx context.Context, _, mappedName string) (bool, string, error) {
+	args := []string{"status", mappedName}
+
+	_, err := l.runCommand(ctx, args, nil)
+	if err != nil {
+		if errors.Is(err, encryption.ErrDeviceNotReady) {
+			return false, "", nil
+		}
+
+		return false, "", err
+	}
+
+	return true, filepath.Join("/dev/mapper", mappedName), nil
+}
+
 // Encrypt implements encryption.Provider.
 func (l *LUKS) Encrypt(ctx context.Context, deviceName string, key *encryption.Key) error {
 	cipher, err := l.cipher.String()
@@ -358,6 +374,8 @@ func (l *LUKS) runCommand(ctx context.Context, args []string, stdin []byte) (str
 				}
 			case 2:
 				return "", encryption.ErrEncryptionKeyRejected
+			case 4:
+				return "", encryption.ErrDeviceNotReady
 			case 5:
 				return "", encryption.ErrDeviceBusy
 			}

encryption/luks/luks_test.go

@@ -101,11 +101,24 @@ func testEncrypt(t *testing.T) {
 
 	t.Logf("unencrypted partition path %s", path)
 
+	isOpen, _, err := provider.IsOpen(ctx, path, mappedName)
+	require.NoError(t, err)
+	require.False(t, isOpen)
+
 	require.NoError(t, provider.Encrypt(ctx, path, key))
 
+	isOpen, _, err = provider.IsOpen(ctx, path, mappedName)
+	require.NoError(t, err)
+	require.False(t, isOpen)
+
 	encryptedPath, err := provider.Open(ctx, path, mappedName, key)
 	require.NoError(t, err)
 
+	isOpen, isOpenPath, err := provider.IsOpen(ctx, path, mappedName)
+	require.NoError(t, err)
+	require.True(t, isOpen)
+	require.Equal(t, encryptedPath, isOpenPath)
+
 	require.NoError(t, provider.Resize(ctx, encryptedPath, key))
 
 	require.NoError(t, provider.AddKey(ctx, path, key, keyExtra))
@@ -159,6 +172,11 @@ func testEncrypt(t *testing.T) {
 	require.NoError(t, unix.Unmount(mountPath, 0))
 
 	require.NoError(t, provider.Close(ctx, encryptedPath))
+
+	isOpen, _, err = provider.IsOpen(ctx, path, mappedName)
+	require.NoError(t, err)
+	require.False(t, isOpen)
+
 	require.Error(t, provider.Close(ctx, encryptedPath))
 
 	// second key slot

encryption/provider.go

@@ -22,6 +22,7 @@ const (
 type Provider interface {
 	TokenProvider
 	Encrypt(ctx context.Context, devname string, key *Key) error
+	IsOpen(ctx context.Context, devname, mappedName string) (bool, string, error)
 	Open(ctx context.Context, devname, mappedName string, key *Key) (string, error)
 	Close(ctx context.Context, devname string) error
 	AddKey(ctx context.Context, devname string, key, newKey *Key) error
@@ -47,6 +48,9 @@ var (
 
 	// ErrTokenNotFound returned when trying to get/delete not existing token.
 	ErrTokenNotFound = fmt.Errorf("no token with supplied id exists")
+
+	// ErrDeviceNotReady returned when device is not ready.
+	ErrDeviceNotReady = fmt.Errorf("device is not ready")
 )
 
 // Keyslots represents LUKS2 keyslots metadata.