devmapper: Open code createDevice() and createSnapDevice()

Open code createDevice() and createSnapDevice() and move all the logic
in the caller.

This is a sheer code reorganization so that all device Id allocation
logic is in one function. That way in case of erros, one can easily
cleanup and mark device Id free again. (Later patches benefit from
it).

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>

daemon/graphdriver/devmapper/deviceset.go

@@ -505,27 +505,20 @@ func (devices *DeviceSet) getNextDeviceId() int {
 	return devices.NextDeviceId
 }
 
-func (devices *DeviceSet) createDevice(deviceId *int) error {
+func (devices *DeviceSet) createRegisterDevice(hash string) (*DevInfo, error) {
+	deviceId := devices.getNextDeviceId()
 	for {
-		if err := devicemapper.CreateDevice(devices.getPoolDevName(), *deviceId); err != nil {
+		if err := devicemapper.CreateDevice(devices.getPoolDevName(), deviceId); err != nil {
 			if devicemapper.DeviceIdExists(err) {
 				// Device Id already exists. Try a new one.
-				*deviceId = devices.getNextDeviceId()
+				deviceId = devices.getNextDeviceId()
 				continue
 			}
 			log.Debugf("Error creating device: %s", err)
-			return err
+			return nil, err
 		}
 		break
 	}
-	return nil
-}
-
-func (devices *DeviceSet) createRegisterDevice(hash string) (*DevInfo, error) {
-	deviceId := devices.getNextDeviceId()
-	if err := devices.createDevice(&deviceId); err != nil {
-		return nil, err
-	}
 
 	transactionId := devices.allocateTransactionId()
 	log.Debugf("Registering device (id %v) with FS size %v", deviceId, devices.baseFsSize)
@@ -543,15 +536,13 @@ func (devices *DeviceSet) createRegisterDevice(hash string) (*DevInfo, error) {
 	return info, nil
 }
 
-func (devices *DeviceSet) createSnapDevice(baseInfo *DevInfo, deviceId *int) error {
-	log.Debugf("[deviceset] createSnapDevice() DeviceId=%d", *deviceId)
-	defer log.Debugf("[deviceset] createSnapDevice() END DeviceId=%d", *deviceId)
-
+func (devices *DeviceSet) createRegisterSnapDevice(hash string, baseInfo *DevInfo) error {
+	deviceId := devices.getNextDeviceId()
 	for {
-		if err := devicemapper.CreateSnapDevice(devices.getPoolDevName(), *deviceId, baseInfo.Name(), baseInfo.DeviceId); err != nil {
+		if err := devicemapper.CreateSnapDevice(devices.getPoolDevName(), deviceId, baseInfo.Name(), baseInfo.DeviceId); err != nil {
 			if devicemapper.DeviceIdExists(err) {
 				// Device Id already exists. Try a new one.
-				*deviceId = devices.getNextDeviceId()
+				deviceId = devices.getNextDeviceId()
 				continue
 			}
 			log.Debugf("Error creating snap device: %s", err)
@@ -559,15 +550,6 @@ func (devices *DeviceSet) createSnapDevice(baseInfo *DevInfo, deviceId *int) err
 		}
 		break
 	}
-	return nil
-}
-
-func (devices *DeviceSet) createRegisterSnapDevice(hash string, baseInfo *DevInfo) error {
-	deviceId := devices.getNextDeviceId()
-	if err := devices.createSnapDevice(baseInfo, &deviceId); err != nil {
-		log.Debugf("Error creating snap device: %s", err)
-		return err
-	}
 
 	transactionId := devices.allocateTransactionId()
 	if _, err := devices.registerDevice(deviceId, hash, baseInfo.Size, transactionId); err != nil {