attacher/detacher refactor

pkg/kubelet/volumemanager/cache/desired_state_of_world.go

@@ -150,6 +150,10 @@ type volumeToMount struct {
 	// the volume.Attacher interface
 	pluginIsAttachable bool
 
+	// pluginIsDeviceMountable indicates that the plugin for this volume implements
+	// the volume.DeviceMounter interface
+	pluginIsDeviceMountable bool
+
 	// volumeGidValue contains the value of the GID annotation, if present.
 	volumeGidValue string
 
@@ -220,13 +224,16 @@ func (dsw *desiredStateOfWorld) AddPodToVolume(
 		volumeName = util.GetUniqueVolumeNameForNonAttachableVolume(podName, volumePlugin, volumeSpec)
 	}
 
+	deviceMountable := dsw.isDeviceMountableVolume(volumeSpec)
+
 	if _, volumeExists := dsw.volumesToMount[volumeName]; !volumeExists {
 		dsw.volumesToMount[volumeName] = volumeToMount{
-			volumeName:         volumeName,
-			podsToMount:        make(map[types.UniquePodName]podToMount),
-			pluginIsAttachable: attachable,
-			volumeGidValue:     volumeGidValue,
-			reportedInUse:      false,
+			volumeName:              volumeName,
+			podsToMount:             make(map[types.UniquePodName]podToMount),
+			pluginIsAttachable:      attachable,
+			pluginIsDeviceMountable: deviceMountable,
+			volumeGidValue:          volumeGidValue,
+			reportedInUse:           false,
 		}
 	}
 
@@ -346,14 +353,15 @@ func (dsw *desiredStateOfWorld) GetVolumesToMount() []VolumeToMount {
 				volumesToMount,
 				VolumeToMount{
 					VolumeToMount: operationexecutor.VolumeToMount{
-						VolumeName:          volumeName,
-						PodName:             podName,
-						Pod:                 podObj.pod,
-						VolumeSpec:          podObj.volumeSpec,
-						PluginIsAttachable:  volumeObj.pluginIsAttachable,
-						OuterVolumeSpecName: podObj.outerVolumeSpecName,
-						VolumeGidValue:      volumeObj.volumeGidValue,
-						ReportedInUse:       volumeObj.reportedInUse}})
+						VolumeName:              volumeName,
+						PodName:                 podName,
+						Pod:                     podObj.pod,
+						VolumeSpec:              podObj.volumeSpec,
+						PluginIsAttachable:      volumeObj.pluginIsAttachable,
+						PluginIsDeviceMountable: volumeObj.pluginIsDeviceMountable,
+						OuterVolumeSpecName:     podObj.outerVolumeSpecName,
+						VolumeGidValue:          volumeObj.volumeGidValue,
+						ReportedInUse:           volumeObj.reportedInUse}})
 		}
 	}
 	return volumesToMount
@@ -371,3 +379,15 @@ func (dsw *desiredStateOfWorld) isAttachableVolume(volumeSpec *volume.Spec) bool
 
 	return false
 }
+
+func (dsw *desiredStateOfWorld) isDeviceMountableVolume(volumeSpec *volume.Spec) bool {
+	deviceMountableVolumePlugin, _ := dsw.volumePluginMgr.FindDeviceMountablePluginBySpec(volumeSpec)
+	if deviceMountableVolumePlugin != nil {
+		volumeDeviceMounter, err := deviceMountableVolumePlugin.NewDeviceMounter()
+		if err == nil && volumeDeviceMounter != nil {
+			return true
+		}
+	}
+
+	return false
+}

pkg/volume/plugins.go

@@ -202,9 +202,17 @@ type ProvisionableVolumePlugin interface {
 // AttachableVolumePlugin is an extended interface of VolumePlugin and is used for volumes that require attachment
 // to a node before mounting.
 type AttachableVolumePlugin interface {
-	VolumePlugin
+	DeviceMountableVolumePlugin
 	NewAttacher() (Attacher, error)
 	NewDetacher() (Detacher, error)
+}
+
+// DeviceMountableVolumePlugin is an extended interface of VolumePlugin and is used
+// for volumes that requires mount device to a node before binding to volume to pod.
+type DeviceMountableVolumePlugin interface {
+	VolumePlugin
+	NewDeviceMounter() (DeviceMounter, error)
+	NewDeviceUnmounter() (DeviceUnmounter, error)
 	GetDeviceMountRefs(deviceMountPath string) ([]string, error)
 }
 
@@ -757,6 +765,30 @@ func (pm *VolumePluginMgr) FindAttachablePluginByName(name string) (AttachableVo
 	return nil, nil
 }
 
+// FindDeviceMountablePluginBySpec fetches a persistent volume plugin by spec.
+func (pm *VolumePluginMgr) FindDeviceMountablePluginBySpec(spec *Spec) (DeviceMountableVolumePlugin, error) {
+	volumePlugin, err := pm.FindPluginBySpec(spec)
+	if err != nil {
+		return nil, err
+	}
+	if deviceMountableVolumePlugin, ok := volumePlugin.(DeviceMountableVolumePlugin); ok {
+		return deviceMountableVolumePlugin, nil
+	}
+	return nil, nil
+}
+
+// FindDeviceMountablePluginByName fetches a devicemountable volume plugin by name.
+func (pm *VolumePluginMgr) FindDeviceMountablePluginByName(name string) (DeviceMountableVolumePlugin, error) {
+	volumePlugin, err := pm.FindPluginByName(name)
+	if err != nil {
+		return nil, err
+	}
+	if deviceMountableVolumePlugin, ok := volumePlugin.(DeviceMountableVolumePlugin); ok {
+		return deviceMountableVolumePlugin, nil
+	}
+	return nil, nil
+}
+
 // FindExpandablePluginBySpec fetches a persistent volume plugin by spec.
 func (pm *VolumePluginMgr) FindExpandablePluginBySpec(spec *Spec) (ExpandableVolumePlugin, error) {
 	volumePlugin, err := pm.FindPluginBySpec(spec)

pkg/volume/util/operationexecutor/operation_executor.go

@@ -329,6 +329,10 @@ type VolumeToMount struct {
 	// the volume.Attacher interface
 	PluginIsAttachable bool
 
+	// PluginIsDeviceMountable indicates that the plugin for this volume implements
+	// the volume.DeviceMounter interface
+	PluginIsDeviceMountable bool
+
 	// VolumeGidValue contains the value of the GID annotation, if present.
 	VolumeGidValue string
 
@@ -738,8 +742,8 @@ func (oe *operationExecutor) MountVolume(
 	podName := nestedpendingoperations.EmptyUniquePodName
 
 	// TODO: remove this -- not necessary
-	if !volumeToMount.PluginIsAttachable {
-		// Non-attachable volume plugins can execute mount for multiple pods
+	if !volumeToMount.PluginIsAttachable && !volumeToMount.PluginIsDeviceMountable {
+		// volume plugins which are Non-attachable and Non-deviceMountable can execute mount for multiple pods
 		// referencing the same volume in parallel
 		podName = util.GetUniquePodName(volumeToMount.Pod)
 	}

pkg/volume/util/operationexecutor/operation_generator.go

@@ -478,6 +478,13 @@ func (og *operationGenerator) GenerateMountVolumeFunc(
 		volumeAttacher, _ = attachableVolumePlugin.NewAttacher()
 	}
 
+	// get deviceMounter, if possible
+	deviceMountableVolumePlugin, _ := og.volumePluginMgr.FindDeviceMountablePluginBySpec(volumeToMount.VolumeSpec)
+	var volumeDeviceMounter volume.DeviceMounter
+	if deviceMountableVolumePlugin != nil {
+		volumeDeviceMounter, _ = deviceMountableVolumePlugin.NewDeviceMounter()
+	}
+
 	var fsGroup *int64
 	if volumeToMount.Pod.Spec.SecurityContext != nil &&
 		volumeToMount.Pod.Spec.SecurityContext.FSGroup != nil {
@@ -485,28 +492,31 @@ func (og *operationGenerator) GenerateMountVolumeFunc(
 	}
 
 	mountVolumeFunc := func() (error, error) {
+		devicePath := volumeToMount.DevicePath
 		if volumeAttacher != nil {
 			// Wait for attachable volumes to finish attaching
 			glog.Infof(volumeToMount.GenerateMsgDetailed("MountVolume.WaitForAttach entering", fmt.Sprintf("DevicePath %q", volumeToMount.DevicePath)))
 
-			devicePath, err := volumeAttacher.WaitForAttach(
-				volumeToMount.VolumeSpec, volumeToMount.DevicePath, volumeToMount.Pod, waitForAttachTimeout)
+			devicePath, err = volumeAttacher.WaitForAttach(
+				volumeToMount.VolumeSpec, devicePath, volumeToMount.Pod, waitForAttachTimeout)
 			if err != nil {
 				// On failure, return error. Caller will log and retry.
 				return volumeToMount.GenerateError("MountVolume.WaitForAttach failed", err)
 			}
 
 			glog.Infof(volumeToMount.GenerateMsgDetailed("MountVolume.WaitForAttach succeeded", fmt.Sprintf("DevicePath %q", devicePath)))
+		}
 
+		if volumeDeviceMounter != nil {
 			deviceMountPath, err :=
-				volumeAttacher.GetDeviceMountPath(volumeToMount.VolumeSpec)
+				volumeDeviceMounter.GetDeviceMountPath(volumeToMount.VolumeSpec)
 			if err != nil {
 				// On failure, return error. Caller will log and retry.
 				return volumeToMount.GenerateError("MountVolume.GetDeviceMountPath failed", err)
 			}
 
 			// Mount device to global mount path
-			err = volumeAttacher.MountDevice(
+			err = volumeDeviceMounter.MountDevice(
 				volumeToMount.VolumeSpec,
 				devicePath,
 				deviceMountPath)
@@ -532,7 +542,6 @@ func (og *operationGenerator) GenerateMountVolumeFunc(
 			if resizeSimpleError != nil || resizeDetailedError != nil {
 				return resizeSimpleError, resizeDetailedError
 			}
-
 		}
 
 		if og.checkNodeCapabilitiesBeforeMount {
@@ -718,20 +727,31 @@ func (og *operationGenerator) GenerateUnmountDeviceFunc(
 	deviceToDetach AttachedVolume,
 	actualStateOfWorld ActualStateOfWorldMounterUpdater,
 	mounter mount.Interface) (volumetypes.GeneratedOperations, error) {
-	// Get attacher plugin
-	attachableVolumePlugin, err :=
-		og.volumePluginMgr.FindAttachablePluginByName(deviceToDetach.PluginName)
-	if err != nil || attachableVolumePlugin == nil {
-		return volumetypes.GeneratedOperations{}, deviceToDetach.GenerateErrorDetailed("UnmountDevice.FindAttachablePluginBySpec failed", err)
+	// Get DeviceMounter plugin
+	deviceMountableVolumePlugin, err :=
+		og.volumePluginMgr.FindDeviceMountablePluginByName(deviceToDetach.PluginName)
+	if err != nil || deviceMountableVolumePlugin == nil {
+		return volumetypes.GeneratedOperations{}, deviceToDetach.GenerateErrorDetailed("UnmountDevice.FindDeviceMountablePluginByName failed", err)
+	}
+	volumeDeviceUmounter, err := deviceMountableVolumePlugin.NewDeviceUnmounter()
+	if err != nil {
+		return volumetypes.GeneratedOperations{}, deviceToDetach.GenerateErrorDetailed("UnmountDevice.NewDeviceUmounter failed", err)
 	}
 
-	volumeDetacher, err := attachableVolumePlugin.NewDetacher()
+	volumeDeviceMounter, err := deviceMountableVolumePlugin.NewDeviceMounter()
 	if err != nil {
-		return volumetypes.GeneratedOperations{}, deviceToDetach.GenerateErrorDetailed("UnmountDevice.NewDetacher failed", err)
+		return volumetypes.GeneratedOperations{}, deviceToDetach.GenerateErrorDetailed("UnmountDevice.NewDeviceMounter failed", err)
 	}
+
 	unmountDeviceFunc := func() (error, error) {
-		deviceMountPath := deviceToDetach.DeviceMountPath
-		refs, err := attachableVolumePlugin.GetDeviceMountRefs(deviceMountPath)
+		//deviceMountPath := deviceToDetach.DeviceMountPath
+		deviceMountPath, err :=
+			volumeDeviceMounter.GetDeviceMountPath(deviceToDetach.VolumeSpec)
+		if err != nil {
+			// On failure, return error. Caller will log and retry.
+			return deviceToDetach.GenerateError("GetDeviceMountPath failed", err)
+		}
+		refs, err := deviceMountableVolumePlugin.GetDeviceMountRefs(deviceMountPath)
 
 		if err != nil || mount.HasMountRefs(deviceMountPath, refs) {
 			if err == nil {
@@ -740,7 +760,7 @@ func (og *operationGenerator) GenerateUnmountDeviceFunc(
 			return deviceToDetach.GenerateError("GetDeviceMountRefs check failed", err)
 		}
 		// Execute unmount
-		unmountDeviceErr := volumeDetacher.UnmountDevice(deviceMountPath)
+		unmountDeviceErr := volumeDeviceUmounter.UnmountDevice(deviceMountPath)
 		if unmountDeviceErr != nil {
 			// On failure, return error. Caller will log and retry.
 			return deviceToDetach.GenerateError("UnmountDevice failed", unmountDeviceErr)
@@ -775,7 +795,7 @@ func (og *operationGenerator) GenerateUnmountDeviceFunc(
 
 	return volumetypes.GeneratedOperations{
 		OperationFunc:     unmountDeviceFunc,
-		CompleteFunc:      util.OperationCompleteHook(attachableVolumePlugin.GetPluginName(), "unmount_device"),
+		CompleteFunc:      util.OperationCompleteHook(deviceMountableVolumePlugin.GetPluginName(), "unmount_device"),
 		EventRecorderFunc: nil, // nil because we do not want to generate event on error
 	}, nil
 }

pkg/volume/volume.go

@@ -204,6 +204,8 @@ type Deleter interface {
 
 // Attacher can attach a volume to a node.
 type Attacher interface {
+	DeviceMounter
+
 	// Attaches the volume specified by the given spec to the node with the given Name.
 	// On success, returns the device path where the device was attached on the
 	// node.
@@ -219,7 +221,10 @@ type Attacher interface {
 	// is returned. Otherwise, if the device does not attach after
 	// the given timeout period, an error will be returned.
 	WaitForAttach(spec *Spec, devicePath string, pod *v1.Pod, timeout time.Duration) (string, error)
+}
 
+// DeviceMounter can mount a block volume to a global path.
+type DeviceMounter interface {
 	// GetDeviceMountPath returns a path where the device should
 	// be mounted after it is attached. This is a global mount
 	// point which should be bind mounted for individual volumes.
@@ -227,6 +232,7 @@ type Attacher interface {
 
 	// MountDevice mounts the disk to a global path which
 	// individual pods can then bind mount
+	// Note that devicePath can be empty if the volume plugin does not implement any of Attach and WaitForAttach methods.
 	MountDevice(spec *Spec, devicePath string, deviceMountPath string) error
 }
 
@@ -240,11 +246,15 @@ type BulkVolumeVerifier interface {
 
 // Detacher can detach a volume from a node.
 type Detacher interface {
+	DeviceUnmounter
 	// Detach the given volume from the node with the given Name.
 	// volumeName is name of the volume as returned from plugin's
 	// GetVolumeName().
 	Detach(volumeName string, nodeName types.NodeName) error
+}
 
+// DeviceUnmounter can unmount a block volume from the global path.
+type DeviceUnmounter interface {
 	// UnmountDevice unmounts the global mount of the disk. This
 	// should only be called once all bind mounts have been
 	// unmounted.