FC volume plugin: remove block device at DetachDisk

After a volume is unmounted from pod and worker node,
cluster admin or external-provisioner might delete
the disk from storage, therefore block device on
the node should be cleaned up beforehand.

The photon volume plugin already has same functionality.

Fixes #49392

pkg/volume/fc/attacher.go

@@ -142,7 +142,24 @@ func (detacher *fcDetacher) Detach(deviceMountPath string, nodeName types.NodeNa
 }
 
 func (detacher *fcDetacher) UnmountDevice(deviceMountPath string) error {
-	return volumeutil.UnmountPath(deviceMountPath, detacher.mounter)
+	// Specify device name for DetachDisk later
+	devName, _, err := mount.GetDeviceNameFromMount(detacher.mounter, deviceMountPath)
+	if err != nil {
+		glog.Errorf("fc: failed to get device from mnt: %s\nError: %v", deviceMountPath, err)
+		return err
+	}
+	// Unmount for deviceMountPath(=globalPDPath)
+	err = volumeutil.UnmountPath(deviceMountPath, detacher.mounter)
+	if err != nil {
+		return fmt.Errorf("fc: failed to unmount: %s\nError: %v", deviceMountPath, err)
+	}
+	unMounter := volumeSpecToUnmounter(detacher.mounter)
+	err = detacher.manager.DetachDisk(*unMounter, devName)
+	if err != nil {
+		return fmt.Errorf("fc: failed to detach disk: %s\nError: %v", devName, err)
+	}
+	glog.V(4).Infof("fc: successfully detached disk: %s", devName)
+	return nil
 }
 
 func volumeSpecToMounter(spec *volume.Spec, host volume.VolumeHost) (*fcDiskMounter, error) {
@@ -168,3 +185,12 @@ func volumeSpecToMounter(spec *volume.Spec, host volume.VolumeHost) (*fcDiskMoun
 		mounter:  &mount.SafeFormatAndMount{Interface: host.GetMounter(), Runner: exec.New()},
 	}, nil
 }
+
+func volumeSpecToUnmounter(mounter mount.Interface) *fcDiskUnmounter {
+	return &fcDiskUnmounter{
+		fcDisk: &fcDisk{
+			io: &osIOHandler{},
+		},
+		mounter: mounter,
+	}
+}

pkg/volume/fc/disk_manager.go

@@ -30,7 +30,7 @@ type diskManager interface {
 	// Attaches the disk to the kubelet's host machine.
 	AttachDisk(b fcDiskMounter) (string, error)
 	// Detaches the disk from the kubelet's host machine.
-	DetachDisk(disk fcDiskUnmounter, mntPath string) error
+	DetachDisk(disk fcDiskUnmounter, devName string) error
 }
 
 // utility to mount a disk based filesystem

pkg/volume/fc/fc_util.go

@@ -89,6 +89,14 @@ func findDisk(wwn, lun string, io ioHandler) (string, string) {
 	return "", ""
 }
 
+// Removes a scsi device based upon /dev/sdX name
+func removeFromScsiSubsystem(deviceName string, io ioHandler) {
+	fileName := "/sys/block/" + deviceName + "/device/delete"
+	glog.V(4).Infof("fc: remove device from scsi-subsystem: path: %s", fileName)
+	data := []byte("1")
+	io.WriteFile(fileName, data, 0666)
+}
+
 // rescan scsi bus
 func scsiHostRescan(io ioHandler) {
 	scsi_path := "/sys/class/scsi_host/"
@@ -177,9 +185,13 @@ func (util *FCUtil) AttachDisk(b fcDiskMounter) (string, error) {
 	return devicePath, err
 }
 
-func (util *FCUtil) DetachDisk(c fcDiskUnmounter, mntPath string) error {
-	if err := c.mounter.Unmount(mntPath); err != nil {
-		return fmt.Errorf("fc detach disk: failed to unmount: %s\nError: %v", mntPath, err)
+func (util *FCUtil) DetachDisk(c fcDiskUnmounter, devName string) error {
+	// Remove scsi device from the node.
+	if !strings.HasPrefix(devName, "/dev/") {
+		return fmt.Errorf("fc detach disk: invalid device name: %s", devName)
 	}
+	arr := strings.Split(devName, "/")
+	dev := arr[len(arr)-1]
+	removeFromScsiSubsystem(dev, c.io)
 	return nil
 }