[cinder-csi-plugin]: do not allow DetachVolume when status is detaching (kubernetes#2965)

Author: Boston01

pkg/csi/cinder/openstack/openstack_volumes.go

@@ -43,6 +43,7 @@ import (
 const (
 	VolumeAvailableStatus    = "available"
 	VolumeInUseStatus        = "in-use"
+	VolumeDetachingStatus    = "detaching"
 	operationFinishInitDelay = 1 * time.Second
 	operationFinishFactor    = 1.1
 	operationFinishSteps     = 10
@@ -307,6 +308,11 @@ func (os *OpenStack) DetachVolume(ctx context.Context, instanceID, volumeID stri
 		klog.V(2).Infof("volume: %s has been detached from compute: %s ", volume.ID, instanceID)
 		return nil
 	}
+	// If the volume is already in detaching state, we can return nil
+	if volume.Status == VolumeDetachingStatus {
+		klog.V(2).Infof("volume: %s is already in detaching state from compute %s  ", volume.ID, instanceID)
+		return nil
+	}
 
 	if volume.Status != VolumeInUseStatus {
 		return fmt.Errorf("can not detach volume %s, its status is %s", volume.Name, volume.Status)