core: Preallocate blank block volumes (kubevirt#1559)

Importer pod needs to be started for blank block volumes and it needs to
handle the case.

Signed-off-by: Tomasz Baranski <tbaransk@redhat.com>

cmd/cdi-importer/importer.go

@@ -104,9 +104,16 @@ func main() {
 			klog.Warningf("Available space less than requested size, creating blank image sized to available space: %s.\n", minSizeQuantity.String())
 		}
 
-		quantityWithFSOverhead := importer.GetUsableSpace(filesystemOverhead, minSizeQuantity.Value())
-		klog.Infof("Space adjusted for filesystem overhead: %d.\n", quantityWithFSOverhead)
-		err := image.CreateBlankImage(common.ImporterWritePath, *resource.NewScaledQuantity(quantityWithFSOverhead, 0), preallocation)
+		var err error
+		if volumeMode == v1.PersistentVolumeFilesystem {
+			quantityWithFSOverhead := importer.GetUsableSpace(filesystemOverhead, minSizeQuantity.Value())
+			klog.Infof("Space adjusted for filesystem overhead: %d.\n", quantityWithFSOverhead)
+			err = image.CreateBlankImage(common.ImporterWritePath, *resource.NewScaledQuantity(quantityWithFSOverhead, 0), preallocation)
+		} else if volumeMode == v1.PersistentVolumeBlock && preallocation {
+			klog.V(1).Info("Preallocating blank block volume")
+			err = image.PreallocateBlankBlock(common.WriteBlockPath, minSizeQuantity)
+		}
+
 		if err != nil {
 			klog.Errorf("%+v", err)
 			message := fmt.Sprintf("Unable to create blank image: %+v", err)

pkg/controller/import-controller.go

@@ -226,7 +226,7 @@ func (r *ImportReconciler) Reconcile(req reconcile.Request) (reconcile.Result, e
 	// In case this is a request to create a blank disk on a block device, we do not create a pod.
 	// we just mark the DV as successful
 	volumeMode := getVolumeMode(pvc)
-	if volumeMode == corev1.PersistentVolumeBlock && pvc.GetAnnotations()[AnnSource] == SourceNone {
+	if volumeMode == corev1.PersistentVolumeBlock && pvc.GetAnnotations()[AnnSource] == SourceNone && pvc.GetAnnotations()[AnnPreallocationRequested] != "true" {
 		log.V(1).Info("attempting to create blank disk for block mode, this is a no-op, marking pvc with pod-phase succeeded")
 		if pvc.GetAnnotations() == nil {
 			pvc.SetAnnotations(make(map[string]string, 0))

pkg/image/qemu.go

@@ -259,3 +259,17 @@ func (o *qemuOperations) CreateBlankImage(dest string, size resource.Quantity, p
 
 	return nil
 }
+
+// PreallocateBlankBlock writes requested amount of zeros to block device mounted at dest
+func PreallocateBlankBlock(dest string, size resource.Quantity) error {
+	klog.V(3).Infof("block volume size is %s", size.String())
+
+	args := []string{"if=/dev/zero", "of=" + dest, "bs=" + convertQuantityToQemuSize(size), "count=1"}
+	_, err := qemuExecFunction(nil, nil, "dd", args...)
+
+	if err != nil {
+		return errors.Wrap(err, fmt.Sprintf("Could not preallocate blank block volume at %s with size %s", dest, size.String()))
+	}
+
+	return nil
+}

pkg/importer/data-processor.go

@@ -274,7 +274,7 @@ func (dp *DataProcessor) resize() (ProcessingPhase, error) {
 	if dp.requestImageSize != "" && size < int64(0) {
 		var err error
 		klog.V(3).Infoln("Resizing image")
-		shouldPreallocate, err = ResizeImage(dp.dataFile, dp.requestImageSize, dp.availableSpace)
+		shouldPreallocate, err = ResizeImage(dp.dataFile, dp.requestImageSize, dp.getUsableSpace())
 		if err != nil {
 			return ProcessingPhaseError, errors.Wrap(err, "Resize of image failed")
 		}

tests/import_test.go

@@ -933,5 +933,12 @@ var _ = Describe("Preallocation", func() {
 		Entry("Blank image", true, func() *cdiv1.DataVolume {
 			return utils.NewDataVolumeForBlankRawImage("import-dv", "100Mi")
 		}),
+		Entry("Blank block DataVolume", true, func() *cdiv1.DataVolume {
+			if !f.IsBlockVolumeStorageClassAvailable() {
+				Skip("Storage Class for block volume is not available")
+			}
+
+			return utils.NewDataVolumeForBlankRawImageBlock("import-dv", "100Mi", f.BlockSCName)
+		}),
 	)
 })