feat: add real size to backing image

ref: longhorn/longhorn 8757

Signed-off-by: Jack Lin <jack.lin@suse.com>

api/types.go

@@ -13,6 +13,7 @@ type BackingImage struct {
 	UUID             string `json:"uuid"`
 	Size             int64  `json:"size"`
 	VirtualSize      int64  `json:"virtualSize"`
+	RealSize         int64  `json:"realSize"`
 	ExpectedChecksum string `json:"expectedChecksum"`
 
 	Status BackingImageStatus `json:"status"`
@@ -33,6 +34,7 @@ func RPCToBackingImage(obj *rpc.BackingImageResponse) *BackingImage {
 		UUID:             obj.Spec.Uuid,
 		Size:             obj.Spec.Size,
 		VirtualSize:      obj.Spec.VirtualSize,
+		RealSize:         obj.Spec.RealSize,
 		ExpectedChecksum: obj.Spec.Checksum,
 
 		Status: BackingImageStatus{
@@ -114,6 +116,7 @@ type FileInfo struct {
 	UUID             string `json:"uuid"`
 	Size             int64  `json:"size"`
 	VirtualSize      int64  `json:"virtualSize"`
+	RealSize         int64  `json:"realSize"`
 	State            string `json:"state"`
 	Progress         int    `json:"progress"`
 	ProcessedSize    int64  `json:"processedSize"`

pkg/manager/service.go

@@ -300,6 +300,7 @@ func backingImageResponse(fInfo *api.FileInfo) *rpc.BackingImageResponse {
 			Uuid:        fInfo.UUID,
 			Size:        fInfo.Size,
 			VirtualSize: fInfo.VirtualSize,
+			RealSize:    fInfo.RealSize,
 			Checksum:    fInfo.ExpectedChecksum,
 		},
 		Status: &rpc.BackingImageStatus{

pkg/sync/server_test.go

@@ -770,6 +770,7 @@ func getAndWaitFileState(cli *client.SyncClient, curPath, desireState string, wa
 				UUID:             fInfo.UUID,
 				Size:             fInfo.Size,
 				VirtualSize:      fInfo.VirtualSize,
+				RealSize:         fInfo.RealSize,
 				ExpectedChecksum: fInfo.ExpectedChecksum,
 				CurrentChecksum:  fInfo.CurrentChecksum,
 				ModificationTime: fInfo.ModificationTime,

pkg/sync/sync_file.go

@@ -85,6 +85,7 @@ type SyncingFile struct {
 	diskUUID         string
 	size             int64
 	virtualSize      int64
+	realSize         int64
 	state            types.State
 	progress         int
 	processedSize    int64
@@ -258,6 +259,7 @@ func (sf *SyncingFile) checkAndReuseFile() (err error) {
 	sf.modificationTime = info.ModTime().UTC().String()
 	sf.updateSyncReadyNoLock()
 	sf.updateVirtualSizeNoLock(sf.filePath)
+	sf.updateRealSizeNoLock(sf.filePath)
 	sf.writeConfigNoLock()
 	sf.lock.Unlock()
 
@@ -359,6 +361,7 @@ func (sf *SyncingFile) getNoLock() api.FileInfo {
 		UUID:             sf.uuid,
 		Size:             sf.size,
 		VirtualSize:      sf.virtualSize,
+		RealSize:         sf.realSize,
 		State:            string(sf.state),
 		Progress:         sf.progress,
 		ProcessedSize:    sf.processedSize,
@@ -917,6 +920,7 @@ func (sf *SyncingFile) finishProcessing(err error) (finalErr error) {
 		sf.currentChecksum = config.CurrentChecksum
 		sf.updateSyncReadyNoLock()
 		sf.updateVirtualSizeNoLock(sf.tmpFilePath)
+		sf.updateRealSizeNoLock(sf.tmpFilePath)
 		sf.writeConfigNoLock()
 
 		// Renaming won't change the file modification time.
@@ -966,6 +970,7 @@ func (sf *SyncingFile) postProcessSyncFile() {
 	}
 	sf.updateSyncReadyNoLock()
 	sf.updateVirtualSizeNoLock(sf.tmpFilePath)
+	sf.updateRealSizeNoLock(sf.tmpFilePath)
 	sf.writeConfigNoLock()
 
 	// Renaming won't change the file modification time.
@@ -1000,6 +1005,18 @@ func (sf *SyncingFile) updateVirtualSizeNoLock(filePath string) {
 	sf.virtualSize = imgInfo.VirtualSize
 }
 
+func (sf *SyncingFile) updateRealSizeNoLock(filePath string) {
+	realSize, err := util.GetFileRealSize(filePath)
+	if err != nil {
+		sf.log.Warnf("SyncingFile: failed to get backing image virtual size: %v", err)
+	}
+
+	// This will be zero when there is an error, which allows components
+	// further up the stack to know that the real size somehow isn't
+	// available yet.
+	sf.realSize = realSize
+}
+
 func (sf *SyncingFile) handleFailureNoLock(err error) {
 	if err == nil {
 		return
@@ -1029,6 +1046,7 @@ func (sf *SyncingFile) writeConfigNoLock() {
 		UUID:             sf.uuid,
 		Size:             sf.size,
 		VirtualSize:      sf.virtualSize,
+		RealSize:         sf.realSize,
 		ExpectedChecksum: sf.expectedChecksum,
 		CurrentChecksum:  sf.currentChecksum,
 		ModificationTime: sf.modificationTime,

pkg/util/util.go

@@ -14,6 +14,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"regexp"
+	"syscall"
 	"time"
 
 	"github.com/pkg/errors"
@@ -151,6 +152,7 @@ type SyncingFileConfig struct {
 	UUID             string `json:"uuid"`
 	Size             int64  `json:"size"`
 	VirtualSize      int64  `json:"virtualSize"`
+	RealSize         int64  `json:"realSize"`
 	ExpectedChecksum string `json:"expectedChecksum"`
 	CurrentChecksum  string `json:"currentChecksum"`
 	ModificationTime string `json:"modificationTime"`
@@ -313,6 +315,18 @@ func ConvertFromQcow2ToRaw(sourcePath, targetPath string) error {
 	return nil
 }
 
+func GetFileRealSize(filePath string) (int64, error) {
+	var stat syscall.Stat_t
+	err := syscall.Stat(filePath, &stat)
+	if err != nil {
+		return 0, err
+	}
+	fmt.Printf("stat.Blksize: %v\n", stat.Blksize)
+
+	// 512 is defined in the Linux kernel and remains consistent across all distributions.
+	return stat.Blocks * 512, nil
+}
+
 func FileModificationTime(filePath string) string {
 	fi, err := os.Stat(filePath)
 	if err != nil {