repair the error replications of the volume

weed/storage/volume.go

@@ -79,6 +79,25 @@ func (v *Volume) Size() int64 {
 	return 0 // -1 causes integer overflow and the volume to become unwritable.
 }
 
+func (v *Volume)IndexFileSize() uint64 {
+	return v.nm.IndexFileSize()
+}
+
+func (v *Volume)DataFileSize() uint64 {
+	return uint64(v.Size())
+}
+
+/**
+unix time in seconds
+ */
+func (v *Volume)LastModifiedTime() uint64 {
+	return v.lastModifiedTime
+}
+
+func (v *Volume)FileCount() uint {
+	return uint(v.nm.FileCount())
+}
+
 // Close cleanly shuts down this volume
 func (v *Volume) Close() {
 	v.dataFileAccessLock.Lock()