Fixes #9283. Consider hardlinks in image size.

Based on #8984. This patch fixes behavior when image size calculation
didn't consider hardlinks.

Signed-off-by: Dmitry Vorobev <dimahabr@gmail.com>

archive/changes.go

@@ -328,13 +328,29 @@ func ChangesDirs(newDir, oldDir string) ([]Change, error) {
 
 // ChangesSize calculates the size in bytes of the provided changes, based on newDir.
 func ChangesSize(newDir string, changes []Change) int64 {
-	var size int64
+	var (
+		size int64
+		sf   = make(map[uint64]struct{})
+	)
 	for _, change := range changes {
 		if change.Kind == ChangeModify || change.Kind == ChangeAdd {
 			file := filepath.Join(newDir, change.Path)
-			fileInfo, _ := os.Lstat(file)
+			fileInfo, err := os.Lstat(file)
+			if err != nil {
+				logrus.Errorf("Can not stat %q: %s", file, err)
+				continue
+			}
+
 			if fileInfo != nil && !fileInfo.IsDir() {
-				size += fileInfo.Size()
+				if hasHardlinks(fileInfo) {
+					inode := getIno(fileInfo)
+					if _, ok := sf[inode]; !ok {
+						size += fileInfo.Size()
+						sf[inode] = struct{}{}
+					}
+				} else {
+					size += fileInfo.Size()
+				}
 			}
 		}
 	}