test if FileInfo.Sys() returns a *file.FileInfo and use that

file/file.go

@@ -11,17 +11,11 @@ type FileInfo struct {
 	Fileid uint64
 }
 
-// FileInfoGetter allows os.FileInfo implementations that implement
-// the GetFileInfo() method to explicitly return a *FileInfo.
-// Useful for explicitly setting a Fileid without having to use the syscall package
-type FileInfoGetter interface {
-	GetFileInfo() *FileInfo
-}
-
 // GetInfo extracts some non-standardized items from the result of a Stat call.
 func GetInfo(fi os.FileInfo) *FileInfo {
-	if v, ok := fi.(FileInfoGetter); ok {
-		return v.GetFileInfo()
+	sys := fi.Sys()
+	if v, ok := sys.(*FileInfo); ok {
+		return v
 	}
 	return getOSFileInfo(fi)
 }