[IMP] add helper method to get a path relative to another

fs_storage/models/fs_storage.py

@@ -10,6 +10,7 @@
 import os.path
 import re
 import warnings
+from pathlib import Path
 from typing import AnyStr
 
 import fsspec
@@ -518,3 +519,10 @@ def _get_root_filesystem(self):
         while hasattr(fs, "fs"):
             fs = fs.fs
         return fs
+
+    @api.model
+    def get_relative_path(self, absolute_path, root_path):
+        path = Path(absolute_path)
+        if path.is_relative_to(root_path):
+            return path.relative_to(root_path).as_posix()
+        return absolute_path