-extern struct address_space_operations udf_aops;
-extern struct address_space_operations udf_adinicb_aops;
-extern struct address_space_operations udf_symlink_aops;
+extern const struct address_space_operations udf_aops;
+extern const struct address_space_operations udf_adinicb_aops;
+extern const struct address_space_operations udf_symlink_aops;