+void *radix_tree_tag_set(struct radix_tree_root *root, unsigned long index, unsigned int tag);
+void *radix_tree_tag_clear(struct radix_tree_root *root, unsigned long index, unsigned int tag);
+int radix_tree_tagged(const struct radix_tree_root *root, unsigned int tag);
+unsigned int radix_tree_gang_lookup(const struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items);
+unsigned int radix_tree_gang_lookup_tag(const struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items, unsigned int tag);