v4.19.13 snapshot.
diff --git a/include/linux/interval_tree.h b/include/linux/interval_tree.h
new file mode 100644
index 0000000..288c26f
--- /dev/null
+++ b/include/linux/interval_tree.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_INTERVAL_TREE_H
+#define _LINUX_INTERVAL_TREE_H
+
+#include <linux/rbtree.h>
+
+struct interval_tree_node {
+ struct rb_node rb;
+ unsigned long start; /* Start of interval */
+ unsigned long last; /* Last location _in_ interval */
+ unsigned long __subtree_last;
+};
+
+extern void
+interval_tree_insert(struct interval_tree_node *node,
+ struct rb_root_cached *root);
+
+extern void
+interval_tree_remove(struct interval_tree_node *node,
+ struct rb_root_cached *root);
+
+extern struct interval_tree_node *
+interval_tree_iter_first(struct rb_root_cached *root,
+ unsigned long start, unsigned long last);
+
+extern struct interval_tree_node *
+interval_tree_iter_next(struct interval_tree_node *node,
+ unsigned long start, unsigned long last);
+
+#endif /* _LINUX_INTERVAL_TREE_H */