diff --git a/kmod/src/Makefile b/kmod/src/Makefile
index c9f6a961..ce1599f8 100644
--- a/kmod/src/Makefile
+++ b/kmod/src/Makefile
@@ -13,6 +13,7 @@ scoutfs-y +=			\
 	avl.o			\
 	alloc.o			\
 	block.o			\
+	bsearch_index.o		\
 	btree.o			\
 	client.o		\
 	counters.o		\
diff --git a/kmod/src/bsearch_index.c b/kmod/src/bsearch_index.c
new file mode 100644
index 00000000..556b097d
--- /dev/null
+++ b/kmod/src/bsearch_index.c
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2026 Versity Software, Inc.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/kernel.h>
+#include <linux/bsearch.h>
+
+#include "bsearch_index.h"
+
+struct bsearch_index_key {
+	int (*cmp)(const void *key, const void *elt);
+	/* the key has to be const, so we have to update the index through a pointer */
+	void **index_elt;
+	const void *key;
+	size_t size;
+};
+
+static int cmp_index(const void *key, const void *elt)
+{
+	const struct bsearch_index_key *bik = key;
+	int cmp = bik->cmp(bik->key, elt);
+
+	if (cmp > 0)
+		*(bik->index_elt) = (void *)elt + bik->size;
+	else
+		*(bik->index_elt) = (void *)elt;
+
+	return cmp;
+}
+
+/*
+ * A bsearch() wrapper that returns the index of the element of the
+ * array that the key would be stored in to maintain sort order.  It's
+ * the first element where the existing element is greater than the key.
+ * It returns the size of the array if the key is greater than the last
+ * element in the array.
+ */
+size_t bsearch_index(const void *key, const void *base, size_t num, size_t size,
+		     int (*cmp)(const void *key, const void *elt))
+{
+	void *index_elt = (void *)base;
+	struct bsearch_index_key bik = {
+		.cmp = cmp,
+		.index_elt = &index_elt,
+		.key = key,
+		.size = size,
+	};
+
+	bsearch(&bik, base, num, size, cmp_index);
+	return ((unsigned long)index_elt - (unsigned long)base) / size;
+}
diff --git a/kmod/src/bsearch_index.h b/kmod/src/bsearch_index.h
new file mode 100644
index 00000000..d3115a17
--- /dev/null
+++ b/kmod/src/bsearch_index.h
@@ -0,0 +1,7 @@
+#ifndef _SCOUTFS_BSEARCH_INDEX_H_
+#define _SCOUTFS_BSEARCH_INDEX_H_
+
+size_t bsearch_index(const void *key, const void *base, size_t num, size_t size,
+		     int (*cmp)(const void *key, const void *elt));
+
+#endif