From aa1b1fa34f6ae9be060b209d7cd2f3b4a3e610de Mon Sep 17 00:00:00 2001
From: Zach Brown <zab@versity.com>
Date: Wed, 6 Jan 2021 09:20:14 -0800
Subject: [PATCH] Add util.h for kernel helpers

Add a little header for inline convenience functions.

Signed-off-by: Zach Brown <zab@versity.com>
---
 kmod/src/util.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 kmod/src/util.h

diff --git a/kmod/src/util.h b/kmod/src/util.h
new file mode 100644
index 00000000..20d9db79
--- /dev/null
+++ b/kmod/src/util.h
@@ -0,0 +1,20 @@
+#ifndef _SCOUTFS_UTIL_H_
+#define _SCOUTFS_UTIL_H_
+
+/*
+ * Little utility helpers that probably belong upstream.
+ */
+
+static inline void down_write_two(struct rw_semaphore *a,
+				  struct rw_semaphore *b)
+{
+	BUG_ON(a == b);
+
+	if (a > b)
+		swap(a, b);
+
+	down_write(a);
+	down_write_nested(b, SINGLE_DEPTH_NESTING);
+}
+
+#endif