Index: head/sys/compat/linuxkpi/common/include/linux/refcount.h
===================================================================
--- head/sys/compat/linuxkpi/common/include/linux/refcount.h
+++ head/sys/compat/linuxkpi/common/include/linux/refcount.h
@@ -0,0 +1,82 @@
+/*-
+ * Copyright (c) 2020 The FreeBSD Foundation
+ *
+ * This software was developed by Emmanuel Vadot under sponsorship
+ * from the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _LINUX_REFCOUNT_H
+#define _LINUX_REFCOUNT_H
+
+#include <linux/atomic.h>
+
+struct refcount_linux {
+	atomic_t value;
+};
+typedef struct refcount_linux refcount_t;
+
+static inline void
+refcount_set(refcount_t *ref, unsigned int i)
+{
+	atomic_set(&ref->value, i);
+}
+
+static inline void
+refcount_inc(refcount_t *ref)
+{
+	atomic_inc(&ref->value);
+}
+
+static inline bool
+refcount_inc_not_zero(refcount_t *ref)
+{
+	return (atomic_inc_not_zero(&ref->value));
+}
+
+static inline void
+refcount_dec(refcount_t *ref)
+{
+	atomic_dec(&ref->value);
+}
+
+static inline unsigned int
+refcount_read(refcount_t *ref)
+{
+	return atomic_read(&ref->value);
+}
+
+static inline bool
+refcount_dec_and_lock_irqsave(refcount_t *ref, spinlock_t *lock,
+    unsigned long *flags)
+{
+	if (atomic_dec_and_test(&ref->value) == true) {
+		spin_lock_irqsave(lock, flags);
+		return (true);
+	}
+	return (false);
+}
+
+#endif /* __LINUX_REFCOUNT_H__ */