diff --git a/sys/compat/linuxkpi/common/include/linux/rbtree.h b/sys/compat/linuxkpi/common/include/linux/rbtree.h
index 78bf938eb000..e6033cfd760d 100644
--- a/sys/compat/linuxkpi/common/include/linux/rbtree.h
+++ b/sys/compat/linuxkpi/common/include/linux/rbtree.h
@@ -1,182 +1,206 @@
 /*-
  * Copyright (c) 2010 Isilon Systems, Inc.
  * Copyright (c) 2010 iX Systems, Inc.
  * Copyright (c) 2010 Panasas, Inc.
  * Copyright (c) 2013, 2014 Mellanox Technologies, Ltd.
  * All rights reserved.
  *
  * 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 unmodified, 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 ``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 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.
  */
 #ifndef	_LINUXKPI_LINUX_RBTREE_H_
 #define	_LINUXKPI_LINUX_RBTREE_H_
 
 #ifndef _STANDALONE
 #include <sys/stddef.h>
 #endif
 
 #include <sys/types.h>
 #include <sys/tree.h>
 
 struct rb_node {
 	RB_ENTRY(rb_node)	__entry;
 };
 #define	rb_left		__entry.rbe_link[_RB_L]
 #define	rb_right	__entry.rbe_link[_RB_R]
 
 /*
  * We provide a false structure that has the same bit pattern as tree.h
  * presents so it matches the member names expected by linux.
  */
 struct rb_root {
 	struct	rb_node	*rb_node;
 };
 
 struct rb_root_cached {
 	struct rb_root rb_root;
 	struct rb_node *rb_leftmost;
 };
 
 /*
  * In linux all of the comparisons are done by the caller.
  */
 int panic_cmp(struct rb_node *one, struct rb_node *two);
 
 RB_HEAD(linux_root, rb_node);
 RB_PROTOTYPE(linux_root, rb_node, __entry, panic_cmp);
 
 #define	rb_parent(r)	RB_PARENT(r, __entry)
 #define	rb_entry(ptr, type, member)	container_of(ptr, type, member)
 #define	rb_entry_safe(ptr, type, member) \
 	((ptr) != NULL ? rb_entry(ptr, type, member) : NULL)
 
 #define	RB_EMPTY_ROOT(root)	((root)->rb_node == NULL)
 #define RB_EMPTY_NODE(node)     (RB_PARENT(node, __entry) == node)
 #define RB_CLEAR_NODE(node)     RB_SET_PARENT(node, node, __entry)
 
 #define rb_insert_color(node, root) do {				\
 	if (rb_parent(node))						\
 		linux_root_RB_INSERT_COLOR((struct linux_root *)(root), \
 		    rb_parent(node), (node));				\
 } while (0)
 #define	rb_erase(node, root)						\
 	linux_root_RB_REMOVE((struct linux_root *)(root), (node))
 #define	rb_next(node)	RB_NEXT(linux_root, NULL, (node))
 #define	rb_prev(node)	RB_PREV(linux_root, NULL, (node))
 #define	rb_first(root)	RB_MIN(linux_root, (struct linux_root *)(root))
 #define	rb_last(root)	RB_MAX(linux_root, (struct linux_root *)(root))
 #define	rb_first_cached(root)	(root)->rb_leftmost
 
 static inline struct rb_node *
 __rb_deepest_left(struct rb_node *node)
 {
 	struct rb_node *parent = NULL;
 	while (node != NULL) {
 		parent = node;
 		if (RB_LEFT(node, __entry))
 			node = RB_LEFT(node, __entry);
 		else
 			node = RB_RIGHT(node, __entry);
 	}
 	return (parent);
 }
 
 static inline struct rb_node *
 rb_next_postorder(const struct rb_node *node)
 {
 	struct rb_node *parent =
 	    RB_PARENT(__DECONST(struct rb_node *, node), __entry);
 	/* left -> right, right -> root */
 	if (parent != NULL &&
 	    (node == RB_LEFT(parent, __entry)) &&
 	    (RB_RIGHT(parent, __entry)))
 		return (__rb_deepest_left(RB_RIGHT(parent, __entry)));
 	else
 		return (parent);
 }
 
 #define	rbtree_postorder_for_each_entry_safe(x, y, head, member)	\
 	for ((x) = rb_entry_safe(__rb_deepest_left((head)->rb_node),	\
 	    __typeof(*x), member);					\
 	    ((x) != NULL) && ((y) =					\
 	    rb_entry_safe(rb_next_postorder(&x->member), typeof(*x), member), 1); \
 	    (x) = (y))
 
 static inline void
 rb_link_node(struct rb_node *node, struct rb_node *parent,
     struct rb_node **rb_link)
 {
 	RB_SET(node, parent, __entry);
 	*rb_link = node;
 }
 
 static inline void
 rb_replace_node(struct rb_node *victim, struct rb_node *new,
     struct rb_root *root)
 {
 
 	RB_SWAP_CHILD((struct linux_root *)root, rb_parent(victim),
 	    victim, new, __entry);
 	if (RB_LEFT(victim, __entry))
 		RB_SET_PARENT(RB_LEFT(victim, __entry), new, __entry);
 	if (RB_RIGHT(victim, __entry))
 		RB_SET_PARENT(RB_RIGHT(victim, __entry), new, __entry);
 	*new = *victim;
 }
 
 static inline void
 rb_insert_color_cached(struct rb_node *node, struct rb_root_cached *root,
     bool leftmost)
 {
 	if (rb_parent(node))
 		linux_root_RB_INSERT_COLOR((struct linux_root *)&root->rb_root,
 		    rb_parent(node), node);
 	if (leftmost)
 		root->rb_leftmost = node;
 }
 
 static inline struct rb_node *
 rb_erase_cached(struct rb_node *node, struct rb_root_cached *root)
 {
 	struct rb_node *retval;
 
 	if (node == root->rb_leftmost)
 		retval = root->rb_leftmost = linux_root_RB_NEXT(node);
 	else
 		retval = NULL;
 	linux_root_RB_REMOVE((struct linux_root *)&root->rb_root, node);
 	return (retval);
 }
 
 static inline void
 rb_replace_node_cached(struct rb_node *old, struct rb_node *new,
     struct rb_root_cached *root)
 {
 	rb_replace_node(old, new, &root->rb_root);
 	if (root->rb_leftmost == old)
 		root->rb_leftmost = new;
 }
 
+static inline struct rb_node *
+rb_add_cached(struct rb_node *node, struct rb_root_cached *tree,
+    bool (*less)(struct rb_node *, const struct rb_node *))
+{
+	struct rb_node **link = &tree->rb_root.rb_node;
+	struct rb_node *parent = NULL;
+	bool leftmost = true;
+
+	while (*link != NULL) {
+		parent = *link;
+		if (less(node, parent)) {
+			link = &RB_LEFT(parent, __entry);
+		} else {
+			link = &RB_RIGHT(parent, __entry);
+			leftmost = false;
+		}
+	}
+
+	rb_link_node(node, parent, link);
+	rb_insert_color_cached(node, tree, leftmost);
+
+	return (leftmost ? node : NULL);
+}
+
 #undef RB_ROOT
 #define RB_ROOT		(struct rb_root) { NULL }
 #define	RB_ROOT_CACHED	(struct rb_root_cached) { RB_ROOT, NULL }
 
 #endif	/* _LINUXKPI_LINUX_RBTREE_H_ */