diff --git a/include/spdk/tree.h b/include/spdk/tree.h
new file mode 100644
index 000000000..958185cee
--- /dev/null
+++ b/include/spdk/tree.h
@@ -0,0 +1,829 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * 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, 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	SPDK_TREE_H
+#define SPDK_TREE_H
+
+#include <sys/cdefs.h>
+
+/*
+ * This file defines data structures for different types of trees:
+ * splay trees and rank-balanced trees.
+ *
+ * A splay tree is a self-organizing data structure.  Every operation
+ * on the tree causes a splay to happen.  The splay moves the requested
+ * node to the root of the tree and partly rebalances it.
+ *
+ * This has the benefit that request locality causes faster lookups as
+ * the requested nodes move to the top of the tree.  On the other hand,
+ * every lookup causes memory writes.
+ *
+ * The Balance Theorem bounds the total access time for m operations
+ * and n inserts on an initially empty tree as O((m + n)lg n).  The
+ * amortized cost for a sequence of m accesses to a splay tree is O(lg n);
+ *
+ * A rank-balanced tree is a binary search tree with an integer
+ * rank-difference as an attribute of each pointer from parent to child.
+ * The sum of the rank-differences on any path from a node down to null is
+ * the same, and defines the rank of that node. The rank of the null node
+ * is -1.
+ *
+ * Different additional conditions define different sorts of balanced
+ * trees, including "red-black" and "AVL" trees.  The set of conditions
+ * applied here are the "weak-AVL" conditions of Haeupler, Sen and Tarjan:
+ *	- every rank-difference is 1 or 2.
+ *	- the rank of any leaf is 1.
+ *
+ * For historical reasons, rank differences that are even are associated
+ * with the color red (Rank-Even-Difference), and the child that a red edge
+ * points to is called a red child.
+ *
+ * Every operation on a rank-balanced tree is bounded as O(lg n).
+ * The maximum height of a rank-balanced tree is 2lg (n+1).
+ */
+
+#define SPLAY_HEAD(name, type)						\
+struct name {								\
+	struct type *sph_root; /* root of the tree */			\
+}
+
+#define SPLAY_INITIALIZER(root)						\
+	{ NULL }
+
+#define SPLAY_INIT(root) do {						\
+	(root)->sph_root = NULL;					\
+} while (/* CONSTCOND */ 0)
+
+#define SPLAY_ENTRY(type)						\
+struct {								\
+	struct type *spe_left; /* left element */			\
+	struct type *spe_right; /* right element */			\
+}
+
+#define SPLAY_LEFT(elm, field)		(elm)->field.spe_left
+#define SPLAY_RIGHT(elm, field)		(elm)->field.spe_right
+#define SPLAY_ROOT(head)		(head)->sph_root
+#define SPLAY_EMPTY(head)		(SPLAY_ROOT(head) == NULL)
+
+/* SPLAY_ROTATE_{LEFT,RIGHT} expect that tmp hold SPLAY_{RIGHT,LEFT} */
+#define SPLAY_ROTATE_RIGHT(head, tmp, field) do {			\
+	SPLAY_LEFT((head)->sph_root, field) = SPLAY_RIGHT(tmp, field);	\
+	SPLAY_RIGHT(tmp, field) = (head)->sph_root;			\
+	(head)->sph_root = tmp;						\
+} while (/* CONSTCOND */ 0)
+
+#define SPLAY_ROTATE_LEFT(head, tmp, field) do {			\
+	SPLAY_RIGHT((head)->sph_root, field) = SPLAY_LEFT(tmp, field);	\
+	SPLAY_LEFT(tmp, field) = (head)->sph_root;			\
+	(head)->sph_root = tmp;						\
+} while (/* CONSTCOND */ 0)
+
+#define SPLAY_LINKLEFT(head, tmp, field) do {				\
+	SPLAY_LEFT(tmp, field) = (head)->sph_root;			\
+	tmp = (head)->sph_root;						\
+	(head)->sph_root = SPLAY_LEFT((head)->sph_root, field);		\
+} while (/* CONSTCOND */ 0)
+
+#define SPLAY_LINKRIGHT(head, tmp, field) do {				\
+	SPLAY_RIGHT(tmp, field) = (head)->sph_root;			\
+	tmp = (head)->sph_root;						\
+	(head)->sph_root = SPLAY_RIGHT((head)->sph_root, field);	\
+} while (/* CONSTCOND */ 0)
+
+#define SPLAY_ASSEMBLE(head, node, left, right, field) do {		\
+	SPLAY_RIGHT(left, field) = SPLAY_LEFT((head)->sph_root, field);	\
+	SPLAY_LEFT(right, field) = SPLAY_RIGHT((head)->sph_root, field);\
+	SPLAY_LEFT((head)->sph_root, field) = SPLAY_RIGHT(node, field);	\
+	SPLAY_RIGHT((head)->sph_root, field) = SPLAY_LEFT(node, field);	\
+} while (/* CONSTCOND */ 0)
+
+/* Generates prototypes and inline functions */
+
+#define SPLAY_PROTOTYPE(name, type, field, cmp)				\
+void name##_SPLAY(struct name *, struct type *);			\
+void name##_SPLAY_MINMAX(struct name *, int);				\
+struct type *name##_SPLAY_INSERT(struct name *, struct type *);		\
+struct type *name##_SPLAY_REMOVE(struct name *, struct type *);		\
+									\
+/* Finds the node with the same key as elm */				\
+static __attribute__((unused)) __inline struct type *					\
+name##_SPLAY_FIND(struct name *head, struct type *elm)			\
+{									\
+	if (SPLAY_EMPTY(head))						\
+		return(NULL);						\
+	name##_SPLAY(head, elm);					\
+	if ((cmp)(elm, (head)->sph_root) == 0)				\
+		return (head->sph_root);				\
+	return (NULL);							\
+}									\
+									\
+static __attribute__((unused)) __inline struct type *					\
+name##_SPLAY_NEXT(struct name *head, struct type *elm)			\
+{									\
+	name##_SPLAY(head, elm);					\
+	if (SPLAY_RIGHT(elm, field) != NULL) {				\
+		elm = SPLAY_RIGHT(elm, field);				\
+		while (SPLAY_LEFT(elm, field) != NULL) {		\
+			elm = SPLAY_LEFT(elm, field);			\
+		}							\
+	} else								\
+		elm = NULL;						\
+	return (elm);							\
+}									\
+									\
+static __attribute__((unused)) __inline struct type *					\
+name##_SPLAY_MIN_MAX(struct name *head, int val)			\
+{									\
+	name##_SPLAY_MINMAX(head, val);					\
+        return (SPLAY_ROOT(head));					\
+}
+
+/* Main splay operation.
+ * Moves node close to the key of elm to top
+ */
+#define SPLAY_GENERATE(name, type, field, cmp)				\
+struct type *								\
+name##_SPLAY_INSERT(struct name *head, struct type *elm)		\
+{									\
+    if (SPLAY_EMPTY(head)) {						\
+	    SPLAY_LEFT(elm, field) = SPLAY_RIGHT(elm, field) = NULL;	\
+    } else {								\
+	    int __comp;							\
+	    name##_SPLAY(head, elm);					\
+	    __comp = (cmp)(elm, (head)->sph_root);			\
+	    if (__comp < 0) {						\
+		    SPLAY_LEFT(elm, field) = SPLAY_LEFT((head)->sph_root, field);\
+		    SPLAY_RIGHT(elm, field) = (head)->sph_root;		\
+		    SPLAY_LEFT((head)->sph_root, field) = NULL;		\
+	    } else if (__comp > 0) {					\
+		    SPLAY_RIGHT(elm, field) = SPLAY_RIGHT((head)->sph_root, field);\
+		    SPLAY_LEFT(elm, field) = (head)->sph_root;		\
+		    SPLAY_RIGHT((head)->sph_root, field) = NULL;	\
+	    } else							\
+		    return ((head)->sph_root);				\
+    }									\
+    (head)->sph_root = (elm);						\
+    return (NULL);							\
+}									\
+									\
+struct type *								\
+name##_SPLAY_REMOVE(struct name *head, struct type *elm)		\
+{									\
+	struct type *__tmp;						\
+	if (SPLAY_EMPTY(head))						\
+		return (NULL);						\
+	name##_SPLAY(head, elm);					\
+	if ((cmp)(elm, (head)->sph_root) == 0) {			\
+		if (SPLAY_LEFT((head)->sph_root, field) == NULL) {	\
+			(head)->sph_root = SPLAY_RIGHT((head)->sph_root, field);\
+		} else {						\
+			__tmp = SPLAY_RIGHT((head)->sph_root, field);	\
+			(head)->sph_root = SPLAY_LEFT((head)->sph_root, field);\
+			name##_SPLAY(head, elm);			\
+			SPLAY_RIGHT((head)->sph_root, field) = __tmp;	\
+		}							\
+		return (elm);						\
+	}								\
+	return (NULL);							\
+}									\
+									\
+void									\
+name##_SPLAY(struct name *head, struct type *elm)			\
+{									\
+	struct type __node, *__left, *__right, *__tmp;			\
+	int __comp;							\
+\
+	SPLAY_LEFT(&__node, field) = SPLAY_RIGHT(&__node, field) = NULL;\
+	__left = __right = &__node;					\
+\
+	while ((__comp = (cmp)(elm, (head)->sph_root)) != 0) {		\
+		if (__comp < 0) {					\
+			__tmp = SPLAY_LEFT((head)->sph_root, field);	\
+			if (__tmp == NULL)				\
+				break;					\
+			if ((cmp)(elm, __tmp) < 0){			\
+				SPLAY_ROTATE_RIGHT(head, __tmp, field);	\
+				if (SPLAY_LEFT((head)->sph_root, field) == NULL)\
+					break;				\
+			}						\
+			SPLAY_LINKLEFT(head, __right, field);		\
+		} else if (__comp > 0) {				\
+			__tmp = SPLAY_RIGHT((head)->sph_root, field);	\
+			if (__tmp == NULL)				\
+				break;					\
+			if ((cmp)(elm, __tmp) > 0){			\
+				SPLAY_ROTATE_LEFT(head, __tmp, field);	\
+				if (SPLAY_RIGHT((head)->sph_root, field) == NULL)\
+					break;				\
+			}						\
+			SPLAY_LINKRIGHT(head, __left, field);		\
+		}							\
+	}								\
+	SPLAY_ASSEMBLE(head, &__node, __left, __right, field);		\
+}									\
+									\
+/* Splay with either the minimum or the maximum element			\
+ * Used to find minimum or maximum element in tree.			\
+ */									\
+void name##_SPLAY_MINMAX(struct name *head, int __comp) \
+{									\
+	struct type __node, *__left, *__right, *__tmp;			\
+\
+	SPLAY_LEFT(&__node, field) = SPLAY_RIGHT(&__node, field) = NULL;\
+	__left = __right = &__node;					\
+\
+	while (1) {							\
+		if (__comp < 0) {					\
+			__tmp = SPLAY_LEFT((head)->sph_root, field);	\
+			if (__tmp == NULL)				\
+				break;					\
+			if (__comp < 0){				\
+				SPLAY_ROTATE_RIGHT(head, __tmp, field);	\
+				if (SPLAY_LEFT((head)->sph_root, field) == NULL)\
+					break;				\
+			}						\
+			SPLAY_LINKLEFT(head, __right, field);		\
+		} else if (__comp > 0) {				\
+			__tmp = SPLAY_RIGHT((head)->sph_root, field);	\
+			if (__tmp == NULL)				\
+				break;					\
+			if (__comp > 0) {				\
+				SPLAY_ROTATE_LEFT(head, __tmp, field);	\
+				if (SPLAY_RIGHT((head)->sph_root, field) == NULL)\
+					break;				\
+			}						\
+			SPLAY_LINKRIGHT(head, __left, field);		\
+		}							\
+	}								\
+	SPLAY_ASSEMBLE(head, &__node, __left, __right, field);		\
+}
+
+#define SPLAY_NEGINF	-1
+#define SPLAY_INF	1
+
+#define SPLAY_INSERT(name, x, y)	name##_SPLAY_INSERT(x, y)
+#define SPLAY_REMOVE(name, x, y)	name##_SPLAY_REMOVE(x, y)
+#define SPLAY_FIND(name, x, y)		name##_SPLAY_FIND(x, y)
+#define SPLAY_NEXT(name, x, y)		name##_SPLAY_NEXT(x, y)
+#define SPLAY_MIN(name, x)		(SPLAY_EMPTY(x) ? NULL	\
+					: name##_SPLAY_MIN_MAX(x, SPLAY_NEGINF))
+#define SPLAY_MAX(name, x)		(SPLAY_EMPTY(x) ? NULL	\
+					: name##_SPLAY_MIN_MAX(x, SPLAY_INF))
+
+#define SPLAY_FOREACH(x, name, head)					\
+	for ((x) = SPLAY_MIN(name, head);				\
+	     (x) != NULL;						\
+	     (x) = SPLAY_NEXT(name, head, x))
+
+/* Macros that define a rank-balanced tree */
+#define RB_HEAD(name, type)						\
+struct name {								\
+	struct type *rbh_root; /* root of the tree */			\
+}
+
+#define RB_INITIALIZER(root)						\
+	{ NULL }
+
+#define RB_INIT(root) do {						\
+	(root)->rbh_root = NULL;					\
+} while (/* CONSTCOND */ 0)
+
+#define RB_ENTRY(type)							\
+struct {								\
+	struct type *rbe_left;		/* left element */		\
+	struct type *rbe_right;		/* right element */		\
+	struct type *rbe_parent;	/* parent element */		\
+}
+
+#define RB_LEFT(elm, field)		(elm)->field.rbe_left
+#define RB_RIGHT(elm, field)		(elm)->field.rbe_right
+
+/*
+ * With the expectation that any object of struct type has an
+ * address that is a multiple of 4, and that therefore the
+ * 2 least significant bits of a pointer to struct type are
+ * always zero, this implementation sets those bits to indicate
+ * that the left or right child of the tree node is "red".
+ */
+#define RB_UP(elm, field)		(elm)->field.rbe_parent
+#define RB_BITS(elm, field)		(*(uintptr_t *)&RB_UP(elm, field))
+#define RB_RED_L			((uintptr_t)1)
+#define RB_RED_R			((uintptr_t)2)
+#define RB_RED_MASK			((uintptr_t)3)
+#define RB_FLIP_LEFT(elm, field)	(RB_BITS(elm, field) ^= RB_RED_L)
+#define RB_FLIP_RIGHT(elm, field)	(RB_BITS(elm, field) ^= RB_RED_R)
+#define RB_RED_LEFT(elm, field)		((RB_BITS(elm, field) & RB_RED_L) != 0)
+#define RB_RED_RIGHT(elm, field)	((RB_BITS(elm, field) & RB_RED_R) != 0)
+#define RB_PARENT(elm, field)		((__typeof(RB_UP(elm, field)))	\
+					 (RB_BITS(elm, field) & ~RB_RED_MASK))
+#define RB_ROOT(head)			(head)->rbh_root
+#define RB_EMPTY(head)			(RB_ROOT(head) == NULL)
+
+#define RB_SET_PARENT(dst, src, field) do {				\
+	RB_BITS(dst, field) &= RB_RED_MASK;				\
+	RB_BITS(dst, field) |= (uintptr_t)src;			\
+} while (/* CONSTCOND */ 0)
+
+#define RB_SET(elm, parent, field) do {					\
+	RB_UP(elm, field) = parent;					\
+	RB_LEFT(elm, field) = RB_RIGHT(elm, field) = NULL;		\
+} while (/* CONSTCOND */ 0)
+
+#define RB_COLOR(elm, field)	(RB_PARENT(elm, field) == NULL ? 0 :	\
+				RB_LEFT(RB_PARENT(elm, field), field) == elm ? \
+				RB_RED_LEFT(RB_PARENT(elm, field), field) : \
+				RB_RED_RIGHT(RB_PARENT(elm, field), field))
+
+/*
+ * Something to be invoked in a loop at the root of every modified subtree,
+ * from the bottom up to the root, to update augmented node data.
+ */
+#ifndef RB_AUGMENT
+#define RB_AUGMENT(x)	break
+#endif
+
+#define RB_SWAP_CHILD(head, out, in, field) do {			\
+	if (RB_PARENT(out, field) == NULL)				\
+		RB_ROOT(head) = (in);					\
+	else if ((out) == RB_LEFT(RB_PARENT(out, field), field))	\
+		RB_LEFT(RB_PARENT(out, field), field) = (in);		\
+	else								\
+		RB_RIGHT(RB_PARENT(out, field), field) = (in);		\
+} while (/* CONSTCOND */ 0)
+
+#define RB_ROTATE_LEFT(head, elm, tmp, field) do {			\
+	(tmp) = RB_RIGHT(elm, field);					\
+	if ((RB_RIGHT(elm, field) = RB_LEFT(tmp, field)) != NULL) {	\
+		RB_SET_PARENT(RB_RIGHT(elm, field), elm, field);	\
+	}								\
+	RB_SET_PARENT(tmp, RB_PARENT(elm, field), field);		\
+	RB_SWAP_CHILD(head, elm, tmp, field);				\
+	RB_LEFT(tmp, field) = (elm);					\
+	RB_SET_PARENT(elm, tmp, field);					\
+	RB_AUGMENT(elm);						\
+} while (/* CONSTCOND */ 0)
+
+#define RB_ROTATE_RIGHT(head, elm, tmp, field) do {			\
+	(tmp) = RB_LEFT(elm, field);					\
+	if ((RB_LEFT(elm, field) = RB_RIGHT(tmp, field)) != NULL) {	\
+		RB_SET_PARENT(RB_LEFT(elm, field), elm, field);		\
+	}								\
+	RB_SET_PARENT(tmp, RB_PARENT(elm, field), field);		\
+	RB_SWAP_CHILD(head, elm, tmp, field);				\
+	RB_RIGHT(tmp, field) = (elm);					\
+	RB_SET_PARENT(elm, tmp, field);					\
+	RB_AUGMENT(elm);						\
+} while (/* CONSTCOND */ 0)
+
+/* Generates prototypes and inline functions */
+#define	RB_PROTOTYPE(name, type, field, cmp)				\
+	RB_PROTOTYPE_INTERNAL(name, type, field, cmp,)
+#define	RB_PROTOTYPE_STATIC(name, type, field, cmp)			\
+	RB_PROTOTYPE_INTERNAL(name, type, field, cmp, __attribute__((unused)) static)
+#define RB_PROTOTYPE_INTERNAL(name, type, field, cmp, attr)		\
+	RB_PROTOTYPE_INSERT_COLOR(name, type, attr);			\
+	RB_PROTOTYPE_REMOVE_COLOR(name, type, attr);			\
+	RB_PROTOTYPE_INSERT(name, type, attr);				\
+	RB_PROTOTYPE_REMOVE(name, type, attr);				\
+	RB_PROTOTYPE_FIND(name, type, attr);				\
+	RB_PROTOTYPE_NFIND(name, type, attr);				\
+	RB_PROTOTYPE_NEXT(name, type, attr);				\
+	RB_PROTOTYPE_PREV(name, type, attr);				\
+	RB_PROTOTYPE_MINMAX(name, type, attr);				\
+	RB_PROTOTYPE_REINSERT(name, type, attr);
+#define RB_PROTOTYPE_INSERT_COLOR(name, type, attr)			\
+	attr void name##_RB_INSERT_COLOR(struct name *, struct type *)
+#define RB_PROTOTYPE_REMOVE_COLOR(name, type, attr)			\
+	attr void name##_RB_REMOVE_COLOR(struct name *,			\
+	    struct type *, struct type *)
+#define RB_PROTOTYPE_REMOVE(name, type, attr)				\
+	attr struct type *name##_RB_REMOVE(struct name *, struct type *)
+#define RB_PROTOTYPE_INSERT(name, type, attr)				\
+	attr struct type *name##_RB_INSERT(struct name *, struct type *)
+#define RB_PROTOTYPE_FIND(name, type, attr)				\
+	attr struct type *name##_RB_FIND(struct name *, struct type *)
+#define RB_PROTOTYPE_NFIND(name, type, attr)				\
+	attr struct type *name##_RB_NFIND(struct name *, struct type *)
+#define RB_PROTOTYPE_NEXT(name, type, attr)				\
+	attr struct type *name##_RB_NEXT(struct type *)
+#define RB_PROTOTYPE_PREV(name, type, attr)				\
+	attr struct type *name##_RB_PREV(struct type *)
+#define RB_PROTOTYPE_MINMAX(name, type, attr)				\
+	attr struct type *name##_RB_MINMAX(struct name *, int)
+#define RB_PROTOTYPE_REINSERT(name, type, attr)			\
+	attr struct type *name##_RB_REINSERT(struct name *, struct type *)
+
+/* Main rb operation.
+ * Moves node close to the key of elm to top
+ */
+#define	RB_GENERATE(name, type, field, cmp)				\
+	RB_GENERATE_INTERNAL(name, type, field, cmp,)
+#define	RB_GENERATE_STATIC(name, type, field, cmp)			\
+	RB_GENERATE_INTERNAL(name, type, field, cmp, __attribute__((unused)) static)
+#define RB_GENERATE_INTERNAL(name, type, field, cmp, attr)		\
+	RB_GENERATE_INSERT_COLOR(name, type, field, attr)		\
+	RB_GENERATE_REMOVE_COLOR(name, type, field, attr)		\
+	RB_GENERATE_INSERT(name, type, field, cmp, attr)		\
+	RB_GENERATE_REMOVE(name, type, field, attr)			\
+	RB_GENERATE_FIND(name, type, field, cmp, attr)			\
+	RB_GENERATE_NFIND(name, type, field, cmp, attr)			\
+	RB_GENERATE_NEXT(name, type, field, attr)			\
+	RB_GENERATE_PREV(name, type, field, attr)			\
+	RB_GENERATE_MINMAX(name, type, field, attr)			\
+	RB_GENERATE_REINSERT(name, type, field, cmp, attr)
+
+#define RB_GENERATE_INSERT_COLOR(name, type, field, attr)		\
+attr void								\
+name##_RB_INSERT_COLOR(struct name *head, struct type *elm)		\
+{									\
+	struct type *child, *parent;					\
+	while ((parent = RB_PARENT(elm, field)) != NULL) {		\
+		if (RB_LEFT(parent, field) == elm) {			\
+			if (RB_RED_LEFT(parent, field)) {		\
+				RB_FLIP_LEFT(parent, field);		\
+				return;					\
+			}						\
+			RB_FLIP_RIGHT(parent, field);			\
+			if (RB_RED_RIGHT(parent, field)) {		\
+				elm = parent;				\
+				continue;				\
+			}						\
+			if (!RB_RED_RIGHT(elm, field)) {		\
+				RB_FLIP_LEFT(elm, field);		\
+				RB_ROTATE_LEFT(head, elm, child, field);\
+				if (RB_RED_LEFT(child, field))		\
+					RB_FLIP_RIGHT(elm, field);	\
+				else if (RB_RED_RIGHT(child, field))	\
+					RB_FLIP_LEFT(parent, field);	\
+				elm = child;				\
+			}						\
+			RB_ROTATE_RIGHT(head, parent, elm, field);	\
+		} else {						\
+			if (RB_RED_RIGHT(parent, field)) {		\
+				RB_FLIP_RIGHT(parent, field);		\
+				return;					\
+			}						\
+			RB_FLIP_LEFT(parent, field);			\
+			if (RB_RED_LEFT(parent, field)) {		\
+				elm = parent;				\
+				continue;				\
+			}						\
+			if (!RB_RED_LEFT(elm, field)) {			\
+				RB_FLIP_RIGHT(elm, field);		\
+				RB_ROTATE_RIGHT(head, elm, child, field);\
+				if (RB_RED_RIGHT(child, field))		\
+					RB_FLIP_LEFT(elm, field);	\
+				else if (RB_RED_LEFT(child, field))	\
+					RB_FLIP_RIGHT(parent, field);	\
+				elm = child;				\
+			}						\
+			RB_ROTATE_LEFT(head, parent, elm, field);	\
+		}							\
+		RB_BITS(elm, field) &= ~RB_RED_MASK;			\
+		break;							\
+	}								\
+}
+
+#define RB_GENERATE_REMOVE_COLOR(name, type, field, attr)		\
+attr void								\
+name##_RB_REMOVE_COLOR(struct name *head,				\
+    struct type *parent, struct type *elm)				\
+{									\
+	struct type *sib;						\
+	if (RB_LEFT(parent, field) == elm &&				\
+	    RB_RIGHT(parent, field) == elm) {				\
+		RB_BITS(parent, field) &= ~RB_RED_MASK;			\
+		elm = parent;						\
+		parent = RB_PARENT(elm, field);				\
+		if (parent == NULL)					\
+			return;						\
+	}								\
+	do  {								\
+		if (RB_LEFT(parent, field) == elm) {			\
+			if (!RB_RED_LEFT(parent, field)) {		\
+				RB_FLIP_LEFT(parent, field);		\
+				return;					\
+			}						\
+			if (RB_RED_RIGHT(parent, field)) {		\
+				RB_FLIP_RIGHT(parent, field);		\
+				elm = parent;				\
+				continue;				\
+			}						\
+			sib = RB_RIGHT(parent, field);			\
+			if ((~RB_BITS(sib, field) & RB_RED_MASK) == 0) {\
+				RB_BITS(sib, field) &= ~RB_RED_MASK;	\
+				elm = parent;				\
+				continue;				\
+			}						\
+			RB_FLIP_RIGHT(sib, field);			\
+			if (RB_RED_LEFT(sib, field))			\
+				RB_FLIP_LEFT(parent, field);		\
+			else if (!RB_RED_RIGHT(sib, field)) {		\
+				RB_FLIP_LEFT(parent, field);		\
+				RB_ROTATE_RIGHT(head, sib, elm, field);	\
+				if (RB_RED_RIGHT(elm, field))		\
+					RB_FLIP_LEFT(sib, field);	\
+				if (RB_RED_LEFT(elm, field))		\
+					RB_FLIP_RIGHT(parent, field);	\
+				RB_BITS(elm, field) |= RB_RED_MASK;	\
+				sib = elm;				\
+			}						\
+			RB_ROTATE_LEFT(head, parent, sib, field);	\
+		} else {						\
+			if (!RB_RED_RIGHT(parent, field)) {		\
+				RB_FLIP_RIGHT(parent, field);		\
+				return;					\
+			}						\
+			if (RB_RED_LEFT(parent, field)) {		\
+				RB_FLIP_LEFT(parent, field);		\
+				elm = parent;				\
+				continue;				\
+			}						\
+			sib = RB_LEFT(parent, field);			\
+			if ((~RB_BITS(sib, field) & RB_RED_MASK) == 0) {\
+				RB_BITS(sib, field) &= ~RB_RED_MASK;	\
+				elm = parent;				\
+				continue;				\
+			}						\
+			RB_FLIP_LEFT(sib, field);			\
+			if (RB_RED_RIGHT(sib, field))			\
+				RB_FLIP_RIGHT(parent, field);		\
+			else if (!RB_RED_LEFT(sib, field)) {		\
+				RB_FLIP_RIGHT(parent, field);		\
+				RB_ROTATE_LEFT(head, sib, elm, field);	\
+				if (RB_RED_LEFT(elm, field))		\
+					RB_FLIP_RIGHT(sib, field);	\
+				if (RB_RED_RIGHT(elm, field))		\
+					RB_FLIP_LEFT(parent, field);	\
+				RB_BITS(elm, field) |= RB_RED_MASK;	\
+				sib = elm;				\
+			}						\
+			RB_ROTATE_RIGHT(head, parent, sib, field);	\
+		}							\
+		break;							\
+	} while ((parent = RB_PARENT(elm, field)) != NULL);		\
+}
+
+#define RB_GENERATE_REMOVE(name, type, field, attr)			\
+attr struct type *							\
+name##_RB_REMOVE(struct name *head, struct type *elm)			\
+{									\
+	struct type *child, *old, *parent, *right;			\
+									\
+	old = elm;							\
+	parent = RB_PARENT(elm, field);					\
+	right = RB_RIGHT(elm, field);					\
+	if (RB_LEFT(elm, field) == NULL)				\
+		elm = child = right;					\
+	else if (right == NULL)						\
+		elm = child = RB_LEFT(elm, field);			\
+	else {								\
+		if ((child = RB_LEFT(right, field)) == NULL) {		\
+			child = RB_RIGHT(right, field);			\
+			RB_RIGHT(old, field) = child;			\
+			parent = elm = right;				\
+		} else {						\
+			do						\
+				elm = child;				\
+			while ((child = RB_LEFT(elm, field)) != NULL);	\
+			child = RB_RIGHT(elm, field);			\
+			parent = RB_PARENT(elm, field);			\
+			RB_LEFT(parent, field) = child;			\
+			RB_SET_PARENT(RB_RIGHT(old, field), elm, field);\
+		}							\
+		RB_SET_PARENT(RB_LEFT(old, field), elm, field);		\
+		elm->field = old->field;				\
+	}								\
+	RB_SWAP_CHILD(head, old, elm, field);				\
+	if (child != NULL)						\
+		RB_SET_PARENT(child, parent, field);			\
+	if (parent != NULL)						\
+		name##_RB_REMOVE_COLOR(head, parent, child);		\
+	while (parent != NULL) {					\
+		RB_AUGMENT(parent);					\
+		parent = RB_PARENT(parent, field);			\
+	}								\
+	return (old);							\
+}
+
+#define RB_GENERATE_INSERT(name, type, field, cmp, attr)		\
+/* Inserts a node into the RB tree */					\
+attr struct type *							\
+name##_RB_INSERT(struct name *head, struct type *elm)			\
+{									\
+	struct type *tmp;						\
+	struct type *parent = NULL;					\
+	int comp = 0;							\
+	tmp = RB_ROOT(head);						\
+	while (tmp) {							\
+		parent = tmp;						\
+		comp = (cmp)(elm, parent);				\
+		if (comp < 0)						\
+			tmp = RB_LEFT(tmp, field);			\
+		else if (comp > 0)					\
+			tmp = RB_RIGHT(tmp, field);			\
+		else							\
+			return (tmp);					\
+	}								\
+	RB_SET(elm, parent, field);					\
+	if (parent == NULL)						\
+		RB_ROOT(head) = elm;					\
+	else if (comp < 0)						\
+		RB_LEFT(parent, field) = elm;				\
+	else								\
+		RB_RIGHT(parent, field) = elm;				\
+	name##_RB_INSERT_COLOR(head, elm);				\
+	while (elm != NULL) {						\
+		RB_AUGMENT(elm);					\
+		elm = RB_PARENT(elm, field);				\
+	}								\
+	return (NULL);							\
+}
+
+#define RB_GENERATE_FIND(name, type, field, cmp, attr)			\
+/* Finds the node with the same key as elm */				\
+attr struct type *							\
+name##_RB_FIND(struct name *head, struct type *elm)			\
+{									\
+	struct type *tmp = RB_ROOT(head);				\
+	int comp;							\
+	while (tmp) {							\
+		comp = cmp(elm, tmp);					\
+		if (comp < 0)						\
+			tmp = RB_LEFT(tmp, field);			\
+		else if (comp > 0)					\
+			tmp = RB_RIGHT(tmp, field);			\
+		else							\
+			return (tmp);					\
+	}								\
+	return (NULL);							\
+}
+
+#define RB_GENERATE_NFIND(name, type, field, cmp, attr)			\
+/* Finds the first node greater than or equal to the search key */	\
+attr struct type *							\
+name##_RB_NFIND(struct name *head, struct type *elm)			\
+{									\
+	struct type *tmp = RB_ROOT(head);				\
+	struct type *res = NULL;					\
+	int comp;							\
+	while (tmp) {							\
+		comp = cmp(elm, tmp);					\
+		if (comp < 0) {						\
+			res = tmp;					\
+			tmp = RB_LEFT(tmp, field);			\
+		}							\
+		else if (comp > 0)					\
+			tmp = RB_RIGHT(tmp, field);			\
+		else							\
+			return (tmp);					\
+	}								\
+	return (res);							\
+}
+
+#define RB_GENERATE_NEXT(name, type, field, attr)			\
+/* ARGSUSED */								\
+attr struct type *							\
+name##_RB_NEXT(struct type *elm)					\
+{									\
+	if (RB_RIGHT(elm, field)) {					\
+		elm = RB_RIGHT(elm, field);				\
+		while (RB_LEFT(elm, field))				\
+			elm = RB_LEFT(elm, field);			\
+	} else {							\
+		if (RB_PARENT(elm, field) &&				\
+		    (elm == RB_LEFT(RB_PARENT(elm, field), field)))	\
+			elm = RB_PARENT(elm, field);			\
+		else {							\
+			while (RB_PARENT(elm, field) &&			\
+			    (elm == RB_RIGHT(RB_PARENT(elm, field), field)))\
+				elm = RB_PARENT(elm, field);		\
+			elm = RB_PARENT(elm, field);			\
+		}							\
+	}								\
+	return (elm);							\
+}
+
+#define RB_GENERATE_PREV(name, type, field, attr)			\
+/* ARGSUSED */								\
+attr struct type *							\
+name##_RB_PREV(struct type *elm)					\
+{									\
+	if (RB_LEFT(elm, field)) {					\
+		elm = RB_LEFT(elm, field);				\
+		while (RB_RIGHT(elm, field))				\
+			elm = RB_RIGHT(elm, field);			\
+	} else {							\
+		if (RB_PARENT(elm, field) &&				\
+		    (elm == RB_RIGHT(RB_PARENT(elm, field), field)))	\
+			elm = RB_PARENT(elm, field);			\
+		else {							\
+			while (RB_PARENT(elm, field) &&			\
+			    (elm == RB_LEFT(RB_PARENT(elm, field), field)))\
+				elm = RB_PARENT(elm, field);		\
+			elm = RB_PARENT(elm, field);			\
+		}							\
+	}								\
+	return (elm);							\
+}
+
+#define RB_GENERATE_MINMAX(name, type, field, attr)			\
+attr struct type *							\
+name##_RB_MINMAX(struct name *head, int val)				\
+{									\
+	struct type *tmp = RB_ROOT(head);				\
+	struct type *parent = NULL;					\
+	while (tmp) {							\
+		parent = tmp;						\
+		if (val < 0)						\
+			tmp = RB_LEFT(tmp, field);			\
+		else							\
+			tmp = RB_RIGHT(tmp, field);			\
+	}								\
+	return (parent);						\
+}
+
+#define	RB_GENERATE_REINSERT(name, type, field, cmp, attr)		\
+attr struct type *							\
+name##_RB_REINSERT(struct name *head, struct type *elm)			\
+{									\
+	struct type *cmpelm;						\
+	if (((cmpelm = RB_PREV(name, head, elm)) != NULL &&		\
+	    cmp(cmpelm, elm) >= 0) ||					\
+	    ((cmpelm = RB_NEXT(name, head, elm)) != NULL &&		\
+	    cmp(elm, cmpelm) >= 0)) {					\
+		/* XXXLAS: Remove/insert is heavy handed. */		\
+		RB_REMOVE(name, head, elm);				\
+		return (RB_INSERT(name, head, elm));			\
+	}								\
+	return (NULL);							\
+}									\
+
+#define RB_NEGINF	-1
+#define RB_INF	1
+
+#define RB_INSERT(name, x, y)	name##_RB_INSERT(x, y)
+#define RB_REMOVE(name, x, y)	name##_RB_REMOVE(x, y)
+#define RB_FIND(name, x, y)	name##_RB_FIND(x, y)
+#define RB_NFIND(name, x, y)	name##_RB_NFIND(x, y)
+#define RB_NEXT(name, x, y)	name##_RB_NEXT(y)
+#define RB_PREV(name, x, y)	name##_RB_PREV(y)
+#define RB_MIN(name, x)		name##_RB_MINMAX(x, RB_NEGINF)
+#define RB_MAX(name, x)		name##_RB_MINMAX(x, RB_INF)
+#define RB_REINSERT(name, x, y)	name##_RB_REINSERT(x, y)
+
+#define RB_FOREACH(x, name, head)					\
+	for ((x) = RB_MIN(name, head);					\
+	     (x) != NULL;						\
+	     (x) = name##_RB_NEXT(x))
+
+#define RB_FOREACH_FROM(x, name, y)					\
+	for ((x) = (y);							\
+	    ((x) != NULL) && ((y) = name##_RB_NEXT(x), (x) != NULL);	\
+	     (x) = (y))
+
+#define RB_FOREACH_SAFE(x, name, head, y)				\
+	for ((x) = RB_MIN(name, head);					\
+	    ((x) != NULL) && ((y) = name##_RB_NEXT(x), (x) != NULL);	\
+	     (x) = (y))
+
+#define RB_FOREACH_REVERSE(x, name, head)				\
+	for ((x) = RB_MAX(name, head);					\
+	     (x) != NULL;						\
+	     (x) = name##_RB_PREV(x))
+
+#define RB_FOREACH_REVERSE_FROM(x, name, y)				\
+	for ((x) = (y);							\
+	    ((x) != NULL) && ((y) = name##_RB_PREV(x), (x) != NULL);	\
+	     (x) = (y))
+
+#define RB_FOREACH_REVERSE_SAFE(x, name, head, y)			\
+	for ((x) = RB_MAX(name, head);					\
+	    ((x) != NULL) && ((y) = name##_RB_PREV(x), (x) != NULL);	\
+	     (x) = (y))
+
+#endif	/* SPDK_TREE_H */