diff --git a/fs/btrfs/radix-tree.c b/fs/btrfs/radix-tree.c
new file mode 100644
index 0000000..baa25ca
--- /dev/null
+++ b/fs/btrfs/radix-tree.c
@@ -0,0 +1,836 @@
+/*
+ * Copyright (C) 2001 Momchil Velikov
+ * Portions Copyright (C) 2001 Christoph Hellwig
+ * Copyright (C) 2005 SGI, Christoph Lameter <clameter@sgi.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2, or (at
+ * your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "kerncompat.h"
+#include "radix-tree.h"
+#ifdef __KERNEL__
+#define RADIX_TREE_MAP_SHIFT	(CONFIG_BASE_SMALL ? 4 : 6)
+#else
+#define RADIX_TREE_MAP_SHIFT	3	/* For more stressful testing */
+#endif
+
+#define RADIX_TREE_MAP_SIZE	(1UL << RADIX_TREE_MAP_SHIFT)
+#define RADIX_TREE_MAP_MASK	(RADIX_TREE_MAP_SIZE-1)
+
+#define RADIX_TREE_TAG_LONGS	\
+	((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
+
+struct radix_tree_node {
+	unsigned int	count;
+	void		*slots[RADIX_TREE_MAP_SIZE];
+	unsigned long	tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
+};
+
+struct radix_tree_path {
+	struct radix_tree_node *node;
+	int offset;
+};
+
+#define RADIX_TREE_INDEX_BITS  (8 /* CHAR_BIT */ * sizeof(unsigned long))
+#define RADIX_TREE_MAX_PATH (RADIX_TREE_INDEX_BITS/RADIX_TREE_MAP_SHIFT + 2)
+
+static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH] __read_mostly;
+
+/*
+ * Per-cpu pool of preloaded nodes
+ */
+struct radix_tree_preload {
+	int nr;
+	struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
+};
+struct radix_tree_preload radix_tree_preloads = { 0, };
+
+static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
+{
+	return root->gfp_mask & __GFP_BITS_MASK;
+}
+
+static int internal_nodes = 0;
+/*
+ * This assumes that the caller has performed appropriate preallocation, and
+ * that the caller has pinned this thread of control to the current CPU.
+ */
+static struct radix_tree_node *
+radix_tree_node_alloc(struct radix_tree_root *root)
+{
+	struct radix_tree_node *ret;
+	ret = malloc(sizeof(struct radix_tree_node));
+	if (ret) {
+		memset(ret, 0, sizeof(struct radix_tree_node));
+		internal_nodes++;
+	}
+	return ret;
+}
+
+static inline void
+radix_tree_node_free(struct radix_tree_node *node)
+{
+	internal_nodes--;
+	free(node);
+}
+
+/*
+ * Load up this CPU's radix_tree_node buffer with sufficient objects to
+ * ensure that the addition of a single element in the tree cannot fail.  On
+ * success, return zero, with preemption disabled.  On error, return -ENOMEM
+ * with preemption not disabled.
+ */
+int radix_tree_preload(gfp_t gfp_mask)
+{
+	struct radix_tree_preload *rtp;
+	struct radix_tree_node *node;
+	int ret = -ENOMEM;
+
+	preempt_disable();
+	rtp = &__get_cpu_var(radix_tree_preloads);
+	while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
+		preempt_enable();
+		node = radix_tree_node_alloc(NULL);
+		if (node == NULL)
+			goto out;
+		preempt_disable();
+		rtp = &__get_cpu_var(radix_tree_preloads);
+		if (rtp->nr < ARRAY_SIZE(rtp->nodes))
+			rtp->nodes[rtp->nr++] = node;
+		else
+			radix_tree_node_free(node);
+	}
+	ret = 0;
+out:
+	return ret;
+}
+
+static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
+		int offset)
+{
+	__set_bit(offset, node->tags[tag]);
+}
+
+static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
+		int offset)
+{
+	__clear_bit(offset, node->tags[tag]);
+}
+
+static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
+		int offset)
+{
+	return test_bit(offset, node->tags[tag]);
+}
+
+static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
+{
+	root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
+}
+
+
+static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
+{
+	root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
+}
+
+static inline void root_tag_clear_all(struct radix_tree_root *root)
+{
+	root->gfp_mask &= __GFP_BITS_MASK;
+}
+
+static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
+{
+	return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
+}
+
+/*
+ * Returns 1 if any slot in the node has this tag set.
+ * Otherwise returns 0.
+ */
+static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
+{
+	int idx;
+	for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
+		if (node->tags[tag][idx])
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ *	Return the maximum key which can be store into a
+ *	radix tree with height HEIGHT.
+ */
+static inline unsigned long radix_tree_maxindex(unsigned int height)
+{
+	return height_to_maxindex[height];
+}
+
+/*
+ *	Extend a radix tree so it can store key @index.
+ */
+static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
+{
+	struct radix_tree_node *node;
+	unsigned int height;
+	int tag;
+
+	/* Figure out what the height should be.  */
+	height = root->height + 1;
+	while (index > radix_tree_maxindex(height))
+		height++;
+
+	if (root->rnode == NULL) {
+		root->height = height;
+		goto out;
+	}
+
+	do {
+		if (!(node = radix_tree_node_alloc(root)))
+			return -ENOMEM;
+
+		/* Increase the height.  */
+		node->slots[0] = root->rnode;
+
+		/* Propagate the aggregated tag info into the new root */
+		for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
+			if (root_tag_get(root, tag))
+				tag_set(node, tag, 0);
+		}
+
+		node->count = 1;
+		root->rnode = node;
+		root->height++;
+	} while (height > root->height);
+out:
+	return 0;
+}
+
+/**
+ *	radix_tree_insert    -    insert into a radix tree
+ *	@root:		radix tree root
+ *	@index:		index key
+ *	@item:		item to insert
+ *
+ *	Insert an item into the radix tree at position @index.
+ */
+int radix_tree_insert(struct radix_tree_root *root,
+			unsigned long index, void *item)
+{
+	struct radix_tree_node *node = NULL, *slot;
+	unsigned int height, shift;
+	int offset;
+	int error;
+
+	/* Make sure the tree is high enough.  */
+	if (index > radix_tree_maxindex(root->height)) {
+		error = radix_tree_extend(root, index);
+		if (error)
+			return error;
+	}
+
+	slot = root->rnode;
+	height = root->height;
+	shift = (height-1) * RADIX_TREE_MAP_SHIFT;
+
+	offset = 0;			/* uninitialised var warning */
+	while (height > 0) {
+		if (slot == NULL) {
+			/* Have to add a child node.  */
+			if (!(slot = radix_tree_node_alloc(root)))
+				return -ENOMEM;
+			if (node) {
+				node->slots[offset] = slot;
+				node->count++;
+			} else
+				root->rnode = slot;
+		}
+
+		/* Go a level down */
+		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+		node = slot;
+		slot = node->slots[offset];
+		shift -= RADIX_TREE_MAP_SHIFT;
+		height--;
+	}
+
+	if (slot != NULL)
+		return -EEXIST;
+
+	if (node) {
+		node->count++;
+		node->slots[offset] = item;
+		BUG_ON(tag_get(node, 0, offset));
+		BUG_ON(tag_get(node, 1, offset));
+	} else {
+		root->rnode = item;
+		BUG_ON(root_tag_get(root, 0));
+		BUG_ON(root_tag_get(root, 1));
+	}
+
+	return 0;
+}
+
+static inline void **__lookup_slot(struct radix_tree_root *root,
+				   unsigned long index)
+{
+	unsigned int height, shift;
+	struct radix_tree_node **slot;
+
+	height = root->height;
+
+	if (index > radix_tree_maxindex(height))
+		return NULL;
+
+	if (height == 0 && root->rnode)
+		return (void **)&root->rnode;
+
+	shift = (height-1) * RADIX_TREE_MAP_SHIFT;
+	slot = &root->rnode;
+
+	while (height > 0) {
+		if (*slot == NULL)
+			return NULL;
+
+		slot = (struct radix_tree_node **)
+			((*slot)->slots +
+				((index >> shift) & RADIX_TREE_MAP_MASK));
+		shift -= RADIX_TREE_MAP_SHIFT;
+		height--;
+	}
+
+	return (void **)slot;
+}
+
+/**
+ *	radix_tree_lookup_slot    -    lookup a slot in a radix tree
+ *	@root:		radix tree root
+ *	@index:		index key
+ *
+ *	Lookup the slot corresponding to the position @index in the radix tree
+ *	@root. This is useful for update-if-exists operations.
+ */
+void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
+{
+	return __lookup_slot(root, index);
+}
+
+/**
+ *	radix_tree_lookup    -    perform lookup operation on a radix tree
+ *	@root:		radix tree root
+ *	@index:		index key
+ *
+ *	Lookup the item at the position @index in the radix tree @root.
+ */
+void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
+{
+	void **slot;
+
+	slot = __lookup_slot(root, index);
+	return slot != NULL ? *slot : NULL;
+}
+
+/**
+ *	radix_tree_tag_set - set a tag on a radix tree node
+ *	@root:		radix tree root
+ *	@index:		index key
+ *	@tag: 		tag index
+ *
+ *	Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
+ *	corresponding to @index in the radix tree.  From
+ *	the root all the way down to the leaf node.
+ *
+ *	Returns the address of the tagged item.   Setting a tag on a not-present
+ *	item is a bug.
+ */
+void *radix_tree_tag_set(struct radix_tree_root *root,
+			unsigned long index, unsigned int tag)
+{
+	unsigned int height, shift;
+	struct radix_tree_node *slot;
+
+	height = root->height;
+	BUG_ON(index > radix_tree_maxindex(height));
+
+	slot = root->rnode;
+	shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
+
+	while (height > 0) {
+		int offset;
+
+		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+		if (!tag_get(slot, tag, offset))
+			tag_set(slot, tag, offset);
+		slot = slot->slots[offset];
+		BUG_ON(slot == NULL);
+		shift -= RADIX_TREE_MAP_SHIFT;
+		height--;
+	}
+
+	/* set the root's tag bit */
+	if (slot && !root_tag_get(root, tag))
+		root_tag_set(root, tag);
+
+	return slot;
+}
+
+/**
+ *	radix_tree_tag_clear - clear a tag on a radix tree node
+ *	@root:		radix tree root
+ *	@index:		index key
+ *	@tag: 		tag index
+ *
+ *	Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
+ *	corresponding to @index in the radix tree.  If
+ *	this causes the leaf node to have no tags set then clear the tag in the
+ *	next-to-leaf node, etc.
+ *
+ *	Returns the address of the tagged item on success, else NULL.  ie:
+ *	has the same return value and semantics as radix_tree_lookup().
+ */
+void *radix_tree_tag_clear(struct radix_tree_root *root,
+			unsigned long index, unsigned int tag)
+{
+	struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
+	struct radix_tree_node *slot = NULL;
+	unsigned int height, shift;
+
+	height = root->height;
+	if (index > radix_tree_maxindex(height))
+		goto out;
+
+	shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
+	pathp->node = NULL;
+	slot = root->rnode;
+
+	while (height > 0) {
+		int offset;
+
+		if (slot == NULL)
+			goto out;
+
+		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+		pathp[1].offset = offset;
+		pathp[1].node = slot;
+		slot = slot->slots[offset];
+		pathp++;
+		shift -= RADIX_TREE_MAP_SHIFT;
+		height--;
+	}
+
+	if (slot == NULL)
+		goto out;
+
+	while (pathp->node) {
+		if (!tag_get(pathp->node, tag, pathp->offset))
+			goto out;
+		tag_clear(pathp->node, tag, pathp->offset);
+		if (any_tag_set(pathp->node, tag))
+			goto out;
+		pathp--;
+	}
+
+	/* clear the root's tag bit */
+	if (root_tag_get(root, tag))
+		root_tag_clear(root, tag);
+
+out:
+	return slot;
+}
+
+#ifndef __KERNEL__	/* Only the test harness uses this at present */
+/**
+ * radix_tree_tag_get - get a tag on a radix tree node
+ * @root:		radix tree root
+ * @index:		index key
+ * @tag: 		tag index (< RADIX_TREE_MAX_TAGS)
+ *
+ * Return values:
+ *
+ *  0: tag not present or not set
+ *  1: tag set
+ */
+int radix_tree_tag_get(struct radix_tree_root *root,
+			unsigned long index, unsigned int tag)
+{
+	unsigned int height, shift;
+	struct radix_tree_node *slot;
+	int saw_unset_tag = 0;
+
+	height = root->height;
+	if (index > radix_tree_maxindex(height))
+		return 0;
+
+	/* check the root's tag bit */
+	if (!root_tag_get(root, tag))
+		return 0;
+
+	if (height == 0)
+		return 1;
+
+	shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
+	slot = root->rnode;
+
+	for ( ; ; ) {
+		int offset;
+
+		if (slot == NULL)
+			return 0;
+
+		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+
+		/*
+		 * This is just a debug check.  Later, we can bale as soon as
+		 * we see an unset tag.
+		 */
+		if (!tag_get(slot, tag, offset))
+			saw_unset_tag = 1;
+		if (height == 1) {
+			int ret = tag_get(slot, tag, offset);
+
+			BUG_ON(ret && saw_unset_tag);
+			return !!ret;
+		}
+		slot = slot->slots[offset];
+		shift -= RADIX_TREE_MAP_SHIFT;
+		height--;
+	}
+}
+#endif
+
+static unsigned int
+__lookup(struct radix_tree_root *root, void **results, unsigned long index,
+	unsigned int max_items, unsigned long *next_index)
+{
+	unsigned int nr_found = 0;
+	unsigned int shift, height;
+	struct radix_tree_node *slot;
+	unsigned long i;
+
+	height = root->height;
+	if (height == 0) {
+		if (root->rnode && index == 0)
+			results[nr_found++] = root->rnode;
+		goto out;
+	}
+
+	shift = (height-1) * RADIX_TREE_MAP_SHIFT;
+	slot = root->rnode;
+
+	for ( ; height > 1; height--) {
+
+		for (i = (index >> shift) & RADIX_TREE_MAP_MASK ;
+				i < RADIX_TREE_MAP_SIZE; i++) {
+			if (slot->slots[i] != NULL)
+				break;
+			index &= ~((1UL << shift) - 1);
+			index += 1UL << shift;
+			if (index == 0)
+				goto out;	/* 32-bit wraparound */
+		}
+		if (i == RADIX_TREE_MAP_SIZE)
+			goto out;
+
+		shift -= RADIX_TREE_MAP_SHIFT;
+		slot = slot->slots[i];
+	}
+
+	/* Bottom level: grab some items */
+	for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
+		index++;
+		if (slot->slots[i]) {
+			results[nr_found++] = slot->slots[i];
+			if (nr_found == max_items)
+				goto out;
+		}
+	}
+out:
+	*next_index = index;
+	return nr_found;
+}
+
+/**
+ *	radix_tree_gang_lookup - perform multiple lookup on a radix tree
+ *	@root:		radix tree root
+ *	@results:	where the results of the lookup are placed
+ *	@first_index:	start the lookup from this key
+ *	@max_items:	place up to this many items at *results
+ *
+ *	Performs an index-ascending scan of the tree for present items.  Places
+ *	them at *@results and returns the number of items which were placed at
+ *	*@results.
+ *
+ *	The implementation is naive.
+ */
+unsigned int
+radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
+			unsigned long first_index, unsigned int max_items)
+{
+	const unsigned long max_index = radix_tree_maxindex(root->height);
+	unsigned long cur_index = first_index;
+	unsigned int ret = 0;
+
+	while (ret < max_items) {
+		unsigned int nr_found;
+		unsigned long next_index;	/* Index of next search */
+
+		if (cur_index > max_index)
+			break;
+		nr_found = __lookup(root, results + ret, cur_index,
+					max_items - ret, &next_index);
+		ret += nr_found;
+		if (next_index == 0)
+			break;
+		cur_index = next_index;
+	}
+	return ret;
+}
+
+/*
+ * FIXME: the two tag_get()s here should use find_next_bit() instead of
+ * open-coding the search.
+ */
+static unsigned int
+__lookup_tag(struct radix_tree_root *root, void **results, unsigned long index,
+	unsigned int max_items, unsigned long *next_index, unsigned int tag)
+{
+	unsigned int nr_found = 0;
+	unsigned int shift;
+	unsigned int height = root->height;
+	struct radix_tree_node *slot;
+
+	if (height == 0) {
+		if (root->rnode && index == 0)
+			results[nr_found++] = root->rnode;
+		goto out;
+	}
+
+	shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
+	slot = root->rnode;
+
+	do {
+		unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
+
+		for ( ; i < RADIX_TREE_MAP_SIZE; i++) {
+			if (tag_get(slot, tag, i)) {
+				BUG_ON(slot->slots[i] == NULL);
+				break;
+			}
+			index &= ~((1UL << shift) - 1);
+			index += 1UL << shift;
+			if (index == 0)
+				goto out;	/* 32-bit wraparound */
+		}
+		if (i == RADIX_TREE_MAP_SIZE)
+			goto out;
+		height--;
+		if (height == 0) {	/* Bottom level: grab some items */
+			unsigned long j = index & RADIX_TREE_MAP_MASK;
+
+			for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
+				index++;
+				if (tag_get(slot, tag, j)) {
+					BUG_ON(slot->slots[j] == NULL);
+					results[nr_found++] = slot->slots[j];
+					if (nr_found == max_items)
+						goto out;
+				}
+			}
+		}
+		shift -= RADIX_TREE_MAP_SHIFT;
+		slot = slot->slots[i];
+	} while (height > 0);
+out:
+	*next_index = index;
+	return nr_found;
+}
+
+/**
+ *	radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
+ *	                             based on a tag
+ *	@root:		radix tree root
+ *	@results:	where the results of the lookup are placed
+ *	@first_index:	start the lookup from this key
+ *	@max_items:	place up to this many items at *results
+ *	@tag:		the tag index (< RADIX_TREE_MAX_TAGS)
+ *
+ *	Performs an index-ascending scan of the tree for present items which
+ *	have the tag indexed by @tag set.  Places the items at *@results and
+ *	returns the number of items which were placed at *@results.
+ */
+unsigned int
+radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
+		unsigned long first_index, unsigned int max_items,
+		unsigned int tag)
+{
+	const unsigned long max_index = radix_tree_maxindex(root->height);
+	unsigned long cur_index = first_index;
+	unsigned int ret = 0;
+
+	/* check the root's tag bit */
+	if (!root_tag_get(root, tag))
+		return 0;
+
+	while (ret < max_items) {
+		unsigned int nr_found;
+		unsigned long next_index;	/* Index of next search */
+
+		if (cur_index > max_index)
+			break;
+		nr_found = __lookup_tag(root, results + ret, cur_index,
+					max_items - ret, &next_index, tag);
+		ret += nr_found;
+		if (next_index == 0)
+			break;
+		cur_index = next_index;
+	}
+	return ret;
+}
+
+/**
+ *	radix_tree_shrink    -    shrink height of a radix tree to minimal
+ *	@root		radix tree root
+ */
+static inline void radix_tree_shrink(struct radix_tree_root *root)
+{
+	/* try to shrink tree height */
+	while (root->height > 0 &&
+			root->rnode->count == 1 &&
+			root->rnode->slots[0]) {
+		struct radix_tree_node *to_free = root->rnode;
+
+		root->rnode = to_free->slots[0];
+		root->height--;
+		/* must only free zeroed nodes into the slab */
+		tag_clear(to_free, 0, 0);
+		tag_clear(to_free, 1, 0);
+		to_free->slots[0] = NULL;
+		to_free->count = 0;
+		radix_tree_node_free(to_free);
+	}
+}
+
+/**
+ *	radix_tree_delete    -    delete an item from a radix tree
+ *	@root:		radix tree root
+ *	@index:		index key
+ *
+ *	Remove the item at @index from the radix tree rooted at @root.
+ *
+ *	Returns the address of the deleted item, or NULL if it was not present.
+ */
+void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
+{
+	struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
+	struct radix_tree_node *slot = NULL;
+	unsigned int height, shift;
+	int tag;
+	int offset;
+
+	height = root->height;
+	if (index > radix_tree_maxindex(height))
+		goto out;
+
+	slot = root->rnode;
+	if (height == 0 && root->rnode) {
+		root_tag_clear_all(root);
+		root->rnode = NULL;
+		goto out;
+	}
+
+	shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
+	pathp->node = NULL;
+
+	do {
+		if (slot == NULL)
+			goto out;
+
+		pathp++;
+		offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+		pathp->offset = offset;
+		pathp->node = slot;
+		slot = slot->slots[offset];
+		shift -= RADIX_TREE_MAP_SHIFT;
+		height--;
+	} while (height > 0);
+
+	if (slot == NULL)
+		goto out;
+
+	/*
+	 * Clear all tags associated with the just-deleted item
+	 */
+	for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
+		if (tag_get(pathp->node, tag, pathp->offset))
+			radix_tree_tag_clear(root, index, tag);
+	}
+
+	/* Now free the nodes we do not need anymore */
+	while (pathp->node) {
+		pathp->node->slots[pathp->offset] = NULL;
+		pathp->node->count--;
+
+		if (pathp->node->count) {
+			if (pathp->node == root->rnode)
+				radix_tree_shrink(root);
+			goto out;
+		}
+
+		/* Node with zero slots in use so free it */
+		radix_tree_node_free(pathp->node);
+
+		pathp--;
+	}
+	root_tag_clear_all(root);
+	root->height = 0;
+	root->rnode = NULL;
+
+out:
+	return slot;
+}
+
+/**
+ *	radix_tree_tagged - test whether any items in the tree are tagged
+ *	@root:		radix tree root
+ *	@tag:		tag to test
+ */
+int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
+{
+	return root_tag_get(root, tag);
+}
+
+static unsigned long __maxindex(unsigned int height)
+{
+	unsigned int tmp = height * RADIX_TREE_MAP_SHIFT;
+	unsigned long index = (~0UL >> (RADIX_TREE_INDEX_BITS - tmp - 1)) >> 1;
+
+	if (tmp >= RADIX_TREE_INDEX_BITS)
+		index = ~0UL;
+	return index;
+}
+
+static void radix_tree_init_maxindex(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
+		height_to_maxindex[i] = __maxindex(i);
+}
+
+void radix_tree_init(void)
+{
+	radix_tree_init_maxindex();
+}