Btrfs: Add backing store, memory management
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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();
+}