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/*
* 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 <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stdint.h>
#include "platform_defs.h"
#include "radix-tree.h"
#ifndef ARRAY_SIZE
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
#endif
#define RADIX_TREE_MAP_SHIFT 6
#define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT)
#define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1)
#ifdef RADIX_TREE_TAGS
#define RADIX_TREE_TAG_LONGS \
((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
#endif
struct radix_tree_node {
unsigned int count;
void *slots[RADIX_TREE_MAP_SIZE];
#ifdef RADIX_TREE_TAGS
unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
#endif
};
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];
/*
* Radix tree node cache.
*/
#define radix_tree_node_alloc(r) ((struct radix_tree_node *) \
calloc(1, sizeof(struct radix_tree_node)))
#define radix_tree_node_free(n) free(n)
#ifdef RADIX_TREE_TAGS
static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
int offset)
{
*((uint32_t *)node->tags[tag] + (offset >> 5)) |= (1 << (offset & 31));
}
static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
int offset)
{
uint32_t *p = (uint32_t*)node->tags[tag] + (offset >> 5);
uint32_t m = 1 << (offset & 31);
*p &= ~m;
}
static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
int offset)
{
return 1 & (((const uint32_t *)node->tags[tag])[offset >> 5] >> (offset & 31));
}
/*
* 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;
}
#endif
/*
* 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;
#ifdef RADIX_TREE_TAGS
char tags[RADIX_TREE_MAX_TAGS];
int tag;
#endif
/* 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;
}
#ifdef RADIX_TREE_TAGS
/*
* Prepare the tag status of the top-level node for propagation
* into the newly-pushed top-level node(s)
*/
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
tags[tag] = 0;
if (any_tag_set(root->rnode, tag))
tags[tag] = 1;
}
#endif
do {
if (!(node = radix_tree_node_alloc(root)))
return -ENOMEM;
/* Increase the height. */
node->slots[0] = root->rnode;
#ifdef RADIX_TREE_TAGS
/* Propagate the aggregated tag info into the new root */
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
if (tags[tag])
tag_set(node, tag, 0);
}
#endif
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 && !root->rnode) ||
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 */
do {
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--;
} while (height > 0);
if (slot != NULL)
return -EEXIST;
ASSERT(node);
node->count++;
node->slots[offset] = item;
#ifdef RADIX_TREE_TAGS
ASSERT(!tag_get(node, 0, offset));
ASSERT(!tag_get(node, 1, offset));
#endif
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;
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;
}
/**
* raid_tree_first_key - find the first index key in the radix tree
* @root: radix tree root
* @index: where the first index will be placed
*
* Returns the first entry and index key in the radix tree @root.
*/
void *radix_tree_lookup_first(struct radix_tree_root *root, unsigned long *index)
{
unsigned int height, shift;
struct radix_tree_node *slot;
unsigned long i;
height = root->height;
*index = 0;
if (height == 0)
return NULL;
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
slot = root->rnode;
for (; height > 1; height--) {
for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
if (slot->slots[i] != NULL)
break;
}
ASSERT(i < RADIX_TREE_MAP_SIZE);
*index |= (i << shift);
shift -= RADIX_TREE_MAP_SHIFT;
slot = slot->slots[i];
}
for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
if (slot->slots[i] != NULL) {
*index |= i;
return slot->slots[i];
}
}
return NULL;
}
#ifdef RADIX_TREE_TAGS
/**
* 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;
if (index > radix_tree_maxindex(height))
return NULL;
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
slot = root->rnode;
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];
ASSERT(slot != NULL);
shift -= RADIX_TREE_MAP_SHIFT;
height--;
}
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 + 1], *pathp = path;
struct radix_tree_node *slot;
unsigned int height, shift;
void *ret = NULL;
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--;
}
ret = slot;
if (ret == NULL)
goto out;
do {
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--;
} while (pathp->node);
out:
return ret;
}
#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)
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;
}
/**
* radix_tree_gang_lookup_ex - 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
* @last_index: don't lookup past this key
* @max_items: place up to this many items at *results
*
* Performs an index-ascending scan of the tree for present items starting
* @first_index until @last_index up to as many as @max_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_ex(struct radix_tree_root *root, void **results,
unsigned long first_index, unsigned long last_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 && cur_index < last_index) {
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;
}
#ifdef RADIX_TREE_TAGS
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;
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
slot = root->rnode;
while (height > 0) {
unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
for ( ; i < RADIX_TREE_MAP_SIZE; i++) {
if (tag_get(slot, tag, i)) {
ASSERT(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)) {
ASSERT(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];
}
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;
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;
}
#endif
/**
* 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 > 1 &&
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 */
#ifdef RADIX_TREE_TAGS
tag_clear(to_free, 0, 0);
tag_clear(to_free, 1, 0);
#endif
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 + 1], *pathp = path;
struct radix_tree_path *orig_pathp;
struct radix_tree_node *slot;
unsigned int height, shift;
void *ret = NULL;
#ifdef RADIX_TREE_TAGS
char tags[RADIX_TREE_MAX_TAGS];
int nr_cleared_tags;
int tag;
#endif
int offset;
height = root->height;
if (index > radix_tree_maxindex(height))
goto out;
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
pathp->node = NULL;
slot = root->rnode;
for ( ; height > 0; height--) {
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;
}
ret = slot;
if (ret == NULL)
goto out;
orig_pathp = pathp;
#ifdef RADIX_TREE_TAGS
/*
* Clear all tags associated with the just-deleted item
*/
nr_cleared_tags = 0;
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
tags[tag] = 1;
if (tag_get(pathp->node, tag, pathp->offset)) {
tag_clear(pathp->node, tag, pathp->offset);
if (!any_tag_set(pathp->node, tag)) {
tags[tag] = 0;
nr_cleared_tags++;
}
}
}
for (pathp--; nr_cleared_tags && pathp->node; pathp--) {
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
if (tags[tag])
continue;
tag_clear(pathp->node, tag, pathp->offset);
if (any_tag_set(pathp->node, tag)) {
tags[tag] = 1;
nr_cleared_tags--;
}
}
}
#endif
/* Now free the nodes we do not need anymore */
for (pathp = orig_pathp; pathp->node; pathp--) {
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);
}
root->rnode = NULL;
root->height = 0;
out:
return ret;
}
#ifdef RADIX_TREE_TAGS
/**
* 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)
{
struct radix_tree_node *rnode;
rnode = root->rnode;
if (!rnode)
return 0;
return any_tag_set(rnode, tag);
}
#endif
static unsigned long __maxindex(unsigned int height)
{
unsigned int width = height * RADIX_TREE_MAP_SHIFT;
int shift = RADIX_TREE_INDEX_BITS - width;
if (shift < 0)
return ~0UL;
if (shift >= BITS_PER_LONG)
return 0UL;
return ~0UL >> shift;
}
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();
}