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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Copyright (C) 2001 Momchil Velikov
3 * Portions Copyright (C) 2001 Christoph Hellwig
Christoph Lametercde53532008-07-04 09:59:22 -07004 * Copyright (C) 2005 SGI, Christoph Lameter
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08005 * Copyright (C) 2006 Nick Piggin
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2, or (at
10 * your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 */
21
22#include <linux/errno.h>
23#include <linux/init.h>
24#include <linux/kernel.h>
25#include <linux/module.h>
26#include <linux/radix-tree.h>
27#include <linux/percpu.h>
28#include <linux/slab.h>
29#include <linux/notifier.h>
30#include <linux/cpu.h>
31#include <linux/gfp.h>
32#include <linux/string.h>
33#include <linux/bitops.h>
Nick Piggin7cf9c2c2006-12-06 20:33:44 -080034#include <linux/rcupdate.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035
36
37#ifdef __KERNEL__
Nick Piggincfd9b7d2006-06-23 02:03:22 -070038#define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
Linus Torvalds1da177e2005-04-16 15:20:36 -070039#else
40#define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */
41#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
43#define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT)
44#define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1)
45
46#define RADIX_TREE_TAG_LONGS \
47 ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
48
49struct radix_tree_node {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -080050 unsigned int height; /* Height from the bottom */
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 unsigned int count;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -080052 struct rcu_head rcu_head;
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 void *slots[RADIX_TREE_MAP_SIZE];
Jonathan Corbetdaff89f2006-03-25 03:08:05 -080054 unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
Linus Torvalds1da177e2005-04-16 15:20:36 -070055};
56
57struct radix_tree_path {
Christoph Lameter201b6262005-09-06 15:16:46 -070058 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 int offset;
60};
61
62#define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
Jeff Moyer26fb1582007-10-16 01:24:49 -070063#define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
64 RADIX_TREE_MAP_SHIFT))
Linus Torvalds1da177e2005-04-16 15:20:36 -070065
Jeff Moyer26fb1582007-10-16 01:24:49 -070066/*
67 * The height_to_maxindex array needs to be one deeper than the maximum
68 * path as height 0 holds only 1 entry.
69 */
70static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070071
72/*
73 * Radix tree node cache.
74 */
Christoph Lametere18b8902006-12-06 20:33:20 -080075static struct kmem_cache *radix_tree_node_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070076
77/*
78 * Per-cpu pool of preloaded nodes
79 */
80struct radix_tree_preload {
81 int nr;
82 struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH];
83};
84DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
85
Nick Piggin612d6c12006-06-23 02:03:22 -070086static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
87{
88 return root->gfp_mask & __GFP_BITS_MASK;
89}
90
Nick Piggin643b52b2008-06-12 15:21:52 -070091static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
92 int offset)
93{
94 __set_bit(offset, node->tags[tag]);
95}
96
97static inline void tag_clear(struct radix_tree_node *node, unsigned int tag,
98 int offset)
99{
100 __clear_bit(offset, node->tags[tag]);
101}
102
103static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
104 int offset)
105{
106 return test_bit(offset, node->tags[tag]);
107}
108
109static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
110{
111 root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT));
112}
113
114static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
115{
116 root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT));
117}
118
119static inline void root_tag_clear_all(struct radix_tree_root *root)
120{
121 root->gfp_mask &= __GFP_BITS_MASK;
122}
123
124static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
125{
126 return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
127}
128
129/*
130 * Returns 1 if any slot in the node has this tag set.
131 * Otherwise returns 0.
132 */
133static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag)
134{
135 int idx;
136 for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
137 if (node->tags[tag][idx])
138 return 1;
139 }
140 return 0;
141}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142/*
143 * This assumes that the caller has performed appropriate preallocation, and
144 * that the caller has pinned this thread of control to the current CPU.
145 */
146static struct radix_tree_node *
147radix_tree_node_alloc(struct radix_tree_root *root)
148{
Nick Piggine2848a02008-02-04 22:29:10 -0800149 struct radix_tree_node *ret = NULL;
Nick Piggin612d6c12006-06-23 02:03:22 -0700150 gfp_t gfp_mask = root_gfp_mask(root);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151
Nick Piggine2848a02008-02-04 22:29:10 -0800152 if (!(gfp_mask & __GFP_WAIT)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 struct radix_tree_preload *rtp;
154
Nick Piggine2848a02008-02-04 22:29:10 -0800155 /*
156 * Provided the caller has preloaded here, we will always
157 * succeed in getting a node here (and never reach
158 * kmem_cache_alloc)
159 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 rtp = &__get_cpu_var(radix_tree_preloads);
161 if (rtp->nr) {
162 ret = rtp->nodes[rtp->nr - 1];
163 rtp->nodes[rtp->nr - 1] = NULL;
164 rtp->nr--;
165 }
166 }
Nick Piggine2848a02008-02-04 22:29:10 -0800167 if (ret == NULL)
Christoph Lameter488514d2008-04-28 02:12:05 -0700168 ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
Nick Piggine2848a02008-02-04 22:29:10 -0800169
Nick Pigginc0bc9872007-10-16 01:24:42 -0700170 BUG_ON(radix_tree_is_indirect_ptr(ret));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 return ret;
172}
173
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800174static void radix_tree_node_rcu_free(struct rcu_head *head)
175{
176 struct radix_tree_node *node =
177 container_of(head, struct radix_tree_node, rcu_head);
Nick Piggin643b52b2008-06-12 15:21:52 -0700178
179 /*
180 * must only free zeroed nodes into the slab. radix_tree_shrink
181 * can leave us with a non-NULL entry in the first slot, so clear
182 * that here to make sure.
183 */
184 tag_clear(node, 0, 0);
185 tag_clear(node, 1, 0);
186 node->slots[0] = NULL;
187 node->count = 0;
188
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800189 kmem_cache_free(radix_tree_node_cachep, node);
190}
191
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192static inline void
193radix_tree_node_free(struct radix_tree_node *node)
194{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800195 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196}
197
198/*
199 * Load up this CPU's radix_tree_node buffer with sufficient objects to
200 * ensure that the addition of a single element in the tree cannot fail. On
201 * success, return zero, with preemption disabled. On error, return -ENOMEM
202 * with preemption not disabled.
203 */
Al Virodd0fc662005-10-07 07:46:04 +0100204int radix_tree_preload(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205{
206 struct radix_tree_preload *rtp;
207 struct radix_tree_node *node;
208 int ret = -ENOMEM;
209
210 preempt_disable();
211 rtp = &__get_cpu_var(radix_tree_preloads);
212 while (rtp->nr < ARRAY_SIZE(rtp->nodes)) {
213 preempt_enable();
Christoph Lameter488514d2008-04-28 02:12:05 -0700214 node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 if (node == NULL)
216 goto out;
217 preempt_disable();
218 rtp = &__get_cpu_var(radix_tree_preloads);
219 if (rtp->nr < ARRAY_SIZE(rtp->nodes))
220 rtp->nodes[rtp->nr++] = node;
221 else
222 kmem_cache_free(radix_tree_node_cachep, node);
223 }
224 ret = 0;
225out:
226 return ret;
227}
David Chinnerd7f09232007-07-14 16:05:04 +1000228EXPORT_SYMBOL(radix_tree_preload);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229
Nick Piggin6e954b92006-01-08 01:01:40 -0800230/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 * Return the maximum key which can be store into a
232 * radix tree with height HEIGHT.
233 */
234static inline unsigned long radix_tree_maxindex(unsigned int height)
235{
236 return height_to_maxindex[height];
237}
238
239/*
240 * Extend a radix tree so it can store key @index.
241 */
242static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
243{
244 struct radix_tree_node *node;
245 unsigned int height;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 int tag;
247
248 /* Figure out what the height should be. */
249 height = root->height + 1;
250 while (index > radix_tree_maxindex(height))
251 height++;
252
253 if (root->rnode == NULL) {
254 root->height = height;
255 goto out;
256 }
257
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 do {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800259 unsigned int newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 if (!(node = radix_tree_node_alloc(root)))
261 return -ENOMEM;
262
263 /* Increase the height. */
Nick Pigginc0bc9872007-10-16 01:24:42 -0700264 node->slots[0] = radix_tree_indirect_to_ptr(root->rnode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265
266 /* Propagate the aggregated tag info into the new root */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800267 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
Nick Piggin612d6c12006-06-23 02:03:22 -0700268 if (root_tag_get(root, tag))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 tag_set(node, tag, 0);
270 }
271
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800272 newheight = root->height+1;
273 node->height = newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 node->count = 1;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700275 node = radix_tree_ptr_to_indirect(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800276 rcu_assign_pointer(root->rnode, node);
277 root->height = newheight;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 } while (height > root->height);
279out:
280 return 0;
281}
282
283/**
284 * radix_tree_insert - insert into a radix tree
285 * @root: radix tree root
286 * @index: index key
287 * @item: item to insert
288 *
289 * Insert an item into the radix tree at position @index.
290 */
291int radix_tree_insert(struct radix_tree_root *root,
292 unsigned long index, void *item)
293{
Christoph Lameter201b6262005-09-06 15:16:46 -0700294 struct radix_tree_node *node = NULL, *slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 unsigned int height, shift;
296 int offset;
297 int error;
298
Nick Pigginc0bc9872007-10-16 01:24:42 -0700299 BUG_ON(radix_tree_is_indirect_ptr(item));
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800300
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 /* Make sure the tree is high enough. */
Nick Piggin612d6c12006-06-23 02:03:22 -0700302 if (index > radix_tree_maxindex(root->height)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 error = radix_tree_extend(root, index);
304 if (error)
305 return error;
306 }
307
Nick Pigginc0bc9872007-10-16 01:24:42 -0700308 slot = radix_tree_indirect_to_ptr(root->rnode);
309
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 height = root->height;
311 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
312
313 offset = 0; /* uninitialised var warning */
Nick Piggin612d6c12006-06-23 02:03:22 -0700314 while (height > 0) {
Christoph Lameter201b6262005-09-06 15:16:46 -0700315 if (slot == NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 /* Have to add a child node. */
Christoph Lameter201b6262005-09-06 15:16:46 -0700317 if (!(slot = radix_tree_node_alloc(root)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 return -ENOMEM;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800319 slot->height = height;
Christoph Lameter201b6262005-09-06 15:16:46 -0700320 if (node) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800321 rcu_assign_pointer(node->slots[offset], slot);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 node->count++;
Christoph Lameter201b6262005-09-06 15:16:46 -0700323 } else
Nick Pigginc0bc9872007-10-16 01:24:42 -0700324 rcu_assign_pointer(root->rnode,
325 radix_tree_ptr_to_indirect(slot));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 }
327
328 /* Go a level down */
329 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
Christoph Lameter201b6262005-09-06 15:16:46 -0700330 node = slot;
331 slot = node->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 shift -= RADIX_TREE_MAP_SHIFT;
333 height--;
Nick Piggin612d6c12006-06-23 02:03:22 -0700334 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335
Christoph Lameter201b6262005-09-06 15:16:46 -0700336 if (slot != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 return -EEXIST;
Christoph Lameter201b6262005-09-06 15:16:46 -0700338
Nick Piggin612d6c12006-06-23 02:03:22 -0700339 if (node) {
340 node->count++;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800341 rcu_assign_pointer(node->slots[offset], item);
Nick Piggin612d6c12006-06-23 02:03:22 -0700342 BUG_ON(tag_get(node, 0, offset));
343 BUG_ON(tag_get(node, 1, offset));
344 } else {
Nick Pigginc0bc9872007-10-16 01:24:42 -0700345 rcu_assign_pointer(root->rnode, item);
Nick Piggin612d6c12006-06-23 02:03:22 -0700346 BUG_ON(root_tag_get(root, 0));
347 BUG_ON(root_tag_get(root, 1));
348 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 return 0;
351}
352EXPORT_SYMBOL(radix_tree_insert);
353
Hans Reisera4331362005-11-07 00:59:29 -0800354/**
355 * radix_tree_lookup_slot - lookup a slot in a radix tree
356 * @root: radix tree root
357 * @index: index key
358 *
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800359 * Returns: the slot corresponding to the position @index in the
360 * radix tree @root. This is useful for update-if-exists operations.
361 *
362 * This function cannot be called under rcu_read_lock, it must be
363 * excluded from writers, as must the returned slot for subsequent
364 * use by radix_tree_deref_slot() and radix_tree_replace slot.
365 * Caller must hold tree write locked across slot lookup and
366 * replace.
Hans Reisera4331362005-11-07 00:59:29 -0800367 */
368void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
369{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800370 unsigned int height, shift;
371 struct radix_tree_node *node, **slot;
372
373 node = root->rnode;
374 if (node == NULL)
375 return NULL;
376
Nick Pigginc0bc9872007-10-16 01:24:42 -0700377 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800378 if (index > 0)
379 return NULL;
380 return (void **)&root->rnode;
381 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700382 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800383
384 height = node->height;
385 if (index > radix_tree_maxindex(height))
386 return NULL;
387
388 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
389
390 do {
391 slot = (struct radix_tree_node **)
392 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
393 node = *slot;
394 if (node == NULL)
395 return NULL;
396
397 shift -= RADIX_TREE_MAP_SHIFT;
398 height--;
399 } while (height > 0);
400
401 return (void **)slot;
Hans Reisera4331362005-11-07 00:59:29 -0800402}
403EXPORT_SYMBOL(radix_tree_lookup_slot);
404
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405/**
406 * radix_tree_lookup - perform lookup operation on a radix tree
407 * @root: radix tree root
408 * @index: index key
409 *
410 * Lookup the item at the position @index in the radix tree @root.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800411 *
412 * This function can be called under rcu_read_lock, however the caller
413 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
414 * them safely). No RCU barriers are required to access or modify the
415 * returned item, however.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 */
417void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
418{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800419 unsigned int height, shift;
420 struct radix_tree_node *node, **slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800422 node = rcu_dereference(root->rnode);
423 if (node == NULL)
424 return NULL;
425
Nick Pigginc0bc9872007-10-16 01:24:42 -0700426 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800427 if (index > 0)
428 return NULL;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700429 return node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800430 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700431 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800432
433 height = node->height;
434 if (index > radix_tree_maxindex(height))
435 return NULL;
436
437 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
438
439 do {
440 slot = (struct radix_tree_node **)
441 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
442 node = rcu_dereference(*slot);
443 if (node == NULL)
444 return NULL;
445
446 shift -= RADIX_TREE_MAP_SHIFT;
447 height--;
448 } while (height > 0);
449
450 return node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451}
452EXPORT_SYMBOL(radix_tree_lookup);
453
454/**
455 * radix_tree_tag_set - set a tag on a radix tree node
456 * @root: radix tree root
457 * @index: index key
458 * @tag: tag index
459 *
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800460 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
461 * corresponding to @index in the radix tree. From
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 * the root all the way down to the leaf node.
463 *
464 * Returns the address of the tagged item. Setting a tag on a not-present
465 * item is a bug.
466 */
467void *radix_tree_tag_set(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800468 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469{
470 unsigned int height, shift;
Christoph Lameter201b6262005-09-06 15:16:46 -0700471 struct radix_tree_node *slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472
473 height = root->height;
Peter Zijlstra4c91c362006-06-23 02:03:25 -0700474 BUG_ON(index > radix_tree_maxindex(height));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475
Nick Pigginc0bc9872007-10-16 01:24:42 -0700476 slot = radix_tree_indirect_to_ptr(root->rnode);
Nick Piggin612d6c12006-06-23 02:03:22 -0700477 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478
479 while (height > 0) {
480 int offset;
481
482 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
Nick Piggind5274262006-01-08 01:01:41 -0800483 if (!tag_get(slot, tag, offset))
484 tag_set(slot, tag, offset);
Christoph Lameter201b6262005-09-06 15:16:46 -0700485 slot = slot->slots[offset];
486 BUG_ON(slot == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 shift -= RADIX_TREE_MAP_SHIFT;
488 height--;
489 }
490
Nick Piggin612d6c12006-06-23 02:03:22 -0700491 /* set the root's tag bit */
492 if (slot && !root_tag_get(root, tag))
493 root_tag_set(root, tag);
494
Christoph Lameter201b6262005-09-06 15:16:46 -0700495 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496}
497EXPORT_SYMBOL(radix_tree_tag_set);
498
499/**
500 * radix_tree_tag_clear - clear a tag on a radix tree node
501 * @root: radix tree root
502 * @index: index key
503 * @tag: tag index
504 *
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800505 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
506 * corresponding to @index in the radix tree. If
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 * this causes the leaf node to have no tags set then clear the tag in the
508 * next-to-leaf node, etc.
509 *
510 * Returns the address of the tagged item on success, else NULL. ie:
511 * has the same return value and semantics as radix_tree_lookup().
512 */
513void *radix_tree_tag_clear(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800514 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515{
Jeff Moyer26fb1582007-10-16 01:24:49 -0700516 /*
517 * The radix tree path needs to be one longer than the maximum path
518 * since the "list" is null terminated.
519 */
520 struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
Nick Piggin612d6c12006-06-23 02:03:22 -0700521 struct radix_tree_node *slot = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 unsigned int height, shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523
524 height = root->height;
525 if (index > radix_tree_maxindex(height))
526 goto out;
527
528 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
529 pathp->node = NULL;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700530 slot = radix_tree_indirect_to_ptr(root->rnode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531
532 while (height > 0) {
533 int offset;
534
Christoph Lameter201b6262005-09-06 15:16:46 -0700535 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 goto out;
537
538 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
539 pathp[1].offset = offset;
Christoph Lameter201b6262005-09-06 15:16:46 -0700540 pathp[1].node = slot;
541 slot = slot->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 pathp++;
543 shift -= RADIX_TREE_MAP_SHIFT;
544 height--;
545 }
546
Nick Piggin612d6c12006-06-23 02:03:22 -0700547 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 goto out;
549
Nick Piggin612d6c12006-06-23 02:03:22 -0700550 while (pathp->node) {
Nick Piggind5274262006-01-08 01:01:41 -0800551 if (!tag_get(pathp->node, tag, pathp->offset))
552 goto out;
Christoph Lameter201b6262005-09-06 15:16:46 -0700553 tag_clear(pathp->node, tag, pathp->offset);
Nick Piggin6e954b92006-01-08 01:01:40 -0800554 if (any_tag_set(pathp->node, tag))
555 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 pathp--;
Nick Piggin612d6c12006-06-23 02:03:22 -0700557 }
558
559 /* clear the root's tag bit */
560 if (root_tag_get(root, tag))
561 root_tag_clear(root, tag);
562
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563out:
Nick Piggin612d6c12006-06-23 02:03:22 -0700564 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565}
566EXPORT_SYMBOL(radix_tree_tag_clear);
567
568#ifndef __KERNEL__ /* Only the test harness uses this at present */
569/**
Marcelo Tosatti32605a12005-09-06 15:16:48 -0700570 * radix_tree_tag_get - get a tag on a radix tree node
571 * @root: radix tree root
572 * @index: index key
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800573 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 *
Marcelo Tosatti32605a12005-09-06 15:16:48 -0700575 * Return values:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 *
Nick Piggin612d6c12006-06-23 02:03:22 -0700577 * 0: tag not present or not set
578 * 1: tag set
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 */
580int radix_tree_tag_get(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800581 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582{
583 unsigned int height, shift;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800584 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585 int saw_unset_tag = 0;
586
Nick Piggin612d6c12006-06-23 02:03:22 -0700587 /* check the root's tag bit */
588 if (!root_tag_get(root, tag))
589 return 0;
590
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800591 node = rcu_dereference(root->rnode);
592 if (node == NULL)
593 return 0;
594
Nick Pigginc0bc9872007-10-16 01:24:42 -0700595 if (!radix_tree_is_indirect_ptr(node))
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800596 return (index == 0);
Nick Pigginc0bc9872007-10-16 01:24:42 -0700597 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800598
599 height = node->height;
600 if (index > radix_tree_maxindex(height))
601 return 0;
Nick Piggin612d6c12006-06-23 02:03:22 -0700602
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604
605 for ( ; ; ) {
606 int offset;
607
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800608 if (node == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 return 0;
610
611 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
612
613 /*
614 * This is just a debug check. Later, we can bale as soon as
615 * we see an unset tag.
616 */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800617 if (!tag_get(node, tag, offset))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618 saw_unset_tag = 1;
619 if (height == 1) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800620 int ret = tag_get(node, tag, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621
622 BUG_ON(ret && saw_unset_tag);
Wu Fengguange5dcd902006-06-25 05:48:14 -0700623 return !!ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800625 node = rcu_dereference(node->slots[offset]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626 shift -= RADIX_TREE_MAP_SHIFT;
627 height--;
628 }
629}
630EXPORT_SYMBOL(radix_tree_tag_get);
631#endif
632
Fengguang Wu6df8ba42007-10-16 01:24:33 -0700633/**
634 * radix_tree_next_hole - find the next hole (not-present entry)
635 * @root: tree root
636 * @index: index key
637 * @max_scan: maximum range to search
638 *
639 * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest
640 * indexed hole.
641 *
642 * Returns: the index of the hole if found, otherwise returns an index
643 * outside of the set specified (in which case 'return - index >= max_scan'
644 * will be true).
645 *
646 * radix_tree_next_hole may be called under rcu_read_lock. However, like
647 * radix_tree_gang_lookup, this will not atomically search a snapshot of the
648 * tree at a single point in time. For example, if a hole is created at index
649 * 5, then subsequently a hole is created at index 10, radix_tree_next_hole
650 * covering both indexes may return 10 if called under rcu_read_lock.
651 */
652unsigned long radix_tree_next_hole(struct radix_tree_root *root,
653 unsigned long index, unsigned long max_scan)
654{
655 unsigned long i;
656
657 for (i = 0; i < max_scan; i++) {
658 if (!radix_tree_lookup(root, index))
659 break;
660 index++;
661 if (index == 0)
662 break;
663 }
664
665 return index;
666}
667EXPORT_SYMBOL(radix_tree_next_hole);
668
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669static unsigned int
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800670__lookup(struct radix_tree_node *slot, void **results, unsigned long index,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 unsigned int max_items, unsigned long *next_index)
672{
673 unsigned int nr_found = 0;
Christoph Lameter201b6262005-09-06 15:16:46 -0700674 unsigned int shift, height;
Christoph Lameter201b6262005-09-06 15:16:46 -0700675 unsigned long i;
676
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800677 height = slot->height;
678 if (height == 0)
Christoph Lameter201b6262005-09-06 15:16:46 -0700679 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681
Christoph Lameter201b6262005-09-06 15:16:46 -0700682 for ( ; height > 1; height--) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800683 i = (index >> shift) & RADIX_TREE_MAP_MASK;
684 for (;;) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 if (slot->slots[i] != NULL)
686 break;
687 index &= ~((1UL << shift) - 1);
688 index += 1UL << shift;
689 if (index == 0)
690 goto out; /* 32-bit wraparound */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800691 i++;
692 if (i == RADIX_TREE_MAP_SIZE)
693 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696 shift -= RADIX_TREE_MAP_SHIFT;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800697 slot = rcu_dereference(slot->slots[i]);
698 if (slot == NULL)
699 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 }
Christoph Lameter201b6262005-09-06 15:16:46 -0700701
702 /* Bottom level: grab some items */
703 for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800704 struct radix_tree_node *node;
Christoph Lameter201b6262005-09-06 15:16:46 -0700705 index++;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800706 node = slot->slots[i];
707 if (node) {
708 results[nr_found++] = rcu_dereference(node);
Christoph Lameter201b6262005-09-06 15:16:46 -0700709 if (nr_found == max_items)
710 goto out;
711 }
712 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713out:
714 *next_index = index;
715 return nr_found;
716}
717
718/**
719 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
720 * @root: radix tree root
721 * @results: where the results of the lookup are placed
722 * @first_index: start the lookup from this key
723 * @max_items: place up to this many items at *results
724 *
725 * Performs an index-ascending scan of the tree for present items. Places
726 * them at *@results and returns the number of items which were placed at
727 * *@results.
728 *
729 * The implementation is naive.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800730 *
731 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
732 * rcu_read_lock. In this case, rather than the returned results being
733 * an atomic snapshot of the tree at a single point in time, the semantics
734 * of an RCU protected gang lookup are as though multiple radix_tree_lookups
735 * have been issued in individual locks, and results stored in 'results'.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736 */
737unsigned int
738radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
739 unsigned long first_index, unsigned int max_items)
740{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800741 unsigned long max_index;
742 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 unsigned long cur_index = first_index;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800744 unsigned int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800746 node = rcu_dereference(root->rnode);
747 if (!node)
748 return 0;
749
Nick Pigginc0bc9872007-10-16 01:24:42 -0700750 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800751 if (first_index > 0)
752 return 0;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700753 results[0] = node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800754 return 1;
755 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700756 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800757
758 max_index = radix_tree_maxindex(node->height);
759
760 ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761 while (ret < max_items) {
762 unsigned int nr_found;
763 unsigned long next_index; /* Index of next search */
764
765 if (cur_index > max_index)
766 break;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800767 nr_found = __lookup(node, results + ret, cur_index,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768 max_items - ret, &next_index);
769 ret += nr_found;
770 if (next_index == 0)
771 break;
772 cur_index = next_index;
773 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800774
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 return ret;
776}
777EXPORT_SYMBOL(radix_tree_gang_lookup);
778
779/*
780 * FIXME: the two tag_get()s here should use find_next_bit() instead of
781 * open-coding the search.
782 */
783static unsigned int
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800784__lookup_tag(struct radix_tree_node *slot, void **results, unsigned long index,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800785 unsigned int max_items, unsigned long *next_index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786{
787 unsigned int nr_found = 0;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800788 unsigned int shift, height;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800790 height = slot->height;
791 if (height == 0)
Nick Piggin612d6c12006-06-23 02:03:22 -0700792 goto out;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800793 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
Nick Piggin612d6c12006-06-23 02:03:22 -0700794
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800795 while (height > 0) {
796 unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800798 for (;;) {
799 if (tag_get(slot, tag, i))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 index &= ~((1UL << shift) - 1);
802 index += 1UL << shift;
803 if (index == 0)
804 goto out; /* 32-bit wraparound */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800805 i++;
806 if (i == RADIX_TREE_MAP_SIZE)
807 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809 height--;
810 if (height == 0) { /* Bottom level: grab some items */
811 unsigned long j = index & RADIX_TREE_MAP_MASK;
812
813 for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800814 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815 index++;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800816 if (!tag_get(slot, tag, j))
817 continue;
818 node = slot->slots[j];
819 /*
820 * Even though the tag was found set, we need to
821 * recheck that we have a non-NULL node, because
822 * if this lookup is lockless, it may have been
823 * subsequently deleted.
824 *
825 * Similar care must be taken in any place that
826 * lookup ->slots[x] without a lock (ie. can't
827 * rely on its value remaining the same).
828 */
829 if (node) {
830 node = rcu_dereference(node);
831 results[nr_found++] = node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 if (nr_found == max_items)
833 goto out;
834 }
835 }
836 }
837 shift -= RADIX_TREE_MAP_SHIFT;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800838 slot = rcu_dereference(slot->slots[i]);
839 if (slot == NULL)
840 break;
841 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842out:
843 *next_index = index;
844 return nr_found;
845}
846
847/**
848 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
849 * based on a tag
850 * @root: radix tree root
851 * @results: where the results of the lookup are placed
852 * @first_index: start the lookup from this key
853 * @max_items: place up to this many items at *results
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800854 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 *
856 * Performs an index-ascending scan of the tree for present items which
857 * have the tag indexed by @tag set. Places the items at *@results and
858 * returns the number of items which were placed at *@results.
859 */
860unsigned int
861radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800862 unsigned long first_index, unsigned int max_items,
863 unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800865 struct radix_tree_node *node;
866 unsigned long max_index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867 unsigned long cur_index = first_index;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800868 unsigned int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869
Nick Piggin612d6c12006-06-23 02:03:22 -0700870 /* check the root's tag bit */
871 if (!root_tag_get(root, tag))
872 return 0;
873
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800874 node = rcu_dereference(root->rnode);
875 if (!node)
876 return 0;
877
Nick Pigginc0bc9872007-10-16 01:24:42 -0700878 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800879 if (first_index > 0)
880 return 0;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700881 results[0] = node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800882 return 1;
883 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700884 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800885
886 max_index = radix_tree_maxindex(node->height);
887
888 ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889 while (ret < max_items) {
890 unsigned int nr_found;
891 unsigned long next_index; /* Index of next search */
892
893 if (cur_index > max_index)
894 break;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800895 nr_found = __lookup_tag(node, results + ret, cur_index,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 max_items - ret, &next_index, tag);
897 ret += nr_found;
898 if (next_index == 0)
899 break;
900 cur_index = next_index;
901 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800902
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903 return ret;
904}
905EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
906
907/**
Nick Piggina5f51c92006-01-08 01:01:41 -0800908 * radix_tree_shrink - shrink height of a radix tree to minimal
909 * @root radix tree root
910 */
911static inline void radix_tree_shrink(struct radix_tree_root *root)
912{
913 /* try to shrink tree height */
Nick Pigginc0bc9872007-10-16 01:24:42 -0700914 while (root->height > 0) {
Nick Piggina5f51c92006-01-08 01:01:41 -0800915 struct radix_tree_node *to_free = root->rnode;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800916 void *newptr;
Nick Piggina5f51c92006-01-08 01:01:41 -0800917
Nick Pigginc0bc9872007-10-16 01:24:42 -0700918 BUG_ON(!radix_tree_is_indirect_ptr(to_free));
919 to_free = radix_tree_indirect_to_ptr(to_free);
920
921 /*
922 * The candidate node has more than one child, or its child
923 * is not at the leftmost slot, we cannot shrink.
924 */
925 if (to_free->count != 1)
926 break;
927 if (!to_free->slots[0])
928 break;
929
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800930 /*
931 * We don't need rcu_assign_pointer(), since we are simply
932 * moving the node from one part of the tree to another. If
933 * it was safe to dereference the old pointer to it
934 * (to_free->slots[0]), it will be safe to dereference the new
935 * one (root->rnode).
936 */
937 newptr = to_free->slots[0];
Nick Pigginc0bc9872007-10-16 01:24:42 -0700938 if (root->height > 1)
939 newptr = radix_tree_ptr_to_indirect(newptr);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800940 root->rnode = newptr;
Nick Piggina5f51c92006-01-08 01:01:41 -0800941 root->height--;
Nick Piggina5f51c92006-01-08 01:01:41 -0800942 radix_tree_node_free(to_free);
943 }
944}
945
946/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947 * radix_tree_delete - delete an item from a radix tree
948 * @root: radix tree root
949 * @index: index key
950 *
951 * Remove the item at @index from the radix tree rooted at @root.
952 *
953 * Returns the address of the deleted item, or NULL if it was not present.
954 */
955void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
956{
Jeff Moyer26fb1582007-10-16 01:24:49 -0700957 /*
958 * The radix tree path needs to be one longer than the maximum path
959 * since the "list" is null terminated.
960 */
961 struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
Nick Piggin612d6c12006-06-23 02:03:22 -0700962 struct radix_tree_node *slot = NULL;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800963 struct radix_tree_node *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964 unsigned int height, shift;
Nick Piggind5274262006-01-08 01:01:41 -0800965 int tag;
966 int offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967
968 height = root->height;
969 if (index > radix_tree_maxindex(height))
970 goto out;
971
Nick Piggin612d6c12006-06-23 02:03:22 -0700972 slot = root->rnode;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700973 if (height == 0) {
Nick Piggin612d6c12006-06-23 02:03:22 -0700974 root_tag_clear_all(root);
975 root->rnode = NULL;
976 goto out;
977 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700978 slot = radix_tree_indirect_to_ptr(slot);
Nick Piggin612d6c12006-06-23 02:03:22 -0700979
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
981 pathp->node = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982
Nick Piggin612d6c12006-06-23 02:03:22 -0700983 do {
Christoph Lameter201b6262005-09-06 15:16:46 -0700984 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 goto out;
986
Linus Torvalds1da177e2005-04-16 15:20:36 -0700987 pathp++;
Nick Piggind5274262006-01-08 01:01:41 -0800988 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
989 pathp->offset = offset;
990 pathp->node = slot;
991 slot = slot->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992 shift -= RADIX_TREE_MAP_SHIFT;
Nick Piggin612d6c12006-06-23 02:03:22 -0700993 height--;
994 } while (height > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700995
Nick Piggin612d6c12006-06-23 02:03:22 -0700996 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 goto out;
998
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 /*
1000 * Clear all tags associated with the just-deleted item
1001 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001002 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
Nick Piggin612d6c12006-06-23 02:03:22 -07001003 if (tag_get(pathp->node, tag, pathp->offset))
1004 radix_tree_tag_clear(root, index, tag);
Nick Piggind5274262006-01-08 01:01:41 -08001005 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001007 to_free = NULL;
Christoph Lameter201b6262005-09-06 15:16:46 -07001008 /* Now free the nodes we do not need anymore */
Nick Piggin612d6c12006-06-23 02:03:22 -07001009 while (pathp->node) {
Christoph Lameter201b6262005-09-06 15:16:46 -07001010 pathp->node->slots[pathp->offset] = NULL;
Nick Piggina5f51c92006-01-08 01:01:41 -08001011 pathp->node->count--;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001012 /*
1013 * Queue the node for deferred freeing after the
1014 * last reference to it disappears (set NULL, above).
1015 */
1016 if (to_free)
1017 radix_tree_node_free(to_free);
Nick Piggina5f51c92006-01-08 01:01:41 -08001018
1019 if (pathp->node->count) {
Nick Pigginc0bc9872007-10-16 01:24:42 -07001020 if (pathp->node ==
1021 radix_tree_indirect_to_ptr(root->rnode))
Nick Piggina5f51c92006-01-08 01:01:41 -08001022 radix_tree_shrink(root);
Christoph Lameter201b6262005-09-06 15:16:46 -07001023 goto out;
Nick Piggina5f51c92006-01-08 01:01:41 -08001024 }
Christoph Lameter201b6262005-09-06 15:16:46 -07001025
1026 /* Node with zero slots in use so free it */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001027 to_free = pathp->node;
Nick Piggin612d6c12006-06-23 02:03:22 -07001028 pathp--;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001029
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030 }
Nick Piggin612d6c12006-06-23 02:03:22 -07001031 root_tag_clear_all(root);
Christoph Lameter201b6262005-09-06 15:16:46 -07001032 root->height = 0;
Nick Piggin612d6c12006-06-23 02:03:22 -07001033 root->rnode = NULL;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001034 if (to_free)
1035 radix_tree_node_free(to_free);
Nick Piggin612d6c12006-06-23 02:03:22 -07001036
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037out:
Nick Piggin612d6c12006-06-23 02:03:22 -07001038 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039}
1040EXPORT_SYMBOL(radix_tree_delete);
1041
1042/**
1043 * radix_tree_tagged - test whether any items in the tree are tagged
1044 * @root: radix tree root
1045 * @tag: tag to test
1046 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001047int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048{
Nick Piggin612d6c12006-06-23 02:03:22 -07001049 return root_tag_get(root, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050}
1051EXPORT_SYMBOL(radix_tree_tagged);
1052
1053static void
Christoph Lameter4ba9b9d2007-10-16 23:25:51 -07001054radix_tree_node_ctor(struct kmem_cache *cachep, void *node)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055{
1056 memset(node, 0, sizeof(struct radix_tree_node));
1057}
1058
1059static __init unsigned long __maxindex(unsigned int height)
1060{
Peter Lund430d2752007-10-16 23:29:35 -07001061 unsigned int width = height * RADIX_TREE_MAP_SHIFT;
1062 int shift = RADIX_TREE_INDEX_BITS - width;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063
Peter Lund430d2752007-10-16 23:29:35 -07001064 if (shift < 0)
1065 return ~0UL;
1066 if (shift >= BITS_PER_LONG)
1067 return 0UL;
1068 return ~0UL >> shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069}
1070
1071static __init void radix_tree_init_maxindex(void)
1072{
1073 unsigned int i;
1074
1075 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
1076 height_to_maxindex[i] = __maxindex(i);
1077}
1078
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079static int radix_tree_callback(struct notifier_block *nfb,
1080 unsigned long action,
1081 void *hcpu)
1082{
1083 int cpu = (long)hcpu;
1084 struct radix_tree_preload *rtp;
1085
1086 /* Free per-cpu pool of perloaded nodes */
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07001087 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088 rtp = &per_cpu(radix_tree_preloads, cpu);
1089 while (rtp->nr) {
1090 kmem_cache_free(radix_tree_node_cachep,
1091 rtp->nodes[rtp->nr-1]);
1092 rtp->nodes[rtp->nr-1] = NULL;
1093 rtp->nr--;
1094 }
1095 }
1096 return NOTIFY_OK;
1097}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001098
1099void __init radix_tree_init(void)
1100{
1101 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1102 sizeof(struct radix_tree_node), 0,
Christoph Lameter488514d2008-04-28 02:12:05 -07001103 SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
1104 radix_tree_node_ctor);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105 radix_tree_init_maxindex();
1106 hotcpu_notifier(radix_tree_callback, 0);
1107}