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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 *
Nick Piggin47feff22008-07-25 19:45:29 -0700362 * This function can be called under rcu_read_lock iff the slot is not
363 * modified by radix_tree_replace_slot, otherwise it must be called
364 * exclusive from other writers. Any dereference of the slot must be done
365 * using radix_tree_deref_slot.
Hans Reisera4331362005-11-07 00:59:29 -0800366 */
367void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)
368{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800369 unsigned int height, shift;
370 struct radix_tree_node *node, **slot;
371
Nick Piggin47feff22008-07-25 19:45:29 -0700372 node = rcu_dereference(root->rnode);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800373 if (node == NULL)
374 return NULL;
375
Nick Pigginc0bc9872007-10-16 01:24:42 -0700376 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800377 if (index > 0)
378 return NULL;
379 return (void **)&root->rnode;
380 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700381 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800382
383 height = node->height;
384 if (index > radix_tree_maxindex(height))
385 return NULL;
386
387 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
388
389 do {
390 slot = (struct radix_tree_node **)
391 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
Nick Piggin47feff22008-07-25 19:45:29 -0700392 node = rcu_dereference(*slot);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800393 if (node == NULL)
394 return NULL;
395
396 shift -= RADIX_TREE_MAP_SHIFT;
397 height--;
398 } while (height > 0);
399
400 return (void **)slot;
Hans Reisera4331362005-11-07 00:59:29 -0800401}
402EXPORT_SYMBOL(radix_tree_lookup_slot);
403
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404/**
405 * radix_tree_lookup - perform lookup operation on a radix tree
406 * @root: radix tree root
407 * @index: index key
408 *
409 * Lookup the item at the position @index in the radix tree @root.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800410 *
411 * This function can be called under rcu_read_lock, however the caller
412 * must manage lifetimes of leaf nodes (eg. RCU may also be used to free
413 * them safely). No RCU barriers are required to access or modify the
414 * returned item, however.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 */
416void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
417{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800418 unsigned int height, shift;
419 struct radix_tree_node *node, **slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800421 node = rcu_dereference(root->rnode);
422 if (node == NULL)
423 return NULL;
424
Nick Pigginc0bc9872007-10-16 01:24:42 -0700425 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800426 if (index > 0)
427 return NULL;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700428 return node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800429 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700430 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800431
432 height = node->height;
433 if (index > radix_tree_maxindex(height))
434 return NULL;
435
436 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
437
438 do {
439 slot = (struct radix_tree_node **)
440 (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK));
441 node = rcu_dereference(*slot);
442 if (node == NULL)
443 return NULL;
444
445 shift -= RADIX_TREE_MAP_SHIFT;
446 height--;
447 } while (height > 0);
448
449 return node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450}
451EXPORT_SYMBOL(radix_tree_lookup);
452
453/**
454 * radix_tree_tag_set - set a tag on a radix tree node
455 * @root: radix tree root
456 * @index: index key
457 * @tag: tag index
458 *
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800459 * Set the search tag (which must be < RADIX_TREE_MAX_TAGS)
460 * corresponding to @index in the radix tree. From
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461 * the root all the way down to the leaf node.
462 *
463 * Returns the address of the tagged item. Setting a tag on a not-present
464 * item is a bug.
465 */
466void *radix_tree_tag_set(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800467 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468{
469 unsigned int height, shift;
Christoph Lameter201b6262005-09-06 15:16:46 -0700470 struct radix_tree_node *slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471
472 height = root->height;
Peter Zijlstra4c91c362006-06-23 02:03:25 -0700473 BUG_ON(index > radix_tree_maxindex(height));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474
Nick Pigginc0bc9872007-10-16 01:24:42 -0700475 slot = radix_tree_indirect_to_ptr(root->rnode);
Nick Piggin612d6c12006-06-23 02:03:22 -0700476 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477
478 while (height > 0) {
479 int offset;
480
481 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
Nick Piggind5274262006-01-08 01:01:41 -0800482 if (!tag_get(slot, tag, offset))
483 tag_set(slot, tag, offset);
Christoph Lameter201b6262005-09-06 15:16:46 -0700484 slot = slot->slots[offset];
485 BUG_ON(slot == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 shift -= RADIX_TREE_MAP_SHIFT;
487 height--;
488 }
489
Nick Piggin612d6c12006-06-23 02:03:22 -0700490 /* set the root's tag bit */
491 if (slot && !root_tag_get(root, tag))
492 root_tag_set(root, tag);
493
Christoph Lameter201b6262005-09-06 15:16:46 -0700494 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495}
496EXPORT_SYMBOL(radix_tree_tag_set);
497
498/**
499 * radix_tree_tag_clear - clear a tag on a radix tree node
500 * @root: radix tree root
501 * @index: index key
502 * @tag: tag index
503 *
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800504 * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS)
505 * corresponding to @index in the radix tree. If
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506 * this causes the leaf node to have no tags set then clear the tag in the
507 * next-to-leaf node, etc.
508 *
509 * Returns the address of the tagged item on success, else NULL. ie:
510 * has the same return value and semantics as radix_tree_lookup().
511 */
512void *radix_tree_tag_clear(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800513 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514{
Jeff Moyer26fb1582007-10-16 01:24:49 -0700515 /*
516 * The radix tree path needs to be one longer than the maximum path
517 * since the "list" is null terminated.
518 */
519 struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
Nick Piggin612d6c12006-06-23 02:03:22 -0700520 struct radix_tree_node *slot = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 unsigned int height, shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522
523 height = root->height;
524 if (index > radix_tree_maxindex(height))
525 goto out;
526
527 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
528 pathp->node = NULL;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700529 slot = radix_tree_indirect_to_ptr(root->rnode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530
531 while (height > 0) {
532 int offset;
533
Christoph Lameter201b6262005-09-06 15:16:46 -0700534 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 goto out;
536
537 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
538 pathp[1].offset = offset;
Christoph Lameter201b6262005-09-06 15:16:46 -0700539 pathp[1].node = slot;
540 slot = slot->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 pathp++;
542 shift -= RADIX_TREE_MAP_SHIFT;
543 height--;
544 }
545
Nick Piggin612d6c12006-06-23 02:03:22 -0700546 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 goto out;
548
Nick Piggin612d6c12006-06-23 02:03:22 -0700549 while (pathp->node) {
Nick Piggind5274262006-01-08 01:01:41 -0800550 if (!tag_get(pathp->node, tag, pathp->offset))
551 goto out;
Christoph Lameter201b6262005-09-06 15:16:46 -0700552 tag_clear(pathp->node, tag, pathp->offset);
Nick Piggin6e954b92006-01-08 01:01:40 -0800553 if (any_tag_set(pathp->node, tag))
554 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555 pathp--;
Nick Piggin612d6c12006-06-23 02:03:22 -0700556 }
557
558 /* clear the root's tag bit */
559 if (root_tag_get(root, tag))
560 root_tag_clear(root, tag);
561
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562out:
Nick Piggin612d6c12006-06-23 02:03:22 -0700563 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564}
565EXPORT_SYMBOL(radix_tree_tag_clear);
566
567#ifndef __KERNEL__ /* Only the test harness uses this at present */
568/**
Marcelo Tosatti32605a12005-09-06 15:16:48 -0700569 * radix_tree_tag_get - get a tag on a radix tree node
570 * @root: radix tree root
571 * @index: index key
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800572 * @tag: tag index (< RADIX_TREE_MAX_TAGS)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573 *
Marcelo Tosatti32605a12005-09-06 15:16:48 -0700574 * Return values:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 *
Nick Piggin612d6c12006-06-23 02:03:22 -0700576 * 0: tag not present or not set
577 * 1: tag set
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578 */
579int radix_tree_tag_get(struct radix_tree_root *root,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800580 unsigned long index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581{
582 unsigned int height, shift;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800583 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 int saw_unset_tag = 0;
585
Nick Piggin612d6c12006-06-23 02:03:22 -0700586 /* check the root's tag bit */
587 if (!root_tag_get(root, tag))
588 return 0;
589
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800590 node = rcu_dereference(root->rnode);
591 if (node == NULL)
592 return 0;
593
Nick Pigginc0bc9872007-10-16 01:24:42 -0700594 if (!radix_tree_is_indirect_ptr(node))
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800595 return (index == 0);
Nick Pigginc0bc9872007-10-16 01:24:42 -0700596 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800597
598 height = node->height;
599 if (index > radix_tree_maxindex(height))
600 return 0;
Nick Piggin612d6c12006-06-23 02:03:22 -0700601
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603
604 for ( ; ; ) {
605 int offset;
606
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800607 if (node == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608 return 0;
609
610 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
611
612 /*
613 * This is just a debug check. Later, we can bale as soon as
614 * we see an unset tag.
615 */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800616 if (!tag_get(node, tag, offset))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700617 saw_unset_tag = 1;
618 if (height == 1) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800619 int ret = tag_get(node, tag, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620
621 BUG_ON(ret && saw_unset_tag);
Wu Fengguange5dcd902006-06-25 05:48:14 -0700622 return !!ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800624 node = rcu_dereference(node->slots[offset]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 shift -= RADIX_TREE_MAP_SHIFT;
626 height--;
627 }
628}
629EXPORT_SYMBOL(radix_tree_tag_get);
630#endif
631
Fengguang Wu6df8ba42007-10-16 01:24:33 -0700632/**
633 * radix_tree_next_hole - find the next hole (not-present entry)
634 * @root: tree root
635 * @index: index key
636 * @max_scan: maximum range to search
637 *
638 * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest
639 * indexed hole.
640 *
641 * Returns: the index of the hole if found, otherwise returns an index
642 * outside of the set specified (in which case 'return - index >= max_scan'
Wu Fengguang8e6bdb72008-11-27 11:42:22 +0100643 * will be true). In rare cases of index wrap-around, 0 will be returned.
Fengguang Wu6df8ba42007-10-16 01:24:33 -0700644 *
645 * radix_tree_next_hole may be called under rcu_read_lock. However, like
Wu Fengguang8e6bdb72008-11-27 11:42:22 +0100646 * radix_tree_gang_lookup, this will not atomically search a snapshot of
647 * the tree at a single point in time. For example, if a hole is created
648 * at index 5, then subsequently a hole is created at index 10,
649 * radix_tree_next_hole covering both indexes may return 10 if called
650 * under rcu_read_lock.
Fengguang Wu6df8ba42007-10-16 01:24:33 -0700651 */
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 Piggin47feff22008-07-25 19:45:29 -0700670__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++) {
704 index++;
Nick Piggin47feff22008-07-25 19:45:29 -0700705 if (slot->slots[i]) {
706 results[nr_found++] = &(slot->slots[i]);
Christoph Lameter201b6262005-09-06 15:16:46 -0700707 if (nr_found == max_items)
708 goto out;
709 }
710 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711out:
712 *next_index = index;
713 return nr_found;
714}
715
716/**
717 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
718 * @root: radix tree root
719 * @results: where the results of the lookup are placed
720 * @first_index: start the lookup from this key
721 * @max_items: place up to this many items at *results
722 *
723 * Performs an index-ascending scan of the tree for present items. Places
724 * them at *@results and returns the number of items which were placed at
725 * *@results.
726 *
727 * The implementation is naive.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800728 *
729 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
730 * rcu_read_lock. In this case, rather than the returned results being
731 * an atomic snapshot of the tree at a single point in time, the semantics
732 * of an RCU protected gang lookup are as though multiple radix_tree_lookups
733 * have been issued in individual locks, and results stored in 'results'.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 */
735unsigned int
736radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
737 unsigned long first_index, unsigned int max_items)
738{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800739 unsigned long max_index;
740 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 unsigned long cur_index = first_index;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800742 unsigned int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800744 node = rcu_dereference(root->rnode);
745 if (!node)
746 return 0;
747
Nick Pigginc0bc9872007-10-16 01:24:42 -0700748 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800749 if (first_index > 0)
750 return 0;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700751 results[0] = node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800752 return 1;
753 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700754 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800755
756 max_index = radix_tree_maxindex(node->height);
757
758 ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759 while (ret < max_items) {
Nick Piggin47feff22008-07-25 19:45:29 -0700760 unsigned int nr_found, slots_found, i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761 unsigned long next_index; /* Index of next search */
762
763 if (cur_index > max_index)
764 break;
Nick Piggin47feff22008-07-25 19:45:29 -0700765 slots_found = __lookup(node, (void ***)results + ret, cur_index,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766 max_items - ret, &next_index);
Nick Piggin47feff22008-07-25 19:45:29 -0700767 nr_found = 0;
768 for (i = 0; i < slots_found; i++) {
769 struct radix_tree_node *slot;
770 slot = *(((void ***)results)[ret + i]);
771 if (!slot)
772 continue;
773 results[ret + nr_found] = rcu_dereference(slot);
774 nr_found++;
775 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 ret += nr_found;
777 if (next_index == 0)
778 break;
779 cur_index = next_index;
780 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800781
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 return ret;
783}
784EXPORT_SYMBOL(radix_tree_gang_lookup);
785
Nick Piggin47feff22008-07-25 19:45:29 -0700786/**
787 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
788 * @root: radix tree root
789 * @results: where the results of the lookup are placed
790 * @first_index: start the lookup from this key
791 * @max_items: place up to this many items at *results
792 *
793 * Performs an index-ascending scan of the tree for present items. Places
794 * their slots at *@results and returns the number of items which were
795 * placed at *@results.
796 *
797 * The implementation is naive.
798 *
799 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
800 * be dereferenced with radix_tree_deref_slot, and if using only RCU
801 * protection, radix_tree_deref_slot may fail requiring a retry.
802 */
803unsigned int
804radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
805 unsigned long first_index, unsigned int max_items)
806{
807 unsigned long max_index;
808 struct radix_tree_node *node;
809 unsigned long cur_index = first_index;
810 unsigned int ret;
811
812 node = rcu_dereference(root->rnode);
813 if (!node)
814 return 0;
815
816 if (!radix_tree_is_indirect_ptr(node)) {
817 if (first_index > 0)
818 return 0;
819 results[0] = (void **)&root->rnode;
820 return 1;
821 }
822 node = radix_tree_indirect_to_ptr(node);
823
824 max_index = radix_tree_maxindex(node->height);
825
826 ret = 0;
827 while (ret < max_items) {
828 unsigned int slots_found;
829 unsigned long next_index; /* Index of next search */
830
831 if (cur_index > max_index)
832 break;
833 slots_found = __lookup(node, results + ret, cur_index,
834 max_items - ret, &next_index);
835 ret += slots_found;
836 if (next_index == 0)
837 break;
838 cur_index = next_index;
839 }
840
841 return ret;
842}
843EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
844
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845/*
846 * FIXME: the two tag_get()s here should use find_next_bit() instead of
847 * open-coding the search.
848 */
849static unsigned int
Nick Piggin47feff22008-07-25 19:45:29 -0700850__lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800851 unsigned int max_items, unsigned long *next_index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852{
853 unsigned int nr_found = 0;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800854 unsigned int shift, height;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800856 height = slot->height;
857 if (height == 0)
Nick Piggin612d6c12006-06-23 02:03:22 -0700858 goto out;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800859 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
Nick Piggin612d6c12006-06-23 02:03:22 -0700860
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800861 while (height > 0) {
862 unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800864 for (;;) {
865 if (tag_get(slot, tag, i))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867 index &= ~((1UL << shift) - 1);
868 index += 1UL << shift;
869 if (index == 0)
870 goto out; /* 32-bit wraparound */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800871 i++;
872 if (i == RADIX_TREE_MAP_SIZE)
873 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875 height--;
876 if (height == 0) { /* Bottom level: grab some items */
877 unsigned long j = index & RADIX_TREE_MAP_MASK;
878
879 for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
880 index++;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800881 if (!tag_get(slot, tag, j))
882 continue;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800883 /*
884 * Even though the tag was found set, we need to
885 * recheck that we have a non-NULL node, because
886 * if this lookup is lockless, it may have been
887 * subsequently deleted.
888 *
889 * Similar care must be taken in any place that
890 * lookup ->slots[x] without a lock (ie. can't
891 * rely on its value remaining the same).
892 */
Nick Piggin47feff22008-07-25 19:45:29 -0700893 if (slot->slots[j]) {
894 results[nr_found++] = &(slot->slots[j]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895 if (nr_found == max_items)
896 goto out;
897 }
898 }
899 }
900 shift -= RADIX_TREE_MAP_SHIFT;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800901 slot = rcu_dereference(slot->slots[i]);
902 if (slot == NULL)
903 break;
904 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905out:
906 *next_index = index;
907 return nr_found;
908}
909
910/**
911 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
912 * based on a tag
913 * @root: radix tree root
914 * @results: where the results of the lookup are placed
915 * @first_index: start the lookup from this key
916 * @max_items: place up to this many items at *results
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800917 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700918 *
919 * Performs an index-ascending scan of the tree for present items which
920 * have the tag indexed by @tag set. Places the items at *@results and
921 * returns the number of items which were placed at *@results.
922 */
923unsigned int
924radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800925 unsigned long first_index, unsigned int max_items,
926 unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700927{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800928 struct radix_tree_node *node;
929 unsigned long max_index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 unsigned long cur_index = first_index;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800931 unsigned int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932
Nick Piggin612d6c12006-06-23 02:03:22 -0700933 /* check the root's tag bit */
934 if (!root_tag_get(root, tag))
935 return 0;
936
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800937 node = rcu_dereference(root->rnode);
938 if (!node)
939 return 0;
940
Nick Pigginc0bc9872007-10-16 01:24:42 -0700941 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800942 if (first_index > 0)
943 return 0;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700944 results[0] = node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800945 return 1;
946 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700947 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800948
949 max_index = radix_tree_maxindex(node->height);
950
951 ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952 while (ret < max_items) {
Nick Piggin47feff22008-07-25 19:45:29 -0700953 unsigned int nr_found, slots_found, i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954 unsigned long next_index; /* Index of next search */
955
956 if (cur_index > max_index)
957 break;
Nick Piggin47feff22008-07-25 19:45:29 -0700958 slots_found = __lookup_tag(node, (void ***)results + ret,
959 cur_index, max_items - ret, &next_index, tag);
960 nr_found = 0;
961 for (i = 0; i < slots_found; i++) {
962 struct radix_tree_node *slot;
963 slot = *(((void ***)results)[ret + i]);
964 if (!slot)
965 continue;
966 results[ret + nr_found] = rcu_dereference(slot);
967 nr_found++;
968 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 ret += nr_found;
970 if (next_index == 0)
971 break;
972 cur_index = next_index;
973 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800974
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 return ret;
976}
977EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
978
979/**
Nick Piggin47feff22008-07-25 19:45:29 -0700980 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
981 * radix tree based on a tag
982 * @root: radix tree root
983 * @results: where the results of the lookup are placed
984 * @first_index: start the lookup from this key
985 * @max_items: place up to this many items at *results
986 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
987 *
988 * Performs an index-ascending scan of the tree for present items which
989 * have the tag indexed by @tag set. Places the slots at *@results and
990 * returns the number of slots which were placed at *@results.
991 */
992unsigned int
993radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
994 unsigned long first_index, unsigned int max_items,
995 unsigned int tag)
996{
997 struct radix_tree_node *node;
998 unsigned long max_index;
999 unsigned long cur_index = first_index;
1000 unsigned int ret;
1001
1002 /* check the root's tag bit */
1003 if (!root_tag_get(root, tag))
1004 return 0;
1005
1006 node = rcu_dereference(root->rnode);
1007 if (!node)
1008 return 0;
1009
1010 if (!radix_tree_is_indirect_ptr(node)) {
1011 if (first_index > 0)
1012 return 0;
1013 results[0] = (void **)&root->rnode;
1014 return 1;
1015 }
1016 node = radix_tree_indirect_to_ptr(node);
1017
1018 max_index = radix_tree_maxindex(node->height);
1019
1020 ret = 0;
1021 while (ret < max_items) {
1022 unsigned int slots_found;
1023 unsigned long next_index; /* Index of next search */
1024
1025 if (cur_index > max_index)
1026 break;
1027 slots_found = __lookup_tag(node, results + ret,
1028 cur_index, max_items - ret, &next_index, tag);
1029 ret += slots_found;
1030 if (next_index == 0)
1031 break;
1032 cur_index = next_index;
1033 }
1034
1035 return ret;
1036}
1037EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1038
1039
1040/**
Nick Piggina5f51c92006-01-08 01:01:41 -08001041 * radix_tree_shrink - shrink height of a radix tree to minimal
1042 * @root radix tree root
1043 */
1044static inline void radix_tree_shrink(struct radix_tree_root *root)
1045{
1046 /* try to shrink tree height */
Nick Pigginc0bc9872007-10-16 01:24:42 -07001047 while (root->height > 0) {
Nick Piggina5f51c92006-01-08 01:01:41 -08001048 struct radix_tree_node *to_free = root->rnode;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001049 void *newptr;
Nick Piggina5f51c92006-01-08 01:01:41 -08001050
Nick Pigginc0bc9872007-10-16 01:24:42 -07001051 BUG_ON(!radix_tree_is_indirect_ptr(to_free));
1052 to_free = radix_tree_indirect_to_ptr(to_free);
1053
1054 /*
1055 * The candidate node has more than one child, or its child
1056 * is not at the leftmost slot, we cannot shrink.
1057 */
1058 if (to_free->count != 1)
1059 break;
1060 if (!to_free->slots[0])
1061 break;
1062
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001063 /*
1064 * We don't need rcu_assign_pointer(), since we are simply
1065 * moving the node from one part of the tree to another. If
1066 * it was safe to dereference the old pointer to it
1067 * (to_free->slots[0]), it will be safe to dereference the new
1068 * one (root->rnode).
1069 */
1070 newptr = to_free->slots[0];
Nick Pigginc0bc9872007-10-16 01:24:42 -07001071 if (root->height > 1)
1072 newptr = radix_tree_ptr_to_indirect(newptr);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001073 root->rnode = newptr;
Nick Piggina5f51c92006-01-08 01:01:41 -08001074 root->height--;
Nick Piggina5f51c92006-01-08 01:01:41 -08001075 radix_tree_node_free(to_free);
1076 }
1077}
1078
1079/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080 * radix_tree_delete - delete an item from a radix tree
1081 * @root: radix tree root
1082 * @index: index key
1083 *
1084 * Remove the item at @index from the radix tree rooted at @root.
1085 *
1086 * Returns the address of the deleted item, or NULL if it was not present.
1087 */
1088void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
1089{
Jeff Moyer26fb1582007-10-16 01:24:49 -07001090 /*
1091 * The radix tree path needs to be one longer than the maximum path
1092 * since the "list" is null terminated.
1093 */
1094 struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
Nick Piggin612d6c12006-06-23 02:03:22 -07001095 struct radix_tree_node *slot = NULL;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001096 struct radix_tree_node *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097 unsigned int height, shift;
Nick Piggind5274262006-01-08 01:01:41 -08001098 int tag;
1099 int offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100
1101 height = root->height;
1102 if (index > radix_tree_maxindex(height))
1103 goto out;
1104
Nick Piggin612d6c12006-06-23 02:03:22 -07001105 slot = root->rnode;
Nick Pigginc0bc9872007-10-16 01:24:42 -07001106 if (height == 0) {
Nick Piggin612d6c12006-06-23 02:03:22 -07001107 root_tag_clear_all(root);
1108 root->rnode = NULL;
1109 goto out;
1110 }
Nick Pigginc0bc9872007-10-16 01:24:42 -07001111 slot = radix_tree_indirect_to_ptr(slot);
Nick Piggin612d6c12006-06-23 02:03:22 -07001112
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
1114 pathp->node = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115
Nick Piggin612d6c12006-06-23 02:03:22 -07001116 do {
Christoph Lameter201b6262005-09-06 15:16:46 -07001117 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001118 goto out;
1119
Linus Torvalds1da177e2005-04-16 15:20:36 -07001120 pathp++;
Nick Piggind5274262006-01-08 01:01:41 -08001121 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
1122 pathp->offset = offset;
1123 pathp->node = slot;
1124 slot = slot->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 shift -= RADIX_TREE_MAP_SHIFT;
Nick Piggin612d6c12006-06-23 02:03:22 -07001126 height--;
1127 } while (height > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128
Nick Piggin612d6c12006-06-23 02:03:22 -07001129 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130 goto out;
1131
Linus Torvalds1da177e2005-04-16 15:20:36 -07001132 /*
1133 * Clear all tags associated with the just-deleted item
1134 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001135 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
Nick Piggin612d6c12006-06-23 02:03:22 -07001136 if (tag_get(pathp->node, tag, pathp->offset))
1137 radix_tree_tag_clear(root, index, tag);
Nick Piggind5274262006-01-08 01:01:41 -08001138 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001140 to_free = NULL;
Christoph Lameter201b6262005-09-06 15:16:46 -07001141 /* Now free the nodes we do not need anymore */
Nick Piggin612d6c12006-06-23 02:03:22 -07001142 while (pathp->node) {
Christoph Lameter201b6262005-09-06 15:16:46 -07001143 pathp->node->slots[pathp->offset] = NULL;
Nick Piggina5f51c92006-01-08 01:01:41 -08001144 pathp->node->count--;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001145 /*
1146 * Queue the node for deferred freeing after the
1147 * last reference to it disappears (set NULL, above).
1148 */
1149 if (to_free)
1150 radix_tree_node_free(to_free);
Nick Piggina5f51c92006-01-08 01:01:41 -08001151
1152 if (pathp->node->count) {
Nick Pigginc0bc9872007-10-16 01:24:42 -07001153 if (pathp->node ==
1154 radix_tree_indirect_to_ptr(root->rnode))
Nick Piggina5f51c92006-01-08 01:01:41 -08001155 radix_tree_shrink(root);
Christoph Lameter201b6262005-09-06 15:16:46 -07001156 goto out;
Nick Piggina5f51c92006-01-08 01:01:41 -08001157 }
Christoph Lameter201b6262005-09-06 15:16:46 -07001158
1159 /* Node with zero slots in use so free it */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001160 to_free = pathp->node;
Nick Piggin612d6c12006-06-23 02:03:22 -07001161 pathp--;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001162
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163 }
Nick Piggin612d6c12006-06-23 02:03:22 -07001164 root_tag_clear_all(root);
Christoph Lameter201b6262005-09-06 15:16:46 -07001165 root->height = 0;
Nick Piggin612d6c12006-06-23 02:03:22 -07001166 root->rnode = NULL;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001167 if (to_free)
1168 radix_tree_node_free(to_free);
Nick Piggin612d6c12006-06-23 02:03:22 -07001169
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170out:
Nick Piggin612d6c12006-06-23 02:03:22 -07001171 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172}
1173EXPORT_SYMBOL(radix_tree_delete);
1174
1175/**
1176 * radix_tree_tagged - test whether any items in the tree are tagged
1177 * @root: radix tree root
1178 * @tag: tag to test
1179 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001180int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181{
Nick Piggin612d6c12006-06-23 02:03:22 -07001182 return root_tag_get(root, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183}
1184EXPORT_SYMBOL(radix_tree_tagged);
1185
1186static void
Alexey Dobriyan51cc5062008-07-25 19:45:34 -07001187radix_tree_node_ctor(void *node)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188{
1189 memset(node, 0, sizeof(struct radix_tree_node));
1190}
1191
1192static __init unsigned long __maxindex(unsigned int height)
1193{
Peter Lund430d2752007-10-16 23:29:35 -07001194 unsigned int width = height * RADIX_TREE_MAP_SHIFT;
1195 int shift = RADIX_TREE_INDEX_BITS - width;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196
Peter Lund430d2752007-10-16 23:29:35 -07001197 if (shift < 0)
1198 return ~0UL;
1199 if (shift >= BITS_PER_LONG)
1200 return 0UL;
1201 return ~0UL >> shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001202}
1203
1204static __init void radix_tree_init_maxindex(void)
1205{
1206 unsigned int i;
1207
1208 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
1209 height_to_maxindex[i] = __maxindex(i);
1210}
1211
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212static int radix_tree_callback(struct notifier_block *nfb,
1213 unsigned long action,
1214 void *hcpu)
1215{
1216 int cpu = (long)hcpu;
1217 struct radix_tree_preload *rtp;
1218
1219 /* Free per-cpu pool of perloaded nodes */
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07001220 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221 rtp = &per_cpu(radix_tree_preloads, cpu);
1222 while (rtp->nr) {
1223 kmem_cache_free(radix_tree_node_cachep,
1224 rtp->nodes[rtp->nr-1]);
1225 rtp->nodes[rtp->nr-1] = NULL;
1226 rtp->nr--;
1227 }
1228 }
1229 return NOTIFY_OK;
1230}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231
1232void __init radix_tree_init(void)
1233{
1234 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1235 sizeof(struct radix_tree_node), 0,
Christoph Lameter488514d2008-04-28 02:12:05 -07001236 SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
1237 radix_tree_node_ctor);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 radix_tree_init_maxindex();
1239 hotcpu_notifier(radix_tree_callback, 0);
1240}