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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'
643 * will be true).
644 *
645 * radix_tree_next_hole may be called under rcu_read_lock. However, like
646 * radix_tree_gang_lookup, this will not atomically search a snapshot of the
647 * tree at a single point in time. For example, if a hole is created at index
648 * 5, then subsequently a hole is created at index 10, radix_tree_next_hole
649 * covering both indexes may return 10 if called under rcu_read_lock.
650 */
651unsigned long radix_tree_next_hole(struct radix_tree_root *root,
652 unsigned long index, unsigned long max_scan)
653{
654 unsigned long i;
655
656 for (i = 0; i < max_scan; i++) {
657 if (!radix_tree_lookup(root, index))
658 break;
659 index++;
660 if (index == 0)
661 break;
662 }
663
664 return index;
665}
666EXPORT_SYMBOL(radix_tree_next_hole);
667
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668static unsigned int
Nick Piggin47feff22008-07-25 19:45:29 -0700669__lookup(struct radix_tree_node *slot, void ***results, unsigned long index,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 unsigned int max_items, unsigned long *next_index)
671{
672 unsigned int nr_found = 0;
Christoph Lameter201b6262005-09-06 15:16:46 -0700673 unsigned int shift, height;
Christoph Lameter201b6262005-09-06 15:16:46 -0700674 unsigned long i;
675
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800676 height = slot->height;
677 if (height == 0)
Christoph Lameter201b6262005-09-06 15:16:46 -0700678 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680
Christoph Lameter201b6262005-09-06 15:16:46 -0700681 for ( ; height > 1; height--) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800682 i = (index >> shift) & RADIX_TREE_MAP_MASK;
683 for (;;) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684 if (slot->slots[i] != NULL)
685 break;
686 index &= ~((1UL << shift) - 1);
687 index += 1UL << shift;
688 if (index == 0)
689 goto out; /* 32-bit wraparound */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800690 i++;
691 if (i == RADIX_TREE_MAP_SIZE)
692 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695 shift -= RADIX_TREE_MAP_SHIFT;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800696 slot = rcu_dereference(slot->slots[i]);
697 if (slot == NULL)
698 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 }
Christoph Lameter201b6262005-09-06 15:16:46 -0700700
701 /* Bottom level: grab some items */
702 for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
703 index++;
Nick Piggin47feff22008-07-25 19:45:29 -0700704 if (slot->slots[i]) {
705 results[nr_found++] = &(slot->slots[i]);
Christoph Lameter201b6262005-09-06 15:16:46 -0700706 if (nr_found == max_items)
707 goto out;
708 }
709 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710out:
711 *next_index = index;
712 return nr_found;
713}
714
715/**
716 * radix_tree_gang_lookup - perform multiple lookup on a radix tree
717 * @root: radix tree root
718 * @results: where the results of the lookup are placed
719 * @first_index: start the lookup from this key
720 * @max_items: place up to this many items at *results
721 *
722 * Performs an index-ascending scan of the tree for present items. Places
723 * them at *@results and returns the number of items which were placed at
724 * *@results.
725 *
726 * The implementation is naive.
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800727 *
728 * Like radix_tree_lookup, radix_tree_gang_lookup may be called under
729 * rcu_read_lock. In this case, rather than the returned results being
730 * an atomic snapshot of the tree at a single point in time, the semantics
731 * of an RCU protected gang lookup are as though multiple radix_tree_lookups
732 * have been issued in individual locks, and results stored in 'results'.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733 */
734unsigned int
735radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
736 unsigned long first_index, unsigned int max_items)
737{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800738 unsigned long max_index;
739 struct radix_tree_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 unsigned long cur_index = first_index;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800741 unsigned int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800743 node = rcu_dereference(root->rnode);
744 if (!node)
745 return 0;
746
Nick Pigginc0bc9872007-10-16 01:24:42 -0700747 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800748 if (first_index > 0)
749 return 0;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700750 results[0] = node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800751 return 1;
752 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700753 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800754
755 max_index = radix_tree_maxindex(node->height);
756
757 ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758 while (ret < max_items) {
Nick Piggin47feff22008-07-25 19:45:29 -0700759 unsigned int nr_found, slots_found, i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760 unsigned long next_index; /* Index of next search */
761
762 if (cur_index > max_index)
763 break;
Nick Piggin47feff22008-07-25 19:45:29 -0700764 slots_found = __lookup(node, (void ***)results + ret, cur_index,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 max_items - ret, &next_index);
Nick Piggin47feff22008-07-25 19:45:29 -0700766 nr_found = 0;
767 for (i = 0; i < slots_found; i++) {
768 struct radix_tree_node *slot;
769 slot = *(((void ***)results)[ret + i]);
770 if (!slot)
771 continue;
772 results[ret + nr_found] = rcu_dereference(slot);
773 nr_found++;
774 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 ret += nr_found;
776 if (next_index == 0)
777 break;
778 cur_index = next_index;
779 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800780
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 return ret;
782}
783EXPORT_SYMBOL(radix_tree_gang_lookup);
784
Nick Piggin47feff22008-07-25 19:45:29 -0700785/**
786 * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
787 * @root: radix tree root
788 * @results: where the results of the lookup are placed
789 * @first_index: start the lookup from this key
790 * @max_items: place up to this many items at *results
791 *
792 * Performs an index-ascending scan of the tree for present items. Places
793 * their slots at *@results and returns the number of items which were
794 * placed at *@results.
795 *
796 * The implementation is naive.
797 *
798 * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
799 * be dereferenced with radix_tree_deref_slot, and if using only RCU
800 * protection, radix_tree_deref_slot may fail requiring a retry.
801 */
802unsigned int
803radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results,
804 unsigned long first_index, unsigned int max_items)
805{
806 unsigned long max_index;
807 struct radix_tree_node *node;
808 unsigned long cur_index = first_index;
809 unsigned int ret;
810
811 node = rcu_dereference(root->rnode);
812 if (!node)
813 return 0;
814
815 if (!radix_tree_is_indirect_ptr(node)) {
816 if (first_index > 0)
817 return 0;
818 results[0] = (void **)&root->rnode;
819 return 1;
820 }
821 node = radix_tree_indirect_to_ptr(node);
822
823 max_index = radix_tree_maxindex(node->height);
824
825 ret = 0;
826 while (ret < max_items) {
827 unsigned int slots_found;
828 unsigned long next_index; /* Index of next search */
829
830 if (cur_index > max_index)
831 break;
832 slots_found = __lookup(node, results + ret, cur_index,
833 max_items - ret, &next_index);
834 ret += slots_found;
835 if (next_index == 0)
836 break;
837 cur_index = next_index;
838 }
839
840 return ret;
841}
842EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
843
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844/*
845 * FIXME: the two tag_get()s here should use find_next_bit() instead of
846 * open-coding the search.
847 */
848static unsigned int
Nick Piggin47feff22008-07-25 19:45:29 -0700849__lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800850 unsigned int max_items, unsigned long *next_index, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851{
852 unsigned int nr_found = 0;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800853 unsigned int shift, height;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800855 height = slot->height;
856 if (height == 0)
Nick Piggin612d6c12006-06-23 02:03:22 -0700857 goto out;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800858 shift = (height-1) * RADIX_TREE_MAP_SHIFT;
Nick Piggin612d6c12006-06-23 02:03:22 -0700859
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800860 while (height > 0) {
861 unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800863 for (;;) {
864 if (tag_get(slot, tag, i))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866 index &= ~((1UL << shift) - 1);
867 index += 1UL << shift;
868 if (index == 0)
869 goto out; /* 32-bit wraparound */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800870 i++;
871 if (i == RADIX_TREE_MAP_SIZE)
872 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874 height--;
875 if (height == 0) { /* Bottom level: grab some items */
876 unsigned long j = index & RADIX_TREE_MAP_MASK;
877
878 for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
879 index++;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800880 if (!tag_get(slot, tag, j))
881 continue;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800882 /*
883 * Even though the tag was found set, we need to
884 * recheck that we have a non-NULL node, because
885 * if this lookup is lockless, it may have been
886 * subsequently deleted.
887 *
888 * Similar care must be taken in any place that
889 * lookup ->slots[x] without a lock (ie. can't
890 * rely on its value remaining the same).
891 */
Nick Piggin47feff22008-07-25 19:45:29 -0700892 if (slot->slots[j]) {
893 results[nr_found++] = &(slot->slots[j]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894 if (nr_found == max_items)
895 goto out;
896 }
897 }
898 }
899 shift -= RADIX_TREE_MAP_SHIFT;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800900 slot = rcu_dereference(slot->slots[i]);
901 if (slot == NULL)
902 break;
903 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904out:
905 *next_index = index;
906 return nr_found;
907}
908
909/**
910 * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
911 * based on a tag
912 * @root: radix tree root
913 * @results: where the results of the lookup are placed
914 * @first_index: start the lookup from this key
915 * @max_items: place up to this many items at *results
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800916 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 *
918 * Performs an index-ascending scan of the tree for present items which
919 * have the tag indexed by @tag set. Places the items at *@results and
920 * returns the number of items which were placed at *@results.
921 */
922unsigned int
923radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
Jonathan Corbetdaff89f2006-03-25 03:08:05 -0800924 unsigned long first_index, unsigned int max_items,
925 unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700926{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800927 struct radix_tree_node *node;
928 unsigned long max_index;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 unsigned long cur_index = first_index;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800930 unsigned int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931
Nick Piggin612d6c12006-06-23 02:03:22 -0700932 /* check the root's tag bit */
933 if (!root_tag_get(root, tag))
934 return 0;
935
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800936 node = rcu_dereference(root->rnode);
937 if (!node)
938 return 0;
939
Nick Pigginc0bc9872007-10-16 01:24:42 -0700940 if (!radix_tree_is_indirect_ptr(node)) {
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800941 if (first_index > 0)
942 return 0;
Nick Pigginc0bc9872007-10-16 01:24:42 -0700943 results[0] = node;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800944 return 1;
945 }
Nick Pigginc0bc9872007-10-16 01:24:42 -0700946 node = radix_tree_indirect_to_ptr(node);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800947
948 max_index = radix_tree_maxindex(node->height);
949
950 ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 while (ret < max_items) {
Nick Piggin47feff22008-07-25 19:45:29 -0700952 unsigned int nr_found, slots_found, i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953 unsigned long next_index; /* Index of next search */
954
955 if (cur_index > max_index)
956 break;
Nick Piggin47feff22008-07-25 19:45:29 -0700957 slots_found = __lookup_tag(node, (void ***)results + ret,
958 cur_index, max_items - ret, &next_index, tag);
959 nr_found = 0;
960 for (i = 0; i < slots_found; i++) {
961 struct radix_tree_node *slot;
962 slot = *(((void ***)results)[ret + i]);
963 if (!slot)
964 continue;
965 results[ret + nr_found] = rcu_dereference(slot);
966 nr_found++;
967 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 ret += nr_found;
969 if (next_index == 0)
970 break;
971 cur_index = next_index;
972 }
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800973
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 return ret;
975}
976EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
977
978/**
Nick Piggin47feff22008-07-25 19:45:29 -0700979 * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a
980 * radix tree based on a tag
981 * @root: radix tree root
982 * @results: where the results of the lookup are placed
983 * @first_index: start the lookup from this key
984 * @max_items: place up to this many items at *results
985 * @tag: the tag index (< RADIX_TREE_MAX_TAGS)
986 *
987 * Performs an index-ascending scan of the tree for present items which
988 * have the tag indexed by @tag set. Places the slots at *@results and
989 * returns the number of slots which were placed at *@results.
990 */
991unsigned int
992radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
993 unsigned long first_index, unsigned int max_items,
994 unsigned int tag)
995{
996 struct radix_tree_node *node;
997 unsigned long max_index;
998 unsigned long cur_index = first_index;
999 unsigned int ret;
1000
1001 /* check the root's tag bit */
1002 if (!root_tag_get(root, tag))
1003 return 0;
1004
1005 node = rcu_dereference(root->rnode);
1006 if (!node)
1007 return 0;
1008
1009 if (!radix_tree_is_indirect_ptr(node)) {
1010 if (first_index > 0)
1011 return 0;
1012 results[0] = (void **)&root->rnode;
1013 return 1;
1014 }
1015 node = radix_tree_indirect_to_ptr(node);
1016
1017 max_index = radix_tree_maxindex(node->height);
1018
1019 ret = 0;
1020 while (ret < max_items) {
1021 unsigned int slots_found;
1022 unsigned long next_index; /* Index of next search */
1023
1024 if (cur_index > max_index)
1025 break;
1026 slots_found = __lookup_tag(node, results + ret,
1027 cur_index, max_items - ret, &next_index, tag);
1028 ret += slots_found;
1029 if (next_index == 0)
1030 break;
1031 cur_index = next_index;
1032 }
1033
1034 return ret;
1035}
1036EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
1037
1038
1039/**
Nick Piggina5f51c92006-01-08 01:01:41 -08001040 * radix_tree_shrink - shrink height of a radix tree to minimal
1041 * @root radix tree root
1042 */
1043static inline void radix_tree_shrink(struct radix_tree_root *root)
1044{
1045 /* try to shrink tree height */
Nick Pigginc0bc9872007-10-16 01:24:42 -07001046 while (root->height > 0) {
Nick Piggina5f51c92006-01-08 01:01:41 -08001047 struct radix_tree_node *to_free = root->rnode;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001048 void *newptr;
Nick Piggina5f51c92006-01-08 01:01:41 -08001049
Nick Pigginc0bc9872007-10-16 01:24:42 -07001050 BUG_ON(!radix_tree_is_indirect_ptr(to_free));
1051 to_free = radix_tree_indirect_to_ptr(to_free);
1052
1053 /*
1054 * The candidate node has more than one child, or its child
1055 * is not at the leftmost slot, we cannot shrink.
1056 */
1057 if (to_free->count != 1)
1058 break;
1059 if (!to_free->slots[0])
1060 break;
1061
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001062 /*
1063 * We don't need rcu_assign_pointer(), since we are simply
1064 * moving the node from one part of the tree to another. If
1065 * it was safe to dereference the old pointer to it
1066 * (to_free->slots[0]), it will be safe to dereference the new
1067 * one (root->rnode).
1068 */
1069 newptr = to_free->slots[0];
Nick Pigginc0bc9872007-10-16 01:24:42 -07001070 if (root->height > 1)
1071 newptr = radix_tree_ptr_to_indirect(newptr);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001072 root->rnode = newptr;
Nick Piggina5f51c92006-01-08 01:01:41 -08001073 root->height--;
Nick Piggina5f51c92006-01-08 01:01:41 -08001074 radix_tree_node_free(to_free);
1075 }
1076}
1077
1078/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079 * radix_tree_delete - delete an item from a radix tree
1080 * @root: radix tree root
1081 * @index: index key
1082 *
1083 * Remove the item at @index from the radix tree rooted at @root.
1084 *
1085 * Returns the address of the deleted item, or NULL if it was not present.
1086 */
1087void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
1088{
Jeff Moyer26fb1582007-10-16 01:24:49 -07001089 /*
1090 * The radix tree path needs to be one longer than the maximum path
1091 * since the "list" is null terminated.
1092 */
1093 struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path;
Nick Piggin612d6c12006-06-23 02:03:22 -07001094 struct radix_tree_node *slot = NULL;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001095 struct radix_tree_node *to_free;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096 unsigned int height, shift;
Nick Piggind5274262006-01-08 01:01:41 -08001097 int tag;
1098 int offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099
1100 height = root->height;
1101 if (index > radix_tree_maxindex(height))
1102 goto out;
1103
Nick Piggin612d6c12006-06-23 02:03:22 -07001104 slot = root->rnode;
Nick Pigginc0bc9872007-10-16 01:24:42 -07001105 if (height == 0) {
Nick Piggin612d6c12006-06-23 02:03:22 -07001106 root_tag_clear_all(root);
1107 root->rnode = NULL;
1108 goto out;
1109 }
Nick Pigginc0bc9872007-10-16 01:24:42 -07001110 slot = radix_tree_indirect_to_ptr(slot);
Nick Piggin612d6c12006-06-23 02:03:22 -07001111
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112 shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
1113 pathp->node = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114
Nick Piggin612d6c12006-06-23 02:03:22 -07001115 do {
Christoph Lameter201b6262005-09-06 15:16:46 -07001116 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001117 goto out;
1118
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119 pathp++;
Nick Piggind5274262006-01-08 01:01:41 -08001120 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
1121 pathp->offset = offset;
1122 pathp->node = slot;
1123 slot = slot->slots[offset];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124 shift -= RADIX_TREE_MAP_SHIFT;
Nick Piggin612d6c12006-06-23 02:03:22 -07001125 height--;
1126 } while (height > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127
Nick Piggin612d6c12006-06-23 02:03:22 -07001128 if (slot == NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129 goto out;
1130
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131 /*
1132 * Clear all tags associated with the just-deleted item
1133 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001134 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
Nick Piggin612d6c12006-06-23 02:03:22 -07001135 if (tag_get(pathp->node, tag, pathp->offset))
1136 radix_tree_tag_clear(root, index, tag);
Nick Piggind5274262006-01-08 01:01:41 -08001137 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001139 to_free = NULL;
Christoph Lameter201b6262005-09-06 15:16:46 -07001140 /* Now free the nodes we do not need anymore */
Nick Piggin612d6c12006-06-23 02:03:22 -07001141 while (pathp->node) {
Christoph Lameter201b6262005-09-06 15:16:46 -07001142 pathp->node->slots[pathp->offset] = NULL;
Nick Piggina5f51c92006-01-08 01:01:41 -08001143 pathp->node->count--;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001144 /*
1145 * Queue the node for deferred freeing after the
1146 * last reference to it disappears (set NULL, above).
1147 */
1148 if (to_free)
1149 radix_tree_node_free(to_free);
Nick Piggina5f51c92006-01-08 01:01:41 -08001150
1151 if (pathp->node->count) {
Nick Pigginc0bc9872007-10-16 01:24:42 -07001152 if (pathp->node ==
1153 radix_tree_indirect_to_ptr(root->rnode))
Nick Piggina5f51c92006-01-08 01:01:41 -08001154 radix_tree_shrink(root);
Christoph Lameter201b6262005-09-06 15:16:46 -07001155 goto out;
Nick Piggina5f51c92006-01-08 01:01:41 -08001156 }
Christoph Lameter201b6262005-09-06 15:16:46 -07001157
1158 /* Node with zero slots in use so free it */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001159 to_free = pathp->node;
Nick Piggin612d6c12006-06-23 02:03:22 -07001160 pathp--;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001161
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 }
Nick Piggin612d6c12006-06-23 02:03:22 -07001163 root_tag_clear_all(root);
Christoph Lameter201b6262005-09-06 15:16:46 -07001164 root->height = 0;
Nick Piggin612d6c12006-06-23 02:03:22 -07001165 root->rnode = NULL;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -08001166 if (to_free)
1167 radix_tree_node_free(to_free);
Nick Piggin612d6c12006-06-23 02:03:22 -07001168
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169out:
Nick Piggin612d6c12006-06-23 02:03:22 -07001170 return slot;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171}
1172EXPORT_SYMBOL(radix_tree_delete);
1173
1174/**
1175 * radix_tree_tagged - test whether any items in the tree are tagged
1176 * @root: radix tree root
1177 * @tag: tag to test
1178 */
Jonathan Corbetdaff89f2006-03-25 03:08:05 -08001179int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180{
Nick Piggin612d6c12006-06-23 02:03:22 -07001181 return root_tag_get(root, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001182}
1183EXPORT_SYMBOL(radix_tree_tagged);
1184
1185static void
Alexey Dobriyan51cc5062008-07-25 19:45:34 -07001186radix_tree_node_ctor(void *node)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001187{
1188 memset(node, 0, sizeof(struct radix_tree_node));
1189}
1190
1191static __init unsigned long __maxindex(unsigned int height)
1192{
Peter Lund430d2752007-10-16 23:29:35 -07001193 unsigned int width = height * RADIX_TREE_MAP_SHIFT;
1194 int shift = RADIX_TREE_INDEX_BITS - width;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195
Peter Lund430d2752007-10-16 23:29:35 -07001196 if (shift < 0)
1197 return ~0UL;
1198 if (shift >= BITS_PER_LONG)
1199 return 0UL;
1200 return ~0UL >> shift;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201}
1202
1203static __init void radix_tree_init_maxindex(void)
1204{
1205 unsigned int i;
1206
1207 for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
1208 height_to_maxindex[i] = __maxindex(i);
1209}
1210
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211static int radix_tree_callback(struct notifier_block *nfb,
1212 unsigned long action,
1213 void *hcpu)
1214{
1215 int cpu = (long)hcpu;
1216 struct radix_tree_preload *rtp;
1217
1218 /* Free per-cpu pool of perloaded nodes */
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07001219 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 rtp = &per_cpu(radix_tree_preloads, cpu);
1221 while (rtp->nr) {
1222 kmem_cache_free(radix_tree_node_cachep,
1223 rtp->nodes[rtp->nr-1]);
1224 rtp->nodes[rtp->nr-1] = NULL;
1225 rtp->nr--;
1226 }
1227 }
1228 return NOTIFY_OK;
1229}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230
1231void __init radix_tree_init(void)
1232{
1233 radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
1234 sizeof(struct radix_tree_node), 0,
Christoph Lameter488514d2008-04-28 02:12:05 -07001235 SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
1236 radix_tree_node_ctor);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237 radix_tree_init_maxindex();
1238 hotcpu_notifier(radix_tree_callback, 0);
1239}