Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Copyright (C) 2001 Momchil Velikov | |
3 | * Portions Copyright (C) 2001 Christoph Hellwig | |
cde53535 | 4 | * Copyright (C) 2005 SGI, Christoph Lameter |
7cf9c2c7 | 5 | * Copyright (C) 2006 Nick Piggin |
1da177e4 LT |
6 | * |
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> | |
1da177e4 LT |
31 | #include <linux/string.h> |
32 | #include <linux/bitops.h> | |
7cf9c2c7 | 33 | #include <linux/rcupdate.h> |
1da177e4 LT |
34 | |
35 | ||
36 | #ifdef __KERNEL__ | |
cfd9b7df | 37 | #define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) |
1da177e4 LT |
38 | #else |
39 | #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ | |
40 | #endif | |
1da177e4 LT |
41 | |
42 | #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) | |
43 | #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1) | |
44 | ||
45 | #define RADIX_TREE_TAG_LONGS \ | |
46 | ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG) | |
47 | ||
48 | struct radix_tree_node { | |
7cf9c2c7 | 49 | unsigned int height; /* Height from the bottom */ |
1da177e4 | 50 | unsigned int count; |
7cf9c2c7 | 51 | struct rcu_head rcu_head; |
1da177e4 | 52 | void *slots[RADIX_TREE_MAP_SIZE]; |
daff89f3 | 53 | unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; |
1da177e4 LT |
54 | }; |
55 | ||
56 | struct radix_tree_path { | |
201b6264 | 57 | struct radix_tree_node *node; |
1da177e4 LT |
58 | int offset; |
59 | }; | |
60 | ||
61 | #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) | |
26fb1589 JM |
62 | #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \ |
63 | RADIX_TREE_MAP_SHIFT)) | |
1da177e4 | 64 | |
26fb1589 JM |
65 | /* |
66 | * The height_to_maxindex array needs to be one deeper than the maximum | |
67 | * path as height 0 holds only 1 entry. | |
68 | */ | |
69 | static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly; | |
1da177e4 LT |
70 | |
71 | /* | |
72 | * Radix tree node cache. | |
73 | */ | |
e18b890b | 74 | static struct kmem_cache *radix_tree_node_cachep; |
1da177e4 LT |
75 | |
76 | /* | |
77 | * Per-cpu pool of preloaded nodes | |
78 | */ | |
79 | struct radix_tree_preload { | |
80 | int nr; | |
81 | struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH]; | |
82 | }; | |
8cef7d57 | 83 | static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; |
1da177e4 | 84 | |
612d6c19 NP |
85 | static inline gfp_t root_gfp_mask(struct radix_tree_root *root) |
86 | { | |
87 | return root->gfp_mask & __GFP_BITS_MASK; | |
88 | } | |
89 | ||
643b52b9 NP |
90 | static inline void tag_set(struct radix_tree_node *node, unsigned int tag, |
91 | int offset) | |
92 | { | |
93 | __set_bit(offset, node->tags[tag]); | |
94 | } | |
95 | ||
96 | static inline void tag_clear(struct radix_tree_node *node, unsigned int tag, | |
97 | int offset) | |
98 | { | |
99 | __clear_bit(offset, node->tags[tag]); | |
100 | } | |
101 | ||
102 | static inline int tag_get(struct radix_tree_node *node, unsigned int tag, | |
103 | int offset) | |
104 | { | |
105 | return test_bit(offset, node->tags[tag]); | |
106 | } | |
107 | ||
108 | static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag) | |
109 | { | |
110 | root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT)); | |
111 | } | |
112 | ||
113 | static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag) | |
114 | { | |
115 | root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT)); | |
116 | } | |
117 | ||
118 | static inline void root_tag_clear_all(struct radix_tree_root *root) | |
119 | { | |
120 | root->gfp_mask &= __GFP_BITS_MASK; | |
121 | } | |
122 | ||
123 | static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag) | |
124 | { | |
125 | return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT)); | |
126 | } | |
127 | ||
128 | /* | |
129 | * Returns 1 if any slot in the node has this tag set. | |
130 | * Otherwise returns 0. | |
131 | */ | |
132 | static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag) | |
133 | { | |
134 | int idx; | |
135 | for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { | |
136 | if (node->tags[tag][idx]) | |
137 | return 1; | |
138 | } | |
139 | return 0; | |
140 | } | |
1da177e4 LT |
141 | /* |
142 | * This assumes that the caller has performed appropriate preallocation, and | |
143 | * that the caller has pinned this thread of control to the current CPU. | |
144 | */ | |
145 | static struct radix_tree_node * | |
146 | radix_tree_node_alloc(struct radix_tree_root *root) | |
147 | { | |
e2848a0e | 148 | struct radix_tree_node *ret = NULL; |
612d6c19 | 149 | gfp_t gfp_mask = root_gfp_mask(root); |
1da177e4 | 150 | |
e2848a0e | 151 | if (!(gfp_mask & __GFP_WAIT)) { |
1da177e4 LT |
152 | struct radix_tree_preload *rtp; |
153 | ||
e2848a0e NP |
154 | /* |
155 | * Provided the caller has preloaded here, we will always | |
156 | * succeed in getting a node here (and never reach | |
157 | * kmem_cache_alloc) | |
158 | */ | |
1da177e4 LT |
159 | rtp = &__get_cpu_var(radix_tree_preloads); |
160 | if (rtp->nr) { | |
161 | ret = rtp->nodes[rtp->nr - 1]; | |
162 | rtp->nodes[rtp->nr - 1] = NULL; | |
163 | rtp->nr--; | |
164 | } | |
165 | } | |
e2848a0e | 166 | if (ret == NULL) |
488514d1 | 167 | ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
e2848a0e | 168 | |
c0bc9875 | 169 | BUG_ON(radix_tree_is_indirect_ptr(ret)); |
1da177e4 LT |
170 | return ret; |
171 | } | |
172 | ||
7cf9c2c7 NP |
173 | static void radix_tree_node_rcu_free(struct rcu_head *head) |
174 | { | |
175 | struct radix_tree_node *node = | |
176 | container_of(head, struct radix_tree_node, rcu_head); | |
643b52b9 NP |
177 | |
178 | /* | |
179 | * must only free zeroed nodes into the slab. radix_tree_shrink | |
180 | * can leave us with a non-NULL entry in the first slot, so clear | |
181 | * that here to make sure. | |
182 | */ | |
183 | tag_clear(node, 0, 0); | |
184 | tag_clear(node, 1, 0); | |
185 | node->slots[0] = NULL; | |
186 | node->count = 0; | |
187 | ||
7cf9c2c7 NP |
188 | kmem_cache_free(radix_tree_node_cachep, node); |
189 | } | |
190 | ||
1da177e4 LT |
191 | static inline void |
192 | radix_tree_node_free(struct radix_tree_node *node) | |
193 | { | |
7cf9c2c7 | 194 | call_rcu(&node->rcu_head, radix_tree_node_rcu_free); |
1da177e4 LT |
195 | } |
196 | ||
197 | /* | |
198 | * Load up this CPU's radix_tree_node buffer with sufficient objects to | |
199 | * ensure that the addition of a single element in the tree cannot fail. On | |
200 | * success, return zero, with preemption disabled. On error, return -ENOMEM | |
201 | * with preemption not disabled. | |
b34df792 DH |
202 | * |
203 | * To make use of this facility, the radix tree must be initialised without | |
204 | * __GFP_WAIT being passed to INIT_RADIX_TREE(). | |
1da177e4 | 205 | */ |
dd0fc66f | 206 | int radix_tree_preload(gfp_t gfp_mask) |
1da177e4 LT |
207 | { |
208 | struct radix_tree_preload *rtp; | |
209 | struct radix_tree_node *node; | |
210 | int ret = -ENOMEM; | |
211 | ||
212 | preempt_disable(); | |
213 | rtp = &__get_cpu_var(radix_tree_preloads); | |
214 | while (rtp->nr < ARRAY_SIZE(rtp->nodes)) { | |
215 | preempt_enable(); | |
488514d1 | 216 | node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
1da177e4 LT |
217 | if (node == NULL) |
218 | goto out; | |
219 | preempt_disable(); | |
220 | rtp = &__get_cpu_var(radix_tree_preloads); | |
221 | if (rtp->nr < ARRAY_SIZE(rtp->nodes)) | |
222 | rtp->nodes[rtp->nr++] = node; | |
223 | else | |
224 | kmem_cache_free(radix_tree_node_cachep, node); | |
225 | } | |
226 | ret = 0; | |
227 | out: | |
228 | return ret; | |
229 | } | |
d7f0923d | 230 | EXPORT_SYMBOL(radix_tree_preload); |
1da177e4 | 231 | |
1da177e4 LT |
232 | /* |
233 | * Return the maximum key which can be store into a | |
234 | * radix tree with height HEIGHT. | |
235 | */ | |
236 | static inline unsigned long radix_tree_maxindex(unsigned int height) | |
237 | { | |
238 | return height_to_maxindex[height]; | |
239 | } | |
240 | ||
241 | /* | |
242 | * Extend a radix tree so it can store key @index. | |
243 | */ | |
244 | static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) | |
245 | { | |
246 | struct radix_tree_node *node; | |
247 | unsigned int height; | |
1da177e4 LT |
248 | int tag; |
249 | ||
250 | /* Figure out what the height should be. */ | |
251 | height = root->height + 1; | |
252 | while (index > radix_tree_maxindex(height)) | |
253 | height++; | |
254 | ||
255 | if (root->rnode == NULL) { | |
256 | root->height = height; | |
257 | goto out; | |
258 | } | |
259 | ||
1da177e4 | 260 | do { |
7cf9c2c7 | 261 | unsigned int newheight; |
1da177e4 LT |
262 | if (!(node = radix_tree_node_alloc(root))) |
263 | return -ENOMEM; | |
264 | ||
265 | /* Increase the height. */ | |
c0bc9875 | 266 | node->slots[0] = radix_tree_indirect_to_ptr(root->rnode); |
1da177e4 LT |
267 | |
268 | /* Propagate the aggregated tag info into the new root */ | |
daff89f3 | 269 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { |
612d6c19 | 270 | if (root_tag_get(root, tag)) |
1da177e4 LT |
271 | tag_set(node, tag, 0); |
272 | } | |
273 | ||
7cf9c2c7 NP |
274 | newheight = root->height+1; |
275 | node->height = newheight; | |
1da177e4 | 276 | node->count = 1; |
c0bc9875 | 277 | node = radix_tree_ptr_to_indirect(node); |
7cf9c2c7 NP |
278 | rcu_assign_pointer(root->rnode, node); |
279 | root->height = newheight; | |
1da177e4 LT |
280 | } while (height > root->height); |
281 | out: | |
282 | return 0; | |
283 | } | |
284 | ||
285 | /** | |
286 | * radix_tree_insert - insert into a radix tree | |
287 | * @root: radix tree root | |
288 | * @index: index key | |
289 | * @item: item to insert | |
290 | * | |
291 | * Insert an item into the radix tree at position @index. | |
292 | */ | |
293 | int radix_tree_insert(struct radix_tree_root *root, | |
294 | unsigned long index, void *item) | |
295 | { | |
201b6264 | 296 | struct radix_tree_node *node = NULL, *slot; |
1da177e4 LT |
297 | unsigned int height, shift; |
298 | int offset; | |
299 | int error; | |
300 | ||
c0bc9875 | 301 | BUG_ON(radix_tree_is_indirect_ptr(item)); |
7cf9c2c7 | 302 | |
1da177e4 | 303 | /* Make sure the tree is high enough. */ |
612d6c19 | 304 | if (index > radix_tree_maxindex(root->height)) { |
1da177e4 LT |
305 | error = radix_tree_extend(root, index); |
306 | if (error) | |
307 | return error; | |
308 | } | |
309 | ||
c0bc9875 NP |
310 | slot = radix_tree_indirect_to_ptr(root->rnode); |
311 | ||
1da177e4 LT |
312 | height = root->height; |
313 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
314 | ||
315 | offset = 0; /* uninitialised var warning */ | |
612d6c19 | 316 | while (height > 0) { |
201b6264 | 317 | if (slot == NULL) { |
1da177e4 | 318 | /* Have to add a child node. */ |
201b6264 | 319 | if (!(slot = radix_tree_node_alloc(root))) |
1da177e4 | 320 | return -ENOMEM; |
7cf9c2c7 | 321 | slot->height = height; |
201b6264 | 322 | if (node) { |
7cf9c2c7 | 323 | rcu_assign_pointer(node->slots[offset], slot); |
1da177e4 | 324 | node->count++; |
201b6264 | 325 | } else |
c0bc9875 NP |
326 | rcu_assign_pointer(root->rnode, |
327 | radix_tree_ptr_to_indirect(slot)); | |
1da177e4 LT |
328 | } |
329 | ||
330 | /* Go a level down */ | |
331 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
201b6264 CL |
332 | node = slot; |
333 | slot = node->slots[offset]; | |
1da177e4 LT |
334 | shift -= RADIX_TREE_MAP_SHIFT; |
335 | height--; | |
612d6c19 | 336 | } |
1da177e4 | 337 | |
201b6264 | 338 | if (slot != NULL) |
1da177e4 | 339 | return -EEXIST; |
201b6264 | 340 | |
612d6c19 NP |
341 | if (node) { |
342 | node->count++; | |
7cf9c2c7 | 343 | rcu_assign_pointer(node->slots[offset], item); |
612d6c19 NP |
344 | BUG_ON(tag_get(node, 0, offset)); |
345 | BUG_ON(tag_get(node, 1, offset)); | |
346 | } else { | |
c0bc9875 | 347 | rcu_assign_pointer(root->rnode, item); |
612d6c19 NP |
348 | BUG_ON(root_tag_get(root, 0)); |
349 | BUG_ON(root_tag_get(root, 1)); | |
350 | } | |
1da177e4 | 351 | |
1da177e4 LT |
352 | return 0; |
353 | } | |
354 | EXPORT_SYMBOL(radix_tree_insert); | |
355 | ||
b72b71c6 HS |
356 | /* |
357 | * is_slot == 1 : search for the slot. | |
358 | * is_slot == 0 : search for the node. | |
7cf9c2c7 | 359 | */ |
b72b71c6 HS |
360 | static void *radix_tree_lookup_element(struct radix_tree_root *root, |
361 | unsigned long index, int is_slot) | |
1da177e4 LT |
362 | { |
363 | unsigned int height, shift; | |
7cf9c2c7 | 364 | struct radix_tree_node *node, **slot; |
612d6c19 | 365 | |
2676a58c | 366 | node = rcu_dereference_raw(root->rnode); |
7cf9c2c7 | 367 | if (node == NULL) |
1da177e4 LT |
368 | return NULL; |
369 | ||
c0bc9875 | 370 | if (!radix_tree_is_indirect_ptr(node)) { |
7cf9c2c7 NP |
371 | if (index > 0) |
372 | return NULL; | |
b72b71c6 | 373 | return is_slot ? (void *)&root->rnode : node; |
7cf9c2c7 | 374 | } |
c0bc9875 | 375 | node = radix_tree_indirect_to_ptr(node); |
7cf9c2c7 NP |
376 | |
377 | height = node->height; | |
378 | if (index > radix_tree_maxindex(height)) | |
379 | return NULL; | |
612d6c19 | 380 | |
1da177e4 | 381 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 | 382 | |
7cf9c2c7 NP |
383 | do { |
384 | slot = (struct radix_tree_node **) | |
385 | (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); | |
2676a58c | 386 | node = rcu_dereference_raw(*slot); |
7cf9c2c7 | 387 | if (node == NULL) |
1da177e4 LT |
388 | return NULL; |
389 | ||
1da177e4 LT |
390 | shift -= RADIX_TREE_MAP_SHIFT; |
391 | height--; | |
7cf9c2c7 | 392 | } while (height > 0); |
1da177e4 | 393 | |
b72b71c6 HS |
394 | return is_slot ? (void *)slot:node; |
395 | } | |
396 | ||
397 | /** | |
398 | * radix_tree_lookup_slot - lookup a slot in a radix tree | |
399 | * @root: radix tree root | |
400 | * @index: index key | |
401 | * | |
402 | * Returns: the slot corresponding to the position @index in the | |
403 | * radix tree @root. This is useful for update-if-exists operations. | |
404 | * | |
405 | * This function can be called under rcu_read_lock iff the slot is not | |
406 | * modified by radix_tree_replace_slot, otherwise it must be called | |
407 | * exclusive from other writers. Any dereference of the slot must be done | |
408 | * using radix_tree_deref_slot. | |
409 | */ | |
410 | void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) | |
411 | { | |
412 | return (void **)radix_tree_lookup_element(root, index, 1); | |
a4331366 | 413 | } |
a4331366 HR |
414 | EXPORT_SYMBOL(radix_tree_lookup_slot); |
415 | ||
416 | /** | |
417 | * radix_tree_lookup - perform lookup operation on a radix tree | |
418 | * @root: radix tree root | |
419 | * @index: index key | |
420 | * | |
421 | * Lookup the item at the position @index in the radix tree @root. | |
7cf9c2c7 NP |
422 | * |
423 | * This function can be called under rcu_read_lock, however the caller | |
424 | * must manage lifetimes of leaf nodes (eg. RCU may also be used to free | |
425 | * them safely). No RCU barriers are required to access or modify the | |
426 | * returned item, however. | |
a4331366 HR |
427 | */ |
428 | void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) | |
429 | { | |
b72b71c6 | 430 | return radix_tree_lookup_element(root, index, 0); |
1da177e4 LT |
431 | } |
432 | EXPORT_SYMBOL(radix_tree_lookup); | |
433 | ||
434 | /** | |
435 | * radix_tree_tag_set - set a tag on a radix tree node | |
436 | * @root: radix tree root | |
437 | * @index: index key | |
438 | * @tag: tag index | |
439 | * | |
daff89f3 JC |
440 | * Set the search tag (which must be < RADIX_TREE_MAX_TAGS) |
441 | * corresponding to @index in the radix tree. From | |
1da177e4 LT |
442 | * the root all the way down to the leaf node. |
443 | * | |
444 | * Returns the address of the tagged item. Setting a tag on a not-present | |
445 | * item is a bug. | |
446 | */ | |
447 | void *radix_tree_tag_set(struct radix_tree_root *root, | |
daff89f3 | 448 | unsigned long index, unsigned int tag) |
1da177e4 LT |
449 | { |
450 | unsigned int height, shift; | |
201b6264 | 451 | struct radix_tree_node *slot; |
1da177e4 LT |
452 | |
453 | height = root->height; | |
4c91c364 | 454 | BUG_ON(index > radix_tree_maxindex(height)); |
1da177e4 | 455 | |
c0bc9875 | 456 | slot = radix_tree_indirect_to_ptr(root->rnode); |
612d6c19 | 457 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 LT |
458 | |
459 | while (height > 0) { | |
460 | int offset; | |
461 | ||
462 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
d5274261 NP |
463 | if (!tag_get(slot, tag, offset)) |
464 | tag_set(slot, tag, offset); | |
201b6264 CL |
465 | slot = slot->slots[offset]; |
466 | BUG_ON(slot == NULL); | |
1da177e4 LT |
467 | shift -= RADIX_TREE_MAP_SHIFT; |
468 | height--; | |
469 | } | |
470 | ||
612d6c19 NP |
471 | /* set the root's tag bit */ |
472 | if (slot && !root_tag_get(root, tag)) | |
473 | root_tag_set(root, tag); | |
474 | ||
201b6264 | 475 | return slot; |
1da177e4 LT |
476 | } |
477 | EXPORT_SYMBOL(radix_tree_tag_set); | |
478 | ||
479 | /** | |
480 | * radix_tree_tag_clear - clear a tag on a radix tree node | |
481 | * @root: radix tree root | |
482 | * @index: index key | |
483 | * @tag: tag index | |
484 | * | |
daff89f3 JC |
485 | * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS) |
486 | * corresponding to @index in the radix tree. If | |
1da177e4 LT |
487 | * this causes the leaf node to have no tags set then clear the tag in the |
488 | * next-to-leaf node, etc. | |
489 | * | |
490 | * Returns the address of the tagged item on success, else NULL. ie: | |
491 | * has the same return value and semantics as radix_tree_lookup(). | |
492 | */ | |
493 | void *radix_tree_tag_clear(struct radix_tree_root *root, | |
daff89f3 | 494 | unsigned long index, unsigned int tag) |
1da177e4 | 495 | { |
26fb1589 JM |
496 | /* |
497 | * The radix tree path needs to be one longer than the maximum path | |
498 | * since the "list" is null terminated. | |
499 | */ | |
500 | struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path; | |
612d6c19 | 501 | struct radix_tree_node *slot = NULL; |
1da177e4 | 502 | unsigned int height, shift; |
1da177e4 LT |
503 | |
504 | height = root->height; | |
505 | if (index > radix_tree_maxindex(height)) | |
506 | goto out; | |
507 | ||
508 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
509 | pathp->node = NULL; | |
c0bc9875 | 510 | slot = radix_tree_indirect_to_ptr(root->rnode); |
1da177e4 LT |
511 | |
512 | while (height > 0) { | |
513 | int offset; | |
514 | ||
201b6264 | 515 | if (slot == NULL) |
1da177e4 LT |
516 | goto out; |
517 | ||
518 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
519 | pathp[1].offset = offset; | |
201b6264 CL |
520 | pathp[1].node = slot; |
521 | slot = slot->slots[offset]; | |
1da177e4 LT |
522 | pathp++; |
523 | shift -= RADIX_TREE_MAP_SHIFT; | |
524 | height--; | |
525 | } | |
526 | ||
612d6c19 | 527 | if (slot == NULL) |
1da177e4 LT |
528 | goto out; |
529 | ||
612d6c19 | 530 | while (pathp->node) { |
d5274261 NP |
531 | if (!tag_get(pathp->node, tag, pathp->offset)) |
532 | goto out; | |
201b6264 | 533 | tag_clear(pathp->node, tag, pathp->offset); |
6e954b9e NP |
534 | if (any_tag_set(pathp->node, tag)) |
535 | goto out; | |
1da177e4 | 536 | pathp--; |
612d6c19 NP |
537 | } |
538 | ||
539 | /* clear the root's tag bit */ | |
540 | if (root_tag_get(root, tag)) | |
541 | root_tag_clear(root, tag); | |
542 | ||
1da177e4 | 543 | out: |
612d6c19 | 544 | return slot; |
1da177e4 LT |
545 | } |
546 | EXPORT_SYMBOL(radix_tree_tag_clear); | |
547 | ||
1da177e4 | 548 | /** |
32605a18 MT |
549 | * radix_tree_tag_get - get a tag on a radix tree node |
550 | * @root: radix tree root | |
551 | * @index: index key | |
daff89f3 | 552 | * @tag: tag index (< RADIX_TREE_MAX_TAGS) |
1da177e4 | 553 | * |
32605a18 | 554 | * Return values: |
1da177e4 | 555 | * |
612d6c19 NP |
556 | * 0: tag not present or not set |
557 | * 1: tag set | |
ce82653d DH |
558 | * |
559 | * Note that the return value of this function may not be relied on, even if | |
560 | * the RCU lock is held, unless tag modification and node deletion are excluded | |
561 | * from concurrency. | |
1da177e4 LT |
562 | */ |
563 | int radix_tree_tag_get(struct radix_tree_root *root, | |
daff89f3 | 564 | unsigned long index, unsigned int tag) |
1da177e4 LT |
565 | { |
566 | unsigned int height, shift; | |
7cf9c2c7 | 567 | struct radix_tree_node *node; |
1da177e4 LT |
568 | int saw_unset_tag = 0; |
569 | ||
612d6c19 NP |
570 | /* check the root's tag bit */ |
571 | if (!root_tag_get(root, tag)) | |
572 | return 0; | |
573 | ||
2676a58c | 574 | node = rcu_dereference_raw(root->rnode); |
7cf9c2c7 NP |
575 | if (node == NULL) |
576 | return 0; | |
577 | ||
c0bc9875 | 578 | if (!radix_tree_is_indirect_ptr(node)) |
7cf9c2c7 | 579 | return (index == 0); |
c0bc9875 | 580 | node = radix_tree_indirect_to_ptr(node); |
7cf9c2c7 NP |
581 | |
582 | height = node->height; | |
583 | if (index > radix_tree_maxindex(height)) | |
584 | return 0; | |
612d6c19 | 585 | |
1da177e4 | 586 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 LT |
587 | |
588 | for ( ; ; ) { | |
589 | int offset; | |
590 | ||
7cf9c2c7 | 591 | if (node == NULL) |
1da177e4 LT |
592 | return 0; |
593 | ||
594 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
595 | ||
596 | /* | |
597 | * This is just a debug check. Later, we can bale as soon as | |
598 | * we see an unset tag. | |
599 | */ | |
7cf9c2c7 | 600 | if (!tag_get(node, tag, offset)) |
1da177e4 | 601 | saw_unset_tag = 1; |
ce82653d DH |
602 | if (height == 1) |
603 | return !!tag_get(node, tag, offset); | |
2676a58c | 604 | node = rcu_dereference_raw(node->slots[offset]); |
1da177e4 LT |
605 | shift -= RADIX_TREE_MAP_SHIFT; |
606 | height--; | |
607 | } | |
608 | } | |
609 | EXPORT_SYMBOL(radix_tree_tag_get); | |
1da177e4 | 610 | |
6df8ba4f FW |
611 | /** |
612 | * radix_tree_next_hole - find the next hole (not-present entry) | |
613 | * @root: tree root | |
614 | * @index: index key | |
615 | * @max_scan: maximum range to search | |
616 | * | |
617 | * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest | |
618 | * indexed hole. | |
619 | * | |
620 | * Returns: the index of the hole if found, otherwise returns an index | |
621 | * outside of the set specified (in which case 'return - index >= max_scan' | |
8e6bdb7f | 622 | * will be true). In rare cases of index wrap-around, 0 will be returned. |
6df8ba4f FW |
623 | * |
624 | * radix_tree_next_hole may be called under rcu_read_lock. However, like | |
8e6bdb7f WF |
625 | * radix_tree_gang_lookup, this will not atomically search a snapshot of |
626 | * the tree at a single point in time. For example, if a hole is created | |
627 | * at index 5, then subsequently a hole is created at index 10, | |
628 | * radix_tree_next_hole covering both indexes may return 10 if called | |
629 | * under rcu_read_lock. | |
6df8ba4f FW |
630 | */ |
631 | unsigned long radix_tree_next_hole(struct radix_tree_root *root, | |
632 | unsigned long index, unsigned long max_scan) | |
633 | { | |
634 | unsigned long i; | |
635 | ||
636 | for (i = 0; i < max_scan; i++) { | |
637 | if (!radix_tree_lookup(root, index)) | |
638 | break; | |
639 | index++; | |
640 | if (index == 0) | |
641 | break; | |
642 | } | |
643 | ||
644 | return index; | |
645 | } | |
646 | EXPORT_SYMBOL(radix_tree_next_hole); | |
647 | ||
dc566127 WF |
648 | /** |
649 | * radix_tree_prev_hole - find the prev hole (not-present entry) | |
650 | * @root: tree root | |
651 | * @index: index key | |
652 | * @max_scan: maximum range to search | |
653 | * | |
654 | * Search backwards in the range [max(index-max_scan+1, 0), index] | |
655 | * for the first hole. | |
656 | * | |
657 | * Returns: the index of the hole if found, otherwise returns an index | |
658 | * outside of the set specified (in which case 'index - return >= max_scan' | |
edcd1d84 | 659 | * will be true). In rare cases of wrap-around, ULONG_MAX will be returned. |
dc566127 WF |
660 | * |
661 | * radix_tree_next_hole may be called under rcu_read_lock. However, like | |
662 | * radix_tree_gang_lookup, this will not atomically search a snapshot of | |
663 | * the tree at a single point in time. For example, if a hole is created | |
664 | * at index 10, then subsequently a hole is created at index 5, | |
665 | * radix_tree_prev_hole covering both indexes may return 5 if called under | |
666 | * rcu_read_lock. | |
667 | */ | |
668 | unsigned long radix_tree_prev_hole(struct radix_tree_root *root, | |
669 | unsigned long index, unsigned long max_scan) | |
670 | { | |
671 | unsigned long i; | |
672 | ||
673 | for (i = 0; i < max_scan; i++) { | |
674 | if (!radix_tree_lookup(root, index)) | |
675 | break; | |
676 | index--; | |
edcd1d84 | 677 | if (index == ULONG_MAX) |
dc566127 WF |
678 | break; |
679 | } | |
680 | ||
681 | return index; | |
682 | } | |
683 | EXPORT_SYMBOL(radix_tree_prev_hole); | |
684 | ||
1da177e4 | 685 | static unsigned int |
47feff2c | 686 | __lookup(struct radix_tree_node *slot, void ***results, unsigned long index, |
1da177e4 LT |
687 | unsigned int max_items, unsigned long *next_index) |
688 | { | |
689 | unsigned int nr_found = 0; | |
201b6264 | 690 | unsigned int shift, height; |
201b6264 CL |
691 | unsigned long i; |
692 | ||
7cf9c2c7 NP |
693 | height = slot->height; |
694 | if (height == 0) | |
201b6264 | 695 | goto out; |
1da177e4 | 696 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 | 697 | |
201b6264 | 698 | for ( ; height > 1; height--) { |
7cf9c2c7 NP |
699 | i = (index >> shift) & RADIX_TREE_MAP_MASK; |
700 | for (;;) { | |
1da177e4 LT |
701 | if (slot->slots[i] != NULL) |
702 | break; | |
703 | index &= ~((1UL << shift) - 1); | |
704 | index += 1UL << shift; | |
705 | if (index == 0) | |
706 | goto out; /* 32-bit wraparound */ | |
7cf9c2c7 NP |
707 | i++; |
708 | if (i == RADIX_TREE_MAP_SIZE) | |
709 | goto out; | |
1da177e4 | 710 | } |
1da177e4 | 711 | |
1da177e4 | 712 | shift -= RADIX_TREE_MAP_SHIFT; |
2676a58c | 713 | slot = rcu_dereference_raw(slot->slots[i]); |
7cf9c2c7 NP |
714 | if (slot == NULL) |
715 | goto out; | |
1da177e4 | 716 | } |
201b6264 CL |
717 | |
718 | /* Bottom level: grab some items */ | |
719 | for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) { | |
720 | index++; | |
47feff2c NP |
721 | if (slot->slots[i]) { |
722 | results[nr_found++] = &(slot->slots[i]); | |
201b6264 CL |
723 | if (nr_found == max_items) |
724 | goto out; | |
725 | } | |
726 | } | |
1da177e4 LT |
727 | out: |
728 | *next_index = index; | |
729 | return nr_found; | |
730 | } | |
731 | ||
732 | /** | |
733 | * radix_tree_gang_lookup - perform multiple lookup on a radix tree | |
734 | * @root: radix tree root | |
735 | * @results: where the results of the lookup are placed | |
736 | * @first_index: start the lookup from this key | |
737 | * @max_items: place up to this many items at *results | |
738 | * | |
739 | * Performs an index-ascending scan of the tree for present items. Places | |
740 | * them at *@results and returns the number of items which were placed at | |
741 | * *@results. | |
742 | * | |
743 | * The implementation is naive. | |
7cf9c2c7 NP |
744 | * |
745 | * Like radix_tree_lookup, radix_tree_gang_lookup may be called under | |
746 | * rcu_read_lock. In this case, rather than the returned results being | |
747 | * an atomic snapshot of the tree at a single point in time, the semantics | |
748 | * of an RCU protected gang lookup are as though multiple radix_tree_lookups | |
749 | * have been issued in individual locks, and results stored in 'results'. | |
1da177e4 LT |
750 | */ |
751 | unsigned int | |
752 | radix_tree_gang_lookup(struct radix_tree_root *root, void **results, | |
753 | unsigned long first_index, unsigned int max_items) | |
754 | { | |
7cf9c2c7 NP |
755 | unsigned long max_index; |
756 | struct radix_tree_node *node; | |
1da177e4 | 757 | unsigned long cur_index = first_index; |
7cf9c2c7 NP |
758 | unsigned int ret; |
759 | ||
2676a58c | 760 | node = rcu_dereference_raw(root->rnode); |
7cf9c2c7 NP |
761 | if (!node) |
762 | return 0; | |
1da177e4 | 763 | |
c0bc9875 | 764 | if (!radix_tree_is_indirect_ptr(node)) { |
7cf9c2c7 NP |
765 | if (first_index > 0) |
766 | return 0; | |
c0bc9875 | 767 | results[0] = node; |
7cf9c2c7 NP |
768 | return 1; |
769 | } | |
c0bc9875 | 770 | node = radix_tree_indirect_to_ptr(node); |
7cf9c2c7 NP |
771 | |
772 | max_index = radix_tree_maxindex(node->height); | |
773 | ||
774 | ret = 0; | |
1da177e4 | 775 | while (ret < max_items) { |
47feff2c | 776 | unsigned int nr_found, slots_found, i; |
1da177e4 LT |
777 | unsigned long next_index; /* Index of next search */ |
778 | ||
779 | if (cur_index > max_index) | |
780 | break; | |
47feff2c | 781 | slots_found = __lookup(node, (void ***)results + ret, cur_index, |
1da177e4 | 782 | max_items - ret, &next_index); |
47feff2c NP |
783 | nr_found = 0; |
784 | for (i = 0; i < slots_found; i++) { | |
785 | struct radix_tree_node *slot; | |
786 | slot = *(((void ***)results)[ret + i]); | |
787 | if (!slot) | |
788 | continue; | |
2676a58c | 789 | results[ret + nr_found] = rcu_dereference_raw(slot); |
47feff2c NP |
790 | nr_found++; |
791 | } | |
1da177e4 LT |
792 | ret += nr_found; |
793 | if (next_index == 0) | |
794 | break; | |
795 | cur_index = next_index; | |
796 | } | |
7cf9c2c7 | 797 | |
1da177e4 LT |
798 | return ret; |
799 | } | |
800 | EXPORT_SYMBOL(radix_tree_gang_lookup); | |
801 | ||
47feff2c NP |
802 | /** |
803 | * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree | |
804 | * @root: radix tree root | |
805 | * @results: where the results of the lookup are placed | |
806 | * @first_index: start the lookup from this key | |
807 | * @max_items: place up to this many items at *results | |
808 | * | |
809 | * Performs an index-ascending scan of the tree for present items. Places | |
810 | * their slots at *@results and returns the number of items which were | |
811 | * placed at *@results. | |
812 | * | |
813 | * The implementation is naive. | |
814 | * | |
815 | * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must | |
816 | * be dereferenced with radix_tree_deref_slot, and if using only RCU | |
817 | * protection, radix_tree_deref_slot may fail requiring a retry. | |
818 | */ | |
819 | unsigned int | |
820 | radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results, | |
821 | unsigned long first_index, unsigned int max_items) | |
822 | { | |
823 | unsigned long max_index; | |
824 | struct radix_tree_node *node; | |
825 | unsigned long cur_index = first_index; | |
826 | unsigned int ret; | |
827 | ||
2676a58c | 828 | node = rcu_dereference_raw(root->rnode); |
47feff2c NP |
829 | if (!node) |
830 | return 0; | |
831 | ||
832 | if (!radix_tree_is_indirect_ptr(node)) { | |
833 | if (first_index > 0) | |
834 | return 0; | |
835 | results[0] = (void **)&root->rnode; | |
836 | return 1; | |
837 | } | |
838 | node = radix_tree_indirect_to_ptr(node); | |
839 | ||
840 | max_index = radix_tree_maxindex(node->height); | |
841 | ||
842 | ret = 0; | |
843 | while (ret < max_items) { | |
844 | unsigned int slots_found; | |
845 | unsigned long next_index; /* Index of next search */ | |
846 | ||
847 | if (cur_index > max_index) | |
848 | break; | |
849 | slots_found = __lookup(node, results + ret, cur_index, | |
850 | max_items - ret, &next_index); | |
851 | ret += slots_found; | |
852 | if (next_index == 0) | |
853 | break; | |
854 | cur_index = next_index; | |
855 | } | |
856 | ||
857 | return ret; | |
858 | } | |
859 | EXPORT_SYMBOL(radix_tree_gang_lookup_slot); | |
860 | ||
1da177e4 LT |
861 | /* |
862 | * FIXME: the two tag_get()s here should use find_next_bit() instead of | |
863 | * open-coding the search. | |
864 | */ | |
865 | static unsigned int | |
47feff2c | 866 | __lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index, |
daff89f3 | 867 | unsigned int max_items, unsigned long *next_index, unsigned int tag) |
1da177e4 LT |
868 | { |
869 | unsigned int nr_found = 0; | |
7cf9c2c7 | 870 | unsigned int shift, height; |
1da177e4 | 871 | |
7cf9c2c7 NP |
872 | height = slot->height; |
873 | if (height == 0) | |
612d6c19 | 874 | goto out; |
7cf9c2c7 | 875 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 | 876 | |
7cf9c2c7 NP |
877 | while (height > 0) { |
878 | unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ; | |
1da177e4 | 879 | |
7cf9c2c7 NP |
880 | for (;;) { |
881 | if (tag_get(slot, tag, i)) | |
1da177e4 | 882 | break; |
1da177e4 LT |
883 | index &= ~((1UL << shift) - 1); |
884 | index += 1UL << shift; | |
885 | if (index == 0) | |
886 | goto out; /* 32-bit wraparound */ | |
7cf9c2c7 NP |
887 | i++; |
888 | if (i == RADIX_TREE_MAP_SIZE) | |
889 | goto out; | |
1da177e4 | 890 | } |
1da177e4 LT |
891 | height--; |
892 | if (height == 0) { /* Bottom level: grab some items */ | |
893 | unsigned long j = index & RADIX_TREE_MAP_MASK; | |
894 | ||
895 | for ( ; j < RADIX_TREE_MAP_SIZE; j++) { | |
896 | index++; | |
7cf9c2c7 NP |
897 | if (!tag_get(slot, tag, j)) |
898 | continue; | |
7cf9c2c7 NP |
899 | /* |
900 | * Even though the tag was found set, we need to | |
901 | * recheck that we have a non-NULL node, because | |
902 | * if this lookup is lockless, it may have been | |
903 | * subsequently deleted. | |
904 | * | |
905 | * Similar care must be taken in any place that | |
906 | * lookup ->slots[x] without a lock (ie. can't | |
907 | * rely on its value remaining the same). | |
908 | */ | |
47feff2c NP |
909 | if (slot->slots[j]) { |
910 | results[nr_found++] = &(slot->slots[j]); | |
1da177e4 LT |
911 | if (nr_found == max_items) |
912 | goto out; | |
913 | } | |
914 | } | |
915 | } | |
916 | shift -= RADIX_TREE_MAP_SHIFT; | |
2676a58c | 917 | slot = rcu_dereference_raw(slot->slots[i]); |
7cf9c2c7 NP |
918 | if (slot == NULL) |
919 | break; | |
920 | } | |
1da177e4 LT |
921 | out: |
922 | *next_index = index; | |
923 | return nr_found; | |
924 | } | |
925 | ||
926 | /** | |
927 | * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree | |
928 | * based on a tag | |
929 | * @root: radix tree root | |
930 | * @results: where the results of the lookup are placed | |
931 | * @first_index: start the lookup from this key | |
932 | * @max_items: place up to this many items at *results | |
daff89f3 | 933 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) |
1da177e4 LT |
934 | * |
935 | * Performs an index-ascending scan of the tree for present items which | |
936 | * have the tag indexed by @tag set. Places the items at *@results and | |
937 | * returns the number of items which were placed at *@results. | |
938 | */ | |
939 | unsigned int | |
940 | radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, | |
daff89f3 JC |
941 | unsigned long first_index, unsigned int max_items, |
942 | unsigned int tag) | |
1da177e4 | 943 | { |
7cf9c2c7 NP |
944 | struct radix_tree_node *node; |
945 | unsigned long max_index; | |
1da177e4 | 946 | unsigned long cur_index = first_index; |
7cf9c2c7 | 947 | unsigned int ret; |
1da177e4 | 948 | |
612d6c19 NP |
949 | /* check the root's tag bit */ |
950 | if (!root_tag_get(root, tag)) | |
951 | return 0; | |
952 | ||
2676a58c | 953 | node = rcu_dereference_raw(root->rnode); |
7cf9c2c7 NP |
954 | if (!node) |
955 | return 0; | |
956 | ||
c0bc9875 | 957 | if (!radix_tree_is_indirect_ptr(node)) { |
7cf9c2c7 NP |
958 | if (first_index > 0) |
959 | return 0; | |
c0bc9875 | 960 | results[0] = node; |
7cf9c2c7 NP |
961 | return 1; |
962 | } | |
c0bc9875 | 963 | node = radix_tree_indirect_to_ptr(node); |
7cf9c2c7 NP |
964 | |
965 | max_index = radix_tree_maxindex(node->height); | |
966 | ||
967 | ret = 0; | |
1da177e4 | 968 | while (ret < max_items) { |
47feff2c | 969 | unsigned int nr_found, slots_found, i; |
1da177e4 LT |
970 | unsigned long next_index; /* Index of next search */ |
971 | ||
972 | if (cur_index > max_index) | |
973 | break; | |
47feff2c NP |
974 | slots_found = __lookup_tag(node, (void ***)results + ret, |
975 | cur_index, max_items - ret, &next_index, tag); | |
976 | nr_found = 0; | |
977 | for (i = 0; i < slots_found; i++) { | |
978 | struct radix_tree_node *slot; | |
979 | slot = *(((void ***)results)[ret + i]); | |
980 | if (!slot) | |
981 | continue; | |
2676a58c | 982 | results[ret + nr_found] = rcu_dereference_raw(slot); |
47feff2c NP |
983 | nr_found++; |
984 | } | |
1da177e4 LT |
985 | ret += nr_found; |
986 | if (next_index == 0) | |
987 | break; | |
988 | cur_index = next_index; | |
989 | } | |
7cf9c2c7 | 990 | |
1da177e4 LT |
991 | return ret; |
992 | } | |
993 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag); | |
994 | ||
47feff2c NP |
995 | /** |
996 | * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a | |
997 | * radix tree based on a tag | |
998 | * @root: radix tree root | |
999 | * @results: where the results of the lookup are placed | |
1000 | * @first_index: start the lookup from this key | |
1001 | * @max_items: place up to this many items at *results | |
1002 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) | |
1003 | * | |
1004 | * Performs an index-ascending scan of the tree for present items which | |
1005 | * have the tag indexed by @tag set. Places the slots at *@results and | |
1006 | * returns the number of slots which were placed at *@results. | |
1007 | */ | |
1008 | unsigned int | |
1009 | radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, | |
1010 | unsigned long first_index, unsigned int max_items, | |
1011 | unsigned int tag) | |
1012 | { | |
1013 | struct radix_tree_node *node; | |
1014 | unsigned long max_index; | |
1015 | unsigned long cur_index = first_index; | |
1016 | unsigned int ret; | |
1017 | ||
1018 | /* check the root's tag bit */ | |
1019 | if (!root_tag_get(root, tag)) | |
1020 | return 0; | |
1021 | ||
2676a58c | 1022 | node = rcu_dereference_raw(root->rnode); |
47feff2c NP |
1023 | if (!node) |
1024 | return 0; | |
1025 | ||
1026 | if (!radix_tree_is_indirect_ptr(node)) { | |
1027 | if (first_index > 0) | |
1028 | return 0; | |
1029 | results[0] = (void **)&root->rnode; | |
1030 | return 1; | |
1031 | } | |
1032 | node = radix_tree_indirect_to_ptr(node); | |
1033 | ||
1034 | max_index = radix_tree_maxindex(node->height); | |
1035 | ||
1036 | ret = 0; | |
1037 | while (ret < max_items) { | |
1038 | unsigned int slots_found; | |
1039 | unsigned long next_index; /* Index of next search */ | |
1040 | ||
1041 | if (cur_index > max_index) | |
1042 | break; | |
1043 | slots_found = __lookup_tag(node, results + ret, | |
1044 | cur_index, max_items - ret, &next_index, tag); | |
1045 | ret += slots_found; | |
1046 | if (next_index == 0) | |
1047 | break; | |
1048 | cur_index = next_index; | |
1049 | } | |
1050 | ||
1051 | return ret; | |
1052 | } | |
1053 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); | |
1054 | ||
1055 | ||
a5f51c96 NP |
1056 | /** |
1057 | * radix_tree_shrink - shrink height of a radix tree to minimal | |
1058 | * @root radix tree root | |
1059 | */ | |
1060 | static inline void radix_tree_shrink(struct radix_tree_root *root) | |
1061 | { | |
1062 | /* try to shrink tree height */ | |
c0bc9875 | 1063 | while (root->height > 0) { |
a5f51c96 | 1064 | struct radix_tree_node *to_free = root->rnode; |
7cf9c2c7 | 1065 | void *newptr; |
a5f51c96 | 1066 | |
c0bc9875 NP |
1067 | BUG_ON(!radix_tree_is_indirect_ptr(to_free)); |
1068 | to_free = radix_tree_indirect_to_ptr(to_free); | |
1069 | ||
1070 | /* | |
1071 | * The candidate node has more than one child, or its child | |
1072 | * is not at the leftmost slot, we cannot shrink. | |
1073 | */ | |
1074 | if (to_free->count != 1) | |
1075 | break; | |
1076 | if (!to_free->slots[0]) | |
1077 | break; | |
1078 | ||
7cf9c2c7 NP |
1079 | /* |
1080 | * We don't need rcu_assign_pointer(), since we are simply | |
1081 | * moving the node from one part of the tree to another. If | |
1082 | * it was safe to dereference the old pointer to it | |
1083 | * (to_free->slots[0]), it will be safe to dereference the new | |
1084 | * one (root->rnode). | |
1085 | */ | |
1086 | newptr = to_free->slots[0]; | |
c0bc9875 NP |
1087 | if (root->height > 1) |
1088 | newptr = radix_tree_ptr_to_indirect(newptr); | |
7cf9c2c7 | 1089 | root->rnode = newptr; |
a5f51c96 | 1090 | root->height--; |
a5f51c96 NP |
1091 | radix_tree_node_free(to_free); |
1092 | } | |
1093 | } | |
1094 | ||
1da177e4 LT |
1095 | /** |
1096 | * radix_tree_delete - delete an item from a radix tree | |
1097 | * @root: radix tree root | |
1098 | * @index: index key | |
1099 | * | |
1100 | * Remove the item at @index from the radix tree rooted at @root. | |
1101 | * | |
1102 | * Returns the address of the deleted item, or NULL if it was not present. | |
1103 | */ | |
1104 | void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) | |
1105 | { | |
26fb1589 JM |
1106 | /* |
1107 | * The radix tree path needs to be one longer than the maximum path | |
1108 | * since the "list" is null terminated. | |
1109 | */ | |
1110 | struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path; | |
612d6c19 | 1111 | struct radix_tree_node *slot = NULL; |
7cf9c2c7 | 1112 | struct radix_tree_node *to_free; |
1da177e4 | 1113 | unsigned int height, shift; |
d5274261 NP |
1114 | int tag; |
1115 | int offset; | |
1da177e4 LT |
1116 | |
1117 | height = root->height; | |
1118 | if (index > radix_tree_maxindex(height)) | |
1119 | goto out; | |
1120 | ||
612d6c19 | 1121 | slot = root->rnode; |
c0bc9875 | 1122 | if (height == 0) { |
612d6c19 NP |
1123 | root_tag_clear_all(root); |
1124 | root->rnode = NULL; | |
1125 | goto out; | |
1126 | } | |
c0bc9875 | 1127 | slot = radix_tree_indirect_to_ptr(slot); |
612d6c19 | 1128 | |
1da177e4 LT |
1129 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; |
1130 | pathp->node = NULL; | |
1da177e4 | 1131 | |
612d6c19 | 1132 | do { |
201b6264 | 1133 | if (slot == NULL) |
1da177e4 LT |
1134 | goto out; |
1135 | ||
d5274261 | 1136 | pathp++; |
1da177e4 | 1137 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; |
d5274261 NP |
1138 | pathp->offset = offset; |
1139 | pathp->node = slot; | |
201b6264 | 1140 | slot = slot->slots[offset]; |
1da177e4 | 1141 | shift -= RADIX_TREE_MAP_SHIFT; |
612d6c19 NP |
1142 | height--; |
1143 | } while (height > 0); | |
1da177e4 | 1144 | |
612d6c19 | 1145 | if (slot == NULL) |
1da177e4 LT |
1146 | goto out; |
1147 | ||
1da177e4 LT |
1148 | /* |
1149 | * Clear all tags associated with the just-deleted item | |
1150 | */ | |
daff89f3 | 1151 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { |
612d6c19 NP |
1152 | if (tag_get(pathp->node, tag, pathp->offset)) |
1153 | radix_tree_tag_clear(root, index, tag); | |
d5274261 | 1154 | } |
1da177e4 | 1155 | |
7cf9c2c7 | 1156 | to_free = NULL; |
201b6264 | 1157 | /* Now free the nodes we do not need anymore */ |
612d6c19 | 1158 | while (pathp->node) { |
201b6264 | 1159 | pathp->node->slots[pathp->offset] = NULL; |
a5f51c96 | 1160 | pathp->node->count--; |
7cf9c2c7 NP |
1161 | /* |
1162 | * Queue the node for deferred freeing after the | |
1163 | * last reference to it disappears (set NULL, above). | |
1164 | */ | |
1165 | if (to_free) | |
1166 | radix_tree_node_free(to_free); | |
a5f51c96 NP |
1167 | |
1168 | if (pathp->node->count) { | |
c0bc9875 NP |
1169 | if (pathp->node == |
1170 | radix_tree_indirect_to_ptr(root->rnode)) | |
a5f51c96 | 1171 | radix_tree_shrink(root); |
201b6264 | 1172 | goto out; |
a5f51c96 | 1173 | } |
201b6264 CL |
1174 | |
1175 | /* Node with zero slots in use so free it */ | |
7cf9c2c7 | 1176 | to_free = pathp->node; |
612d6c19 | 1177 | pathp--; |
7cf9c2c7 | 1178 | |
1da177e4 | 1179 | } |
612d6c19 | 1180 | root_tag_clear_all(root); |
201b6264 | 1181 | root->height = 0; |
612d6c19 | 1182 | root->rnode = NULL; |
7cf9c2c7 NP |
1183 | if (to_free) |
1184 | radix_tree_node_free(to_free); | |
612d6c19 | 1185 | |
1da177e4 | 1186 | out: |
612d6c19 | 1187 | return slot; |
1da177e4 LT |
1188 | } |
1189 | EXPORT_SYMBOL(radix_tree_delete); | |
1190 | ||
1191 | /** | |
1192 | * radix_tree_tagged - test whether any items in the tree are tagged | |
1193 | * @root: radix tree root | |
1194 | * @tag: tag to test | |
1195 | */ | |
daff89f3 | 1196 | int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) |
1da177e4 | 1197 | { |
612d6c19 | 1198 | return root_tag_get(root, tag); |
1da177e4 LT |
1199 | } |
1200 | EXPORT_SYMBOL(radix_tree_tagged); | |
1201 | ||
1202 | static void | |
51cc5068 | 1203 | radix_tree_node_ctor(void *node) |
1da177e4 LT |
1204 | { |
1205 | memset(node, 0, sizeof(struct radix_tree_node)); | |
1206 | } | |
1207 | ||
1208 | static __init unsigned long __maxindex(unsigned int height) | |
1209 | { | |
430d275a PL |
1210 | unsigned int width = height * RADIX_TREE_MAP_SHIFT; |
1211 | int shift = RADIX_TREE_INDEX_BITS - width; | |
1212 | ||
1213 | if (shift < 0) | |
1214 | return ~0UL; | |
1215 | if (shift >= BITS_PER_LONG) | |
1216 | return 0UL; | |
1217 | return ~0UL >> shift; | |
1da177e4 LT |
1218 | } |
1219 | ||
1220 | static __init void radix_tree_init_maxindex(void) | |
1221 | { | |
1222 | unsigned int i; | |
1223 | ||
1224 | for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++) | |
1225 | height_to_maxindex[i] = __maxindex(i); | |
1226 | } | |
1227 | ||
1da177e4 LT |
1228 | static int radix_tree_callback(struct notifier_block *nfb, |
1229 | unsigned long action, | |
1230 | void *hcpu) | |
1231 | { | |
1232 | int cpu = (long)hcpu; | |
1233 | struct radix_tree_preload *rtp; | |
1234 | ||
1235 | /* Free per-cpu pool of perloaded nodes */ | |
8bb78442 | 1236 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { |
1da177e4 LT |
1237 | rtp = &per_cpu(radix_tree_preloads, cpu); |
1238 | while (rtp->nr) { | |
1239 | kmem_cache_free(radix_tree_node_cachep, | |
1240 | rtp->nodes[rtp->nr-1]); | |
1241 | rtp->nodes[rtp->nr-1] = NULL; | |
1242 | rtp->nr--; | |
1243 | } | |
1244 | } | |
1245 | return NOTIFY_OK; | |
1246 | } | |
1da177e4 LT |
1247 | |
1248 | void __init radix_tree_init(void) | |
1249 | { | |
1250 | radix_tree_node_cachep = kmem_cache_create("radix_tree_node", | |
1251 | sizeof(struct radix_tree_node), 0, | |
488514d1 CL |
1252 | SLAB_PANIC | SLAB_RECLAIM_ACCOUNT, |
1253 | radix_tree_node_ctor); | |
1da177e4 LT |
1254 | radix_tree_init_maxindex(); |
1255 | hotcpu_notifier(radix_tree_callback, 0); | |
1256 | } |