Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Copyright (C) 2001 Momchil Velikov | |
3 | * Portions Copyright (C) 2001 Christoph Hellwig | |
201b6264 | 4 | * Copyright (C) 2005 SGI, Christoph Lameter <clameter@sgi.com> |
1da177e4 LT |
5 | * |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License as | |
8 | * published by the Free Software Foundation; either version 2, or (at | |
9 | * your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, but | |
12 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
19 | */ | |
20 | ||
21 | #include <linux/errno.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/kernel.h> | |
24 | #include <linux/module.h> | |
25 | #include <linux/radix-tree.h> | |
26 | #include <linux/percpu.h> | |
27 | #include <linux/slab.h> | |
28 | #include <linux/notifier.h> | |
29 | #include <linux/cpu.h> | |
30 | #include <linux/gfp.h> | |
31 | #include <linux/string.h> | |
32 | #include <linux/bitops.h> | |
33 | ||
34 | ||
35 | #ifdef __KERNEL__ | |
36 | #define RADIX_TREE_MAP_SHIFT 6 | |
37 | #else | |
38 | #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ | |
39 | #endif | |
40 | #define RADIX_TREE_TAGS 2 | |
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 { | |
49 | unsigned int count; | |
50 | void *slots[RADIX_TREE_MAP_SIZE]; | |
51 | unsigned long tags[RADIX_TREE_TAGS][RADIX_TREE_TAG_LONGS]; | |
52 | }; | |
53 | ||
54 | struct radix_tree_path { | |
201b6264 | 55 | struct radix_tree_node *node; |
1da177e4 LT |
56 | int offset; |
57 | }; | |
58 | ||
59 | #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) | |
60 | #define RADIX_TREE_MAX_PATH (RADIX_TREE_INDEX_BITS/RADIX_TREE_MAP_SHIFT + 2) | |
61 | ||
6c036527 | 62 | static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH] __read_mostly; |
1da177e4 LT |
63 | |
64 | /* | |
65 | * Radix tree node cache. | |
66 | */ | |
67 | static kmem_cache_t *radix_tree_node_cachep; | |
68 | ||
69 | /* | |
70 | * Per-cpu pool of preloaded nodes | |
71 | */ | |
72 | struct radix_tree_preload { | |
73 | int nr; | |
74 | struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH]; | |
75 | }; | |
76 | DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; | |
77 | ||
78 | /* | |
79 | * This assumes that the caller has performed appropriate preallocation, and | |
80 | * that the caller has pinned this thread of control to the current CPU. | |
81 | */ | |
82 | static struct radix_tree_node * | |
83 | radix_tree_node_alloc(struct radix_tree_root *root) | |
84 | { | |
85 | struct radix_tree_node *ret; | |
86 | ||
87 | ret = kmem_cache_alloc(radix_tree_node_cachep, root->gfp_mask); | |
88 | if (ret == NULL && !(root->gfp_mask & __GFP_WAIT)) { | |
89 | struct radix_tree_preload *rtp; | |
90 | ||
91 | rtp = &__get_cpu_var(radix_tree_preloads); | |
92 | if (rtp->nr) { | |
93 | ret = rtp->nodes[rtp->nr - 1]; | |
94 | rtp->nodes[rtp->nr - 1] = NULL; | |
95 | rtp->nr--; | |
96 | } | |
97 | } | |
98 | return ret; | |
99 | } | |
100 | ||
101 | static inline void | |
102 | radix_tree_node_free(struct radix_tree_node *node) | |
103 | { | |
104 | kmem_cache_free(radix_tree_node_cachep, node); | |
105 | } | |
106 | ||
107 | /* | |
108 | * Load up this CPU's radix_tree_node buffer with sufficient objects to | |
109 | * ensure that the addition of a single element in the tree cannot fail. On | |
110 | * success, return zero, with preemption disabled. On error, return -ENOMEM | |
111 | * with preemption not disabled. | |
112 | */ | |
dd0fc66f | 113 | int radix_tree_preload(gfp_t gfp_mask) |
1da177e4 LT |
114 | { |
115 | struct radix_tree_preload *rtp; | |
116 | struct radix_tree_node *node; | |
117 | int ret = -ENOMEM; | |
118 | ||
119 | preempt_disable(); | |
120 | rtp = &__get_cpu_var(radix_tree_preloads); | |
121 | while (rtp->nr < ARRAY_SIZE(rtp->nodes)) { | |
122 | preempt_enable(); | |
123 | node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); | |
124 | if (node == NULL) | |
125 | goto out; | |
126 | preempt_disable(); | |
127 | rtp = &__get_cpu_var(radix_tree_preloads); | |
128 | if (rtp->nr < ARRAY_SIZE(rtp->nodes)) | |
129 | rtp->nodes[rtp->nr++] = node; | |
130 | else | |
131 | kmem_cache_free(radix_tree_node_cachep, node); | |
132 | } | |
133 | ret = 0; | |
134 | out: | |
135 | return ret; | |
136 | } | |
137 | ||
138 | static inline void tag_set(struct radix_tree_node *node, int tag, int offset) | |
139 | { | |
140 | if (!test_bit(offset, &node->tags[tag][0])) | |
141 | __set_bit(offset, &node->tags[tag][0]); | |
142 | } | |
143 | ||
144 | static inline void tag_clear(struct radix_tree_node *node, int tag, int offset) | |
145 | { | |
146 | __clear_bit(offset, &node->tags[tag][0]); | |
147 | } | |
148 | ||
149 | static inline int tag_get(struct radix_tree_node *node, int tag, int offset) | |
150 | { | |
151 | return test_bit(offset, &node->tags[tag][0]); | |
152 | } | |
153 | ||
154 | /* | |
155 | * Return the maximum key which can be store into a | |
156 | * radix tree with height HEIGHT. | |
157 | */ | |
158 | static inline unsigned long radix_tree_maxindex(unsigned int height) | |
159 | { | |
160 | return height_to_maxindex[height]; | |
161 | } | |
162 | ||
163 | /* | |
164 | * Extend a radix tree so it can store key @index. | |
165 | */ | |
166 | static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) | |
167 | { | |
168 | struct radix_tree_node *node; | |
169 | unsigned int height; | |
170 | char tags[RADIX_TREE_TAGS]; | |
171 | int tag; | |
172 | ||
173 | /* Figure out what the height should be. */ | |
174 | height = root->height + 1; | |
175 | while (index > radix_tree_maxindex(height)) | |
176 | height++; | |
177 | ||
178 | if (root->rnode == NULL) { | |
179 | root->height = height; | |
180 | goto out; | |
181 | } | |
182 | ||
183 | /* | |
184 | * Prepare the tag status of the top-level node for propagation | |
185 | * into the newly-pushed top-level node(s) | |
186 | */ | |
187 | for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { | |
188 | int idx; | |
189 | ||
190 | tags[tag] = 0; | |
191 | for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { | |
192 | if (root->rnode->tags[tag][idx]) { | |
193 | tags[tag] = 1; | |
194 | break; | |
195 | } | |
196 | } | |
197 | } | |
198 | ||
199 | do { | |
200 | if (!(node = radix_tree_node_alloc(root))) | |
201 | return -ENOMEM; | |
202 | ||
203 | /* Increase the height. */ | |
204 | node->slots[0] = root->rnode; | |
205 | ||
206 | /* Propagate the aggregated tag info into the new root */ | |
207 | for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { | |
208 | if (tags[tag]) | |
209 | tag_set(node, tag, 0); | |
210 | } | |
211 | ||
212 | node->count = 1; | |
213 | root->rnode = node; | |
214 | root->height++; | |
215 | } while (height > root->height); | |
216 | out: | |
217 | return 0; | |
218 | } | |
219 | ||
220 | /** | |
221 | * radix_tree_insert - insert into a radix tree | |
222 | * @root: radix tree root | |
223 | * @index: index key | |
224 | * @item: item to insert | |
225 | * | |
226 | * Insert an item into the radix tree at position @index. | |
227 | */ | |
228 | int radix_tree_insert(struct radix_tree_root *root, | |
229 | unsigned long index, void *item) | |
230 | { | |
201b6264 | 231 | struct radix_tree_node *node = NULL, *slot; |
1da177e4 LT |
232 | unsigned int height, shift; |
233 | int offset; | |
234 | int error; | |
235 | ||
236 | /* Make sure the tree is high enough. */ | |
237 | if ((!index && !root->rnode) || | |
238 | index > radix_tree_maxindex(root->height)) { | |
239 | error = radix_tree_extend(root, index); | |
240 | if (error) | |
241 | return error; | |
242 | } | |
243 | ||
201b6264 | 244 | slot = root->rnode; |
1da177e4 LT |
245 | height = root->height; |
246 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
247 | ||
248 | offset = 0; /* uninitialised var warning */ | |
249 | while (height > 0) { | |
201b6264 | 250 | if (slot == NULL) { |
1da177e4 | 251 | /* Have to add a child node. */ |
201b6264 | 252 | if (!(slot = radix_tree_node_alloc(root))) |
1da177e4 | 253 | return -ENOMEM; |
201b6264 CL |
254 | if (node) { |
255 | node->slots[offset] = slot; | |
1da177e4 | 256 | node->count++; |
201b6264 CL |
257 | } else |
258 | root->rnode = slot; | |
1da177e4 LT |
259 | } |
260 | ||
261 | /* Go a level down */ | |
262 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
201b6264 CL |
263 | node = slot; |
264 | slot = node->slots[offset]; | |
1da177e4 LT |
265 | shift -= RADIX_TREE_MAP_SHIFT; |
266 | height--; | |
267 | } | |
268 | ||
201b6264 | 269 | if (slot != NULL) |
1da177e4 | 270 | return -EEXIST; |
201b6264 | 271 | |
1da177e4 LT |
272 | if (node) { |
273 | node->count++; | |
201b6264 | 274 | node->slots[offset] = item; |
1da177e4 LT |
275 | BUG_ON(tag_get(node, 0, offset)); |
276 | BUG_ON(tag_get(node, 1, offset)); | |
201b6264 CL |
277 | } else |
278 | root->rnode = item; | |
1da177e4 | 279 | |
1da177e4 LT |
280 | return 0; |
281 | } | |
282 | EXPORT_SYMBOL(radix_tree_insert); | |
283 | ||
a4331366 HR |
284 | static inline void **__lookup_slot(struct radix_tree_root *root, |
285 | unsigned long index) | |
1da177e4 LT |
286 | { |
287 | unsigned int height, shift; | |
a4331366 | 288 | struct radix_tree_node **slot; |
1da177e4 LT |
289 | |
290 | height = root->height; | |
291 | if (index > radix_tree_maxindex(height)) | |
292 | return NULL; | |
293 | ||
294 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
a4331366 | 295 | slot = &root->rnode; |
1da177e4 LT |
296 | |
297 | while (height > 0) { | |
a4331366 | 298 | if (*slot == NULL) |
1da177e4 LT |
299 | return NULL; |
300 | ||
a4331366 HR |
301 | slot = (struct radix_tree_node **) |
302 | ((*slot)->slots + | |
303 | ((index >> shift) & RADIX_TREE_MAP_MASK)); | |
1da177e4 LT |
304 | shift -= RADIX_TREE_MAP_SHIFT; |
305 | height--; | |
306 | } | |
307 | ||
a4331366 HR |
308 | return (void **)slot; |
309 | } | |
310 | ||
311 | /** | |
312 | * radix_tree_lookup_slot - lookup a slot in a radix tree | |
313 | * @root: radix tree root | |
314 | * @index: index key | |
315 | * | |
316 | * Lookup the slot corresponding to the position @index in the radix tree | |
317 | * @root. This is useful for update-if-exists operations. | |
318 | */ | |
319 | void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) | |
320 | { | |
321 | return __lookup_slot(root, index); | |
322 | } | |
323 | EXPORT_SYMBOL(radix_tree_lookup_slot); | |
324 | ||
325 | /** | |
326 | * radix_tree_lookup - perform lookup operation on a radix tree | |
327 | * @root: radix tree root | |
328 | * @index: index key | |
329 | * | |
330 | * Lookup the item at the position @index in the radix tree @root. | |
331 | */ | |
332 | void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) | |
333 | { | |
334 | void **slot; | |
335 | ||
336 | slot = __lookup_slot(root, index); | |
337 | return slot != NULL ? *slot : NULL; | |
1da177e4 LT |
338 | } |
339 | EXPORT_SYMBOL(radix_tree_lookup); | |
340 | ||
341 | /** | |
342 | * radix_tree_tag_set - set a tag on a radix tree node | |
343 | * @root: radix tree root | |
344 | * @index: index key | |
345 | * @tag: tag index | |
346 | * | |
347 | * Set the search tag corresponging to @index in the radix tree. From | |
348 | * the root all the way down to the leaf node. | |
349 | * | |
350 | * Returns the address of the tagged item. Setting a tag on a not-present | |
351 | * item is a bug. | |
352 | */ | |
353 | void *radix_tree_tag_set(struct radix_tree_root *root, | |
354 | unsigned long index, int tag) | |
355 | { | |
356 | unsigned int height, shift; | |
201b6264 | 357 | struct radix_tree_node *slot; |
1da177e4 LT |
358 | |
359 | height = root->height; | |
360 | if (index > radix_tree_maxindex(height)) | |
361 | return NULL; | |
362 | ||
363 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
201b6264 | 364 | slot = root->rnode; |
1da177e4 LT |
365 | |
366 | while (height > 0) { | |
367 | int offset; | |
368 | ||
369 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
201b6264 CL |
370 | tag_set(slot, tag, offset); |
371 | slot = slot->slots[offset]; | |
372 | BUG_ON(slot == NULL); | |
1da177e4 LT |
373 | shift -= RADIX_TREE_MAP_SHIFT; |
374 | height--; | |
375 | } | |
376 | ||
201b6264 | 377 | return slot; |
1da177e4 LT |
378 | } |
379 | EXPORT_SYMBOL(radix_tree_tag_set); | |
380 | ||
381 | /** | |
382 | * radix_tree_tag_clear - clear a tag on a radix tree node | |
383 | * @root: radix tree root | |
384 | * @index: index key | |
385 | * @tag: tag index | |
386 | * | |
387 | * Clear the search tag corresponging to @index in the radix tree. If | |
388 | * this causes the leaf node to have no tags set then clear the tag in the | |
389 | * next-to-leaf node, etc. | |
390 | * | |
391 | * Returns the address of the tagged item on success, else NULL. ie: | |
392 | * has the same return value and semantics as radix_tree_lookup(). | |
393 | */ | |
394 | void *radix_tree_tag_clear(struct radix_tree_root *root, | |
395 | unsigned long index, int tag) | |
396 | { | |
397 | struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path; | |
201b6264 | 398 | struct radix_tree_node *slot; |
1da177e4 LT |
399 | unsigned int height, shift; |
400 | void *ret = NULL; | |
401 | ||
402 | height = root->height; | |
403 | if (index > radix_tree_maxindex(height)) | |
404 | goto out; | |
405 | ||
406 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
407 | pathp->node = NULL; | |
201b6264 | 408 | slot = root->rnode; |
1da177e4 LT |
409 | |
410 | while (height > 0) { | |
411 | int offset; | |
412 | ||
201b6264 | 413 | if (slot == NULL) |
1da177e4 LT |
414 | goto out; |
415 | ||
416 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
417 | pathp[1].offset = offset; | |
201b6264 CL |
418 | pathp[1].node = slot; |
419 | slot = slot->slots[offset]; | |
1da177e4 LT |
420 | pathp++; |
421 | shift -= RADIX_TREE_MAP_SHIFT; | |
422 | height--; | |
423 | } | |
424 | ||
201b6264 | 425 | ret = slot; |
1da177e4 LT |
426 | if (ret == NULL) |
427 | goto out; | |
428 | ||
429 | do { | |
430 | int idx; | |
431 | ||
201b6264 | 432 | tag_clear(pathp->node, tag, pathp->offset); |
1da177e4 | 433 | for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { |
201b6264 | 434 | if (pathp->node->tags[tag][idx]) |
1da177e4 LT |
435 | goto out; |
436 | } | |
437 | pathp--; | |
201b6264 | 438 | } while (pathp->node); |
1da177e4 LT |
439 | out: |
440 | return ret; | |
441 | } | |
442 | EXPORT_SYMBOL(radix_tree_tag_clear); | |
443 | ||
444 | #ifndef __KERNEL__ /* Only the test harness uses this at present */ | |
445 | /** | |
32605a18 MT |
446 | * radix_tree_tag_get - get a tag on a radix tree node |
447 | * @root: radix tree root | |
448 | * @index: index key | |
449 | * @tag: tag index | |
1da177e4 | 450 | * |
32605a18 | 451 | * Return values: |
1da177e4 | 452 | * |
32605a18 MT |
453 | * 0: tag not present |
454 | * 1: tag present, set | |
455 | * -1: tag present, unset | |
1da177e4 LT |
456 | */ |
457 | int radix_tree_tag_get(struct radix_tree_root *root, | |
458 | unsigned long index, int tag) | |
459 | { | |
460 | unsigned int height, shift; | |
201b6264 | 461 | struct radix_tree_node *slot; |
1da177e4 LT |
462 | int saw_unset_tag = 0; |
463 | ||
464 | height = root->height; | |
465 | if (index > radix_tree_maxindex(height)) | |
466 | return 0; | |
467 | ||
468 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
201b6264 | 469 | slot = root->rnode; |
1da177e4 LT |
470 | |
471 | for ( ; ; ) { | |
472 | int offset; | |
473 | ||
201b6264 | 474 | if (slot == NULL) |
1da177e4 LT |
475 | return 0; |
476 | ||
477 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
478 | ||
479 | /* | |
480 | * This is just a debug check. Later, we can bale as soon as | |
481 | * we see an unset tag. | |
482 | */ | |
201b6264 | 483 | if (!tag_get(slot, tag, offset)) |
1da177e4 LT |
484 | saw_unset_tag = 1; |
485 | if (height == 1) { | |
201b6264 | 486 | int ret = tag_get(slot, tag, offset); |
1da177e4 LT |
487 | |
488 | BUG_ON(ret && saw_unset_tag); | |
32605a18 | 489 | return ret ? 1 : -1; |
1da177e4 | 490 | } |
201b6264 | 491 | slot = slot->slots[offset]; |
1da177e4 LT |
492 | shift -= RADIX_TREE_MAP_SHIFT; |
493 | height--; | |
494 | } | |
495 | } | |
496 | EXPORT_SYMBOL(radix_tree_tag_get); | |
497 | #endif | |
498 | ||
499 | static unsigned int | |
500 | __lookup(struct radix_tree_root *root, void **results, unsigned long index, | |
501 | unsigned int max_items, unsigned long *next_index) | |
502 | { | |
503 | unsigned int nr_found = 0; | |
201b6264 | 504 | unsigned int shift, height; |
1da177e4 | 505 | struct radix_tree_node *slot; |
201b6264 CL |
506 | unsigned long i; |
507 | ||
508 | height = root->height; | |
509 | if (height == 0) | |
510 | goto out; | |
1da177e4 LT |
511 | |
512 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
513 | slot = root->rnode; | |
514 | ||
201b6264 | 515 | for ( ; height > 1; height--) { |
1da177e4 | 516 | |
201b6264 CL |
517 | for (i = (index >> shift) & RADIX_TREE_MAP_MASK ; |
518 | i < RADIX_TREE_MAP_SIZE; i++) { | |
1da177e4 LT |
519 | if (slot->slots[i] != NULL) |
520 | break; | |
521 | index &= ~((1UL << shift) - 1); | |
522 | index += 1UL << shift; | |
523 | if (index == 0) | |
524 | goto out; /* 32-bit wraparound */ | |
525 | } | |
526 | if (i == RADIX_TREE_MAP_SIZE) | |
527 | goto out; | |
1da177e4 | 528 | |
1da177e4 LT |
529 | shift -= RADIX_TREE_MAP_SHIFT; |
530 | slot = slot->slots[i]; | |
531 | } | |
201b6264 CL |
532 | |
533 | /* Bottom level: grab some items */ | |
534 | for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) { | |
535 | index++; | |
536 | if (slot->slots[i]) { | |
537 | results[nr_found++] = slot->slots[i]; | |
538 | if (nr_found == max_items) | |
539 | goto out; | |
540 | } | |
541 | } | |
1da177e4 LT |
542 | out: |
543 | *next_index = index; | |
544 | return nr_found; | |
545 | } | |
546 | ||
547 | /** | |
548 | * radix_tree_gang_lookup - perform multiple lookup on a radix tree | |
549 | * @root: radix tree root | |
550 | * @results: where the results of the lookup are placed | |
551 | * @first_index: start the lookup from this key | |
552 | * @max_items: place up to this many items at *results | |
553 | * | |
554 | * Performs an index-ascending scan of the tree for present items. Places | |
555 | * them at *@results and returns the number of items which were placed at | |
556 | * *@results. | |
557 | * | |
558 | * The implementation is naive. | |
559 | */ | |
560 | unsigned int | |
561 | radix_tree_gang_lookup(struct radix_tree_root *root, void **results, | |
562 | unsigned long first_index, unsigned int max_items) | |
563 | { | |
564 | const unsigned long max_index = radix_tree_maxindex(root->height); | |
565 | unsigned long cur_index = first_index; | |
566 | unsigned int ret = 0; | |
567 | ||
568 | while (ret < max_items) { | |
569 | unsigned int nr_found; | |
570 | unsigned long next_index; /* Index of next search */ | |
571 | ||
572 | if (cur_index > max_index) | |
573 | break; | |
574 | nr_found = __lookup(root, results + ret, cur_index, | |
575 | max_items - ret, &next_index); | |
576 | ret += nr_found; | |
577 | if (next_index == 0) | |
578 | break; | |
579 | cur_index = next_index; | |
580 | } | |
581 | return ret; | |
582 | } | |
583 | EXPORT_SYMBOL(radix_tree_gang_lookup); | |
584 | ||
585 | /* | |
586 | * FIXME: the two tag_get()s here should use find_next_bit() instead of | |
587 | * open-coding the search. | |
588 | */ | |
589 | static unsigned int | |
590 | __lookup_tag(struct radix_tree_root *root, void **results, unsigned long index, | |
591 | unsigned int max_items, unsigned long *next_index, int tag) | |
592 | { | |
593 | unsigned int nr_found = 0; | |
594 | unsigned int shift; | |
595 | unsigned int height = root->height; | |
596 | struct radix_tree_node *slot; | |
597 | ||
598 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
599 | slot = root->rnode; | |
600 | ||
601 | while (height > 0) { | |
602 | unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK; | |
603 | ||
604 | for ( ; i < RADIX_TREE_MAP_SIZE; i++) { | |
605 | if (tag_get(slot, tag, i)) { | |
606 | BUG_ON(slot->slots[i] == NULL); | |
607 | break; | |
608 | } | |
609 | index &= ~((1UL << shift) - 1); | |
610 | index += 1UL << shift; | |
611 | if (index == 0) | |
612 | goto out; /* 32-bit wraparound */ | |
613 | } | |
614 | if (i == RADIX_TREE_MAP_SIZE) | |
615 | goto out; | |
616 | height--; | |
617 | if (height == 0) { /* Bottom level: grab some items */ | |
618 | unsigned long j = index & RADIX_TREE_MAP_MASK; | |
619 | ||
620 | for ( ; j < RADIX_TREE_MAP_SIZE; j++) { | |
621 | index++; | |
622 | if (tag_get(slot, tag, j)) { | |
623 | BUG_ON(slot->slots[j] == NULL); | |
624 | results[nr_found++] = slot->slots[j]; | |
625 | if (nr_found == max_items) | |
626 | goto out; | |
627 | } | |
628 | } | |
629 | } | |
630 | shift -= RADIX_TREE_MAP_SHIFT; | |
631 | slot = slot->slots[i]; | |
632 | } | |
633 | out: | |
634 | *next_index = index; | |
635 | return nr_found; | |
636 | } | |
637 | ||
638 | /** | |
639 | * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree | |
640 | * based on a tag | |
641 | * @root: radix tree root | |
642 | * @results: where the results of the lookup are placed | |
643 | * @first_index: start the lookup from this key | |
644 | * @max_items: place up to this many items at *results | |
645 | * @tag: the tag index | |
646 | * | |
647 | * Performs an index-ascending scan of the tree for present items which | |
648 | * have the tag indexed by @tag set. Places the items at *@results and | |
649 | * returns the number of items which were placed at *@results. | |
650 | */ | |
651 | unsigned int | |
652 | radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, | |
653 | unsigned long first_index, unsigned int max_items, int tag) | |
654 | { | |
655 | const unsigned long max_index = radix_tree_maxindex(root->height); | |
656 | unsigned long cur_index = first_index; | |
657 | unsigned int ret = 0; | |
658 | ||
659 | while (ret < max_items) { | |
660 | unsigned int nr_found; | |
661 | unsigned long next_index; /* Index of next search */ | |
662 | ||
663 | if (cur_index > max_index) | |
664 | break; | |
665 | nr_found = __lookup_tag(root, results + ret, cur_index, | |
666 | max_items - ret, &next_index, tag); | |
667 | ret += nr_found; | |
668 | if (next_index == 0) | |
669 | break; | |
670 | cur_index = next_index; | |
671 | } | |
672 | return ret; | |
673 | } | |
674 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag); | |
675 | ||
676 | /** | |
677 | * radix_tree_delete - delete an item from a radix tree | |
678 | * @root: radix tree root | |
679 | * @index: index key | |
680 | * | |
681 | * Remove the item at @index from the radix tree rooted at @root. | |
682 | * | |
683 | * Returns the address of the deleted item, or NULL if it was not present. | |
684 | */ | |
685 | void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) | |
686 | { | |
687 | struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path; | |
688 | struct radix_tree_path *orig_pathp; | |
201b6264 | 689 | struct radix_tree_node *slot; |
1da177e4 LT |
690 | unsigned int height, shift; |
691 | void *ret = NULL; | |
692 | char tags[RADIX_TREE_TAGS]; | |
693 | int nr_cleared_tags; | |
694 | ||
695 | height = root->height; | |
696 | if (index > radix_tree_maxindex(height)) | |
697 | goto out; | |
698 | ||
699 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
700 | pathp->node = NULL; | |
201b6264 | 701 | slot = root->rnode; |
1da177e4 | 702 | |
201b6264 | 703 | for ( ; height > 0; height--) { |
1da177e4 LT |
704 | int offset; |
705 | ||
201b6264 | 706 | if (slot == NULL) |
1da177e4 LT |
707 | goto out; |
708 | ||
709 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
710 | pathp[1].offset = offset; | |
201b6264 CL |
711 | pathp[1].node = slot; |
712 | slot = slot->slots[offset]; | |
1da177e4 LT |
713 | pathp++; |
714 | shift -= RADIX_TREE_MAP_SHIFT; | |
1da177e4 LT |
715 | } |
716 | ||
201b6264 | 717 | ret = slot; |
1da177e4 LT |
718 | if (ret == NULL) |
719 | goto out; | |
720 | ||
721 | orig_pathp = pathp; | |
722 | ||
723 | /* | |
724 | * Clear all tags associated with the just-deleted item | |
725 | */ | |
726 | memset(tags, 0, sizeof(tags)); | |
727 | do { | |
728 | int tag; | |
729 | ||
730 | nr_cleared_tags = RADIX_TREE_TAGS; | |
731 | for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { | |
732 | int idx; | |
733 | ||
734 | if (tags[tag]) | |
735 | continue; | |
736 | ||
201b6264 | 737 | tag_clear(pathp->node, tag, pathp->offset); |
1da177e4 LT |
738 | |
739 | for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { | |
201b6264 | 740 | if (pathp->node->tags[tag][idx]) { |
1da177e4 LT |
741 | tags[tag] = 1; |
742 | nr_cleared_tags--; | |
743 | break; | |
744 | } | |
745 | } | |
746 | } | |
747 | pathp--; | |
201b6264 | 748 | } while (pathp->node && nr_cleared_tags); |
1da177e4 | 749 | |
201b6264 CL |
750 | /* Now free the nodes we do not need anymore */ |
751 | for (pathp = orig_pathp; pathp->node; pathp--) { | |
752 | pathp->node->slots[pathp->offset] = NULL; | |
753 | if (--pathp->node->count) | |
754 | goto out; | |
755 | ||
756 | /* Node with zero slots in use so free it */ | |
757 | radix_tree_node_free(pathp->node); | |
1da177e4 | 758 | } |
201b6264 CL |
759 | root->rnode = NULL; |
760 | root->height = 0; | |
1da177e4 LT |
761 | out: |
762 | return ret; | |
763 | } | |
764 | EXPORT_SYMBOL(radix_tree_delete); | |
765 | ||
766 | /** | |
767 | * radix_tree_tagged - test whether any items in the tree are tagged | |
768 | * @root: radix tree root | |
769 | * @tag: tag to test | |
770 | */ | |
771 | int radix_tree_tagged(struct radix_tree_root *root, int tag) | |
772 | { | |
773 | int idx; | |
774 | ||
775 | if (!root->rnode) | |
776 | return 0; | |
777 | for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { | |
778 | if (root->rnode->tags[tag][idx]) | |
779 | return 1; | |
780 | } | |
781 | return 0; | |
782 | } | |
783 | EXPORT_SYMBOL(radix_tree_tagged); | |
784 | ||
785 | static void | |
786 | radix_tree_node_ctor(void *node, kmem_cache_t *cachep, unsigned long flags) | |
787 | { | |
788 | memset(node, 0, sizeof(struct radix_tree_node)); | |
789 | } | |
790 | ||
791 | static __init unsigned long __maxindex(unsigned int height) | |
792 | { | |
793 | unsigned int tmp = height * RADIX_TREE_MAP_SHIFT; | |
794 | unsigned long index = (~0UL >> (RADIX_TREE_INDEX_BITS - tmp - 1)) >> 1; | |
795 | ||
796 | if (tmp >= RADIX_TREE_INDEX_BITS) | |
797 | index = ~0UL; | |
798 | return index; | |
799 | } | |
800 | ||
801 | static __init void radix_tree_init_maxindex(void) | |
802 | { | |
803 | unsigned int i; | |
804 | ||
805 | for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++) | |
806 | height_to_maxindex[i] = __maxindex(i); | |
807 | } | |
808 | ||
809 | #ifdef CONFIG_HOTPLUG_CPU | |
810 | static int radix_tree_callback(struct notifier_block *nfb, | |
811 | unsigned long action, | |
812 | void *hcpu) | |
813 | { | |
814 | int cpu = (long)hcpu; | |
815 | struct radix_tree_preload *rtp; | |
816 | ||
817 | /* Free per-cpu pool of perloaded nodes */ | |
818 | if (action == CPU_DEAD) { | |
819 | rtp = &per_cpu(radix_tree_preloads, cpu); | |
820 | while (rtp->nr) { | |
821 | kmem_cache_free(radix_tree_node_cachep, | |
822 | rtp->nodes[rtp->nr-1]); | |
823 | rtp->nodes[rtp->nr-1] = NULL; | |
824 | rtp->nr--; | |
825 | } | |
826 | } | |
827 | return NOTIFY_OK; | |
828 | } | |
829 | #endif /* CONFIG_HOTPLUG_CPU */ | |
830 | ||
831 | void __init radix_tree_init(void) | |
832 | { | |
833 | radix_tree_node_cachep = kmem_cache_create("radix_tree_node", | |
834 | sizeof(struct radix_tree_node), 0, | |
835 | SLAB_PANIC, radix_tree_node_ctor, NULL); | |
836 | radix_tree_init_maxindex(); | |
837 | hotcpu_notifier(radix_tree_callback, 0); | |
838 | } |