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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; |
e2bdb933 HD |
51 | union { |
52 | struct radix_tree_node *parent; /* Used when ascending tree */ | |
53 | struct rcu_head rcu_head; /* Used when freeing node */ | |
54 | }; | |
a1115570 | 55 | void __rcu *slots[RADIX_TREE_MAP_SIZE]; |
daff89f3 | 56 | unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; |
1da177e4 LT |
57 | }; |
58 | ||
1da177e4 | 59 | #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) |
26fb1589 JM |
60 | #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \ |
61 | RADIX_TREE_MAP_SHIFT)) | |
1da177e4 | 62 | |
26fb1589 JM |
63 | /* |
64 | * The height_to_maxindex array needs to be one deeper than the maximum | |
65 | * path as height 0 holds only 1 entry. | |
66 | */ | |
67 | static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly; | |
1da177e4 LT |
68 | |
69 | /* | |
70 | * Radix tree node cache. | |
71 | */ | |
e18b890b | 72 | static struct kmem_cache *radix_tree_node_cachep; |
1da177e4 LT |
73 | |
74 | /* | |
75 | * Per-cpu pool of preloaded nodes | |
76 | */ | |
77 | struct radix_tree_preload { | |
78 | int nr; | |
79 | struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH]; | |
80 | }; | |
8cef7d57 | 81 | static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; |
1da177e4 | 82 | |
27d20fdd NP |
83 | static inline void *ptr_to_indirect(void *ptr) |
84 | { | |
85 | return (void *)((unsigned long)ptr | RADIX_TREE_INDIRECT_PTR); | |
86 | } | |
87 | ||
88 | static inline void *indirect_to_ptr(void *ptr) | |
89 | { | |
90 | return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR); | |
91 | } | |
92 | ||
612d6c19 NP |
93 | static inline gfp_t root_gfp_mask(struct radix_tree_root *root) |
94 | { | |
95 | return root->gfp_mask & __GFP_BITS_MASK; | |
96 | } | |
97 | ||
643b52b9 NP |
98 | static inline void tag_set(struct radix_tree_node *node, unsigned int tag, |
99 | int offset) | |
100 | { | |
101 | __set_bit(offset, node->tags[tag]); | |
102 | } | |
103 | ||
104 | static inline void tag_clear(struct radix_tree_node *node, unsigned int tag, | |
105 | int offset) | |
106 | { | |
107 | __clear_bit(offset, node->tags[tag]); | |
108 | } | |
109 | ||
110 | static inline int tag_get(struct radix_tree_node *node, unsigned int tag, | |
111 | int offset) | |
112 | { | |
113 | return test_bit(offset, node->tags[tag]); | |
114 | } | |
115 | ||
116 | static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag) | |
117 | { | |
118 | root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT)); | |
119 | } | |
120 | ||
121 | static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag) | |
122 | { | |
123 | root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT)); | |
124 | } | |
125 | ||
126 | static inline void root_tag_clear_all(struct radix_tree_root *root) | |
127 | { | |
128 | root->gfp_mask &= __GFP_BITS_MASK; | |
129 | } | |
130 | ||
131 | static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag) | |
132 | { | |
133 | return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT)); | |
134 | } | |
135 | ||
136 | /* | |
137 | * Returns 1 if any slot in the node has this tag set. | |
138 | * Otherwise returns 0. | |
139 | */ | |
140 | static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag) | |
141 | { | |
142 | int idx; | |
143 | for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { | |
144 | if (node->tags[tag][idx]) | |
145 | return 1; | |
146 | } | |
147 | return 0; | |
148 | } | |
1da177e4 LT |
149 | /* |
150 | * This assumes that the caller has performed appropriate preallocation, and | |
151 | * that the caller has pinned this thread of control to the current CPU. | |
152 | */ | |
153 | static struct radix_tree_node * | |
154 | radix_tree_node_alloc(struct radix_tree_root *root) | |
155 | { | |
e2848a0e | 156 | struct radix_tree_node *ret = NULL; |
612d6c19 | 157 | gfp_t gfp_mask = root_gfp_mask(root); |
1da177e4 | 158 | |
e2848a0e | 159 | if (!(gfp_mask & __GFP_WAIT)) { |
1da177e4 LT |
160 | struct radix_tree_preload *rtp; |
161 | ||
e2848a0e NP |
162 | /* |
163 | * Provided the caller has preloaded here, we will always | |
164 | * succeed in getting a node here (and never reach | |
165 | * kmem_cache_alloc) | |
166 | */ | |
1da177e4 LT |
167 | rtp = &__get_cpu_var(radix_tree_preloads); |
168 | if (rtp->nr) { | |
169 | ret = rtp->nodes[rtp->nr - 1]; | |
170 | rtp->nodes[rtp->nr - 1] = NULL; | |
171 | rtp->nr--; | |
172 | } | |
173 | } | |
e2848a0e | 174 | if (ret == NULL) |
488514d1 | 175 | ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
e2848a0e | 176 | |
c0bc9875 | 177 | BUG_ON(radix_tree_is_indirect_ptr(ret)); |
1da177e4 LT |
178 | return ret; |
179 | } | |
180 | ||
7cf9c2c7 NP |
181 | static void radix_tree_node_rcu_free(struct rcu_head *head) |
182 | { | |
183 | struct radix_tree_node *node = | |
184 | container_of(head, struct radix_tree_node, rcu_head); | |
b6dd0865 | 185 | int i; |
643b52b9 NP |
186 | |
187 | /* | |
188 | * must only free zeroed nodes into the slab. radix_tree_shrink | |
189 | * can leave us with a non-NULL entry in the first slot, so clear | |
190 | * that here to make sure. | |
191 | */ | |
b6dd0865 DC |
192 | for (i = 0; i < RADIX_TREE_MAX_TAGS; i++) |
193 | tag_clear(node, i, 0); | |
194 | ||
643b52b9 NP |
195 | node->slots[0] = NULL; |
196 | node->count = 0; | |
197 | ||
7cf9c2c7 NP |
198 | kmem_cache_free(radix_tree_node_cachep, node); |
199 | } | |
200 | ||
1da177e4 LT |
201 | static inline void |
202 | radix_tree_node_free(struct radix_tree_node *node) | |
203 | { | |
7cf9c2c7 | 204 | call_rcu(&node->rcu_head, radix_tree_node_rcu_free); |
1da177e4 LT |
205 | } |
206 | ||
207 | /* | |
208 | * Load up this CPU's radix_tree_node buffer with sufficient objects to | |
209 | * ensure that the addition of a single element in the tree cannot fail. On | |
210 | * success, return zero, with preemption disabled. On error, return -ENOMEM | |
211 | * with preemption not disabled. | |
b34df792 DH |
212 | * |
213 | * To make use of this facility, the radix tree must be initialised without | |
214 | * __GFP_WAIT being passed to INIT_RADIX_TREE(). | |
1da177e4 | 215 | */ |
dd0fc66f | 216 | int radix_tree_preload(gfp_t gfp_mask) |
1da177e4 LT |
217 | { |
218 | struct radix_tree_preload *rtp; | |
219 | struct radix_tree_node *node; | |
220 | int ret = -ENOMEM; | |
221 | ||
222 | preempt_disable(); | |
223 | rtp = &__get_cpu_var(radix_tree_preloads); | |
224 | while (rtp->nr < ARRAY_SIZE(rtp->nodes)) { | |
225 | preempt_enable(); | |
488514d1 | 226 | node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
1da177e4 LT |
227 | if (node == NULL) |
228 | goto out; | |
229 | preempt_disable(); | |
230 | rtp = &__get_cpu_var(radix_tree_preloads); | |
231 | if (rtp->nr < ARRAY_SIZE(rtp->nodes)) | |
232 | rtp->nodes[rtp->nr++] = node; | |
233 | else | |
234 | kmem_cache_free(radix_tree_node_cachep, node); | |
235 | } | |
236 | ret = 0; | |
237 | out: | |
238 | return ret; | |
239 | } | |
d7f0923d | 240 | EXPORT_SYMBOL(radix_tree_preload); |
1da177e4 | 241 | |
1da177e4 LT |
242 | /* |
243 | * Return the maximum key which can be store into a | |
244 | * radix tree with height HEIGHT. | |
245 | */ | |
246 | static inline unsigned long radix_tree_maxindex(unsigned int height) | |
247 | { | |
248 | return height_to_maxindex[height]; | |
249 | } | |
250 | ||
251 | /* | |
252 | * Extend a radix tree so it can store key @index. | |
253 | */ | |
254 | static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) | |
255 | { | |
256 | struct radix_tree_node *node; | |
e2bdb933 | 257 | struct radix_tree_node *slot; |
1da177e4 | 258 | unsigned int height; |
1da177e4 LT |
259 | int tag; |
260 | ||
261 | /* Figure out what the height should be. */ | |
262 | height = root->height + 1; | |
263 | while (index > radix_tree_maxindex(height)) | |
264 | height++; | |
265 | ||
266 | if (root->rnode == NULL) { | |
267 | root->height = height; | |
268 | goto out; | |
269 | } | |
270 | ||
1da177e4 | 271 | do { |
7cf9c2c7 | 272 | unsigned int newheight; |
1da177e4 LT |
273 | if (!(node = radix_tree_node_alloc(root))) |
274 | return -ENOMEM; | |
275 | ||
1da177e4 | 276 | /* Propagate the aggregated tag info into the new root */ |
daff89f3 | 277 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { |
612d6c19 | 278 | if (root_tag_get(root, tag)) |
1da177e4 LT |
279 | tag_set(node, tag, 0); |
280 | } | |
281 | ||
e2bdb933 | 282 | /* Increase the height. */ |
7cf9c2c7 NP |
283 | newheight = root->height+1; |
284 | node->height = newheight; | |
1da177e4 | 285 | node->count = 1; |
e2bdb933 HD |
286 | node->parent = NULL; |
287 | slot = root->rnode; | |
288 | if (newheight > 1) { | |
289 | slot = indirect_to_ptr(slot); | |
290 | slot->parent = node; | |
291 | } | |
292 | node->slots[0] = slot; | |
27d20fdd | 293 | node = ptr_to_indirect(node); |
7cf9c2c7 NP |
294 | rcu_assign_pointer(root->rnode, node); |
295 | root->height = newheight; | |
1da177e4 LT |
296 | } while (height > root->height); |
297 | out: | |
298 | return 0; | |
299 | } | |
300 | ||
301 | /** | |
302 | * radix_tree_insert - insert into a radix tree | |
303 | * @root: radix tree root | |
304 | * @index: index key | |
305 | * @item: item to insert | |
306 | * | |
307 | * Insert an item into the radix tree at position @index. | |
308 | */ | |
309 | int radix_tree_insert(struct radix_tree_root *root, | |
310 | unsigned long index, void *item) | |
311 | { | |
201b6264 | 312 | struct radix_tree_node *node = NULL, *slot; |
1da177e4 LT |
313 | unsigned int height, shift; |
314 | int offset; | |
315 | int error; | |
316 | ||
c0bc9875 | 317 | BUG_ON(radix_tree_is_indirect_ptr(item)); |
7cf9c2c7 | 318 | |
1da177e4 | 319 | /* Make sure the tree is high enough. */ |
612d6c19 | 320 | if (index > radix_tree_maxindex(root->height)) { |
1da177e4 LT |
321 | error = radix_tree_extend(root, index); |
322 | if (error) | |
323 | return error; | |
324 | } | |
325 | ||
27d20fdd | 326 | slot = indirect_to_ptr(root->rnode); |
c0bc9875 | 327 | |
1da177e4 LT |
328 | height = root->height; |
329 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
330 | ||
331 | offset = 0; /* uninitialised var warning */ | |
612d6c19 | 332 | while (height > 0) { |
201b6264 | 333 | if (slot == NULL) { |
1da177e4 | 334 | /* Have to add a child node. */ |
201b6264 | 335 | if (!(slot = radix_tree_node_alloc(root))) |
1da177e4 | 336 | return -ENOMEM; |
7cf9c2c7 | 337 | slot->height = height; |
e2bdb933 | 338 | slot->parent = node; |
201b6264 | 339 | if (node) { |
7cf9c2c7 | 340 | rcu_assign_pointer(node->slots[offset], slot); |
1da177e4 | 341 | node->count++; |
201b6264 | 342 | } else |
27d20fdd | 343 | rcu_assign_pointer(root->rnode, ptr_to_indirect(slot)); |
1da177e4 LT |
344 | } |
345 | ||
346 | /* Go a level down */ | |
347 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
201b6264 CL |
348 | node = slot; |
349 | slot = node->slots[offset]; | |
1da177e4 LT |
350 | shift -= RADIX_TREE_MAP_SHIFT; |
351 | height--; | |
612d6c19 | 352 | } |
1da177e4 | 353 | |
201b6264 | 354 | if (slot != NULL) |
1da177e4 | 355 | return -EEXIST; |
201b6264 | 356 | |
612d6c19 NP |
357 | if (node) { |
358 | node->count++; | |
7cf9c2c7 | 359 | rcu_assign_pointer(node->slots[offset], item); |
612d6c19 NP |
360 | BUG_ON(tag_get(node, 0, offset)); |
361 | BUG_ON(tag_get(node, 1, offset)); | |
362 | } else { | |
c0bc9875 | 363 | rcu_assign_pointer(root->rnode, item); |
612d6c19 NP |
364 | BUG_ON(root_tag_get(root, 0)); |
365 | BUG_ON(root_tag_get(root, 1)); | |
366 | } | |
1da177e4 | 367 | |
1da177e4 LT |
368 | return 0; |
369 | } | |
370 | EXPORT_SYMBOL(radix_tree_insert); | |
371 | ||
b72b71c6 HS |
372 | /* |
373 | * is_slot == 1 : search for the slot. | |
374 | * is_slot == 0 : search for the node. | |
7cf9c2c7 | 375 | */ |
b72b71c6 HS |
376 | static void *radix_tree_lookup_element(struct radix_tree_root *root, |
377 | unsigned long index, int is_slot) | |
1da177e4 LT |
378 | { |
379 | unsigned int height, shift; | |
7cf9c2c7 | 380 | struct radix_tree_node *node, **slot; |
612d6c19 | 381 | |
2676a58c | 382 | node = rcu_dereference_raw(root->rnode); |
7cf9c2c7 | 383 | if (node == NULL) |
1da177e4 LT |
384 | return NULL; |
385 | ||
c0bc9875 | 386 | if (!radix_tree_is_indirect_ptr(node)) { |
7cf9c2c7 NP |
387 | if (index > 0) |
388 | return NULL; | |
b72b71c6 | 389 | return is_slot ? (void *)&root->rnode : node; |
7cf9c2c7 | 390 | } |
27d20fdd | 391 | node = indirect_to_ptr(node); |
7cf9c2c7 NP |
392 | |
393 | height = node->height; | |
394 | if (index > radix_tree_maxindex(height)) | |
395 | return NULL; | |
612d6c19 | 396 | |
1da177e4 | 397 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 | 398 | |
7cf9c2c7 NP |
399 | do { |
400 | slot = (struct radix_tree_node **) | |
401 | (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); | |
2676a58c | 402 | node = rcu_dereference_raw(*slot); |
7cf9c2c7 | 403 | if (node == NULL) |
1da177e4 LT |
404 | return NULL; |
405 | ||
1da177e4 LT |
406 | shift -= RADIX_TREE_MAP_SHIFT; |
407 | height--; | |
7cf9c2c7 | 408 | } while (height > 0); |
1da177e4 | 409 | |
27d20fdd | 410 | return is_slot ? (void *)slot : indirect_to_ptr(node); |
b72b71c6 HS |
411 | } |
412 | ||
413 | /** | |
414 | * radix_tree_lookup_slot - lookup a slot in a radix tree | |
415 | * @root: radix tree root | |
416 | * @index: index key | |
417 | * | |
418 | * Returns: the slot corresponding to the position @index in the | |
419 | * radix tree @root. This is useful for update-if-exists operations. | |
420 | * | |
421 | * This function can be called under rcu_read_lock iff the slot is not | |
422 | * modified by radix_tree_replace_slot, otherwise it must be called | |
423 | * exclusive from other writers. Any dereference of the slot must be done | |
424 | * using radix_tree_deref_slot. | |
425 | */ | |
426 | void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) | |
427 | { | |
428 | return (void **)radix_tree_lookup_element(root, index, 1); | |
a4331366 | 429 | } |
a4331366 HR |
430 | EXPORT_SYMBOL(radix_tree_lookup_slot); |
431 | ||
432 | /** | |
433 | * radix_tree_lookup - perform lookup operation on a radix tree | |
434 | * @root: radix tree root | |
435 | * @index: index key | |
436 | * | |
437 | * Lookup the item at the position @index in the radix tree @root. | |
7cf9c2c7 NP |
438 | * |
439 | * This function can be called under rcu_read_lock, however the caller | |
440 | * must manage lifetimes of leaf nodes (eg. RCU may also be used to free | |
441 | * them safely). No RCU barriers are required to access or modify the | |
442 | * returned item, however. | |
a4331366 HR |
443 | */ |
444 | void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) | |
445 | { | |
b72b71c6 | 446 | return radix_tree_lookup_element(root, index, 0); |
1da177e4 LT |
447 | } |
448 | EXPORT_SYMBOL(radix_tree_lookup); | |
449 | ||
450 | /** | |
451 | * radix_tree_tag_set - set a tag on a radix tree node | |
452 | * @root: radix tree root | |
453 | * @index: index key | |
454 | * @tag: tag index | |
455 | * | |
daff89f3 JC |
456 | * Set the search tag (which must be < RADIX_TREE_MAX_TAGS) |
457 | * corresponding to @index in the radix tree. From | |
1da177e4 LT |
458 | * the root all the way down to the leaf node. |
459 | * | |
460 | * Returns the address of the tagged item. Setting a tag on a not-present | |
461 | * item is a bug. | |
462 | */ | |
463 | void *radix_tree_tag_set(struct radix_tree_root *root, | |
daff89f3 | 464 | unsigned long index, unsigned int tag) |
1da177e4 LT |
465 | { |
466 | unsigned int height, shift; | |
201b6264 | 467 | struct radix_tree_node *slot; |
1da177e4 LT |
468 | |
469 | height = root->height; | |
4c91c364 | 470 | BUG_ON(index > radix_tree_maxindex(height)); |
1da177e4 | 471 | |
27d20fdd | 472 | slot = indirect_to_ptr(root->rnode); |
612d6c19 | 473 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 LT |
474 | |
475 | while (height > 0) { | |
476 | int offset; | |
477 | ||
478 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
d5274261 NP |
479 | if (!tag_get(slot, tag, offset)) |
480 | tag_set(slot, tag, offset); | |
201b6264 CL |
481 | slot = slot->slots[offset]; |
482 | BUG_ON(slot == NULL); | |
1da177e4 LT |
483 | shift -= RADIX_TREE_MAP_SHIFT; |
484 | height--; | |
485 | } | |
486 | ||
612d6c19 NP |
487 | /* set the root's tag bit */ |
488 | if (slot && !root_tag_get(root, tag)) | |
489 | root_tag_set(root, tag); | |
490 | ||
201b6264 | 491 | return slot; |
1da177e4 LT |
492 | } |
493 | EXPORT_SYMBOL(radix_tree_tag_set); | |
494 | ||
495 | /** | |
496 | * radix_tree_tag_clear - clear a tag on a radix tree node | |
497 | * @root: radix tree root | |
498 | * @index: index key | |
499 | * @tag: tag index | |
500 | * | |
daff89f3 JC |
501 | * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS) |
502 | * corresponding to @index in the radix tree. If | |
1da177e4 LT |
503 | * this causes the leaf node to have no tags set then clear the tag in the |
504 | * next-to-leaf node, etc. | |
505 | * | |
506 | * Returns the address of the tagged item on success, else NULL. ie: | |
507 | * has the same return value and semantics as radix_tree_lookup(). | |
508 | */ | |
509 | void *radix_tree_tag_clear(struct radix_tree_root *root, | |
daff89f3 | 510 | unsigned long index, unsigned int tag) |
1da177e4 | 511 | { |
e2bdb933 | 512 | struct radix_tree_node *node = NULL; |
612d6c19 | 513 | struct radix_tree_node *slot = NULL; |
1da177e4 | 514 | unsigned int height, shift; |
e2bdb933 | 515 | int uninitialized_var(offset); |
1da177e4 LT |
516 | |
517 | height = root->height; | |
518 | if (index > radix_tree_maxindex(height)) | |
519 | goto out; | |
520 | ||
e2bdb933 | 521 | shift = height * RADIX_TREE_MAP_SHIFT; |
27d20fdd | 522 | slot = indirect_to_ptr(root->rnode); |
1da177e4 | 523 | |
e2bdb933 | 524 | while (shift) { |
201b6264 | 525 | if (slot == NULL) |
1da177e4 LT |
526 | goto out; |
527 | ||
e2bdb933 | 528 | shift -= RADIX_TREE_MAP_SHIFT; |
1da177e4 | 529 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; |
e2bdb933 | 530 | node = slot; |
201b6264 | 531 | slot = slot->slots[offset]; |
1da177e4 LT |
532 | } |
533 | ||
612d6c19 | 534 | if (slot == NULL) |
1da177e4 LT |
535 | goto out; |
536 | ||
e2bdb933 HD |
537 | while (node) { |
538 | if (!tag_get(node, tag, offset)) | |
d5274261 | 539 | goto out; |
e2bdb933 HD |
540 | tag_clear(node, tag, offset); |
541 | if (any_tag_set(node, tag)) | |
6e954b9e | 542 | goto out; |
e2bdb933 HD |
543 | |
544 | index >>= RADIX_TREE_MAP_SHIFT; | |
545 | offset = index & RADIX_TREE_MAP_MASK; | |
546 | node = node->parent; | |
612d6c19 NP |
547 | } |
548 | ||
549 | /* clear the root's tag bit */ | |
550 | if (root_tag_get(root, tag)) | |
551 | root_tag_clear(root, tag); | |
552 | ||
1da177e4 | 553 | out: |
612d6c19 | 554 | return slot; |
1da177e4 LT |
555 | } |
556 | EXPORT_SYMBOL(radix_tree_tag_clear); | |
557 | ||
1da177e4 | 558 | /** |
32605a18 MT |
559 | * radix_tree_tag_get - get a tag on a radix tree node |
560 | * @root: radix tree root | |
561 | * @index: index key | |
daff89f3 | 562 | * @tag: tag index (< RADIX_TREE_MAX_TAGS) |
1da177e4 | 563 | * |
32605a18 | 564 | * Return values: |
1da177e4 | 565 | * |
612d6c19 NP |
566 | * 0: tag not present or not set |
567 | * 1: tag set | |
ce82653d DH |
568 | * |
569 | * Note that the return value of this function may not be relied on, even if | |
570 | * the RCU lock is held, unless tag modification and node deletion are excluded | |
571 | * from concurrency. | |
1da177e4 LT |
572 | */ |
573 | int radix_tree_tag_get(struct radix_tree_root *root, | |
daff89f3 | 574 | unsigned long index, unsigned int tag) |
1da177e4 LT |
575 | { |
576 | unsigned int height, shift; | |
7cf9c2c7 | 577 | struct radix_tree_node *node; |
1da177e4 | 578 | |
612d6c19 NP |
579 | /* check the root's tag bit */ |
580 | if (!root_tag_get(root, tag)) | |
581 | return 0; | |
582 | ||
2676a58c | 583 | node = rcu_dereference_raw(root->rnode); |
7cf9c2c7 NP |
584 | if (node == NULL) |
585 | return 0; | |
586 | ||
c0bc9875 | 587 | if (!radix_tree_is_indirect_ptr(node)) |
7cf9c2c7 | 588 | return (index == 0); |
27d20fdd | 589 | node = indirect_to_ptr(node); |
7cf9c2c7 NP |
590 | |
591 | height = node->height; | |
592 | if (index > radix_tree_maxindex(height)) | |
593 | return 0; | |
612d6c19 | 594 | |
1da177e4 | 595 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 LT |
596 | |
597 | for ( ; ; ) { | |
598 | int offset; | |
599 | ||
7cf9c2c7 | 600 | if (node == NULL) |
1da177e4 LT |
601 | return 0; |
602 | ||
603 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
7cf9c2c7 | 604 | if (!tag_get(node, tag, offset)) |
3fa36acb | 605 | return 0; |
ce82653d | 606 | if (height == 1) |
3fa36acb | 607 | return 1; |
2676a58c | 608 | node = rcu_dereference_raw(node->slots[offset]); |
1da177e4 LT |
609 | shift -= RADIX_TREE_MAP_SHIFT; |
610 | height--; | |
611 | } | |
612 | } | |
613 | EXPORT_SYMBOL(radix_tree_tag_get); | |
1da177e4 | 614 | |
ebf8aa44 JK |
615 | /** |
616 | * radix_tree_range_tag_if_tagged - for each item in given range set given | |
617 | * tag if item has another tag set | |
618 | * @root: radix tree root | |
619 | * @first_indexp: pointer to a starting index of a range to scan | |
620 | * @last_index: last index of a range to scan | |
621 | * @nr_to_tag: maximum number items to tag | |
622 | * @iftag: tag index to test | |
623 | * @settag: tag index to set if tested tag is set | |
624 | * | |
625 | * This function scans range of radix tree from first_index to last_index | |
626 | * (inclusive). For each item in the range if iftag is set, the function sets | |
627 | * also settag. The function stops either after tagging nr_to_tag items or | |
628 | * after reaching last_index. | |
629 | * | |
144dcfc0 DC |
630 | * The tags must be set from the leaf level only and propagated back up the |
631 | * path to the root. We must do this so that we resolve the full path before | |
632 | * setting any tags on intermediate nodes. If we set tags as we descend, then | |
633 | * we can get to the leaf node and find that the index that has the iftag | |
634 | * set is outside the range we are scanning. This reults in dangling tags and | |
635 | * can lead to problems with later tag operations (e.g. livelocks on lookups). | |
636 | * | |
ebf8aa44 JK |
637 | * The function returns number of leaves where the tag was set and sets |
638 | * *first_indexp to the first unscanned index. | |
d5ed3a4a JK |
639 | * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must |
640 | * be prepared to handle that. | |
ebf8aa44 JK |
641 | */ |
642 | unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, | |
643 | unsigned long *first_indexp, unsigned long last_index, | |
644 | unsigned long nr_to_tag, | |
645 | unsigned int iftag, unsigned int settag) | |
646 | { | |
144dcfc0 | 647 | unsigned int height = root->height; |
e2bdb933 | 648 | struct radix_tree_node *node = NULL; |
144dcfc0 DC |
649 | struct radix_tree_node *slot; |
650 | unsigned int shift; | |
651 | unsigned long tagged = 0; | |
652 | unsigned long index = *first_indexp; | |
ebf8aa44 JK |
653 | |
654 | last_index = min(last_index, radix_tree_maxindex(height)); | |
655 | if (index > last_index) | |
656 | return 0; | |
657 | if (!nr_to_tag) | |
658 | return 0; | |
659 | if (!root_tag_get(root, iftag)) { | |
660 | *first_indexp = last_index + 1; | |
661 | return 0; | |
662 | } | |
663 | if (height == 0) { | |
664 | *first_indexp = last_index + 1; | |
665 | root_tag_set(root, settag); | |
666 | return 1; | |
667 | } | |
668 | ||
669 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
27d20fdd | 670 | slot = indirect_to_ptr(root->rnode); |
ebf8aa44 JK |
671 | |
672 | for (;;) { | |
e2bdb933 | 673 | unsigned long upindex; |
ebf8aa44 JK |
674 | int offset; |
675 | ||
676 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
677 | if (!slot->slots[offset]) | |
678 | goto next; | |
679 | if (!tag_get(slot, iftag, offset)) | |
680 | goto next; | |
e2bdb933 | 681 | if (shift) { |
144dcfc0 | 682 | /* Go down one level */ |
144dcfc0 | 683 | shift -= RADIX_TREE_MAP_SHIFT; |
e2bdb933 | 684 | node = slot; |
144dcfc0 DC |
685 | slot = slot->slots[offset]; |
686 | continue; | |
687 | } | |
688 | ||
689 | /* tag the leaf */ | |
690 | tagged++; | |
ebf8aa44 | 691 | tag_set(slot, settag, offset); |
144dcfc0 DC |
692 | |
693 | /* walk back up the path tagging interior nodes */ | |
e2bdb933 HD |
694 | upindex = index; |
695 | while (node) { | |
696 | upindex >>= RADIX_TREE_MAP_SHIFT; | |
697 | offset = upindex & RADIX_TREE_MAP_MASK; | |
698 | ||
144dcfc0 | 699 | /* stop if we find a node with the tag already set */ |
e2bdb933 | 700 | if (tag_get(node, settag, offset)) |
144dcfc0 | 701 | break; |
e2bdb933 HD |
702 | tag_set(node, settag, offset); |
703 | node = node->parent; | |
ebf8aa44 | 704 | } |
144dcfc0 | 705 | |
e2bdb933 HD |
706 | /* |
707 | * Small optimization: now clear that node pointer. | |
708 | * Since all of this slot's ancestors now have the tag set | |
709 | * from setting it above, we have no further need to walk | |
710 | * back up the tree setting tags, until we update slot to | |
711 | * point to another radix_tree_node. | |
712 | */ | |
713 | node = NULL; | |
714 | ||
ebf8aa44 JK |
715 | next: |
716 | /* Go to next item at level determined by 'shift' */ | |
717 | index = ((index >> shift) + 1) << shift; | |
d5ed3a4a JK |
718 | /* Overflow can happen when last_index is ~0UL... */ |
719 | if (index > last_index || !index) | |
ebf8aa44 JK |
720 | break; |
721 | if (tagged >= nr_to_tag) | |
722 | break; | |
723 | while (((index >> shift) & RADIX_TREE_MAP_MASK) == 0) { | |
724 | /* | |
725 | * We've fully scanned this node. Go up. Because | |
726 | * last_index is guaranteed to be in the tree, what | |
727 | * we do below cannot wander astray. | |
728 | */ | |
e2bdb933 | 729 | slot = slot->parent; |
ebf8aa44 JK |
730 | shift += RADIX_TREE_MAP_SHIFT; |
731 | } | |
732 | } | |
733 | /* | |
ac15ee69 TO |
734 | * We need not to tag the root tag if there is no tag which is set with |
735 | * settag within the range from *first_indexp to last_index. | |
ebf8aa44 | 736 | */ |
ac15ee69 TO |
737 | if (tagged > 0) |
738 | root_tag_set(root, settag); | |
ebf8aa44 JK |
739 | *first_indexp = index; |
740 | ||
741 | return tagged; | |
742 | } | |
743 | EXPORT_SYMBOL(radix_tree_range_tag_if_tagged); | |
744 | ||
745 | ||
6df8ba4f FW |
746 | /** |
747 | * radix_tree_next_hole - find the next hole (not-present entry) | |
748 | * @root: tree root | |
749 | * @index: index key | |
750 | * @max_scan: maximum range to search | |
751 | * | |
752 | * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest | |
753 | * indexed hole. | |
754 | * | |
755 | * Returns: the index of the hole if found, otherwise returns an index | |
756 | * outside of the set specified (in which case 'return - index >= max_scan' | |
8e6bdb7f | 757 | * will be true). In rare cases of index wrap-around, 0 will be returned. |
6df8ba4f FW |
758 | * |
759 | * radix_tree_next_hole may be called under rcu_read_lock. However, like | |
8e6bdb7f WF |
760 | * radix_tree_gang_lookup, this will not atomically search a snapshot of |
761 | * the tree at a single point in time. For example, if a hole is created | |
762 | * at index 5, then subsequently a hole is created at index 10, | |
763 | * radix_tree_next_hole covering both indexes may return 10 if called | |
764 | * under rcu_read_lock. | |
6df8ba4f FW |
765 | */ |
766 | unsigned long radix_tree_next_hole(struct radix_tree_root *root, | |
767 | unsigned long index, unsigned long max_scan) | |
768 | { | |
769 | unsigned long i; | |
770 | ||
771 | for (i = 0; i < max_scan; i++) { | |
772 | if (!radix_tree_lookup(root, index)) | |
773 | break; | |
774 | index++; | |
775 | if (index == 0) | |
776 | break; | |
777 | } | |
778 | ||
779 | return index; | |
780 | } | |
781 | EXPORT_SYMBOL(radix_tree_next_hole); | |
782 | ||
dc566127 WF |
783 | /** |
784 | * radix_tree_prev_hole - find the prev hole (not-present entry) | |
785 | * @root: tree root | |
786 | * @index: index key | |
787 | * @max_scan: maximum range to search | |
788 | * | |
789 | * Search backwards in the range [max(index-max_scan+1, 0), index] | |
790 | * for the first hole. | |
791 | * | |
792 | * Returns: the index of the hole if found, otherwise returns an index | |
793 | * outside of the set specified (in which case 'index - return >= max_scan' | |
edcd1d84 | 794 | * will be true). In rare cases of wrap-around, ULONG_MAX will be returned. |
dc566127 WF |
795 | * |
796 | * radix_tree_next_hole may be called under rcu_read_lock. However, like | |
797 | * radix_tree_gang_lookup, this will not atomically search a snapshot of | |
798 | * the tree at a single point in time. For example, if a hole is created | |
799 | * at index 10, then subsequently a hole is created at index 5, | |
800 | * radix_tree_prev_hole covering both indexes may return 5 if called under | |
801 | * rcu_read_lock. | |
802 | */ | |
803 | unsigned long radix_tree_prev_hole(struct radix_tree_root *root, | |
804 | unsigned long index, unsigned long max_scan) | |
805 | { | |
806 | unsigned long i; | |
807 | ||
808 | for (i = 0; i < max_scan; i++) { | |
809 | if (!radix_tree_lookup(root, index)) | |
810 | break; | |
811 | index--; | |
edcd1d84 | 812 | if (index == ULONG_MAX) |
dc566127 WF |
813 | break; |
814 | } | |
815 | ||
816 | return index; | |
817 | } | |
818 | EXPORT_SYMBOL(radix_tree_prev_hole); | |
819 | ||
1da177e4 | 820 | static unsigned int |
6328650b HD |
821 | __lookup(struct radix_tree_node *slot, void ***results, unsigned long *indices, |
822 | unsigned long index, unsigned int max_items, unsigned long *next_index) | |
1da177e4 LT |
823 | { |
824 | unsigned int nr_found = 0; | |
201b6264 | 825 | unsigned int shift, height; |
201b6264 CL |
826 | unsigned long i; |
827 | ||
7cf9c2c7 NP |
828 | height = slot->height; |
829 | if (height == 0) | |
201b6264 | 830 | goto out; |
1da177e4 | 831 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 | 832 | |
201b6264 | 833 | for ( ; height > 1; height--) { |
7cf9c2c7 NP |
834 | i = (index >> shift) & RADIX_TREE_MAP_MASK; |
835 | for (;;) { | |
1da177e4 LT |
836 | if (slot->slots[i] != NULL) |
837 | break; | |
838 | index &= ~((1UL << shift) - 1); | |
839 | index += 1UL << shift; | |
840 | if (index == 0) | |
841 | goto out; /* 32-bit wraparound */ | |
7cf9c2c7 NP |
842 | i++; |
843 | if (i == RADIX_TREE_MAP_SIZE) | |
844 | goto out; | |
1da177e4 | 845 | } |
1da177e4 | 846 | |
1da177e4 | 847 | shift -= RADIX_TREE_MAP_SHIFT; |
2676a58c | 848 | slot = rcu_dereference_raw(slot->slots[i]); |
7cf9c2c7 NP |
849 | if (slot == NULL) |
850 | goto out; | |
1da177e4 | 851 | } |
201b6264 CL |
852 | |
853 | /* Bottom level: grab some items */ | |
854 | for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) { | |
47feff2c | 855 | if (slot->slots[i]) { |
6328650b HD |
856 | results[nr_found] = &(slot->slots[i]); |
857 | if (indices) | |
858 | indices[nr_found] = index; | |
859 | if (++nr_found == max_items) { | |
860 | index++; | |
201b6264 | 861 | goto out; |
6328650b | 862 | } |
201b6264 | 863 | } |
6328650b | 864 | index++; |
201b6264 | 865 | } |
1da177e4 LT |
866 | out: |
867 | *next_index = index; | |
868 | return nr_found; | |
869 | } | |
870 | ||
871 | /** | |
872 | * radix_tree_gang_lookup - perform multiple lookup on a radix tree | |
873 | * @root: radix tree root | |
874 | * @results: where the results of the lookup are placed | |
875 | * @first_index: start the lookup from this key | |
876 | * @max_items: place up to this many items at *results | |
877 | * | |
878 | * Performs an index-ascending scan of the tree for present items. Places | |
879 | * them at *@results and returns the number of items which were placed at | |
880 | * *@results. | |
881 | * | |
882 | * The implementation is naive. | |
7cf9c2c7 NP |
883 | * |
884 | * Like radix_tree_lookup, radix_tree_gang_lookup may be called under | |
885 | * rcu_read_lock. In this case, rather than the returned results being | |
886 | * an atomic snapshot of the tree at a single point in time, the semantics | |
887 | * of an RCU protected gang lookup are as though multiple radix_tree_lookups | |
888 | * have been issued in individual locks, and results stored in 'results'. | |
1da177e4 LT |
889 | */ |
890 | unsigned int | |
891 | radix_tree_gang_lookup(struct radix_tree_root *root, void **results, | |
892 | unsigned long first_index, unsigned int max_items) | |
893 | { | |
7cf9c2c7 NP |
894 | unsigned long max_index; |
895 | struct radix_tree_node *node; | |
1da177e4 | 896 | unsigned long cur_index = first_index; |
7cf9c2c7 NP |
897 | unsigned int ret; |
898 | ||
2676a58c | 899 | node = rcu_dereference_raw(root->rnode); |
7cf9c2c7 NP |
900 | if (!node) |
901 | return 0; | |
1da177e4 | 902 | |
c0bc9875 | 903 | if (!radix_tree_is_indirect_ptr(node)) { |
7cf9c2c7 NP |
904 | if (first_index > 0) |
905 | return 0; | |
c0bc9875 | 906 | results[0] = node; |
7cf9c2c7 NP |
907 | return 1; |
908 | } | |
27d20fdd | 909 | node = indirect_to_ptr(node); |
7cf9c2c7 NP |
910 | |
911 | max_index = radix_tree_maxindex(node->height); | |
912 | ||
913 | ret = 0; | |
1da177e4 | 914 | while (ret < max_items) { |
47feff2c | 915 | unsigned int nr_found, slots_found, i; |
1da177e4 LT |
916 | unsigned long next_index; /* Index of next search */ |
917 | ||
918 | if (cur_index > max_index) | |
919 | break; | |
6328650b HD |
920 | slots_found = __lookup(node, (void ***)results + ret, NULL, |
921 | cur_index, max_items - ret, &next_index); | |
47feff2c NP |
922 | nr_found = 0; |
923 | for (i = 0; i < slots_found; i++) { | |
924 | struct radix_tree_node *slot; | |
925 | slot = *(((void ***)results)[ret + i]); | |
926 | if (!slot) | |
927 | continue; | |
27d20fdd NP |
928 | results[ret + nr_found] = |
929 | indirect_to_ptr(rcu_dereference_raw(slot)); | |
47feff2c NP |
930 | nr_found++; |
931 | } | |
1da177e4 LT |
932 | ret += nr_found; |
933 | if (next_index == 0) | |
934 | break; | |
935 | cur_index = next_index; | |
936 | } | |
7cf9c2c7 | 937 | |
1da177e4 LT |
938 | return ret; |
939 | } | |
940 | EXPORT_SYMBOL(radix_tree_gang_lookup); | |
941 | ||
47feff2c NP |
942 | /** |
943 | * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree | |
944 | * @root: radix tree root | |
945 | * @results: where the results of the lookup are placed | |
6328650b | 946 | * @indices: where their indices should be placed (but usually NULL) |
47feff2c NP |
947 | * @first_index: start the lookup from this key |
948 | * @max_items: place up to this many items at *results | |
949 | * | |
950 | * Performs an index-ascending scan of the tree for present items. Places | |
951 | * their slots at *@results and returns the number of items which were | |
952 | * placed at *@results. | |
953 | * | |
954 | * The implementation is naive. | |
955 | * | |
956 | * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must | |
957 | * be dereferenced with radix_tree_deref_slot, and if using only RCU | |
958 | * protection, radix_tree_deref_slot may fail requiring a retry. | |
959 | */ | |
960 | unsigned int | |
6328650b HD |
961 | radix_tree_gang_lookup_slot(struct radix_tree_root *root, |
962 | void ***results, unsigned long *indices, | |
47feff2c NP |
963 | unsigned long first_index, unsigned int max_items) |
964 | { | |
965 | unsigned long max_index; | |
966 | struct radix_tree_node *node; | |
967 | unsigned long cur_index = first_index; | |
968 | unsigned int ret; | |
969 | ||
2676a58c | 970 | node = rcu_dereference_raw(root->rnode); |
47feff2c NP |
971 | if (!node) |
972 | return 0; | |
973 | ||
974 | if (!radix_tree_is_indirect_ptr(node)) { | |
975 | if (first_index > 0) | |
976 | return 0; | |
977 | results[0] = (void **)&root->rnode; | |
6328650b HD |
978 | if (indices) |
979 | indices[0] = 0; | |
47feff2c NP |
980 | return 1; |
981 | } | |
27d20fdd | 982 | node = indirect_to_ptr(node); |
47feff2c NP |
983 | |
984 | max_index = radix_tree_maxindex(node->height); | |
985 | ||
986 | ret = 0; | |
987 | while (ret < max_items) { | |
988 | unsigned int slots_found; | |
989 | unsigned long next_index; /* Index of next search */ | |
990 | ||
991 | if (cur_index > max_index) | |
992 | break; | |
6328650b HD |
993 | slots_found = __lookup(node, results + ret, |
994 | indices ? indices + ret : NULL, | |
995 | cur_index, max_items - ret, &next_index); | |
47feff2c NP |
996 | ret += slots_found; |
997 | if (next_index == 0) | |
998 | break; | |
999 | cur_index = next_index; | |
1000 | } | |
1001 | ||
1002 | return ret; | |
1003 | } | |
1004 | EXPORT_SYMBOL(radix_tree_gang_lookup_slot); | |
1005 | ||
1da177e4 LT |
1006 | /* |
1007 | * FIXME: the two tag_get()s here should use find_next_bit() instead of | |
1008 | * open-coding the search. | |
1009 | */ | |
1010 | static unsigned int | |
47feff2c | 1011 | __lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index, |
daff89f3 | 1012 | unsigned int max_items, unsigned long *next_index, unsigned int tag) |
1da177e4 LT |
1013 | { |
1014 | unsigned int nr_found = 0; | |
7cf9c2c7 | 1015 | unsigned int shift, height; |
1da177e4 | 1016 | |
7cf9c2c7 NP |
1017 | height = slot->height; |
1018 | if (height == 0) | |
612d6c19 | 1019 | goto out; |
7cf9c2c7 | 1020 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 | 1021 | |
7cf9c2c7 NP |
1022 | while (height > 0) { |
1023 | unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ; | |
1da177e4 | 1024 | |
7cf9c2c7 NP |
1025 | for (;;) { |
1026 | if (tag_get(slot, tag, i)) | |
1da177e4 | 1027 | break; |
1da177e4 LT |
1028 | index &= ~((1UL << shift) - 1); |
1029 | index += 1UL << shift; | |
1030 | if (index == 0) | |
1031 | goto out; /* 32-bit wraparound */ | |
7cf9c2c7 NP |
1032 | i++; |
1033 | if (i == RADIX_TREE_MAP_SIZE) | |
1034 | goto out; | |
1da177e4 | 1035 | } |
1da177e4 LT |
1036 | height--; |
1037 | if (height == 0) { /* Bottom level: grab some items */ | |
1038 | unsigned long j = index & RADIX_TREE_MAP_MASK; | |
1039 | ||
1040 | for ( ; j < RADIX_TREE_MAP_SIZE; j++) { | |
1041 | index++; | |
7cf9c2c7 NP |
1042 | if (!tag_get(slot, tag, j)) |
1043 | continue; | |
7cf9c2c7 NP |
1044 | /* |
1045 | * Even though the tag was found set, we need to | |
1046 | * recheck that we have a non-NULL node, because | |
1047 | * if this lookup is lockless, it may have been | |
1048 | * subsequently deleted. | |
1049 | * | |
1050 | * Similar care must be taken in any place that | |
1051 | * lookup ->slots[x] without a lock (ie. can't | |
1052 | * rely on its value remaining the same). | |
1053 | */ | |
47feff2c NP |
1054 | if (slot->slots[j]) { |
1055 | results[nr_found++] = &(slot->slots[j]); | |
1da177e4 LT |
1056 | if (nr_found == max_items) |
1057 | goto out; | |
1058 | } | |
1059 | } | |
1060 | } | |
1061 | shift -= RADIX_TREE_MAP_SHIFT; | |
2676a58c | 1062 | slot = rcu_dereference_raw(slot->slots[i]); |
7cf9c2c7 NP |
1063 | if (slot == NULL) |
1064 | break; | |
1065 | } | |
1da177e4 LT |
1066 | out: |
1067 | *next_index = index; | |
1068 | return nr_found; | |
1069 | } | |
1070 | ||
1071 | /** | |
1072 | * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree | |
1073 | * based on a tag | |
1074 | * @root: radix tree root | |
1075 | * @results: where the results of the lookup are placed | |
1076 | * @first_index: start the lookup from this key | |
1077 | * @max_items: place up to this many items at *results | |
daff89f3 | 1078 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) |
1da177e4 LT |
1079 | * |
1080 | * Performs an index-ascending scan of the tree for present items which | |
1081 | * have the tag indexed by @tag set. Places the items at *@results and | |
1082 | * returns the number of items which were placed at *@results. | |
1083 | */ | |
1084 | unsigned int | |
1085 | radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, | |
daff89f3 JC |
1086 | unsigned long first_index, unsigned int max_items, |
1087 | unsigned int tag) | |
1da177e4 | 1088 | { |
7cf9c2c7 NP |
1089 | struct radix_tree_node *node; |
1090 | unsigned long max_index; | |
1da177e4 | 1091 | unsigned long cur_index = first_index; |
7cf9c2c7 | 1092 | unsigned int ret; |
1da177e4 | 1093 | |
612d6c19 NP |
1094 | /* check the root's tag bit */ |
1095 | if (!root_tag_get(root, tag)) | |
1096 | return 0; | |
1097 | ||
2676a58c | 1098 | node = rcu_dereference_raw(root->rnode); |
7cf9c2c7 NP |
1099 | if (!node) |
1100 | return 0; | |
1101 | ||
c0bc9875 | 1102 | if (!radix_tree_is_indirect_ptr(node)) { |
7cf9c2c7 NP |
1103 | if (first_index > 0) |
1104 | return 0; | |
c0bc9875 | 1105 | results[0] = node; |
7cf9c2c7 NP |
1106 | return 1; |
1107 | } | |
27d20fdd | 1108 | node = indirect_to_ptr(node); |
7cf9c2c7 NP |
1109 | |
1110 | max_index = radix_tree_maxindex(node->height); | |
1111 | ||
1112 | ret = 0; | |
1da177e4 | 1113 | while (ret < max_items) { |
47feff2c | 1114 | unsigned int nr_found, slots_found, i; |
1da177e4 LT |
1115 | unsigned long next_index; /* Index of next search */ |
1116 | ||
1117 | if (cur_index > max_index) | |
1118 | break; | |
47feff2c NP |
1119 | slots_found = __lookup_tag(node, (void ***)results + ret, |
1120 | cur_index, max_items - ret, &next_index, tag); | |
1121 | nr_found = 0; | |
1122 | for (i = 0; i < slots_found; i++) { | |
1123 | struct radix_tree_node *slot; | |
1124 | slot = *(((void ***)results)[ret + i]); | |
1125 | if (!slot) | |
1126 | continue; | |
27d20fdd NP |
1127 | results[ret + nr_found] = |
1128 | indirect_to_ptr(rcu_dereference_raw(slot)); | |
47feff2c NP |
1129 | nr_found++; |
1130 | } | |
1da177e4 LT |
1131 | ret += nr_found; |
1132 | if (next_index == 0) | |
1133 | break; | |
1134 | cur_index = next_index; | |
1135 | } | |
7cf9c2c7 | 1136 | |
1da177e4 LT |
1137 | return ret; |
1138 | } | |
1139 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag); | |
1140 | ||
47feff2c NP |
1141 | /** |
1142 | * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a | |
1143 | * radix tree based on a tag | |
1144 | * @root: radix tree root | |
1145 | * @results: where the results of the lookup are placed | |
1146 | * @first_index: start the lookup from this key | |
1147 | * @max_items: place up to this many items at *results | |
1148 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) | |
1149 | * | |
1150 | * Performs an index-ascending scan of the tree for present items which | |
1151 | * have the tag indexed by @tag set. Places the slots at *@results and | |
1152 | * returns the number of slots which were placed at *@results. | |
1153 | */ | |
1154 | unsigned int | |
1155 | radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, | |
1156 | unsigned long first_index, unsigned int max_items, | |
1157 | unsigned int tag) | |
1158 | { | |
1159 | struct radix_tree_node *node; | |
1160 | unsigned long max_index; | |
1161 | unsigned long cur_index = first_index; | |
1162 | unsigned int ret; | |
1163 | ||
1164 | /* check the root's tag bit */ | |
1165 | if (!root_tag_get(root, tag)) | |
1166 | return 0; | |
1167 | ||
2676a58c | 1168 | node = rcu_dereference_raw(root->rnode); |
47feff2c NP |
1169 | if (!node) |
1170 | return 0; | |
1171 | ||
1172 | if (!radix_tree_is_indirect_ptr(node)) { | |
1173 | if (first_index > 0) | |
1174 | return 0; | |
1175 | results[0] = (void **)&root->rnode; | |
1176 | return 1; | |
1177 | } | |
27d20fdd | 1178 | node = indirect_to_ptr(node); |
47feff2c NP |
1179 | |
1180 | max_index = radix_tree_maxindex(node->height); | |
1181 | ||
1182 | ret = 0; | |
1183 | while (ret < max_items) { | |
1184 | unsigned int slots_found; | |
1185 | unsigned long next_index; /* Index of next search */ | |
1186 | ||
1187 | if (cur_index > max_index) | |
1188 | break; | |
1189 | slots_found = __lookup_tag(node, results + ret, | |
1190 | cur_index, max_items - ret, &next_index, tag); | |
1191 | ret += slots_found; | |
1192 | if (next_index == 0) | |
1193 | break; | |
1194 | cur_index = next_index; | |
1195 | } | |
1196 | ||
1197 | return ret; | |
1198 | } | |
1199 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); | |
1200 | ||
e504f3fd HD |
1201 | #if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP) |
1202 | #include <linux/sched.h> /* for cond_resched() */ | |
1203 | ||
1204 | /* | |
1205 | * This linear search is at present only useful to shmem_unuse_inode(). | |
1206 | */ | |
1207 | static unsigned long __locate(struct radix_tree_node *slot, void *item, | |
1208 | unsigned long index, unsigned long *found_index) | |
1209 | { | |
1210 | unsigned int shift, height; | |
1211 | unsigned long i; | |
1212 | ||
1213 | height = slot->height; | |
1214 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
1215 | ||
1216 | for ( ; height > 1; height--) { | |
1217 | i = (index >> shift) & RADIX_TREE_MAP_MASK; | |
1218 | for (;;) { | |
1219 | if (slot->slots[i] != NULL) | |
1220 | break; | |
1221 | index &= ~((1UL << shift) - 1); | |
1222 | index += 1UL << shift; | |
1223 | if (index == 0) | |
1224 | goto out; /* 32-bit wraparound */ | |
1225 | i++; | |
1226 | if (i == RADIX_TREE_MAP_SIZE) | |
1227 | goto out; | |
1228 | } | |
1229 | ||
1230 | shift -= RADIX_TREE_MAP_SHIFT; | |
1231 | slot = rcu_dereference_raw(slot->slots[i]); | |
1232 | if (slot == NULL) | |
1233 | goto out; | |
1234 | } | |
1235 | ||
1236 | /* Bottom level: check items */ | |
1237 | for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) { | |
1238 | if (slot->slots[i] == item) { | |
1239 | *found_index = index + i; | |
1240 | index = 0; | |
1241 | goto out; | |
1242 | } | |
1243 | } | |
1244 | index += RADIX_TREE_MAP_SIZE; | |
1245 | out: | |
1246 | return index; | |
1247 | } | |
1248 | ||
1249 | /** | |
1250 | * radix_tree_locate_item - search through radix tree for item | |
1251 | * @root: radix tree root | |
1252 | * @item: item to be found | |
1253 | * | |
1254 | * Returns index where item was found, or -1 if not found. | |
1255 | * Caller must hold no lock (since this time-consuming function needs | |
1256 | * to be preemptible), and must check afterwards if item is still there. | |
1257 | */ | |
1258 | unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) | |
1259 | { | |
1260 | struct radix_tree_node *node; | |
1261 | unsigned long max_index; | |
1262 | unsigned long cur_index = 0; | |
1263 | unsigned long found_index = -1; | |
1264 | ||
1265 | do { | |
1266 | rcu_read_lock(); | |
1267 | node = rcu_dereference_raw(root->rnode); | |
1268 | if (!radix_tree_is_indirect_ptr(node)) { | |
1269 | rcu_read_unlock(); | |
1270 | if (node == item) | |
1271 | found_index = 0; | |
1272 | break; | |
1273 | } | |
1274 | ||
1275 | node = indirect_to_ptr(node); | |
1276 | max_index = radix_tree_maxindex(node->height); | |
1277 | if (cur_index > max_index) | |
1278 | break; | |
1279 | ||
1280 | cur_index = __locate(node, item, cur_index, &found_index); | |
1281 | rcu_read_unlock(); | |
1282 | cond_resched(); | |
1283 | } while (cur_index != 0 && cur_index <= max_index); | |
1284 | ||
1285 | return found_index; | |
1286 | } | |
1287 | #else | |
1288 | unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) | |
1289 | { | |
1290 | return -1; | |
1291 | } | |
1292 | #endif /* CONFIG_SHMEM && CONFIG_SWAP */ | |
47feff2c | 1293 | |
a5f51c96 NP |
1294 | /** |
1295 | * radix_tree_shrink - shrink height of a radix tree to minimal | |
1296 | * @root radix tree root | |
1297 | */ | |
1298 | static inline void radix_tree_shrink(struct radix_tree_root *root) | |
1299 | { | |
1300 | /* try to shrink tree height */ | |
c0bc9875 | 1301 | while (root->height > 0) { |
a5f51c96 | 1302 | struct radix_tree_node *to_free = root->rnode; |
e2bdb933 | 1303 | struct radix_tree_node *slot; |
a5f51c96 | 1304 | |
c0bc9875 | 1305 | BUG_ON(!radix_tree_is_indirect_ptr(to_free)); |
27d20fdd | 1306 | to_free = indirect_to_ptr(to_free); |
c0bc9875 NP |
1307 | |
1308 | /* | |
1309 | * The candidate node has more than one child, or its child | |
1310 | * is not at the leftmost slot, we cannot shrink. | |
1311 | */ | |
1312 | if (to_free->count != 1) | |
1313 | break; | |
1314 | if (!to_free->slots[0]) | |
1315 | break; | |
1316 | ||
7cf9c2c7 NP |
1317 | /* |
1318 | * We don't need rcu_assign_pointer(), since we are simply | |
27d20fdd NP |
1319 | * moving the node from one part of the tree to another: if it |
1320 | * was safe to dereference the old pointer to it | |
7cf9c2c7 | 1321 | * (to_free->slots[0]), it will be safe to dereference the new |
27d20fdd | 1322 | * one (root->rnode) as far as dependent read barriers go. |
7cf9c2c7 | 1323 | */ |
e2bdb933 HD |
1324 | slot = to_free->slots[0]; |
1325 | if (root->height > 1) { | |
1326 | slot->parent = NULL; | |
1327 | slot = ptr_to_indirect(slot); | |
1328 | } | |
1329 | root->rnode = slot; | |
a5f51c96 | 1330 | root->height--; |
27d20fdd NP |
1331 | |
1332 | /* | |
1333 | * We have a dilemma here. The node's slot[0] must not be | |
1334 | * NULLed in case there are concurrent lookups expecting to | |
1335 | * find the item. However if this was a bottom-level node, | |
1336 | * then it may be subject to the slot pointer being visible | |
1337 | * to callers dereferencing it. If item corresponding to | |
1338 | * slot[0] is subsequently deleted, these callers would expect | |
1339 | * their slot to become empty sooner or later. | |
1340 | * | |
1341 | * For example, lockless pagecache will look up a slot, deref | |
1342 | * the page pointer, and if the page is 0 refcount it means it | |
1343 | * was concurrently deleted from pagecache so try the deref | |
1344 | * again. Fortunately there is already a requirement for logic | |
1345 | * to retry the entire slot lookup -- the indirect pointer | |
1346 | * problem (replacing direct root node with an indirect pointer | |
1347 | * also results in a stale slot). So tag the slot as indirect | |
1348 | * to force callers to retry. | |
1349 | */ | |
1350 | if (root->height == 0) | |
1351 | *((unsigned long *)&to_free->slots[0]) |= | |
1352 | RADIX_TREE_INDIRECT_PTR; | |
1353 | ||
a5f51c96 NP |
1354 | radix_tree_node_free(to_free); |
1355 | } | |
1356 | } | |
1357 | ||
1da177e4 LT |
1358 | /** |
1359 | * radix_tree_delete - delete an item from a radix tree | |
1360 | * @root: radix tree root | |
1361 | * @index: index key | |
1362 | * | |
1363 | * Remove the item at @index from the radix tree rooted at @root. | |
1364 | * | |
1365 | * Returns the address of the deleted item, or NULL if it was not present. | |
1366 | */ | |
1367 | void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) | |
1368 | { | |
e2bdb933 | 1369 | struct radix_tree_node *node = NULL; |
612d6c19 | 1370 | struct radix_tree_node *slot = NULL; |
7cf9c2c7 | 1371 | struct radix_tree_node *to_free; |
1da177e4 | 1372 | unsigned int height, shift; |
d5274261 | 1373 | int tag; |
e2bdb933 | 1374 | int uninitialized_var(offset); |
1da177e4 LT |
1375 | |
1376 | height = root->height; | |
1377 | if (index > radix_tree_maxindex(height)) | |
1378 | goto out; | |
1379 | ||
612d6c19 | 1380 | slot = root->rnode; |
c0bc9875 | 1381 | if (height == 0) { |
612d6c19 NP |
1382 | root_tag_clear_all(root); |
1383 | root->rnode = NULL; | |
1384 | goto out; | |
1385 | } | |
27d20fdd | 1386 | slot = indirect_to_ptr(slot); |
e2bdb933 | 1387 | shift = height * RADIX_TREE_MAP_SHIFT; |
1da177e4 | 1388 | |
612d6c19 | 1389 | do { |
201b6264 | 1390 | if (slot == NULL) |
1da177e4 LT |
1391 | goto out; |
1392 | ||
e2bdb933 | 1393 | shift -= RADIX_TREE_MAP_SHIFT; |
1da177e4 | 1394 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; |
e2bdb933 | 1395 | node = slot; |
201b6264 | 1396 | slot = slot->slots[offset]; |
e2bdb933 | 1397 | } while (shift); |
1da177e4 | 1398 | |
612d6c19 | 1399 | if (slot == NULL) |
1da177e4 LT |
1400 | goto out; |
1401 | ||
1da177e4 | 1402 | /* |
e2bdb933 HD |
1403 | * Clear all tags associated with the item to be deleted. |
1404 | * This way of doing it would be inefficient, but seldom is any set. | |
1da177e4 | 1405 | */ |
daff89f3 | 1406 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { |
e2bdb933 | 1407 | if (tag_get(node, tag, offset)) |
612d6c19 | 1408 | radix_tree_tag_clear(root, index, tag); |
d5274261 | 1409 | } |
1da177e4 | 1410 | |
7cf9c2c7 | 1411 | to_free = NULL; |
201b6264 | 1412 | /* Now free the nodes we do not need anymore */ |
e2bdb933 HD |
1413 | while (node) { |
1414 | node->slots[offset] = NULL; | |
1415 | node->count--; | |
7cf9c2c7 NP |
1416 | /* |
1417 | * Queue the node for deferred freeing after the | |
1418 | * last reference to it disappears (set NULL, above). | |
1419 | */ | |
1420 | if (to_free) | |
1421 | radix_tree_node_free(to_free); | |
a5f51c96 | 1422 | |
e2bdb933 HD |
1423 | if (node->count) { |
1424 | if (node == indirect_to_ptr(root->rnode)) | |
a5f51c96 | 1425 | radix_tree_shrink(root); |
201b6264 | 1426 | goto out; |
a5f51c96 | 1427 | } |
201b6264 CL |
1428 | |
1429 | /* Node with zero slots in use so free it */ | |
e2bdb933 | 1430 | to_free = node; |
7cf9c2c7 | 1431 | |
e2bdb933 HD |
1432 | index >>= RADIX_TREE_MAP_SHIFT; |
1433 | offset = index & RADIX_TREE_MAP_MASK; | |
1434 | node = node->parent; | |
1da177e4 | 1435 | } |
e2bdb933 | 1436 | |
612d6c19 | 1437 | root_tag_clear_all(root); |
201b6264 | 1438 | root->height = 0; |
612d6c19 | 1439 | root->rnode = NULL; |
7cf9c2c7 NP |
1440 | if (to_free) |
1441 | radix_tree_node_free(to_free); | |
612d6c19 | 1442 | |
1da177e4 | 1443 | out: |
612d6c19 | 1444 | return slot; |
1da177e4 LT |
1445 | } |
1446 | EXPORT_SYMBOL(radix_tree_delete); | |
1447 | ||
1448 | /** | |
1449 | * radix_tree_tagged - test whether any items in the tree are tagged | |
1450 | * @root: radix tree root | |
1451 | * @tag: tag to test | |
1452 | */ | |
daff89f3 | 1453 | int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) |
1da177e4 | 1454 | { |
612d6c19 | 1455 | return root_tag_get(root, tag); |
1da177e4 LT |
1456 | } |
1457 | EXPORT_SYMBOL(radix_tree_tagged); | |
1458 | ||
1459 | static void | |
51cc5068 | 1460 | radix_tree_node_ctor(void *node) |
1da177e4 LT |
1461 | { |
1462 | memset(node, 0, sizeof(struct radix_tree_node)); | |
1463 | } | |
1464 | ||
1465 | static __init unsigned long __maxindex(unsigned int height) | |
1466 | { | |
430d275a PL |
1467 | unsigned int width = height * RADIX_TREE_MAP_SHIFT; |
1468 | int shift = RADIX_TREE_INDEX_BITS - width; | |
1469 | ||
1470 | if (shift < 0) | |
1471 | return ~0UL; | |
1472 | if (shift >= BITS_PER_LONG) | |
1473 | return 0UL; | |
1474 | return ~0UL >> shift; | |
1da177e4 LT |
1475 | } |
1476 | ||
1477 | static __init void radix_tree_init_maxindex(void) | |
1478 | { | |
1479 | unsigned int i; | |
1480 | ||
1481 | for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++) | |
1482 | height_to_maxindex[i] = __maxindex(i); | |
1483 | } | |
1484 | ||
1da177e4 LT |
1485 | static int radix_tree_callback(struct notifier_block *nfb, |
1486 | unsigned long action, | |
1487 | void *hcpu) | |
1488 | { | |
1489 | int cpu = (long)hcpu; | |
1490 | struct radix_tree_preload *rtp; | |
1491 | ||
1492 | /* Free per-cpu pool of perloaded nodes */ | |
8bb78442 | 1493 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { |
1da177e4 LT |
1494 | rtp = &per_cpu(radix_tree_preloads, cpu); |
1495 | while (rtp->nr) { | |
1496 | kmem_cache_free(radix_tree_node_cachep, | |
1497 | rtp->nodes[rtp->nr-1]); | |
1498 | rtp->nodes[rtp->nr-1] = NULL; | |
1499 | rtp->nr--; | |
1500 | } | |
1501 | } | |
1502 | return NOTIFY_OK; | |
1503 | } | |
1da177e4 LT |
1504 | |
1505 | void __init radix_tree_init(void) | |
1506 | { | |
1507 | radix_tree_node_cachep = kmem_cache_create("radix_tree_node", | |
1508 | sizeof(struct radix_tree_node), 0, | |
488514d1 CL |
1509 | SLAB_PANIC | SLAB_RECLAIM_ACCOUNT, |
1510 | radix_tree_node_ctor); | |
1da177e4 LT |
1511 | radix_tree_init_maxindex(); |
1512 | hotcpu_notifier(radix_tree_callback, 0); | |
1513 | } |