Commit | Line | Data |
---|---|---|
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 |
78c1d784 | 6 | * Copyright (C) 2012 Konstantin Khlebnikov |
1da177e4 LT |
7 | * |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public License as | |
10 | * published by the Free Software Foundation; either version 2, or (at | |
11 | * your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, but | |
14 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
21 | */ | |
22 | ||
23 | #include <linux/errno.h> | |
24 | #include <linux/init.h> | |
25 | #include <linux/kernel.h> | |
8bc3bcc9 | 26 | #include <linux/export.h> |
1da177e4 LT |
27 | #include <linux/radix-tree.h> |
28 | #include <linux/percpu.h> | |
29 | #include <linux/slab.h> | |
30 | #include <linux/notifier.h> | |
31 | #include <linux/cpu.h> | |
1da177e4 LT |
32 | #include <linux/string.h> |
33 | #include <linux/bitops.h> | |
7cf9c2c7 | 34 | #include <linux/rcupdate.h> |
5e4c0d97 | 35 | #include <linux/hardirq.h> /* in_interrupt() */ |
1da177e4 LT |
36 | |
37 | ||
38 | #ifdef __KERNEL__ | |
cfd9b7df | 39 | #define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) |
1da177e4 LT |
40 | #else |
41 | #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ | |
42 | #endif | |
1da177e4 LT |
43 | |
44 | #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) | |
45 | #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1) | |
46 | ||
47 | #define RADIX_TREE_TAG_LONGS \ | |
48 | ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG) | |
49 | ||
50 | struct radix_tree_node { | |
7cf9c2c7 | 51 | unsigned int height; /* Height from the bottom */ |
1da177e4 | 52 | unsigned int count; |
e2bdb933 HD |
53 | union { |
54 | struct radix_tree_node *parent; /* Used when ascending tree */ | |
55 | struct rcu_head rcu_head; /* Used when freeing node */ | |
56 | }; | |
a1115570 | 57 | void __rcu *slots[RADIX_TREE_MAP_SIZE]; |
daff89f3 | 58 | unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; |
1da177e4 LT |
59 | }; |
60 | ||
1da177e4 | 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 | 75 | |
55368052 NP |
76 | /* |
77 | * The radix tree is variable-height, so an insert operation not only has | |
78 | * to build the branch to its corresponding item, it also has to build the | |
79 | * branch to existing items if the size has to be increased (by | |
80 | * radix_tree_extend). | |
81 | * | |
82 | * The worst case is a zero height tree with just a single item at index 0, | |
83 | * and then inserting an item at index ULONG_MAX. This requires 2 new branches | |
84 | * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. | |
85 | * Hence: | |
86 | */ | |
87 | #define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1) | |
88 | ||
1da177e4 LT |
89 | /* |
90 | * Per-cpu pool of preloaded nodes | |
91 | */ | |
92 | struct radix_tree_preload { | |
93 | int nr; | |
55368052 | 94 | struct radix_tree_node *nodes[RADIX_TREE_PRELOAD_SIZE]; |
1da177e4 | 95 | }; |
8cef7d57 | 96 | static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; |
1da177e4 | 97 | |
27d20fdd NP |
98 | static inline void *ptr_to_indirect(void *ptr) |
99 | { | |
100 | return (void *)((unsigned long)ptr | RADIX_TREE_INDIRECT_PTR); | |
101 | } | |
102 | ||
103 | static inline void *indirect_to_ptr(void *ptr) | |
104 | { | |
105 | return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR); | |
106 | } | |
107 | ||
612d6c19 NP |
108 | static inline gfp_t root_gfp_mask(struct radix_tree_root *root) |
109 | { | |
110 | return root->gfp_mask & __GFP_BITS_MASK; | |
111 | } | |
112 | ||
643b52b9 NP |
113 | static inline void tag_set(struct radix_tree_node *node, unsigned int tag, |
114 | int offset) | |
115 | { | |
116 | __set_bit(offset, node->tags[tag]); | |
117 | } | |
118 | ||
119 | static inline void tag_clear(struct radix_tree_node *node, unsigned int tag, | |
120 | int offset) | |
121 | { | |
122 | __clear_bit(offset, node->tags[tag]); | |
123 | } | |
124 | ||
125 | static inline int tag_get(struct radix_tree_node *node, unsigned int tag, | |
126 | int offset) | |
127 | { | |
128 | return test_bit(offset, node->tags[tag]); | |
129 | } | |
130 | ||
131 | static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag) | |
132 | { | |
133 | root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT)); | |
134 | } | |
135 | ||
136 | static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag) | |
137 | { | |
138 | root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT)); | |
139 | } | |
140 | ||
141 | static inline void root_tag_clear_all(struct radix_tree_root *root) | |
142 | { | |
143 | root->gfp_mask &= __GFP_BITS_MASK; | |
144 | } | |
145 | ||
146 | static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag) | |
147 | { | |
148 | return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT)); | |
149 | } | |
150 | ||
151 | /* | |
152 | * Returns 1 if any slot in the node has this tag set. | |
153 | * Otherwise returns 0. | |
154 | */ | |
155 | static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag) | |
156 | { | |
157 | int idx; | |
158 | for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { | |
159 | if (node->tags[tag][idx]) | |
160 | return 1; | |
161 | } | |
162 | return 0; | |
163 | } | |
78c1d784 KK |
164 | |
165 | /** | |
166 | * radix_tree_find_next_bit - find the next set bit in a memory region | |
167 | * | |
168 | * @addr: The address to base the search on | |
169 | * @size: The bitmap size in bits | |
170 | * @offset: The bitnumber to start searching at | |
171 | * | |
172 | * Unrollable variant of find_next_bit() for constant size arrays. | |
173 | * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero. | |
174 | * Returns next bit offset, or size if nothing found. | |
175 | */ | |
176 | static __always_inline unsigned long | |
177 | radix_tree_find_next_bit(const unsigned long *addr, | |
178 | unsigned long size, unsigned long offset) | |
179 | { | |
180 | if (!__builtin_constant_p(size)) | |
181 | return find_next_bit(addr, size, offset); | |
182 | ||
183 | if (offset < size) { | |
184 | unsigned long tmp; | |
185 | ||
186 | addr += offset / BITS_PER_LONG; | |
187 | tmp = *addr >> (offset % BITS_PER_LONG); | |
188 | if (tmp) | |
189 | return __ffs(tmp) + offset; | |
190 | offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1); | |
191 | while (offset < size) { | |
192 | tmp = *++addr; | |
193 | if (tmp) | |
194 | return __ffs(tmp) + offset; | |
195 | offset += BITS_PER_LONG; | |
196 | } | |
197 | } | |
198 | return size; | |
199 | } | |
200 | ||
1da177e4 LT |
201 | /* |
202 | * This assumes that the caller has performed appropriate preallocation, and | |
203 | * that the caller has pinned this thread of control to the current CPU. | |
204 | */ | |
205 | static struct radix_tree_node * | |
206 | radix_tree_node_alloc(struct radix_tree_root *root) | |
207 | { | |
e2848a0e | 208 | struct radix_tree_node *ret = NULL; |
612d6c19 | 209 | gfp_t gfp_mask = root_gfp_mask(root); |
1da177e4 | 210 | |
5e4c0d97 JK |
211 | /* |
212 | * Preload code isn't irq safe and it doesn't make sence to use | |
213 | * preloading in the interrupt anyway as all the allocations have to | |
214 | * be atomic. So just do normal allocation when in interrupt. | |
215 | */ | |
216 | if (!(gfp_mask & __GFP_WAIT) && !in_interrupt()) { | |
1da177e4 LT |
217 | struct radix_tree_preload *rtp; |
218 | ||
e2848a0e NP |
219 | /* |
220 | * Provided the caller has preloaded here, we will always | |
221 | * succeed in getting a node here (and never reach | |
222 | * kmem_cache_alloc) | |
223 | */ | |
1da177e4 LT |
224 | rtp = &__get_cpu_var(radix_tree_preloads); |
225 | if (rtp->nr) { | |
226 | ret = rtp->nodes[rtp->nr - 1]; | |
227 | rtp->nodes[rtp->nr - 1] = NULL; | |
228 | rtp->nr--; | |
229 | } | |
230 | } | |
e2848a0e | 231 | if (ret == NULL) |
488514d1 | 232 | ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
e2848a0e | 233 | |
c0bc9875 | 234 | BUG_ON(radix_tree_is_indirect_ptr(ret)); |
1da177e4 LT |
235 | return ret; |
236 | } | |
237 | ||
7cf9c2c7 NP |
238 | static void radix_tree_node_rcu_free(struct rcu_head *head) |
239 | { | |
240 | struct radix_tree_node *node = | |
241 | container_of(head, struct radix_tree_node, rcu_head); | |
b6dd0865 | 242 | int i; |
643b52b9 NP |
243 | |
244 | /* | |
245 | * must only free zeroed nodes into the slab. radix_tree_shrink | |
246 | * can leave us with a non-NULL entry in the first slot, so clear | |
247 | * that here to make sure. | |
248 | */ | |
b6dd0865 DC |
249 | for (i = 0; i < RADIX_TREE_MAX_TAGS; i++) |
250 | tag_clear(node, i, 0); | |
251 | ||
643b52b9 NP |
252 | node->slots[0] = NULL; |
253 | node->count = 0; | |
254 | ||
7cf9c2c7 NP |
255 | kmem_cache_free(radix_tree_node_cachep, node); |
256 | } | |
257 | ||
1da177e4 LT |
258 | static inline void |
259 | radix_tree_node_free(struct radix_tree_node *node) | |
260 | { | |
7cf9c2c7 | 261 | call_rcu(&node->rcu_head, radix_tree_node_rcu_free); |
1da177e4 LT |
262 | } |
263 | ||
264 | /* | |
265 | * Load up this CPU's radix_tree_node buffer with sufficient objects to | |
266 | * ensure that the addition of a single element in the tree cannot fail. On | |
267 | * success, return zero, with preemption disabled. On error, return -ENOMEM | |
268 | * with preemption not disabled. | |
b34df792 DH |
269 | * |
270 | * To make use of this facility, the radix tree must be initialised without | |
271 | * __GFP_WAIT being passed to INIT_RADIX_TREE(). | |
1da177e4 | 272 | */ |
5e4c0d97 | 273 | static int __radix_tree_preload(gfp_t gfp_mask) |
1da177e4 LT |
274 | { |
275 | struct radix_tree_preload *rtp; | |
276 | struct radix_tree_node *node; | |
277 | int ret = -ENOMEM; | |
278 | ||
279 | preempt_disable(); | |
280 | rtp = &__get_cpu_var(radix_tree_preloads); | |
281 | while (rtp->nr < ARRAY_SIZE(rtp->nodes)) { | |
282 | preempt_enable(); | |
488514d1 | 283 | node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
1da177e4 LT |
284 | if (node == NULL) |
285 | goto out; | |
286 | preempt_disable(); | |
287 | rtp = &__get_cpu_var(radix_tree_preloads); | |
288 | if (rtp->nr < ARRAY_SIZE(rtp->nodes)) | |
289 | rtp->nodes[rtp->nr++] = node; | |
290 | else | |
291 | kmem_cache_free(radix_tree_node_cachep, node); | |
292 | } | |
293 | ret = 0; | |
294 | out: | |
295 | return ret; | |
296 | } | |
5e4c0d97 JK |
297 | |
298 | /* | |
299 | * Load up this CPU's radix_tree_node buffer with sufficient objects to | |
300 | * ensure that the addition of a single element in the tree cannot fail. On | |
301 | * success, return zero, with preemption disabled. On error, return -ENOMEM | |
302 | * with preemption not disabled. | |
303 | * | |
304 | * To make use of this facility, the radix tree must be initialised without | |
305 | * __GFP_WAIT being passed to INIT_RADIX_TREE(). | |
306 | */ | |
307 | int radix_tree_preload(gfp_t gfp_mask) | |
308 | { | |
309 | /* Warn on non-sensical use... */ | |
310 | WARN_ON_ONCE(!(gfp_mask & __GFP_WAIT)); | |
311 | return __radix_tree_preload(gfp_mask); | |
312 | } | |
d7f0923d | 313 | EXPORT_SYMBOL(radix_tree_preload); |
1da177e4 | 314 | |
5e4c0d97 JK |
315 | /* |
316 | * The same as above function, except we don't guarantee preloading happens. | |
317 | * We do it, if we decide it helps. On success, return zero with preemption | |
318 | * disabled. On error, return -ENOMEM with preemption not disabled. | |
319 | */ | |
320 | int radix_tree_maybe_preload(gfp_t gfp_mask) | |
321 | { | |
322 | if (gfp_mask & __GFP_WAIT) | |
323 | return __radix_tree_preload(gfp_mask); | |
324 | /* Preloading doesn't help anything with this gfp mask, skip it */ | |
325 | preempt_disable(); | |
326 | return 0; | |
327 | } | |
328 | EXPORT_SYMBOL(radix_tree_maybe_preload); | |
329 | ||
1da177e4 LT |
330 | /* |
331 | * Return the maximum key which can be store into a | |
332 | * radix tree with height HEIGHT. | |
333 | */ | |
334 | static inline unsigned long radix_tree_maxindex(unsigned int height) | |
335 | { | |
336 | return height_to_maxindex[height]; | |
337 | } | |
338 | ||
339 | /* | |
340 | * Extend a radix tree so it can store key @index. | |
341 | */ | |
342 | static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) | |
343 | { | |
344 | struct radix_tree_node *node; | |
e2bdb933 | 345 | struct radix_tree_node *slot; |
1da177e4 | 346 | unsigned int height; |
1da177e4 LT |
347 | int tag; |
348 | ||
349 | /* Figure out what the height should be. */ | |
350 | height = root->height + 1; | |
351 | while (index > radix_tree_maxindex(height)) | |
352 | height++; | |
353 | ||
354 | if (root->rnode == NULL) { | |
355 | root->height = height; | |
356 | goto out; | |
357 | } | |
358 | ||
1da177e4 | 359 | do { |
7cf9c2c7 | 360 | unsigned int newheight; |
1da177e4 LT |
361 | if (!(node = radix_tree_node_alloc(root))) |
362 | return -ENOMEM; | |
363 | ||
1da177e4 | 364 | /* Propagate the aggregated tag info into the new root */ |
daff89f3 | 365 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { |
612d6c19 | 366 | if (root_tag_get(root, tag)) |
1da177e4 LT |
367 | tag_set(node, tag, 0); |
368 | } | |
369 | ||
e2bdb933 | 370 | /* Increase the height. */ |
7cf9c2c7 NP |
371 | newheight = root->height+1; |
372 | node->height = newheight; | |
1da177e4 | 373 | node->count = 1; |
e2bdb933 HD |
374 | node->parent = NULL; |
375 | slot = root->rnode; | |
376 | if (newheight > 1) { | |
377 | slot = indirect_to_ptr(slot); | |
378 | slot->parent = node; | |
379 | } | |
380 | node->slots[0] = slot; | |
27d20fdd | 381 | node = ptr_to_indirect(node); |
7cf9c2c7 NP |
382 | rcu_assign_pointer(root->rnode, node); |
383 | root->height = newheight; | |
1da177e4 LT |
384 | } while (height > root->height); |
385 | out: | |
386 | return 0; | |
387 | } | |
388 | ||
389 | /** | |
390 | * radix_tree_insert - insert into a radix tree | |
391 | * @root: radix tree root | |
392 | * @index: index key | |
393 | * @item: item to insert | |
394 | * | |
395 | * Insert an item into the radix tree at position @index. | |
396 | */ | |
397 | int radix_tree_insert(struct radix_tree_root *root, | |
398 | unsigned long index, void *item) | |
399 | { | |
201b6264 | 400 | struct radix_tree_node *node = NULL, *slot; |
1da177e4 LT |
401 | unsigned int height, shift; |
402 | int offset; | |
403 | int error; | |
404 | ||
c0bc9875 | 405 | BUG_ON(radix_tree_is_indirect_ptr(item)); |
7cf9c2c7 | 406 | |
1da177e4 | 407 | /* Make sure the tree is high enough. */ |
612d6c19 | 408 | if (index > radix_tree_maxindex(root->height)) { |
1da177e4 LT |
409 | error = radix_tree_extend(root, index); |
410 | if (error) | |
411 | return error; | |
412 | } | |
413 | ||
27d20fdd | 414 | slot = indirect_to_ptr(root->rnode); |
c0bc9875 | 415 | |
1da177e4 LT |
416 | height = root->height; |
417 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
418 | ||
419 | offset = 0; /* uninitialised var warning */ | |
612d6c19 | 420 | while (height > 0) { |
201b6264 | 421 | if (slot == NULL) { |
1da177e4 | 422 | /* Have to add a child node. */ |
201b6264 | 423 | if (!(slot = radix_tree_node_alloc(root))) |
1da177e4 | 424 | return -ENOMEM; |
7cf9c2c7 | 425 | slot->height = height; |
e2bdb933 | 426 | slot->parent = node; |
201b6264 | 427 | if (node) { |
7cf9c2c7 | 428 | rcu_assign_pointer(node->slots[offset], slot); |
1da177e4 | 429 | node->count++; |
201b6264 | 430 | } else |
27d20fdd | 431 | rcu_assign_pointer(root->rnode, ptr_to_indirect(slot)); |
1da177e4 LT |
432 | } |
433 | ||
434 | /* Go a level down */ | |
435 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
201b6264 CL |
436 | node = slot; |
437 | slot = node->slots[offset]; | |
1da177e4 LT |
438 | shift -= RADIX_TREE_MAP_SHIFT; |
439 | height--; | |
612d6c19 | 440 | } |
1da177e4 | 441 | |
201b6264 | 442 | if (slot != NULL) |
1da177e4 | 443 | return -EEXIST; |
201b6264 | 444 | |
612d6c19 NP |
445 | if (node) { |
446 | node->count++; | |
7cf9c2c7 | 447 | rcu_assign_pointer(node->slots[offset], item); |
612d6c19 NP |
448 | BUG_ON(tag_get(node, 0, offset)); |
449 | BUG_ON(tag_get(node, 1, offset)); | |
450 | } else { | |
c0bc9875 | 451 | rcu_assign_pointer(root->rnode, item); |
612d6c19 NP |
452 | BUG_ON(root_tag_get(root, 0)); |
453 | BUG_ON(root_tag_get(root, 1)); | |
454 | } | |
1da177e4 | 455 | |
1da177e4 LT |
456 | return 0; |
457 | } | |
458 | EXPORT_SYMBOL(radix_tree_insert); | |
459 | ||
b72b71c6 HS |
460 | /* |
461 | * is_slot == 1 : search for the slot. | |
462 | * is_slot == 0 : search for the node. | |
7cf9c2c7 | 463 | */ |
b72b71c6 HS |
464 | static void *radix_tree_lookup_element(struct radix_tree_root *root, |
465 | unsigned long index, int is_slot) | |
1da177e4 LT |
466 | { |
467 | unsigned int height, shift; | |
7cf9c2c7 | 468 | struct radix_tree_node *node, **slot; |
612d6c19 | 469 | |
2676a58c | 470 | node = rcu_dereference_raw(root->rnode); |
7cf9c2c7 | 471 | if (node == NULL) |
1da177e4 LT |
472 | return NULL; |
473 | ||
c0bc9875 | 474 | if (!radix_tree_is_indirect_ptr(node)) { |
7cf9c2c7 NP |
475 | if (index > 0) |
476 | return NULL; | |
b72b71c6 | 477 | return is_slot ? (void *)&root->rnode : node; |
7cf9c2c7 | 478 | } |
27d20fdd | 479 | node = indirect_to_ptr(node); |
7cf9c2c7 NP |
480 | |
481 | height = node->height; | |
482 | if (index > radix_tree_maxindex(height)) | |
483 | return NULL; | |
612d6c19 | 484 | |
1da177e4 | 485 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 | 486 | |
7cf9c2c7 NP |
487 | do { |
488 | slot = (struct radix_tree_node **) | |
489 | (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); | |
2676a58c | 490 | node = rcu_dereference_raw(*slot); |
7cf9c2c7 | 491 | if (node == NULL) |
1da177e4 LT |
492 | return NULL; |
493 | ||
1da177e4 LT |
494 | shift -= RADIX_TREE_MAP_SHIFT; |
495 | height--; | |
7cf9c2c7 | 496 | } while (height > 0); |
1da177e4 | 497 | |
27d20fdd | 498 | return is_slot ? (void *)slot : indirect_to_ptr(node); |
b72b71c6 HS |
499 | } |
500 | ||
501 | /** | |
502 | * radix_tree_lookup_slot - lookup a slot in a radix tree | |
503 | * @root: radix tree root | |
504 | * @index: index key | |
505 | * | |
506 | * Returns: the slot corresponding to the position @index in the | |
507 | * radix tree @root. This is useful for update-if-exists operations. | |
508 | * | |
509 | * This function can be called under rcu_read_lock iff the slot is not | |
510 | * modified by radix_tree_replace_slot, otherwise it must be called | |
511 | * exclusive from other writers. Any dereference of the slot must be done | |
512 | * using radix_tree_deref_slot. | |
513 | */ | |
514 | void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) | |
515 | { | |
516 | return (void **)radix_tree_lookup_element(root, index, 1); | |
a4331366 | 517 | } |
a4331366 HR |
518 | EXPORT_SYMBOL(radix_tree_lookup_slot); |
519 | ||
520 | /** | |
521 | * radix_tree_lookup - perform lookup operation on a radix tree | |
522 | * @root: radix tree root | |
523 | * @index: index key | |
524 | * | |
525 | * Lookup the item at the position @index in the radix tree @root. | |
7cf9c2c7 NP |
526 | * |
527 | * This function can be called under rcu_read_lock, however the caller | |
528 | * must manage lifetimes of leaf nodes (eg. RCU may also be used to free | |
529 | * them safely). No RCU barriers are required to access or modify the | |
530 | * returned item, however. | |
a4331366 HR |
531 | */ |
532 | void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) | |
533 | { | |
b72b71c6 | 534 | return radix_tree_lookup_element(root, index, 0); |
1da177e4 LT |
535 | } |
536 | EXPORT_SYMBOL(radix_tree_lookup); | |
537 | ||
538 | /** | |
539 | * radix_tree_tag_set - set a tag on a radix tree node | |
540 | * @root: radix tree root | |
541 | * @index: index key | |
542 | * @tag: tag index | |
543 | * | |
daff89f3 JC |
544 | * Set the search tag (which must be < RADIX_TREE_MAX_TAGS) |
545 | * corresponding to @index in the radix tree. From | |
1da177e4 LT |
546 | * the root all the way down to the leaf node. |
547 | * | |
548 | * Returns the address of the tagged item. Setting a tag on a not-present | |
549 | * item is a bug. | |
550 | */ | |
551 | void *radix_tree_tag_set(struct radix_tree_root *root, | |
daff89f3 | 552 | unsigned long index, unsigned int tag) |
1da177e4 LT |
553 | { |
554 | unsigned int height, shift; | |
201b6264 | 555 | struct radix_tree_node *slot; |
1da177e4 LT |
556 | |
557 | height = root->height; | |
4c91c364 | 558 | BUG_ON(index > radix_tree_maxindex(height)); |
1da177e4 | 559 | |
27d20fdd | 560 | slot = indirect_to_ptr(root->rnode); |
612d6c19 | 561 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 LT |
562 | |
563 | while (height > 0) { | |
564 | int offset; | |
565 | ||
566 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
d5274261 NP |
567 | if (!tag_get(slot, tag, offset)) |
568 | tag_set(slot, tag, offset); | |
201b6264 CL |
569 | slot = slot->slots[offset]; |
570 | BUG_ON(slot == NULL); | |
1da177e4 LT |
571 | shift -= RADIX_TREE_MAP_SHIFT; |
572 | height--; | |
573 | } | |
574 | ||
612d6c19 NP |
575 | /* set the root's tag bit */ |
576 | if (slot && !root_tag_get(root, tag)) | |
577 | root_tag_set(root, tag); | |
578 | ||
201b6264 | 579 | return slot; |
1da177e4 LT |
580 | } |
581 | EXPORT_SYMBOL(radix_tree_tag_set); | |
582 | ||
583 | /** | |
584 | * radix_tree_tag_clear - clear a tag on a radix tree node | |
585 | * @root: radix tree root | |
586 | * @index: index key | |
587 | * @tag: tag index | |
588 | * | |
daff89f3 JC |
589 | * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS) |
590 | * corresponding to @index in the radix tree. If | |
1da177e4 LT |
591 | * this causes the leaf node to have no tags set then clear the tag in the |
592 | * next-to-leaf node, etc. | |
593 | * | |
594 | * Returns the address of the tagged item on success, else NULL. ie: | |
595 | * has the same return value and semantics as radix_tree_lookup(). | |
596 | */ | |
597 | void *radix_tree_tag_clear(struct radix_tree_root *root, | |
daff89f3 | 598 | unsigned long index, unsigned int tag) |
1da177e4 | 599 | { |
e2bdb933 | 600 | struct radix_tree_node *node = NULL; |
612d6c19 | 601 | struct radix_tree_node *slot = NULL; |
1da177e4 | 602 | unsigned int height, shift; |
e2bdb933 | 603 | int uninitialized_var(offset); |
1da177e4 LT |
604 | |
605 | height = root->height; | |
606 | if (index > radix_tree_maxindex(height)) | |
607 | goto out; | |
608 | ||
e2bdb933 | 609 | shift = height * RADIX_TREE_MAP_SHIFT; |
27d20fdd | 610 | slot = indirect_to_ptr(root->rnode); |
1da177e4 | 611 | |
e2bdb933 | 612 | while (shift) { |
201b6264 | 613 | if (slot == NULL) |
1da177e4 LT |
614 | goto out; |
615 | ||
e2bdb933 | 616 | shift -= RADIX_TREE_MAP_SHIFT; |
1da177e4 | 617 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; |
e2bdb933 | 618 | node = slot; |
201b6264 | 619 | slot = slot->slots[offset]; |
1da177e4 LT |
620 | } |
621 | ||
612d6c19 | 622 | if (slot == NULL) |
1da177e4 LT |
623 | goto out; |
624 | ||
e2bdb933 HD |
625 | while (node) { |
626 | if (!tag_get(node, tag, offset)) | |
d5274261 | 627 | goto out; |
e2bdb933 HD |
628 | tag_clear(node, tag, offset); |
629 | if (any_tag_set(node, tag)) | |
6e954b9e | 630 | goto out; |
e2bdb933 HD |
631 | |
632 | index >>= RADIX_TREE_MAP_SHIFT; | |
633 | offset = index & RADIX_TREE_MAP_MASK; | |
634 | node = node->parent; | |
612d6c19 NP |
635 | } |
636 | ||
637 | /* clear the root's tag bit */ | |
638 | if (root_tag_get(root, tag)) | |
639 | root_tag_clear(root, tag); | |
640 | ||
1da177e4 | 641 | out: |
612d6c19 | 642 | return slot; |
1da177e4 LT |
643 | } |
644 | EXPORT_SYMBOL(radix_tree_tag_clear); | |
645 | ||
1da177e4 | 646 | /** |
32605a18 MT |
647 | * radix_tree_tag_get - get a tag on a radix tree node |
648 | * @root: radix tree root | |
649 | * @index: index key | |
daff89f3 | 650 | * @tag: tag index (< RADIX_TREE_MAX_TAGS) |
1da177e4 | 651 | * |
32605a18 | 652 | * Return values: |
1da177e4 | 653 | * |
612d6c19 NP |
654 | * 0: tag not present or not set |
655 | * 1: tag set | |
ce82653d DH |
656 | * |
657 | * Note that the return value of this function may not be relied on, even if | |
658 | * the RCU lock is held, unless tag modification and node deletion are excluded | |
659 | * from concurrency. | |
1da177e4 LT |
660 | */ |
661 | int radix_tree_tag_get(struct radix_tree_root *root, | |
daff89f3 | 662 | unsigned long index, unsigned int tag) |
1da177e4 LT |
663 | { |
664 | unsigned int height, shift; | |
7cf9c2c7 | 665 | struct radix_tree_node *node; |
1da177e4 | 666 | |
612d6c19 NP |
667 | /* check the root's tag bit */ |
668 | if (!root_tag_get(root, tag)) | |
669 | return 0; | |
670 | ||
2676a58c | 671 | node = rcu_dereference_raw(root->rnode); |
7cf9c2c7 NP |
672 | if (node == NULL) |
673 | return 0; | |
674 | ||
c0bc9875 | 675 | if (!radix_tree_is_indirect_ptr(node)) |
7cf9c2c7 | 676 | return (index == 0); |
27d20fdd | 677 | node = indirect_to_ptr(node); |
7cf9c2c7 NP |
678 | |
679 | height = node->height; | |
680 | if (index > radix_tree_maxindex(height)) | |
681 | return 0; | |
612d6c19 | 682 | |
1da177e4 | 683 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; |
1da177e4 LT |
684 | |
685 | for ( ; ; ) { | |
686 | int offset; | |
687 | ||
7cf9c2c7 | 688 | if (node == NULL) |
1da177e4 LT |
689 | return 0; |
690 | ||
691 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
7cf9c2c7 | 692 | if (!tag_get(node, tag, offset)) |
3fa36acb | 693 | return 0; |
ce82653d | 694 | if (height == 1) |
3fa36acb | 695 | return 1; |
2676a58c | 696 | node = rcu_dereference_raw(node->slots[offset]); |
1da177e4 LT |
697 | shift -= RADIX_TREE_MAP_SHIFT; |
698 | height--; | |
699 | } | |
700 | } | |
701 | EXPORT_SYMBOL(radix_tree_tag_get); | |
1da177e4 | 702 | |
78c1d784 KK |
703 | /** |
704 | * radix_tree_next_chunk - find next chunk of slots for iteration | |
705 | * | |
706 | * @root: radix tree root | |
707 | * @iter: iterator state | |
708 | * @flags: RADIX_TREE_ITER_* flags and tag index | |
709 | * Returns: pointer to chunk first slot, or NULL if iteration is over | |
710 | */ | |
711 | void **radix_tree_next_chunk(struct radix_tree_root *root, | |
712 | struct radix_tree_iter *iter, unsigned flags) | |
713 | { | |
714 | unsigned shift, tag = flags & RADIX_TREE_ITER_TAG_MASK; | |
715 | struct radix_tree_node *rnode, *node; | |
716 | unsigned long index, offset; | |
717 | ||
718 | if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag)) | |
719 | return NULL; | |
720 | ||
721 | /* | |
722 | * Catch next_index overflow after ~0UL. iter->index never overflows | |
723 | * during iterating; it can be zero only at the beginning. | |
724 | * And we cannot overflow iter->next_index in a single step, | |
725 | * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG. | |
fffaee36 KK |
726 | * |
727 | * This condition also used by radix_tree_next_slot() to stop | |
728 | * contiguous iterating, and forbid swithing to the next chunk. | |
78c1d784 KK |
729 | */ |
730 | index = iter->next_index; | |
731 | if (!index && iter->index) | |
732 | return NULL; | |
733 | ||
734 | rnode = rcu_dereference_raw(root->rnode); | |
735 | if (radix_tree_is_indirect_ptr(rnode)) { | |
736 | rnode = indirect_to_ptr(rnode); | |
737 | } else if (rnode && !index) { | |
738 | /* Single-slot tree */ | |
739 | iter->index = 0; | |
740 | iter->next_index = 1; | |
741 | iter->tags = 1; | |
742 | return (void **)&root->rnode; | |
743 | } else | |
744 | return NULL; | |
745 | ||
746 | restart: | |
747 | shift = (rnode->height - 1) * RADIX_TREE_MAP_SHIFT; | |
748 | offset = index >> shift; | |
749 | ||
750 | /* Index outside of the tree */ | |
751 | if (offset >= RADIX_TREE_MAP_SIZE) | |
752 | return NULL; | |
753 | ||
754 | node = rnode; | |
755 | while (1) { | |
756 | if ((flags & RADIX_TREE_ITER_TAGGED) ? | |
757 | !test_bit(offset, node->tags[tag]) : | |
758 | !node->slots[offset]) { | |
759 | /* Hole detected */ | |
760 | if (flags & RADIX_TREE_ITER_CONTIG) | |
761 | return NULL; | |
762 | ||
763 | if (flags & RADIX_TREE_ITER_TAGGED) | |
764 | offset = radix_tree_find_next_bit( | |
765 | node->tags[tag], | |
766 | RADIX_TREE_MAP_SIZE, | |
767 | offset + 1); | |
768 | else | |
769 | while (++offset < RADIX_TREE_MAP_SIZE) { | |
770 | if (node->slots[offset]) | |
771 | break; | |
772 | } | |
773 | index &= ~((RADIX_TREE_MAP_SIZE << shift) - 1); | |
774 | index += offset << shift; | |
775 | /* Overflow after ~0UL */ | |
776 | if (!index) | |
777 | return NULL; | |
778 | if (offset == RADIX_TREE_MAP_SIZE) | |
779 | goto restart; | |
780 | } | |
781 | ||
782 | /* This is leaf-node */ | |
783 | if (!shift) | |
784 | break; | |
785 | ||
786 | node = rcu_dereference_raw(node->slots[offset]); | |
787 | if (node == NULL) | |
788 | goto restart; | |
789 | shift -= RADIX_TREE_MAP_SHIFT; | |
790 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
791 | } | |
792 | ||
793 | /* Update the iterator state */ | |
794 | iter->index = index; | |
795 | iter->next_index = (index | RADIX_TREE_MAP_MASK) + 1; | |
796 | ||
797 | /* Construct iter->tags bit-mask from node->tags[tag] array */ | |
798 | if (flags & RADIX_TREE_ITER_TAGGED) { | |
799 | unsigned tag_long, tag_bit; | |
800 | ||
801 | tag_long = offset / BITS_PER_LONG; | |
802 | tag_bit = offset % BITS_PER_LONG; | |
803 | iter->tags = node->tags[tag][tag_long] >> tag_bit; | |
804 | /* This never happens if RADIX_TREE_TAG_LONGS == 1 */ | |
805 | if (tag_long < RADIX_TREE_TAG_LONGS - 1) { | |
806 | /* Pick tags from next element */ | |
807 | if (tag_bit) | |
808 | iter->tags |= node->tags[tag][tag_long + 1] << | |
809 | (BITS_PER_LONG - tag_bit); | |
810 | /* Clip chunk size, here only BITS_PER_LONG tags */ | |
811 | iter->next_index = index + BITS_PER_LONG; | |
812 | } | |
813 | } | |
814 | ||
815 | return node->slots + offset; | |
816 | } | |
817 | EXPORT_SYMBOL(radix_tree_next_chunk); | |
818 | ||
ebf8aa44 JK |
819 | /** |
820 | * radix_tree_range_tag_if_tagged - for each item in given range set given | |
821 | * tag if item has another tag set | |
822 | * @root: radix tree root | |
823 | * @first_indexp: pointer to a starting index of a range to scan | |
824 | * @last_index: last index of a range to scan | |
825 | * @nr_to_tag: maximum number items to tag | |
826 | * @iftag: tag index to test | |
827 | * @settag: tag index to set if tested tag is set | |
828 | * | |
829 | * This function scans range of radix tree from first_index to last_index | |
830 | * (inclusive). For each item in the range if iftag is set, the function sets | |
831 | * also settag. The function stops either after tagging nr_to_tag items or | |
832 | * after reaching last_index. | |
833 | * | |
144dcfc0 DC |
834 | * The tags must be set from the leaf level only and propagated back up the |
835 | * path to the root. We must do this so that we resolve the full path before | |
836 | * setting any tags on intermediate nodes. If we set tags as we descend, then | |
837 | * we can get to the leaf node and find that the index that has the iftag | |
838 | * set is outside the range we are scanning. This reults in dangling tags and | |
839 | * can lead to problems with later tag operations (e.g. livelocks on lookups). | |
840 | * | |
ebf8aa44 JK |
841 | * The function returns number of leaves where the tag was set and sets |
842 | * *first_indexp to the first unscanned index. | |
d5ed3a4a JK |
843 | * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must |
844 | * be prepared to handle that. | |
ebf8aa44 JK |
845 | */ |
846 | unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, | |
847 | unsigned long *first_indexp, unsigned long last_index, | |
848 | unsigned long nr_to_tag, | |
849 | unsigned int iftag, unsigned int settag) | |
850 | { | |
144dcfc0 | 851 | unsigned int height = root->height; |
e2bdb933 | 852 | struct radix_tree_node *node = NULL; |
144dcfc0 DC |
853 | struct radix_tree_node *slot; |
854 | unsigned int shift; | |
855 | unsigned long tagged = 0; | |
856 | unsigned long index = *first_indexp; | |
ebf8aa44 JK |
857 | |
858 | last_index = min(last_index, radix_tree_maxindex(height)); | |
859 | if (index > last_index) | |
860 | return 0; | |
861 | if (!nr_to_tag) | |
862 | return 0; | |
863 | if (!root_tag_get(root, iftag)) { | |
864 | *first_indexp = last_index + 1; | |
865 | return 0; | |
866 | } | |
867 | if (height == 0) { | |
868 | *first_indexp = last_index + 1; | |
869 | root_tag_set(root, settag); | |
870 | return 1; | |
871 | } | |
872 | ||
873 | shift = (height - 1) * RADIX_TREE_MAP_SHIFT; | |
27d20fdd | 874 | slot = indirect_to_ptr(root->rnode); |
ebf8aa44 JK |
875 | |
876 | for (;;) { | |
e2bdb933 | 877 | unsigned long upindex; |
ebf8aa44 JK |
878 | int offset; |
879 | ||
880 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; | |
881 | if (!slot->slots[offset]) | |
882 | goto next; | |
883 | if (!tag_get(slot, iftag, offset)) | |
884 | goto next; | |
e2bdb933 | 885 | if (shift) { |
144dcfc0 | 886 | /* Go down one level */ |
144dcfc0 | 887 | shift -= RADIX_TREE_MAP_SHIFT; |
e2bdb933 | 888 | node = slot; |
144dcfc0 DC |
889 | slot = slot->slots[offset]; |
890 | continue; | |
891 | } | |
892 | ||
893 | /* tag the leaf */ | |
894 | tagged++; | |
ebf8aa44 | 895 | tag_set(slot, settag, offset); |
144dcfc0 DC |
896 | |
897 | /* walk back up the path tagging interior nodes */ | |
e2bdb933 HD |
898 | upindex = index; |
899 | while (node) { | |
900 | upindex >>= RADIX_TREE_MAP_SHIFT; | |
901 | offset = upindex & RADIX_TREE_MAP_MASK; | |
902 | ||
144dcfc0 | 903 | /* stop if we find a node with the tag already set */ |
e2bdb933 | 904 | if (tag_get(node, settag, offset)) |
144dcfc0 | 905 | break; |
e2bdb933 HD |
906 | tag_set(node, settag, offset); |
907 | node = node->parent; | |
ebf8aa44 | 908 | } |
144dcfc0 | 909 | |
e2bdb933 HD |
910 | /* |
911 | * Small optimization: now clear that node pointer. | |
912 | * Since all of this slot's ancestors now have the tag set | |
913 | * from setting it above, we have no further need to walk | |
914 | * back up the tree setting tags, until we update slot to | |
915 | * point to another radix_tree_node. | |
916 | */ | |
917 | node = NULL; | |
918 | ||
ebf8aa44 JK |
919 | next: |
920 | /* Go to next item at level determined by 'shift' */ | |
921 | index = ((index >> shift) + 1) << shift; | |
d5ed3a4a JK |
922 | /* Overflow can happen when last_index is ~0UL... */ |
923 | if (index > last_index || !index) | |
ebf8aa44 JK |
924 | break; |
925 | if (tagged >= nr_to_tag) | |
926 | break; | |
927 | while (((index >> shift) & RADIX_TREE_MAP_MASK) == 0) { | |
928 | /* | |
929 | * We've fully scanned this node. Go up. Because | |
930 | * last_index is guaranteed to be in the tree, what | |
931 | * we do below cannot wander astray. | |
932 | */ | |
e2bdb933 | 933 | slot = slot->parent; |
ebf8aa44 JK |
934 | shift += RADIX_TREE_MAP_SHIFT; |
935 | } | |
936 | } | |
937 | /* | |
ac15ee69 TO |
938 | * We need not to tag the root tag if there is no tag which is set with |
939 | * settag within the range from *first_indexp to last_index. | |
ebf8aa44 | 940 | */ |
ac15ee69 TO |
941 | if (tagged > 0) |
942 | root_tag_set(root, settag); | |
ebf8aa44 JK |
943 | *first_indexp = index; |
944 | ||
945 | return tagged; | |
946 | } | |
947 | EXPORT_SYMBOL(radix_tree_range_tag_if_tagged); | |
948 | ||
949 | ||
6df8ba4f FW |
950 | /** |
951 | * radix_tree_next_hole - find the next hole (not-present entry) | |
952 | * @root: tree root | |
953 | * @index: index key | |
954 | * @max_scan: maximum range to search | |
955 | * | |
956 | * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest | |
957 | * indexed hole. | |
958 | * | |
959 | * Returns: the index of the hole if found, otherwise returns an index | |
960 | * outside of the set specified (in which case 'return - index >= max_scan' | |
8e6bdb7f | 961 | * will be true). In rare cases of index wrap-around, 0 will be returned. |
6df8ba4f FW |
962 | * |
963 | * radix_tree_next_hole may be called under rcu_read_lock. However, like | |
8e6bdb7f WF |
964 | * radix_tree_gang_lookup, this will not atomically search a snapshot of |
965 | * the tree at a single point in time. For example, if a hole is created | |
966 | * at index 5, then subsequently a hole is created at index 10, | |
967 | * radix_tree_next_hole covering both indexes may return 10 if called | |
968 | * under rcu_read_lock. | |
6df8ba4f FW |
969 | */ |
970 | unsigned long radix_tree_next_hole(struct radix_tree_root *root, | |
971 | unsigned long index, unsigned long max_scan) | |
972 | { | |
973 | unsigned long i; | |
974 | ||
975 | for (i = 0; i < max_scan; i++) { | |
976 | if (!radix_tree_lookup(root, index)) | |
977 | break; | |
978 | index++; | |
979 | if (index == 0) | |
980 | break; | |
981 | } | |
982 | ||
983 | return index; | |
984 | } | |
985 | EXPORT_SYMBOL(radix_tree_next_hole); | |
986 | ||
dc566127 WF |
987 | /** |
988 | * radix_tree_prev_hole - find the prev hole (not-present entry) | |
989 | * @root: tree root | |
990 | * @index: index key | |
991 | * @max_scan: maximum range to search | |
992 | * | |
993 | * Search backwards in the range [max(index-max_scan+1, 0), index] | |
994 | * for the first hole. | |
995 | * | |
996 | * Returns: the index of the hole if found, otherwise returns an index | |
997 | * outside of the set specified (in which case 'index - return >= max_scan' | |
edcd1d84 | 998 | * will be true). In rare cases of wrap-around, ULONG_MAX will be returned. |
dc566127 WF |
999 | * |
1000 | * radix_tree_next_hole may be called under rcu_read_lock. However, like | |
1001 | * radix_tree_gang_lookup, this will not atomically search a snapshot of | |
1002 | * the tree at a single point in time. For example, if a hole is created | |
1003 | * at index 10, then subsequently a hole is created at index 5, | |
1004 | * radix_tree_prev_hole covering both indexes may return 5 if called under | |
1005 | * rcu_read_lock. | |
1006 | */ | |
1007 | unsigned long radix_tree_prev_hole(struct radix_tree_root *root, | |
1008 | unsigned long index, unsigned long max_scan) | |
1009 | { | |
1010 | unsigned long i; | |
1011 | ||
1012 | for (i = 0; i < max_scan; i++) { | |
1013 | if (!radix_tree_lookup(root, index)) | |
1014 | break; | |
1015 | index--; | |
edcd1d84 | 1016 | if (index == ULONG_MAX) |
dc566127 WF |
1017 | break; |
1018 | } | |
1019 | ||
1020 | return index; | |
1021 | } | |
1022 | EXPORT_SYMBOL(radix_tree_prev_hole); | |
1023 | ||
1da177e4 LT |
1024 | /** |
1025 | * radix_tree_gang_lookup - perform multiple lookup on a radix tree | |
1026 | * @root: radix tree root | |
1027 | * @results: where the results of the lookup are placed | |
1028 | * @first_index: start the lookup from this key | |
1029 | * @max_items: place up to this many items at *results | |
1030 | * | |
1031 | * Performs an index-ascending scan of the tree for present items. Places | |
1032 | * them at *@results and returns the number of items which were placed at | |
1033 | * *@results. | |
1034 | * | |
1035 | * The implementation is naive. | |
7cf9c2c7 NP |
1036 | * |
1037 | * Like radix_tree_lookup, radix_tree_gang_lookup may be called under | |
1038 | * rcu_read_lock. In this case, rather than the returned results being | |
1039 | * an atomic snapshot of the tree at a single point in time, the semantics | |
1040 | * of an RCU protected gang lookup are as though multiple radix_tree_lookups | |
1041 | * have been issued in individual locks, and results stored in 'results'. | |
1da177e4 LT |
1042 | */ |
1043 | unsigned int | |
1044 | radix_tree_gang_lookup(struct radix_tree_root *root, void **results, | |
1045 | unsigned long first_index, unsigned int max_items) | |
1046 | { | |
cebbd29e KK |
1047 | struct radix_tree_iter iter; |
1048 | void **slot; | |
1049 | unsigned int ret = 0; | |
7cf9c2c7 | 1050 | |
cebbd29e | 1051 | if (unlikely(!max_items)) |
7cf9c2c7 | 1052 | return 0; |
1da177e4 | 1053 | |
cebbd29e KK |
1054 | radix_tree_for_each_slot(slot, root, &iter, first_index) { |
1055 | results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot)); | |
1056 | if (!results[ret]) | |
1057 | continue; | |
1058 | if (++ret == max_items) | |
1da177e4 | 1059 | break; |
1da177e4 | 1060 | } |
7cf9c2c7 | 1061 | |
1da177e4 LT |
1062 | return ret; |
1063 | } | |
1064 | EXPORT_SYMBOL(radix_tree_gang_lookup); | |
1065 | ||
47feff2c NP |
1066 | /** |
1067 | * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree | |
1068 | * @root: radix tree root | |
1069 | * @results: where the results of the lookup are placed | |
6328650b | 1070 | * @indices: where their indices should be placed (but usually NULL) |
47feff2c NP |
1071 | * @first_index: start the lookup from this key |
1072 | * @max_items: place up to this many items at *results | |
1073 | * | |
1074 | * Performs an index-ascending scan of the tree for present items. Places | |
1075 | * their slots at *@results and returns the number of items which were | |
1076 | * placed at *@results. | |
1077 | * | |
1078 | * The implementation is naive. | |
1079 | * | |
1080 | * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must | |
1081 | * be dereferenced with radix_tree_deref_slot, and if using only RCU | |
1082 | * protection, radix_tree_deref_slot may fail requiring a retry. | |
1083 | */ | |
1084 | unsigned int | |
6328650b HD |
1085 | radix_tree_gang_lookup_slot(struct radix_tree_root *root, |
1086 | void ***results, unsigned long *indices, | |
47feff2c NP |
1087 | unsigned long first_index, unsigned int max_items) |
1088 | { | |
cebbd29e KK |
1089 | struct radix_tree_iter iter; |
1090 | void **slot; | |
1091 | unsigned int ret = 0; | |
47feff2c | 1092 | |
cebbd29e | 1093 | if (unlikely(!max_items)) |
47feff2c NP |
1094 | return 0; |
1095 | ||
cebbd29e KK |
1096 | radix_tree_for_each_slot(slot, root, &iter, first_index) { |
1097 | results[ret] = slot; | |
6328650b | 1098 | if (indices) |
cebbd29e KK |
1099 | indices[ret] = iter.index; |
1100 | if (++ret == max_items) | |
47feff2c | 1101 | break; |
47feff2c NP |
1102 | } |
1103 | ||
1104 | return ret; | |
1105 | } | |
1106 | EXPORT_SYMBOL(radix_tree_gang_lookup_slot); | |
1107 | ||
1da177e4 LT |
1108 | /** |
1109 | * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree | |
1110 | * based on a tag | |
1111 | * @root: radix tree root | |
1112 | * @results: where the results of the lookup are placed | |
1113 | * @first_index: start the lookup from this key | |
1114 | * @max_items: place up to this many items at *results | |
daff89f3 | 1115 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) |
1da177e4 LT |
1116 | * |
1117 | * Performs an index-ascending scan of the tree for present items which | |
1118 | * have the tag indexed by @tag set. Places the items at *@results and | |
1119 | * returns the number of items which were placed at *@results. | |
1120 | */ | |
1121 | unsigned int | |
1122 | radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, | |
daff89f3 JC |
1123 | unsigned long first_index, unsigned int max_items, |
1124 | unsigned int tag) | |
1da177e4 | 1125 | { |
cebbd29e KK |
1126 | struct radix_tree_iter iter; |
1127 | void **slot; | |
1128 | unsigned int ret = 0; | |
612d6c19 | 1129 | |
cebbd29e | 1130 | if (unlikely(!max_items)) |
7cf9c2c7 NP |
1131 | return 0; |
1132 | ||
cebbd29e KK |
1133 | radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) { |
1134 | results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot)); | |
1135 | if (!results[ret]) | |
1136 | continue; | |
1137 | if (++ret == max_items) | |
1da177e4 | 1138 | break; |
1da177e4 | 1139 | } |
7cf9c2c7 | 1140 | |
1da177e4 LT |
1141 | return ret; |
1142 | } | |
1143 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag); | |
1144 | ||
47feff2c NP |
1145 | /** |
1146 | * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a | |
1147 | * radix tree based on a tag | |
1148 | * @root: radix tree root | |
1149 | * @results: where the results of the lookup are placed | |
1150 | * @first_index: start the lookup from this key | |
1151 | * @max_items: place up to this many items at *results | |
1152 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) | |
1153 | * | |
1154 | * Performs an index-ascending scan of the tree for present items which | |
1155 | * have the tag indexed by @tag set. Places the slots at *@results and | |
1156 | * returns the number of slots which were placed at *@results. | |
1157 | */ | |
1158 | unsigned int | |
1159 | radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, | |
1160 | unsigned long first_index, unsigned int max_items, | |
1161 | unsigned int tag) | |
1162 | { | |
cebbd29e KK |
1163 | struct radix_tree_iter iter; |
1164 | void **slot; | |
1165 | unsigned int ret = 0; | |
47feff2c | 1166 | |
cebbd29e | 1167 | if (unlikely(!max_items)) |
47feff2c NP |
1168 | return 0; |
1169 | ||
cebbd29e KK |
1170 | radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) { |
1171 | results[ret] = slot; | |
1172 | if (++ret == max_items) | |
47feff2c | 1173 | break; |
47feff2c NP |
1174 | } |
1175 | ||
1176 | return ret; | |
1177 | } | |
1178 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); | |
1179 | ||
e504f3fd HD |
1180 | #if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP) |
1181 | #include <linux/sched.h> /* for cond_resched() */ | |
1182 | ||
1183 | /* | |
1184 | * This linear search is at present only useful to shmem_unuse_inode(). | |
1185 | */ | |
1186 | static unsigned long __locate(struct radix_tree_node *slot, void *item, | |
1187 | unsigned long index, unsigned long *found_index) | |
1188 | { | |
1189 | unsigned int shift, height; | |
1190 | unsigned long i; | |
1191 | ||
1192 | height = slot->height; | |
1193 | shift = (height-1) * RADIX_TREE_MAP_SHIFT; | |
1194 | ||
1195 | for ( ; height > 1; height--) { | |
1196 | i = (index >> shift) & RADIX_TREE_MAP_MASK; | |
1197 | for (;;) { | |
1198 | if (slot->slots[i] != NULL) | |
1199 | break; | |
1200 | index &= ~((1UL << shift) - 1); | |
1201 | index += 1UL << shift; | |
1202 | if (index == 0) | |
1203 | goto out; /* 32-bit wraparound */ | |
1204 | i++; | |
1205 | if (i == RADIX_TREE_MAP_SIZE) | |
1206 | goto out; | |
1207 | } | |
1208 | ||
1209 | shift -= RADIX_TREE_MAP_SHIFT; | |
1210 | slot = rcu_dereference_raw(slot->slots[i]); | |
1211 | if (slot == NULL) | |
1212 | goto out; | |
1213 | } | |
1214 | ||
1215 | /* Bottom level: check items */ | |
1216 | for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) { | |
1217 | if (slot->slots[i] == item) { | |
1218 | *found_index = index + i; | |
1219 | index = 0; | |
1220 | goto out; | |
1221 | } | |
1222 | } | |
1223 | index += RADIX_TREE_MAP_SIZE; | |
1224 | out: | |
1225 | return index; | |
1226 | } | |
1227 | ||
1228 | /** | |
1229 | * radix_tree_locate_item - search through radix tree for item | |
1230 | * @root: radix tree root | |
1231 | * @item: item to be found | |
1232 | * | |
1233 | * Returns index where item was found, or -1 if not found. | |
1234 | * Caller must hold no lock (since this time-consuming function needs | |
1235 | * to be preemptible), and must check afterwards if item is still there. | |
1236 | */ | |
1237 | unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) | |
1238 | { | |
1239 | struct radix_tree_node *node; | |
1240 | unsigned long max_index; | |
1241 | unsigned long cur_index = 0; | |
1242 | unsigned long found_index = -1; | |
1243 | ||
1244 | do { | |
1245 | rcu_read_lock(); | |
1246 | node = rcu_dereference_raw(root->rnode); | |
1247 | if (!radix_tree_is_indirect_ptr(node)) { | |
1248 | rcu_read_unlock(); | |
1249 | if (node == item) | |
1250 | found_index = 0; | |
1251 | break; | |
1252 | } | |
1253 | ||
1254 | node = indirect_to_ptr(node); | |
1255 | max_index = radix_tree_maxindex(node->height); | |
1256 | if (cur_index > max_index) | |
1257 | break; | |
1258 | ||
1259 | cur_index = __locate(node, item, cur_index, &found_index); | |
1260 | rcu_read_unlock(); | |
1261 | cond_resched(); | |
1262 | } while (cur_index != 0 && cur_index <= max_index); | |
1263 | ||
1264 | return found_index; | |
1265 | } | |
1266 | #else | |
1267 | unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) | |
1268 | { | |
1269 | return -1; | |
1270 | } | |
1271 | #endif /* CONFIG_SHMEM && CONFIG_SWAP */ | |
47feff2c | 1272 | |
a5f51c96 NP |
1273 | /** |
1274 | * radix_tree_shrink - shrink height of a radix tree to minimal | |
1275 | * @root radix tree root | |
1276 | */ | |
1277 | static inline void radix_tree_shrink(struct radix_tree_root *root) | |
1278 | { | |
1279 | /* try to shrink tree height */ | |
c0bc9875 | 1280 | while (root->height > 0) { |
a5f51c96 | 1281 | struct radix_tree_node *to_free = root->rnode; |
e2bdb933 | 1282 | struct radix_tree_node *slot; |
a5f51c96 | 1283 | |
c0bc9875 | 1284 | BUG_ON(!radix_tree_is_indirect_ptr(to_free)); |
27d20fdd | 1285 | to_free = indirect_to_ptr(to_free); |
c0bc9875 NP |
1286 | |
1287 | /* | |
1288 | * The candidate node has more than one child, or its child | |
1289 | * is not at the leftmost slot, we cannot shrink. | |
1290 | */ | |
1291 | if (to_free->count != 1) | |
1292 | break; | |
1293 | if (!to_free->slots[0]) | |
1294 | break; | |
1295 | ||
7cf9c2c7 NP |
1296 | /* |
1297 | * We don't need rcu_assign_pointer(), since we are simply | |
27d20fdd NP |
1298 | * moving the node from one part of the tree to another: if it |
1299 | * was safe to dereference the old pointer to it | |
7cf9c2c7 | 1300 | * (to_free->slots[0]), it will be safe to dereference the new |
27d20fdd | 1301 | * one (root->rnode) as far as dependent read barriers go. |
7cf9c2c7 | 1302 | */ |
e2bdb933 HD |
1303 | slot = to_free->slots[0]; |
1304 | if (root->height > 1) { | |
1305 | slot->parent = NULL; | |
1306 | slot = ptr_to_indirect(slot); | |
1307 | } | |
1308 | root->rnode = slot; | |
a5f51c96 | 1309 | root->height--; |
27d20fdd NP |
1310 | |
1311 | /* | |
1312 | * We have a dilemma here. The node's slot[0] must not be | |
1313 | * NULLed in case there are concurrent lookups expecting to | |
1314 | * find the item. However if this was a bottom-level node, | |
1315 | * then it may be subject to the slot pointer being visible | |
1316 | * to callers dereferencing it. If item corresponding to | |
1317 | * slot[0] is subsequently deleted, these callers would expect | |
1318 | * their slot to become empty sooner or later. | |
1319 | * | |
1320 | * For example, lockless pagecache will look up a slot, deref | |
1321 | * the page pointer, and if the page is 0 refcount it means it | |
1322 | * was concurrently deleted from pagecache so try the deref | |
1323 | * again. Fortunately there is already a requirement for logic | |
1324 | * to retry the entire slot lookup -- the indirect pointer | |
1325 | * problem (replacing direct root node with an indirect pointer | |
1326 | * also results in a stale slot). So tag the slot as indirect | |
1327 | * to force callers to retry. | |
1328 | */ | |
1329 | if (root->height == 0) | |
1330 | *((unsigned long *)&to_free->slots[0]) |= | |
1331 | RADIX_TREE_INDIRECT_PTR; | |
1332 | ||
a5f51c96 NP |
1333 | radix_tree_node_free(to_free); |
1334 | } | |
1335 | } | |
1336 | ||
1da177e4 LT |
1337 | /** |
1338 | * radix_tree_delete - delete an item from a radix tree | |
1339 | * @root: radix tree root | |
1340 | * @index: index key | |
1341 | * | |
1342 | * Remove the item at @index from the radix tree rooted at @root. | |
1343 | * | |
1344 | * Returns the address of the deleted item, or NULL if it was not present. | |
1345 | */ | |
1346 | void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) | |
1347 | { | |
e2bdb933 | 1348 | struct radix_tree_node *node = NULL; |
612d6c19 | 1349 | struct radix_tree_node *slot = NULL; |
7cf9c2c7 | 1350 | struct radix_tree_node *to_free; |
1da177e4 | 1351 | unsigned int height, shift; |
d5274261 | 1352 | int tag; |
e2bdb933 | 1353 | int uninitialized_var(offset); |
1da177e4 LT |
1354 | |
1355 | height = root->height; | |
1356 | if (index > radix_tree_maxindex(height)) | |
1357 | goto out; | |
1358 | ||
612d6c19 | 1359 | slot = root->rnode; |
c0bc9875 | 1360 | if (height == 0) { |
612d6c19 NP |
1361 | root_tag_clear_all(root); |
1362 | root->rnode = NULL; | |
1363 | goto out; | |
1364 | } | |
27d20fdd | 1365 | slot = indirect_to_ptr(slot); |
e2bdb933 | 1366 | shift = height * RADIX_TREE_MAP_SHIFT; |
1da177e4 | 1367 | |
612d6c19 | 1368 | do { |
201b6264 | 1369 | if (slot == NULL) |
1da177e4 LT |
1370 | goto out; |
1371 | ||
e2bdb933 | 1372 | shift -= RADIX_TREE_MAP_SHIFT; |
1da177e4 | 1373 | offset = (index >> shift) & RADIX_TREE_MAP_MASK; |
e2bdb933 | 1374 | node = slot; |
201b6264 | 1375 | slot = slot->slots[offset]; |
e2bdb933 | 1376 | } while (shift); |
1da177e4 | 1377 | |
612d6c19 | 1378 | if (slot == NULL) |
1da177e4 LT |
1379 | goto out; |
1380 | ||
1da177e4 | 1381 | /* |
e2bdb933 HD |
1382 | * Clear all tags associated with the item to be deleted. |
1383 | * This way of doing it would be inefficient, but seldom is any set. | |
1da177e4 | 1384 | */ |
daff89f3 | 1385 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { |
e2bdb933 | 1386 | if (tag_get(node, tag, offset)) |
612d6c19 | 1387 | radix_tree_tag_clear(root, index, tag); |
d5274261 | 1388 | } |
1da177e4 | 1389 | |
7cf9c2c7 | 1390 | to_free = NULL; |
201b6264 | 1391 | /* Now free the nodes we do not need anymore */ |
e2bdb933 HD |
1392 | while (node) { |
1393 | node->slots[offset] = NULL; | |
1394 | node->count--; | |
7cf9c2c7 NP |
1395 | /* |
1396 | * Queue the node for deferred freeing after the | |
1397 | * last reference to it disappears (set NULL, above). | |
1398 | */ | |
1399 | if (to_free) | |
1400 | radix_tree_node_free(to_free); | |
a5f51c96 | 1401 | |
e2bdb933 HD |
1402 | if (node->count) { |
1403 | if (node == indirect_to_ptr(root->rnode)) | |
a5f51c96 | 1404 | radix_tree_shrink(root); |
201b6264 | 1405 | goto out; |
a5f51c96 | 1406 | } |
201b6264 CL |
1407 | |
1408 | /* Node with zero slots in use so free it */ | |
e2bdb933 | 1409 | to_free = node; |
7cf9c2c7 | 1410 | |
e2bdb933 HD |
1411 | index >>= RADIX_TREE_MAP_SHIFT; |
1412 | offset = index & RADIX_TREE_MAP_MASK; | |
1413 | node = node->parent; | |
1da177e4 | 1414 | } |
e2bdb933 | 1415 | |
612d6c19 | 1416 | root_tag_clear_all(root); |
201b6264 | 1417 | root->height = 0; |
612d6c19 | 1418 | root->rnode = NULL; |
7cf9c2c7 NP |
1419 | if (to_free) |
1420 | radix_tree_node_free(to_free); | |
612d6c19 | 1421 | |
1da177e4 | 1422 | out: |
612d6c19 | 1423 | return slot; |
1da177e4 LT |
1424 | } |
1425 | EXPORT_SYMBOL(radix_tree_delete); | |
1426 | ||
1427 | /** | |
1428 | * radix_tree_tagged - test whether any items in the tree are tagged | |
1429 | * @root: radix tree root | |
1430 | * @tag: tag to test | |
1431 | */ | |
daff89f3 | 1432 | int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) |
1da177e4 | 1433 | { |
612d6c19 | 1434 | return root_tag_get(root, tag); |
1da177e4 LT |
1435 | } |
1436 | EXPORT_SYMBOL(radix_tree_tagged); | |
1437 | ||
1438 | static void | |
51cc5068 | 1439 | radix_tree_node_ctor(void *node) |
1da177e4 LT |
1440 | { |
1441 | memset(node, 0, sizeof(struct radix_tree_node)); | |
1442 | } | |
1443 | ||
1444 | static __init unsigned long __maxindex(unsigned int height) | |
1445 | { | |
430d275a PL |
1446 | unsigned int width = height * RADIX_TREE_MAP_SHIFT; |
1447 | int shift = RADIX_TREE_INDEX_BITS - width; | |
1448 | ||
1449 | if (shift < 0) | |
1450 | return ~0UL; | |
1451 | if (shift >= BITS_PER_LONG) | |
1452 | return 0UL; | |
1453 | return ~0UL >> shift; | |
1da177e4 LT |
1454 | } |
1455 | ||
1456 | static __init void radix_tree_init_maxindex(void) | |
1457 | { | |
1458 | unsigned int i; | |
1459 | ||
1460 | for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++) | |
1461 | height_to_maxindex[i] = __maxindex(i); | |
1462 | } | |
1463 | ||
1da177e4 LT |
1464 | static int radix_tree_callback(struct notifier_block *nfb, |
1465 | unsigned long action, | |
1466 | void *hcpu) | |
1467 | { | |
1468 | int cpu = (long)hcpu; | |
1469 | struct radix_tree_preload *rtp; | |
1470 | ||
1471 | /* Free per-cpu pool of perloaded nodes */ | |
8bb78442 | 1472 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { |
1da177e4 LT |
1473 | rtp = &per_cpu(radix_tree_preloads, cpu); |
1474 | while (rtp->nr) { | |
1475 | kmem_cache_free(radix_tree_node_cachep, | |
1476 | rtp->nodes[rtp->nr-1]); | |
1477 | rtp->nodes[rtp->nr-1] = NULL; | |
1478 | rtp->nr--; | |
1479 | } | |
1480 | } | |
1481 | return NOTIFY_OK; | |
1482 | } | |
1da177e4 LT |
1483 | |
1484 | void __init radix_tree_init(void) | |
1485 | { | |
1486 | radix_tree_node_cachep = kmem_cache_create("radix_tree_node", | |
1487 | sizeof(struct radix_tree_node), 0, | |
488514d1 CL |
1488 | SLAB_PANIC | SLAB_RECLAIM_ACCOUNT, |
1489 | radix_tree_node_ctor); | |
1da177e4 LT |
1490 | radix_tree_init_maxindex(); |
1491 | hotcpu_notifier(radix_tree_callback, 0); | |
1492 | } |