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1 | /* | |
2 | * Copyright (C) 2001 Momchil Velikov | |
3 | * Portions Copyright (C) 2001 Christoph Hellwig | |
4 | * Copyright (C) 2005 SGI, Christoph Lameter | |
5 | * Copyright (C) 2006 Nick Piggin | |
6 | * Copyright (C) 2012 Konstantin Khlebnikov | |
7 | * Copyright (C) 2016 Intel, Matthew Wilcox | |
8 | * Copyright (C) 2016 Intel, Ross Zwisler | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License as | |
12 | * published by the Free Software Foundation; either version 2, or (at | |
13 | * your option) any later version. | |
14 | * | |
15 | * This program is distributed in the hope that it will be useful, but | |
16 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | * General Public License for more details. | |
19 | * | |
20 | * You should have received a copy of the GNU General Public License | |
21 | * along with this program; if not, write to the Free Software | |
22 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
23 | */ | |
24 | ||
25 | #include <linux/errno.h> | |
26 | #include <linux/init.h> | |
27 | #include <linux/kernel.h> | |
28 | #include <linux/export.h> | |
29 | #include <linux/radix-tree.h> | |
30 | #include <linux/percpu.h> | |
31 | #include <linux/slab.h> | |
32 | #include <linux/kmemleak.h> | |
33 | #include <linux/notifier.h> | |
34 | #include <linux/cpu.h> | |
35 | #include <linux/string.h> | |
36 | #include <linux/bitops.h> | |
37 | #include <linux/rcupdate.h> | |
38 | #include <linux/preempt.h> /* in_interrupt() */ | |
39 | ||
40 | ||
41 | /* Number of nodes in fully populated tree of given height */ | |
42 | static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly; | |
43 | ||
44 | /* | |
45 | * Radix tree node cache. | |
46 | */ | |
47 | static struct kmem_cache *radix_tree_node_cachep; | |
48 | ||
49 | /* | |
50 | * The radix tree is variable-height, so an insert operation not only has | |
51 | * to build the branch to its corresponding item, it also has to build the | |
52 | * branch to existing items if the size has to be increased (by | |
53 | * radix_tree_extend). | |
54 | * | |
55 | * The worst case is a zero height tree with just a single item at index 0, | |
56 | * and then inserting an item at index ULONG_MAX. This requires 2 new branches | |
57 | * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. | |
58 | * Hence: | |
59 | */ | |
60 | #define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1) | |
61 | ||
62 | /* | |
63 | * Per-cpu pool of preloaded nodes | |
64 | */ | |
65 | struct radix_tree_preload { | |
66 | unsigned nr; | |
67 | /* nodes->private_data points to next preallocated node */ | |
68 | struct radix_tree_node *nodes; | |
69 | }; | |
70 | static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; | |
71 | ||
72 | static inline void *node_to_entry(void *ptr) | |
73 | { | |
74 | return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE); | |
75 | } | |
76 | ||
77 | #define RADIX_TREE_RETRY node_to_entry(NULL) | |
78 | ||
79 | #ifdef CONFIG_RADIX_TREE_MULTIORDER | |
80 | /* Sibling slots point directly to another slot in the same node */ | |
81 | static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node) | |
82 | { | |
83 | void **ptr = node; | |
84 | return (parent->slots <= ptr) && | |
85 | (ptr < parent->slots + RADIX_TREE_MAP_SIZE); | |
86 | } | |
87 | #else | |
88 | static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node) | |
89 | { | |
90 | return false; | |
91 | } | |
92 | #endif | |
93 | ||
94 | static inline unsigned long get_slot_offset(struct radix_tree_node *parent, | |
95 | void **slot) | |
96 | { | |
97 | return slot - parent->slots; | |
98 | } | |
99 | ||
100 | static unsigned int radix_tree_descend(struct radix_tree_node *parent, | |
101 | struct radix_tree_node **nodep, unsigned long index) | |
102 | { | |
103 | unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK; | |
104 | void **entry = rcu_dereference_raw(parent->slots[offset]); | |
105 | ||
106 | #ifdef CONFIG_RADIX_TREE_MULTIORDER | |
107 | if (radix_tree_is_internal_node(entry)) { | |
108 | if (is_sibling_entry(parent, entry)) { | |
109 | void **sibentry = (void **) entry_to_node(entry); | |
110 | offset = get_slot_offset(parent, sibentry); | |
111 | entry = rcu_dereference_raw(*sibentry); | |
112 | } | |
113 | } | |
114 | #endif | |
115 | ||
116 | *nodep = (void *)entry; | |
117 | return offset; | |
118 | } | |
119 | ||
120 | static inline gfp_t root_gfp_mask(struct radix_tree_root *root) | |
121 | { | |
122 | return root->gfp_mask & __GFP_BITS_MASK; | |
123 | } | |
124 | ||
125 | static inline void tag_set(struct radix_tree_node *node, unsigned int tag, | |
126 | int offset) | |
127 | { | |
128 | __set_bit(offset, node->tags[tag]); | |
129 | } | |
130 | ||
131 | static inline void tag_clear(struct radix_tree_node *node, unsigned int tag, | |
132 | int offset) | |
133 | { | |
134 | __clear_bit(offset, node->tags[tag]); | |
135 | } | |
136 | ||
137 | static inline int tag_get(struct radix_tree_node *node, unsigned int tag, | |
138 | int offset) | |
139 | { | |
140 | return test_bit(offset, node->tags[tag]); | |
141 | } | |
142 | ||
143 | static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag) | |
144 | { | |
145 | root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT)); | |
146 | } | |
147 | ||
148 | static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag) | |
149 | { | |
150 | root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT)); | |
151 | } | |
152 | ||
153 | static inline void root_tag_clear_all(struct radix_tree_root *root) | |
154 | { | |
155 | root->gfp_mask &= __GFP_BITS_MASK; | |
156 | } | |
157 | ||
158 | static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag) | |
159 | { | |
160 | return (__force int)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT)); | |
161 | } | |
162 | ||
163 | static inline unsigned root_tags_get(struct radix_tree_root *root) | |
164 | { | |
165 | return (__force unsigned)root->gfp_mask >> __GFP_BITS_SHIFT; | |
166 | } | |
167 | ||
168 | /* | |
169 | * Returns 1 if any slot in the node has this tag set. | |
170 | * Otherwise returns 0. | |
171 | */ | |
172 | static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag) | |
173 | { | |
174 | unsigned idx; | |
175 | for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { | |
176 | if (node->tags[tag][idx]) | |
177 | return 1; | |
178 | } | |
179 | return 0; | |
180 | } | |
181 | ||
182 | /** | |
183 | * radix_tree_find_next_bit - find the next set bit in a memory region | |
184 | * | |
185 | * @addr: The address to base the search on | |
186 | * @size: The bitmap size in bits | |
187 | * @offset: The bitnumber to start searching at | |
188 | * | |
189 | * Unrollable variant of find_next_bit() for constant size arrays. | |
190 | * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero. | |
191 | * Returns next bit offset, or size if nothing found. | |
192 | */ | |
193 | static __always_inline unsigned long | |
194 | radix_tree_find_next_bit(const unsigned long *addr, | |
195 | unsigned long size, unsigned long offset) | |
196 | { | |
197 | if (!__builtin_constant_p(size)) | |
198 | return find_next_bit(addr, size, offset); | |
199 | ||
200 | if (offset < size) { | |
201 | unsigned long tmp; | |
202 | ||
203 | addr += offset / BITS_PER_LONG; | |
204 | tmp = *addr >> (offset % BITS_PER_LONG); | |
205 | if (tmp) | |
206 | return __ffs(tmp) + offset; | |
207 | offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1); | |
208 | while (offset < size) { | |
209 | tmp = *++addr; | |
210 | if (tmp) | |
211 | return __ffs(tmp) + offset; | |
212 | offset += BITS_PER_LONG; | |
213 | } | |
214 | } | |
215 | return size; | |
216 | } | |
217 | ||
218 | #ifndef __KERNEL__ | |
219 | static void dump_node(struct radix_tree_node *node, unsigned long index) | |
220 | { | |
221 | unsigned long i; | |
222 | ||
223 | pr_debug("radix node: %p offset %d tags %lx %lx %lx shift %d count %d exceptional %d parent %p\n", | |
224 | node, node->offset, | |
225 | node->tags[0][0], node->tags[1][0], node->tags[2][0], | |
226 | node->shift, node->count, node->exceptional, node->parent); | |
227 | ||
228 | for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) { | |
229 | unsigned long first = index | (i << node->shift); | |
230 | unsigned long last = first | ((1UL << node->shift) - 1); | |
231 | void *entry = node->slots[i]; | |
232 | if (!entry) | |
233 | continue; | |
234 | if (is_sibling_entry(node, entry)) { | |
235 | pr_debug("radix sblng %p offset %ld val %p indices %ld-%ld\n", | |
236 | entry, i, | |
237 | *(void **)entry_to_node(entry), | |
238 | first, last); | |
239 | } else if (!radix_tree_is_internal_node(entry)) { | |
240 | pr_debug("radix entry %p offset %ld indices %ld-%ld\n", | |
241 | entry, i, first, last); | |
242 | } else { | |
243 | dump_node(entry_to_node(entry), first); | |
244 | } | |
245 | } | |
246 | } | |
247 | ||
248 | /* For debug */ | |
249 | static void radix_tree_dump(struct radix_tree_root *root) | |
250 | { | |
251 | pr_debug("radix root: %p rnode %p tags %x\n", | |
252 | root, root->rnode, | |
253 | root->gfp_mask >> __GFP_BITS_SHIFT); | |
254 | if (!radix_tree_is_internal_node(root->rnode)) | |
255 | return; | |
256 | dump_node(entry_to_node(root->rnode), 0); | |
257 | } | |
258 | #endif | |
259 | ||
260 | /* | |
261 | * This assumes that the caller has performed appropriate preallocation, and | |
262 | * that the caller has pinned this thread of control to the current CPU. | |
263 | */ | |
264 | static struct radix_tree_node * | |
265 | radix_tree_node_alloc(struct radix_tree_root *root) | |
266 | { | |
267 | struct radix_tree_node *ret = NULL; | |
268 | gfp_t gfp_mask = root_gfp_mask(root); | |
269 | ||
270 | /* | |
271 | * Preload code isn't irq safe and it doesn't make sense to use | |
272 | * preloading during an interrupt anyway as all the allocations have | |
273 | * to be atomic. So just do normal allocation when in interrupt. | |
274 | */ | |
275 | if (!gfpflags_allow_blocking(gfp_mask) && !in_interrupt()) { | |
276 | struct radix_tree_preload *rtp; | |
277 | ||
278 | /* | |
279 | * Even if the caller has preloaded, try to allocate from the | |
280 | * cache first for the new node to get accounted to the memory | |
281 | * cgroup. | |
282 | */ | |
283 | ret = kmem_cache_alloc(radix_tree_node_cachep, | |
284 | gfp_mask | __GFP_NOWARN); | |
285 | if (ret) | |
286 | goto out; | |
287 | ||
288 | /* | |
289 | * Provided the caller has preloaded here, we will always | |
290 | * succeed in getting a node here (and never reach | |
291 | * kmem_cache_alloc) | |
292 | */ | |
293 | rtp = this_cpu_ptr(&radix_tree_preloads); | |
294 | if (rtp->nr) { | |
295 | ret = rtp->nodes; | |
296 | rtp->nodes = ret->private_data; | |
297 | ret->private_data = NULL; | |
298 | rtp->nr--; | |
299 | } | |
300 | /* | |
301 | * Update the allocation stack trace as this is more useful | |
302 | * for debugging. | |
303 | */ | |
304 | kmemleak_update_trace(ret); | |
305 | goto out; | |
306 | } | |
307 | ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); | |
308 | out: | |
309 | BUG_ON(radix_tree_is_internal_node(ret)); | |
310 | return ret; | |
311 | } | |
312 | ||
313 | static void radix_tree_node_rcu_free(struct rcu_head *head) | |
314 | { | |
315 | struct radix_tree_node *node = | |
316 | container_of(head, struct radix_tree_node, rcu_head); | |
317 | int i; | |
318 | ||
319 | /* | |
320 | * must only free zeroed nodes into the slab. radix_tree_shrink | |
321 | * can leave us with a non-NULL entry in the first slot, so clear | |
322 | * that here to make sure. | |
323 | */ | |
324 | for (i = 0; i < RADIX_TREE_MAX_TAGS; i++) | |
325 | tag_clear(node, i, 0); | |
326 | ||
327 | node->slots[0] = NULL; | |
328 | ||
329 | kmem_cache_free(radix_tree_node_cachep, node); | |
330 | } | |
331 | ||
332 | static inline void | |
333 | radix_tree_node_free(struct radix_tree_node *node) | |
334 | { | |
335 | call_rcu(&node->rcu_head, radix_tree_node_rcu_free); | |
336 | } | |
337 | ||
338 | /* | |
339 | * Load up this CPU's radix_tree_node buffer with sufficient objects to | |
340 | * ensure that the addition of a single element in the tree cannot fail. On | |
341 | * success, return zero, with preemption disabled. On error, return -ENOMEM | |
342 | * with preemption not disabled. | |
343 | * | |
344 | * To make use of this facility, the radix tree must be initialised without | |
345 | * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE(). | |
346 | */ | |
347 | static int __radix_tree_preload(gfp_t gfp_mask, int nr) | |
348 | { | |
349 | struct radix_tree_preload *rtp; | |
350 | struct radix_tree_node *node; | |
351 | int ret = -ENOMEM; | |
352 | ||
353 | /* | |
354 | * Nodes preloaded by one cgroup can be be used by another cgroup, so | |
355 | * they should never be accounted to any particular memory cgroup. | |
356 | */ | |
357 | gfp_mask &= ~__GFP_ACCOUNT; | |
358 | ||
359 | preempt_disable(); | |
360 | rtp = this_cpu_ptr(&radix_tree_preloads); | |
361 | while (rtp->nr < nr) { | |
362 | preempt_enable(); | |
363 | node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); | |
364 | if (node == NULL) | |
365 | goto out; | |
366 | preempt_disable(); | |
367 | rtp = this_cpu_ptr(&radix_tree_preloads); | |
368 | if (rtp->nr < nr) { | |
369 | node->private_data = rtp->nodes; | |
370 | rtp->nodes = node; | |
371 | rtp->nr++; | |
372 | } else { | |
373 | kmem_cache_free(radix_tree_node_cachep, node); | |
374 | } | |
375 | } | |
376 | ret = 0; | |
377 | out: | |
378 | return ret; | |
379 | } | |
380 | ||
381 | /* | |
382 | * Load up this CPU's radix_tree_node buffer with sufficient objects to | |
383 | * ensure that the addition of a single element in the tree cannot fail. On | |
384 | * success, return zero, with preemption disabled. On error, return -ENOMEM | |
385 | * with preemption not disabled. | |
386 | * | |
387 | * To make use of this facility, the radix tree must be initialised without | |
388 | * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE(). | |
389 | */ | |
390 | int radix_tree_preload(gfp_t gfp_mask) | |
391 | { | |
392 | /* Warn on non-sensical use... */ | |
393 | WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask)); | |
394 | return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE); | |
395 | } | |
396 | EXPORT_SYMBOL(radix_tree_preload); | |
397 | ||
398 | /* | |
399 | * The same as above function, except we don't guarantee preloading happens. | |
400 | * We do it, if we decide it helps. On success, return zero with preemption | |
401 | * disabled. On error, return -ENOMEM with preemption not disabled. | |
402 | */ | |
403 | int radix_tree_maybe_preload(gfp_t gfp_mask) | |
404 | { | |
405 | if (gfpflags_allow_blocking(gfp_mask)) | |
406 | return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE); | |
407 | /* Preloading doesn't help anything with this gfp mask, skip it */ | |
408 | preempt_disable(); | |
409 | return 0; | |
410 | } | |
411 | EXPORT_SYMBOL(radix_tree_maybe_preload); | |
412 | ||
413 | /* | |
414 | * The same as function above, but preload number of nodes required to insert | |
415 | * (1 << order) continuous naturally-aligned elements. | |
416 | */ | |
417 | int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order) | |
418 | { | |
419 | unsigned long nr_subtrees; | |
420 | int nr_nodes, subtree_height; | |
421 | ||
422 | /* Preloading doesn't help anything with this gfp mask, skip it */ | |
423 | if (!gfpflags_allow_blocking(gfp_mask)) { | |
424 | preempt_disable(); | |
425 | return 0; | |
426 | } | |
427 | ||
428 | /* | |
429 | * Calculate number and height of fully populated subtrees it takes to | |
430 | * store (1 << order) elements. | |
431 | */ | |
432 | nr_subtrees = 1 << order; | |
433 | for (subtree_height = 0; nr_subtrees > RADIX_TREE_MAP_SIZE; | |
434 | subtree_height++) | |
435 | nr_subtrees >>= RADIX_TREE_MAP_SHIFT; | |
436 | ||
437 | /* | |
438 | * The worst case is zero height tree with a single item at index 0 and | |
439 | * then inserting items starting at ULONG_MAX - (1 << order). | |
440 | * | |
441 | * This requires RADIX_TREE_MAX_PATH nodes to build branch from root to | |
442 | * 0-index item. | |
443 | */ | |
444 | nr_nodes = RADIX_TREE_MAX_PATH; | |
445 | ||
446 | /* Plus branch to fully populated subtrees. */ | |
447 | nr_nodes += RADIX_TREE_MAX_PATH - subtree_height; | |
448 | ||
449 | /* Root node is shared. */ | |
450 | nr_nodes--; | |
451 | ||
452 | /* Plus nodes required to build subtrees. */ | |
453 | nr_nodes += nr_subtrees * height_to_maxnodes[subtree_height]; | |
454 | ||
455 | return __radix_tree_preload(gfp_mask, nr_nodes); | |
456 | } | |
457 | ||
458 | /* | |
459 | * The maximum index which can be stored in a radix tree | |
460 | */ | |
461 | static inline unsigned long shift_maxindex(unsigned int shift) | |
462 | { | |
463 | return (RADIX_TREE_MAP_SIZE << shift) - 1; | |
464 | } | |
465 | ||
466 | static inline unsigned long node_maxindex(struct radix_tree_node *node) | |
467 | { | |
468 | return shift_maxindex(node->shift); | |
469 | } | |
470 | ||
471 | static unsigned radix_tree_load_root(struct radix_tree_root *root, | |
472 | struct radix_tree_node **nodep, unsigned long *maxindex) | |
473 | { | |
474 | struct radix_tree_node *node = rcu_dereference_raw(root->rnode); | |
475 | ||
476 | *nodep = node; | |
477 | ||
478 | if (likely(radix_tree_is_internal_node(node))) { | |
479 | node = entry_to_node(node); | |
480 | *maxindex = node_maxindex(node); | |
481 | return node->shift + RADIX_TREE_MAP_SHIFT; | |
482 | } | |
483 | ||
484 | *maxindex = 0; | |
485 | return 0; | |
486 | } | |
487 | ||
488 | /* | |
489 | * Extend a radix tree so it can store key @index. | |
490 | */ | |
491 | static int radix_tree_extend(struct radix_tree_root *root, | |
492 | unsigned long index, unsigned int shift) | |
493 | { | |
494 | struct radix_tree_node *slot; | |
495 | unsigned int maxshift; | |
496 | int tag; | |
497 | ||
498 | /* Figure out what the shift should be. */ | |
499 | maxshift = shift; | |
500 | while (index > shift_maxindex(maxshift)) | |
501 | maxshift += RADIX_TREE_MAP_SHIFT; | |
502 | ||
503 | slot = root->rnode; | |
504 | if (!slot) | |
505 | goto out; | |
506 | ||
507 | do { | |
508 | struct radix_tree_node *node = radix_tree_node_alloc(root); | |
509 | ||
510 | if (!node) | |
511 | return -ENOMEM; | |
512 | ||
513 | /* Propagate the aggregated tag info into the new root */ | |
514 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { | |
515 | if (root_tag_get(root, tag)) | |
516 | tag_set(node, tag, 0); | |
517 | } | |
518 | ||
519 | BUG_ON(shift > BITS_PER_LONG); | |
520 | node->shift = shift; | |
521 | node->offset = 0; | |
522 | node->count = 1; | |
523 | node->parent = NULL; | |
524 | if (radix_tree_is_internal_node(slot)) { | |
525 | entry_to_node(slot)->parent = node; | |
526 | } else { | |
527 | /* Moving an exceptional root->rnode to a node */ | |
528 | if (radix_tree_exceptional_entry(slot)) | |
529 | node->exceptional = 1; | |
530 | } | |
531 | node->slots[0] = slot; | |
532 | slot = node_to_entry(node); | |
533 | rcu_assign_pointer(root->rnode, slot); | |
534 | shift += RADIX_TREE_MAP_SHIFT; | |
535 | } while (shift <= maxshift); | |
536 | out: | |
537 | return maxshift + RADIX_TREE_MAP_SHIFT; | |
538 | } | |
539 | ||
540 | /** | |
541 | * radix_tree_shrink - shrink radix tree to minimum height | |
542 | * @root radix tree root | |
543 | */ | |
544 | static inline void radix_tree_shrink(struct radix_tree_root *root, | |
545 | radix_tree_update_node_t update_node, | |
546 | void *private) | |
547 | { | |
548 | for (;;) { | |
549 | struct radix_tree_node *node = root->rnode; | |
550 | struct radix_tree_node *child; | |
551 | ||
552 | if (!radix_tree_is_internal_node(node)) | |
553 | break; | |
554 | node = entry_to_node(node); | |
555 | ||
556 | /* | |
557 | * The candidate node has more than one child, or its child | |
558 | * is not at the leftmost slot, or the child is a multiorder | |
559 | * entry, we cannot shrink. | |
560 | */ | |
561 | if (node->count != 1) | |
562 | break; | |
563 | child = node->slots[0]; | |
564 | if (!child) | |
565 | break; | |
566 | if (!radix_tree_is_internal_node(child) && node->shift) | |
567 | break; | |
568 | ||
569 | if (radix_tree_is_internal_node(child)) | |
570 | entry_to_node(child)->parent = NULL; | |
571 | ||
572 | /* | |
573 | * We don't need rcu_assign_pointer(), since we are simply | |
574 | * moving the node from one part of the tree to another: if it | |
575 | * was safe to dereference the old pointer to it | |
576 | * (node->slots[0]), it will be safe to dereference the new | |
577 | * one (root->rnode) as far as dependent read barriers go. | |
578 | */ | |
579 | root->rnode = child; | |
580 | ||
581 | /* | |
582 | * We have a dilemma here. The node's slot[0] must not be | |
583 | * NULLed in case there are concurrent lookups expecting to | |
584 | * find the item. However if this was a bottom-level node, | |
585 | * then it may be subject to the slot pointer being visible | |
586 | * to callers dereferencing it. If item corresponding to | |
587 | * slot[0] is subsequently deleted, these callers would expect | |
588 | * their slot to become empty sooner or later. | |
589 | * | |
590 | * For example, lockless pagecache will look up a slot, deref | |
591 | * the page pointer, and if the page has 0 refcount it means it | |
592 | * was concurrently deleted from pagecache so try the deref | |
593 | * again. Fortunately there is already a requirement for logic | |
594 | * to retry the entire slot lookup -- the indirect pointer | |
595 | * problem (replacing direct root node with an indirect pointer | |
596 | * also results in a stale slot). So tag the slot as indirect | |
597 | * to force callers to retry. | |
598 | */ | |
599 | node->count = 0; | |
600 | if (!radix_tree_is_internal_node(child)) { | |
601 | node->slots[0] = RADIX_TREE_RETRY; | |
602 | if (update_node) | |
603 | update_node(node, private); | |
604 | } | |
605 | ||
606 | radix_tree_node_free(node); | |
607 | } | |
608 | } | |
609 | ||
610 | static void delete_node(struct radix_tree_root *root, | |
611 | struct radix_tree_node *node, | |
612 | radix_tree_update_node_t update_node, void *private) | |
613 | { | |
614 | do { | |
615 | struct radix_tree_node *parent; | |
616 | ||
617 | if (node->count) { | |
618 | if (node == entry_to_node(root->rnode)) | |
619 | radix_tree_shrink(root, update_node, private); | |
620 | return; | |
621 | } | |
622 | ||
623 | parent = node->parent; | |
624 | if (parent) { | |
625 | parent->slots[node->offset] = NULL; | |
626 | parent->count--; | |
627 | } else { | |
628 | root_tag_clear_all(root); | |
629 | root->rnode = NULL; | |
630 | } | |
631 | ||
632 | radix_tree_node_free(node); | |
633 | ||
634 | node = parent; | |
635 | } while (node); | |
636 | } | |
637 | ||
638 | /** | |
639 | * __radix_tree_create - create a slot in a radix tree | |
640 | * @root: radix tree root | |
641 | * @index: index key | |
642 | * @order: index occupies 2^order aligned slots | |
643 | * @nodep: returns node | |
644 | * @slotp: returns slot | |
645 | * | |
646 | * Create, if necessary, and return the node and slot for an item | |
647 | * at position @index in the radix tree @root. | |
648 | * | |
649 | * Until there is more than one item in the tree, no nodes are | |
650 | * allocated and @root->rnode is used as a direct slot instead of | |
651 | * pointing to a node, in which case *@nodep will be NULL. | |
652 | * | |
653 | * Returns -ENOMEM, or 0 for success. | |
654 | */ | |
655 | int __radix_tree_create(struct radix_tree_root *root, unsigned long index, | |
656 | unsigned order, struct radix_tree_node **nodep, | |
657 | void ***slotp) | |
658 | { | |
659 | struct radix_tree_node *node = NULL, *child; | |
660 | void **slot = (void **)&root->rnode; | |
661 | unsigned long maxindex; | |
662 | unsigned int shift, offset = 0; | |
663 | unsigned long max = index | ((1UL << order) - 1); | |
664 | ||
665 | shift = radix_tree_load_root(root, &child, &maxindex); | |
666 | ||
667 | /* Make sure the tree is high enough. */ | |
668 | if (max > maxindex) { | |
669 | int error = radix_tree_extend(root, max, shift); | |
670 | if (error < 0) | |
671 | return error; | |
672 | shift = error; | |
673 | child = root->rnode; | |
674 | if (order == shift) | |
675 | shift += RADIX_TREE_MAP_SHIFT; | |
676 | } | |
677 | ||
678 | while (shift > order) { | |
679 | shift -= RADIX_TREE_MAP_SHIFT; | |
680 | if (child == NULL) { | |
681 | /* Have to add a child node. */ | |
682 | child = radix_tree_node_alloc(root); | |
683 | if (!child) | |
684 | return -ENOMEM; | |
685 | child->shift = shift; | |
686 | child->offset = offset; | |
687 | child->parent = node; | |
688 | rcu_assign_pointer(*slot, node_to_entry(child)); | |
689 | if (node) | |
690 | node->count++; | |
691 | } else if (!radix_tree_is_internal_node(child)) | |
692 | break; | |
693 | ||
694 | /* Go a level down */ | |
695 | node = entry_to_node(child); | |
696 | offset = radix_tree_descend(node, &child, index); | |
697 | slot = &node->slots[offset]; | |
698 | } | |
699 | ||
700 | #ifdef CONFIG_RADIX_TREE_MULTIORDER | |
701 | /* Insert pointers to the canonical entry */ | |
702 | if (order > shift) { | |
703 | unsigned i, n = 1 << (order - shift); | |
704 | offset = offset & ~(n - 1); | |
705 | slot = &node->slots[offset]; | |
706 | child = node_to_entry(slot); | |
707 | for (i = 0; i < n; i++) { | |
708 | if (slot[i]) | |
709 | return -EEXIST; | |
710 | } | |
711 | ||
712 | for (i = 1; i < n; i++) { | |
713 | rcu_assign_pointer(slot[i], child); | |
714 | node->count++; | |
715 | } | |
716 | } | |
717 | #endif | |
718 | ||
719 | if (nodep) | |
720 | *nodep = node; | |
721 | if (slotp) | |
722 | *slotp = slot; | |
723 | return 0; | |
724 | } | |
725 | ||
726 | /** | |
727 | * __radix_tree_insert - insert into a radix tree | |
728 | * @root: radix tree root | |
729 | * @index: index key | |
730 | * @order: key covers the 2^order indices around index | |
731 | * @item: item to insert | |
732 | * | |
733 | * Insert an item into the radix tree at position @index. | |
734 | */ | |
735 | int __radix_tree_insert(struct radix_tree_root *root, unsigned long index, | |
736 | unsigned order, void *item) | |
737 | { | |
738 | struct radix_tree_node *node; | |
739 | void **slot; | |
740 | int error; | |
741 | ||
742 | BUG_ON(radix_tree_is_internal_node(item)); | |
743 | ||
744 | error = __radix_tree_create(root, index, order, &node, &slot); | |
745 | if (error) | |
746 | return error; | |
747 | if (*slot != NULL) | |
748 | return -EEXIST; | |
749 | rcu_assign_pointer(*slot, item); | |
750 | ||
751 | if (node) { | |
752 | unsigned offset = get_slot_offset(node, slot); | |
753 | node->count++; | |
754 | if (radix_tree_exceptional_entry(item)) | |
755 | node->exceptional++; | |
756 | BUG_ON(tag_get(node, 0, offset)); | |
757 | BUG_ON(tag_get(node, 1, offset)); | |
758 | BUG_ON(tag_get(node, 2, offset)); | |
759 | } else { | |
760 | BUG_ON(root_tags_get(root)); | |
761 | } | |
762 | ||
763 | return 0; | |
764 | } | |
765 | EXPORT_SYMBOL(__radix_tree_insert); | |
766 | ||
767 | /** | |
768 | * __radix_tree_lookup - lookup an item in a radix tree | |
769 | * @root: radix tree root | |
770 | * @index: index key | |
771 | * @nodep: returns node | |
772 | * @slotp: returns slot | |
773 | * | |
774 | * Lookup and return the item at position @index in the radix | |
775 | * tree @root. | |
776 | * | |
777 | * Until there is more than one item in the tree, no nodes are | |
778 | * allocated and @root->rnode is used as a direct slot instead of | |
779 | * pointing to a node, in which case *@nodep will be NULL. | |
780 | */ | |
781 | void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index, | |
782 | struct radix_tree_node **nodep, void ***slotp) | |
783 | { | |
784 | struct radix_tree_node *node, *parent; | |
785 | unsigned long maxindex; | |
786 | void **slot; | |
787 | ||
788 | restart: | |
789 | parent = NULL; | |
790 | slot = (void **)&root->rnode; | |
791 | radix_tree_load_root(root, &node, &maxindex); | |
792 | if (index > maxindex) | |
793 | return NULL; | |
794 | ||
795 | while (radix_tree_is_internal_node(node)) { | |
796 | unsigned offset; | |
797 | ||
798 | if (node == RADIX_TREE_RETRY) | |
799 | goto restart; | |
800 | parent = entry_to_node(node); | |
801 | offset = radix_tree_descend(parent, &node, index); | |
802 | slot = parent->slots + offset; | |
803 | } | |
804 | ||
805 | if (nodep) | |
806 | *nodep = parent; | |
807 | if (slotp) | |
808 | *slotp = slot; | |
809 | return node; | |
810 | } | |
811 | ||
812 | /** | |
813 | * radix_tree_lookup_slot - lookup a slot in a radix tree | |
814 | * @root: radix tree root | |
815 | * @index: index key | |
816 | * | |
817 | * Returns: the slot corresponding to the position @index in the | |
818 | * radix tree @root. This is useful for update-if-exists operations. | |
819 | * | |
820 | * This function can be called under rcu_read_lock iff the slot is not | |
821 | * modified by radix_tree_replace_slot, otherwise it must be called | |
822 | * exclusive from other writers. Any dereference of the slot must be done | |
823 | * using radix_tree_deref_slot. | |
824 | */ | |
825 | void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) | |
826 | { | |
827 | void **slot; | |
828 | ||
829 | if (!__radix_tree_lookup(root, index, NULL, &slot)) | |
830 | return NULL; | |
831 | return slot; | |
832 | } | |
833 | EXPORT_SYMBOL(radix_tree_lookup_slot); | |
834 | ||
835 | /** | |
836 | * radix_tree_lookup - perform lookup operation on a radix tree | |
837 | * @root: radix tree root | |
838 | * @index: index key | |
839 | * | |
840 | * Lookup the item at the position @index in the radix tree @root. | |
841 | * | |
842 | * This function can be called under rcu_read_lock, however the caller | |
843 | * must manage lifetimes of leaf nodes (eg. RCU may also be used to free | |
844 | * them safely). No RCU barriers are required to access or modify the | |
845 | * returned item, however. | |
846 | */ | |
847 | void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) | |
848 | { | |
849 | return __radix_tree_lookup(root, index, NULL, NULL); | |
850 | } | |
851 | EXPORT_SYMBOL(radix_tree_lookup); | |
852 | ||
853 | static void replace_slot(struct radix_tree_root *root, | |
854 | struct radix_tree_node *node, | |
855 | void **slot, void *item, | |
856 | bool warn_typeswitch) | |
857 | { | |
858 | void *old = rcu_dereference_raw(*slot); | |
859 | int count, exceptional; | |
860 | ||
861 | WARN_ON_ONCE(radix_tree_is_internal_node(item)); | |
862 | ||
863 | count = !!item - !!old; | |
864 | exceptional = !!radix_tree_exceptional_entry(item) - | |
865 | !!radix_tree_exceptional_entry(old); | |
866 | ||
867 | WARN_ON_ONCE(warn_typeswitch && (count || exceptional)); | |
868 | ||
869 | if (node) { | |
870 | node->count += count; | |
871 | node->exceptional += exceptional; | |
872 | } | |
873 | ||
874 | rcu_assign_pointer(*slot, item); | |
875 | } | |
876 | ||
877 | /** | |
878 | * __radix_tree_replace - replace item in a slot | |
879 | * @root: radix tree root | |
880 | * @node: pointer to tree node | |
881 | * @slot: pointer to slot in @node | |
882 | * @item: new item to store in the slot. | |
883 | * @update_node: callback for changing leaf nodes | |
884 | * @private: private data to pass to @update_node | |
885 | * | |
886 | * For use with __radix_tree_lookup(). Caller must hold tree write locked | |
887 | * across slot lookup and replacement. | |
888 | */ | |
889 | void __radix_tree_replace(struct radix_tree_root *root, | |
890 | struct radix_tree_node *node, | |
891 | void **slot, void *item, | |
892 | radix_tree_update_node_t update_node, void *private) | |
893 | { | |
894 | /* | |
895 | * This function supports replacing exceptional entries and | |
896 | * deleting entries, but that needs accounting against the | |
897 | * node unless the slot is root->rnode. | |
898 | */ | |
899 | replace_slot(root, node, slot, item, | |
900 | !node && slot != (void **)&root->rnode); | |
901 | ||
902 | if (!node) | |
903 | return; | |
904 | ||
905 | if (update_node) | |
906 | update_node(node, private); | |
907 | ||
908 | delete_node(root, node, update_node, private); | |
909 | } | |
910 | ||
911 | /** | |
912 | * radix_tree_replace_slot - replace item in a slot | |
913 | * @root: radix tree root | |
914 | * @slot: pointer to slot | |
915 | * @item: new item to store in the slot. | |
916 | * | |
917 | * For use with radix_tree_lookup_slot(), radix_tree_gang_lookup_slot(), | |
918 | * radix_tree_gang_lookup_tag_slot(). Caller must hold tree write locked | |
919 | * across slot lookup and replacement. | |
920 | * | |
921 | * NOTE: This cannot be used to switch between non-entries (empty slots), | |
922 | * regular entries, and exceptional entries, as that requires accounting | |
923 | * inside the radix tree node. When switching from one type of entry or | |
924 | * deleting, use __radix_tree_lookup() and __radix_tree_replace(). | |
925 | */ | |
926 | void radix_tree_replace_slot(struct radix_tree_root *root, | |
927 | void **slot, void *item) | |
928 | { | |
929 | replace_slot(root, NULL, slot, item, true); | |
930 | } | |
931 | ||
932 | /** | |
933 | * radix_tree_tag_set - set a tag on a radix tree node | |
934 | * @root: radix tree root | |
935 | * @index: index key | |
936 | * @tag: tag index | |
937 | * | |
938 | * Set the search tag (which must be < RADIX_TREE_MAX_TAGS) | |
939 | * corresponding to @index in the radix tree. From | |
940 | * the root all the way down to the leaf node. | |
941 | * | |
942 | * Returns the address of the tagged item. Setting a tag on a not-present | |
943 | * item is a bug. | |
944 | */ | |
945 | void *radix_tree_tag_set(struct radix_tree_root *root, | |
946 | unsigned long index, unsigned int tag) | |
947 | { | |
948 | struct radix_tree_node *node, *parent; | |
949 | unsigned long maxindex; | |
950 | ||
951 | radix_tree_load_root(root, &node, &maxindex); | |
952 | BUG_ON(index > maxindex); | |
953 | ||
954 | while (radix_tree_is_internal_node(node)) { | |
955 | unsigned offset; | |
956 | ||
957 | parent = entry_to_node(node); | |
958 | offset = radix_tree_descend(parent, &node, index); | |
959 | BUG_ON(!node); | |
960 | ||
961 | if (!tag_get(parent, tag, offset)) | |
962 | tag_set(parent, tag, offset); | |
963 | } | |
964 | ||
965 | /* set the root's tag bit */ | |
966 | if (!root_tag_get(root, tag)) | |
967 | root_tag_set(root, tag); | |
968 | ||
969 | return node; | |
970 | } | |
971 | EXPORT_SYMBOL(radix_tree_tag_set); | |
972 | ||
973 | static void node_tag_clear(struct radix_tree_root *root, | |
974 | struct radix_tree_node *node, | |
975 | unsigned int tag, unsigned int offset) | |
976 | { | |
977 | while (node) { | |
978 | if (!tag_get(node, tag, offset)) | |
979 | return; | |
980 | tag_clear(node, tag, offset); | |
981 | if (any_tag_set(node, tag)) | |
982 | return; | |
983 | ||
984 | offset = node->offset; | |
985 | node = node->parent; | |
986 | } | |
987 | ||
988 | /* clear the root's tag bit */ | |
989 | if (root_tag_get(root, tag)) | |
990 | root_tag_clear(root, tag); | |
991 | } | |
992 | ||
993 | /** | |
994 | * radix_tree_tag_clear - clear a tag on a radix tree node | |
995 | * @root: radix tree root | |
996 | * @index: index key | |
997 | * @tag: tag index | |
998 | * | |
999 | * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS) | |
1000 | * corresponding to @index in the radix tree. If this causes | |
1001 | * the leaf node to have no tags set then clear the tag in the | |
1002 | * next-to-leaf node, etc. | |
1003 | * | |
1004 | * Returns the address of the tagged item on success, else NULL. ie: | |
1005 | * has the same return value and semantics as radix_tree_lookup(). | |
1006 | */ | |
1007 | void *radix_tree_tag_clear(struct radix_tree_root *root, | |
1008 | unsigned long index, unsigned int tag) | |
1009 | { | |
1010 | struct radix_tree_node *node, *parent; | |
1011 | unsigned long maxindex; | |
1012 | int uninitialized_var(offset); | |
1013 | ||
1014 | radix_tree_load_root(root, &node, &maxindex); | |
1015 | if (index > maxindex) | |
1016 | return NULL; | |
1017 | ||
1018 | parent = NULL; | |
1019 | ||
1020 | while (radix_tree_is_internal_node(node)) { | |
1021 | parent = entry_to_node(node); | |
1022 | offset = radix_tree_descend(parent, &node, index); | |
1023 | } | |
1024 | ||
1025 | if (node) | |
1026 | node_tag_clear(root, parent, tag, offset); | |
1027 | ||
1028 | return node; | |
1029 | } | |
1030 | EXPORT_SYMBOL(radix_tree_tag_clear); | |
1031 | ||
1032 | /** | |
1033 | * radix_tree_tag_get - get a tag on a radix tree node | |
1034 | * @root: radix tree root | |
1035 | * @index: index key | |
1036 | * @tag: tag index (< RADIX_TREE_MAX_TAGS) | |
1037 | * | |
1038 | * Return values: | |
1039 | * | |
1040 | * 0: tag not present or not set | |
1041 | * 1: tag set | |
1042 | * | |
1043 | * Note that the return value of this function may not be relied on, even if | |
1044 | * the RCU lock is held, unless tag modification and node deletion are excluded | |
1045 | * from concurrency. | |
1046 | */ | |
1047 | int radix_tree_tag_get(struct radix_tree_root *root, | |
1048 | unsigned long index, unsigned int tag) | |
1049 | { | |
1050 | struct radix_tree_node *node, *parent; | |
1051 | unsigned long maxindex; | |
1052 | ||
1053 | if (!root_tag_get(root, tag)) | |
1054 | return 0; | |
1055 | ||
1056 | radix_tree_load_root(root, &node, &maxindex); | |
1057 | if (index > maxindex) | |
1058 | return 0; | |
1059 | if (node == NULL) | |
1060 | return 0; | |
1061 | ||
1062 | while (radix_tree_is_internal_node(node)) { | |
1063 | unsigned offset; | |
1064 | ||
1065 | parent = entry_to_node(node); | |
1066 | offset = radix_tree_descend(parent, &node, index); | |
1067 | ||
1068 | if (!node) | |
1069 | return 0; | |
1070 | if (!tag_get(parent, tag, offset)) | |
1071 | return 0; | |
1072 | if (node == RADIX_TREE_RETRY) | |
1073 | break; | |
1074 | } | |
1075 | ||
1076 | return 1; | |
1077 | } | |
1078 | EXPORT_SYMBOL(radix_tree_tag_get); | |
1079 | ||
1080 | static inline void __set_iter_shift(struct radix_tree_iter *iter, | |
1081 | unsigned int shift) | |
1082 | { | |
1083 | #ifdef CONFIG_RADIX_TREE_MULTIORDER | |
1084 | iter->shift = shift; | |
1085 | #endif | |
1086 | } | |
1087 | ||
1088 | /** | |
1089 | * radix_tree_next_chunk - find next chunk of slots for iteration | |
1090 | * | |
1091 | * @root: radix tree root | |
1092 | * @iter: iterator state | |
1093 | * @flags: RADIX_TREE_ITER_* flags and tag index | |
1094 | * Returns: pointer to chunk first slot, or NULL if iteration is over | |
1095 | */ | |
1096 | void **radix_tree_next_chunk(struct radix_tree_root *root, | |
1097 | struct radix_tree_iter *iter, unsigned flags) | |
1098 | { | |
1099 | unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK; | |
1100 | struct radix_tree_node *node, *child; | |
1101 | unsigned long index, offset, maxindex; | |
1102 | ||
1103 | if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag)) | |
1104 | return NULL; | |
1105 | ||
1106 | /* | |
1107 | * Catch next_index overflow after ~0UL. iter->index never overflows | |
1108 | * during iterating; it can be zero only at the beginning. | |
1109 | * And we cannot overflow iter->next_index in a single step, | |
1110 | * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG. | |
1111 | * | |
1112 | * This condition also used by radix_tree_next_slot() to stop | |
1113 | * contiguous iterating, and forbid swithing to the next chunk. | |
1114 | */ | |
1115 | index = iter->next_index; | |
1116 | if (!index && iter->index) | |
1117 | return NULL; | |
1118 | ||
1119 | restart: | |
1120 | radix_tree_load_root(root, &child, &maxindex); | |
1121 | if (index > maxindex) | |
1122 | return NULL; | |
1123 | if (!child) | |
1124 | return NULL; | |
1125 | ||
1126 | if (!radix_tree_is_internal_node(child)) { | |
1127 | /* Single-slot tree */ | |
1128 | iter->index = index; | |
1129 | iter->next_index = maxindex + 1; | |
1130 | iter->tags = 1; | |
1131 | __set_iter_shift(iter, 0); | |
1132 | return (void **)&root->rnode; | |
1133 | } | |
1134 | ||
1135 | do { | |
1136 | node = entry_to_node(child); | |
1137 | offset = radix_tree_descend(node, &child, index); | |
1138 | ||
1139 | if ((flags & RADIX_TREE_ITER_TAGGED) ? | |
1140 | !tag_get(node, tag, offset) : !child) { | |
1141 | /* Hole detected */ | |
1142 | if (flags & RADIX_TREE_ITER_CONTIG) | |
1143 | return NULL; | |
1144 | ||
1145 | if (flags & RADIX_TREE_ITER_TAGGED) | |
1146 | offset = radix_tree_find_next_bit( | |
1147 | node->tags[tag], | |
1148 | RADIX_TREE_MAP_SIZE, | |
1149 | offset + 1); | |
1150 | else | |
1151 | while (++offset < RADIX_TREE_MAP_SIZE) { | |
1152 | void *slot = node->slots[offset]; | |
1153 | if (is_sibling_entry(node, slot)) | |
1154 | continue; | |
1155 | if (slot) | |
1156 | break; | |
1157 | } | |
1158 | index &= ~node_maxindex(node); | |
1159 | index += offset << node->shift; | |
1160 | /* Overflow after ~0UL */ | |
1161 | if (!index) | |
1162 | return NULL; | |
1163 | if (offset == RADIX_TREE_MAP_SIZE) | |
1164 | goto restart; | |
1165 | child = rcu_dereference_raw(node->slots[offset]); | |
1166 | } | |
1167 | ||
1168 | if ((child == NULL) || (child == RADIX_TREE_RETRY)) | |
1169 | goto restart; | |
1170 | } while (radix_tree_is_internal_node(child)); | |
1171 | ||
1172 | /* Update the iterator state */ | |
1173 | iter->index = (index &~ node_maxindex(node)) | (offset << node->shift); | |
1174 | iter->next_index = (index | node_maxindex(node)) + 1; | |
1175 | __set_iter_shift(iter, node->shift); | |
1176 | ||
1177 | /* Construct iter->tags bit-mask from node->tags[tag] array */ | |
1178 | if (flags & RADIX_TREE_ITER_TAGGED) { | |
1179 | unsigned tag_long, tag_bit; | |
1180 | ||
1181 | tag_long = offset / BITS_PER_LONG; | |
1182 | tag_bit = offset % BITS_PER_LONG; | |
1183 | iter->tags = node->tags[tag][tag_long] >> tag_bit; | |
1184 | /* This never happens if RADIX_TREE_TAG_LONGS == 1 */ | |
1185 | if (tag_long < RADIX_TREE_TAG_LONGS - 1) { | |
1186 | /* Pick tags from next element */ | |
1187 | if (tag_bit) | |
1188 | iter->tags |= node->tags[tag][tag_long + 1] << | |
1189 | (BITS_PER_LONG - tag_bit); | |
1190 | /* Clip chunk size, here only BITS_PER_LONG tags */ | |
1191 | iter->next_index = index + BITS_PER_LONG; | |
1192 | } | |
1193 | } | |
1194 | ||
1195 | return node->slots + offset; | |
1196 | } | |
1197 | EXPORT_SYMBOL(radix_tree_next_chunk); | |
1198 | ||
1199 | /** | |
1200 | * radix_tree_range_tag_if_tagged - for each item in given range set given | |
1201 | * tag if item has another tag set | |
1202 | * @root: radix tree root | |
1203 | * @first_indexp: pointer to a starting index of a range to scan | |
1204 | * @last_index: last index of a range to scan | |
1205 | * @nr_to_tag: maximum number items to tag | |
1206 | * @iftag: tag index to test | |
1207 | * @settag: tag index to set if tested tag is set | |
1208 | * | |
1209 | * This function scans range of radix tree from first_index to last_index | |
1210 | * (inclusive). For each item in the range if iftag is set, the function sets | |
1211 | * also settag. The function stops either after tagging nr_to_tag items or | |
1212 | * after reaching last_index. | |
1213 | * | |
1214 | * The tags must be set from the leaf level only and propagated back up the | |
1215 | * path to the root. We must do this so that we resolve the full path before | |
1216 | * setting any tags on intermediate nodes. If we set tags as we descend, then | |
1217 | * we can get to the leaf node and find that the index that has the iftag | |
1218 | * set is outside the range we are scanning. This reults in dangling tags and | |
1219 | * can lead to problems with later tag operations (e.g. livelocks on lookups). | |
1220 | * | |
1221 | * The function returns the number of leaves where the tag was set and sets | |
1222 | * *first_indexp to the first unscanned index. | |
1223 | * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must | |
1224 | * be prepared to handle that. | |
1225 | */ | |
1226 | unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, | |
1227 | unsigned long *first_indexp, unsigned long last_index, | |
1228 | unsigned long nr_to_tag, | |
1229 | unsigned int iftag, unsigned int settag) | |
1230 | { | |
1231 | struct radix_tree_node *parent, *node, *child; | |
1232 | unsigned long maxindex; | |
1233 | unsigned long tagged = 0; | |
1234 | unsigned long index = *first_indexp; | |
1235 | ||
1236 | radix_tree_load_root(root, &child, &maxindex); | |
1237 | last_index = min(last_index, maxindex); | |
1238 | if (index > last_index) | |
1239 | return 0; | |
1240 | if (!nr_to_tag) | |
1241 | return 0; | |
1242 | if (!root_tag_get(root, iftag)) { | |
1243 | *first_indexp = last_index + 1; | |
1244 | return 0; | |
1245 | } | |
1246 | if (!radix_tree_is_internal_node(child)) { | |
1247 | *first_indexp = last_index + 1; | |
1248 | root_tag_set(root, settag); | |
1249 | return 1; | |
1250 | } | |
1251 | ||
1252 | node = entry_to_node(child); | |
1253 | ||
1254 | for (;;) { | |
1255 | unsigned offset = radix_tree_descend(node, &child, index); | |
1256 | if (!child) | |
1257 | goto next; | |
1258 | if (!tag_get(node, iftag, offset)) | |
1259 | goto next; | |
1260 | /* Sibling slots never have tags set on them */ | |
1261 | if (radix_tree_is_internal_node(child)) { | |
1262 | node = entry_to_node(child); | |
1263 | continue; | |
1264 | } | |
1265 | ||
1266 | /* tag the leaf */ | |
1267 | tagged++; | |
1268 | tag_set(node, settag, offset); | |
1269 | ||
1270 | /* walk back up the path tagging interior nodes */ | |
1271 | parent = node; | |
1272 | for (;;) { | |
1273 | offset = parent->offset; | |
1274 | parent = parent->parent; | |
1275 | if (!parent) | |
1276 | break; | |
1277 | /* stop if we find a node with the tag already set */ | |
1278 | if (tag_get(parent, settag, offset)) | |
1279 | break; | |
1280 | tag_set(parent, settag, offset); | |
1281 | } | |
1282 | next: | |
1283 | /* Go to next entry in node */ | |
1284 | index = ((index >> node->shift) + 1) << node->shift; | |
1285 | /* Overflow can happen when last_index is ~0UL... */ | |
1286 | if (index > last_index || !index) | |
1287 | break; | |
1288 | offset = (index >> node->shift) & RADIX_TREE_MAP_MASK; | |
1289 | while (offset == 0) { | |
1290 | /* | |
1291 | * We've fully scanned this node. Go up. Because | |
1292 | * last_index is guaranteed to be in the tree, what | |
1293 | * we do below cannot wander astray. | |
1294 | */ | |
1295 | node = node->parent; | |
1296 | offset = (index >> node->shift) & RADIX_TREE_MAP_MASK; | |
1297 | } | |
1298 | if (is_sibling_entry(node, node->slots[offset])) | |
1299 | goto next; | |
1300 | if (tagged >= nr_to_tag) | |
1301 | break; | |
1302 | } | |
1303 | /* | |
1304 | * We need not to tag the root tag if there is no tag which is set with | |
1305 | * settag within the range from *first_indexp to last_index. | |
1306 | */ | |
1307 | if (tagged > 0) | |
1308 | root_tag_set(root, settag); | |
1309 | *first_indexp = index; | |
1310 | ||
1311 | return tagged; | |
1312 | } | |
1313 | EXPORT_SYMBOL(radix_tree_range_tag_if_tagged); | |
1314 | ||
1315 | /** | |
1316 | * radix_tree_gang_lookup - perform multiple lookup on a radix tree | |
1317 | * @root: radix tree root | |
1318 | * @results: where the results of the lookup are placed | |
1319 | * @first_index: start the lookup from this key | |
1320 | * @max_items: place up to this many items at *results | |
1321 | * | |
1322 | * Performs an index-ascending scan of the tree for present items. Places | |
1323 | * them at *@results and returns the number of items which were placed at | |
1324 | * *@results. | |
1325 | * | |
1326 | * The implementation is naive. | |
1327 | * | |
1328 | * Like radix_tree_lookup, radix_tree_gang_lookup may be called under | |
1329 | * rcu_read_lock. In this case, rather than the returned results being | |
1330 | * an atomic snapshot of the tree at a single point in time, the | |
1331 | * semantics of an RCU protected gang lookup are as though multiple | |
1332 | * radix_tree_lookups have been issued in individual locks, and results | |
1333 | * stored in 'results'. | |
1334 | */ | |
1335 | unsigned int | |
1336 | radix_tree_gang_lookup(struct radix_tree_root *root, void **results, | |
1337 | unsigned long first_index, unsigned int max_items) | |
1338 | { | |
1339 | struct radix_tree_iter iter; | |
1340 | void **slot; | |
1341 | unsigned int ret = 0; | |
1342 | ||
1343 | if (unlikely(!max_items)) | |
1344 | return 0; | |
1345 | ||
1346 | radix_tree_for_each_slot(slot, root, &iter, first_index) { | |
1347 | results[ret] = rcu_dereference_raw(*slot); | |
1348 | if (!results[ret]) | |
1349 | continue; | |
1350 | if (radix_tree_is_internal_node(results[ret])) { | |
1351 | slot = radix_tree_iter_retry(&iter); | |
1352 | continue; | |
1353 | } | |
1354 | if (++ret == max_items) | |
1355 | break; | |
1356 | } | |
1357 | ||
1358 | return ret; | |
1359 | } | |
1360 | EXPORT_SYMBOL(radix_tree_gang_lookup); | |
1361 | ||
1362 | /** | |
1363 | * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree | |
1364 | * @root: radix tree root | |
1365 | * @results: where the results of the lookup are placed | |
1366 | * @indices: where their indices should be placed (but usually NULL) | |
1367 | * @first_index: start the lookup from this key | |
1368 | * @max_items: place up to this many items at *results | |
1369 | * | |
1370 | * Performs an index-ascending scan of the tree for present items. Places | |
1371 | * their slots at *@results and returns the number of items which were | |
1372 | * placed at *@results. | |
1373 | * | |
1374 | * The implementation is naive. | |
1375 | * | |
1376 | * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must | |
1377 | * be dereferenced with radix_tree_deref_slot, and if using only RCU | |
1378 | * protection, radix_tree_deref_slot may fail requiring a retry. | |
1379 | */ | |
1380 | unsigned int | |
1381 | radix_tree_gang_lookup_slot(struct radix_tree_root *root, | |
1382 | void ***results, unsigned long *indices, | |
1383 | unsigned long first_index, unsigned int max_items) | |
1384 | { | |
1385 | struct radix_tree_iter iter; | |
1386 | void **slot; | |
1387 | unsigned int ret = 0; | |
1388 | ||
1389 | if (unlikely(!max_items)) | |
1390 | return 0; | |
1391 | ||
1392 | radix_tree_for_each_slot(slot, root, &iter, first_index) { | |
1393 | results[ret] = slot; | |
1394 | if (indices) | |
1395 | indices[ret] = iter.index; | |
1396 | if (++ret == max_items) | |
1397 | break; | |
1398 | } | |
1399 | ||
1400 | return ret; | |
1401 | } | |
1402 | EXPORT_SYMBOL(radix_tree_gang_lookup_slot); | |
1403 | ||
1404 | /** | |
1405 | * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree | |
1406 | * based on a tag | |
1407 | * @root: radix tree root | |
1408 | * @results: where the results of the lookup are placed | |
1409 | * @first_index: start the lookup from this key | |
1410 | * @max_items: place up to this many items at *results | |
1411 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) | |
1412 | * | |
1413 | * Performs an index-ascending scan of the tree for present items which | |
1414 | * have the tag indexed by @tag set. Places the items at *@results and | |
1415 | * returns the number of items which were placed at *@results. | |
1416 | */ | |
1417 | unsigned int | |
1418 | radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, | |
1419 | unsigned long first_index, unsigned int max_items, | |
1420 | unsigned int tag) | |
1421 | { | |
1422 | struct radix_tree_iter iter; | |
1423 | void **slot; | |
1424 | unsigned int ret = 0; | |
1425 | ||
1426 | if (unlikely(!max_items)) | |
1427 | return 0; | |
1428 | ||
1429 | radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) { | |
1430 | results[ret] = rcu_dereference_raw(*slot); | |
1431 | if (!results[ret]) | |
1432 | continue; | |
1433 | if (radix_tree_is_internal_node(results[ret])) { | |
1434 | slot = radix_tree_iter_retry(&iter); | |
1435 | continue; | |
1436 | } | |
1437 | if (++ret == max_items) | |
1438 | break; | |
1439 | } | |
1440 | ||
1441 | return ret; | |
1442 | } | |
1443 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag); | |
1444 | ||
1445 | /** | |
1446 | * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a | |
1447 | * radix tree based on a tag | |
1448 | * @root: radix tree root | |
1449 | * @results: where the results of the lookup are placed | |
1450 | * @first_index: start the lookup from this key | |
1451 | * @max_items: place up to this many items at *results | |
1452 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) | |
1453 | * | |
1454 | * Performs an index-ascending scan of the tree for present items which | |
1455 | * have the tag indexed by @tag set. Places the slots at *@results and | |
1456 | * returns the number of slots which were placed at *@results. | |
1457 | */ | |
1458 | unsigned int | |
1459 | radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, | |
1460 | unsigned long first_index, unsigned int max_items, | |
1461 | unsigned int tag) | |
1462 | { | |
1463 | struct radix_tree_iter iter; | |
1464 | void **slot; | |
1465 | unsigned int ret = 0; | |
1466 | ||
1467 | if (unlikely(!max_items)) | |
1468 | return 0; | |
1469 | ||
1470 | radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) { | |
1471 | results[ret] = slot; | |
1472 | if (++ret == max_items) | |
1473 | break; | |
1474 | } | |
1475 | ||
1476 | return ret; | |
1477 | } | |
1478 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); | |
1479 | ||
1480 | #if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP) | |
1481 | #include <linux/sched.h> /* for cond_resched() */ | |
1482 | ||
1483 | struct locate_info { | |
1484 | unsigned long found_index; | |
1485 | bool stop; | |
1486 | }; | |
1487 | ||
1488 | /* | |
1489 | * This linear search is at present only useful to shmem_unuse_inode(). | |
1490 | */ | |
1491 | static unsigned long __locate(struct radix_tree_node *slot, void *item, | |
1492 | unsigned long index, struct locate_info *info) | |
1493 | { | |
1494 | unsigned long i; | |
1495 | ||
1496 | do { | |
1497 | unsigned int shift = slot->shift; | |
1498 | ||
1499 | for (i = (index >> shift) & RADIX_TREE_MAP_MASK; | |
1500 | i < RADIX_TREE_MAP_SIZE; | |
1501 | i++, index += (1UL << shift)) { | |
1502 | struct radix_tree_node *node = | |
1503 | rcu_dereference_raw(slot->slots[i]); | |
1504 | if (node == RADIX_TREE_RETRY) | |
1505 | goto out; | |
1506 | if (!radix_tree_is_internal_node(node)) { | |
1507 | if (node == item) { | |
1508 | info->found_index = index; | |
1509 | info->stop = true; | |
1510 | goto out; | |
1511 | } | |
1512 | continue; | |
1513 | } | |
1514 | node = entry_to_node(node); | |
1515 | if (is_sibling_entry(slot, node)) | |
1516 | continue; | |
1517 | slot = node; | |
1518 | break; | |
1519 | } | |
1520 | } while (i < RADIX_TREE_MAP_SIZE); | |
1521 | ||
1522 | out: | |
1523 | if ((index == 0) && (i == RADIX_TREE_MAP_SIZE)) | |
1524 | info->stop = true; | |
1525 | return index; | |
1526 | } | |
1527 | ||
1528 | /** | |
1529 | * radix_tree_locate_item - search through radix tree for item | |
1530 | * @root: radix tree root | |
1531 | * @item: item to be found | |
1532 | * | |
1533 | * Returns index where item was found, or -1 if not found. | |
1534 | * Caller must hold no lock (since this time-consuming function needs | |
1535 | * to be preemptible), and must check afterwards if item is still there. | |
1536 | */ | |
1537 | unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) | |
1538 | { | |
1539 | struct radix_tree_node *node; | |
1540 | unsigned long max_index; | |
1541 | unsigned long cur_index = 0; | |
1542 | struct locate_info info = { | |
1543 | .found_index = -1, | |
1544 | .stop = false, | |
1545 | }; | |
1546 | ||
1547 | do { | |
1548 | rcu_read_lock(); | |
1549 | node = rcu_dereference_raw(root->rnode); | |
1550 | if (!radix_tree_is_internal_node(node)) { | |
1551 | rcu_read_unlock(); | |
1552 | if (node == item) | |
1553 | info.found_index = 0; | |
1554 | break; | |
1555 | } | |
1556 | ||
1557 | node = entry_to_node(node); | |
1558 | ||
1559 | max_index = node_maxindex(node); | |
1560 | if (cur_index > max_index) { | |
1561 | rcu_read_unlock(); | |
1562 | break; | |
1563 | } | |
1564 | ||
1565 | cur_index = __locate(node, item, cur_index, &info); | |
1566 | rcu_read_unlock(); | |
1567 | cond_resched(); | |
1568 | } while (!info.stop && cur_index <= max_index); | |
1569 | ||
1570 | return info.found_index; | |
1571 | } | |
1572 | #else | |
1573 | unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) | |
1574 | { | |
1575 | return -1; | |
1576 | } | |
1577 | #endif /* CONFIG_SHMEM && CONFIG_SWAP */ | |
1578 | ||
1579 | /** | |
1580 | * __radix_tree_delete_node - try to free node after clearing a slot | |
1581 | * @root: radix tree root | |
1582 | * @node: node containing @index | |
1583 | * | |
1584 | * After clearing the slot at @index in @node from radix tree | |
1585 | * rooted at @root, call this function to attempt freeing the | |
1586 | * node and shrinking the tree. | |
1587 | */ | |
1588 | void __radix_tree_delete_node(struct radix_tree_root *root, | |
1589 | struct radix_tree_node *node) | |
1590 | { | |
1591 | delete_node(root, node, NULL, NULL); | |
1592 | } | |
1593 | ||
1594 | static inline void delete_sibling_entries(struct radix_tree_node *node, | |
1595 | void *ptr, unsigned offset) | |
1596 | { | |
1597 | #ifdef CONFIG_RADIX_TREE_MULTIORDER | |
1598 | int i; | |
1599 | for (i = 1; offset + i < RADIX_TREE_MAP_SIZE; i++) { | |
1600 | if (node->slots[offset + i] != ptr) | |
1601 | break; | |
1602 | node->slots[offset + i] = NULL; | |
1603 | node->count--; | |
1604 | } | |
1605 | #endif | |
1606 | } | |
1607 | ||
1608 | /** | |
1609 | * radix_tree_delete_item - delete an item from a radix tree | |
1610 | * @root: radix tree root | |
1611 | * @index: index key | |
1612 | * @item: expected item | |
1613 | * | |
1614 | * Remove @item at @index from the radix tree rooted at @root. | |
1615 | * | |
1616 | * Returns the address of the deleted item, or NULL if it was not present | |
1617 | * or the entry at the given @index was not @item. | |
1618 | */ | |
1619 | void *radix_tree_delete_item(struct radix_tree_root *root, | |
1620 | unsigned long index, void *item) | |
1621 | { | |
1622 | struct radix_tree_node *node; | |
1623 | unsigned int offset; | |
1624 | void **slot; | |
1625 | void *entry; | |
1626 | int tag; | |
1627 | ||
1628 | entry = __radix_tree_lookup(root, index, &node, &slot); | |
1629 | if (!entry) | |
1630 | return NULL; | |
1631 | ||
1632 | if (item && entry != item) | |
1633 | return NULL; | |
1634 | ||
1635 | if (!node) { | |
1636 | root_tag_clear_all(root); | |
1637 | root->rnode = NULL; | |
1638 | return entry; | |
1639 | } | |
1640 | ||
1641 | offset = get_slot_offset(node, slot); | |
1642 | ||
1643 | /* Clear all tags associated with the item to be deleted. */ | |
1644 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) | |
1645 | node_tag_clear(root, node, tag, offset); | |
1646 | ||
1647 | delete_sibling_entries(node, node_to_entry(slot), offset); | |
1648 | __radix_tree_replace(root, node, slot, NULL, NULL, NULL); | |
1649 | ||
1650 | return entry; | |
1651 | } | |
1652 | EXPORT_SYMBOL(radix_tree_delete_item); | |
1653 | ||
1654 | /** | |
1655 | * radix_tree_delete - delete an item from a radix tree | |
1656 | * @root: radix tree root | |
1657 | * @index: index key | |
1658 | * | |
1659 | * Remove the item at @index from the radix tree rooted at @root. | |
1660 | * | |
1661 | * Returns the address of the deleted item, or NULL if it was not present. | |
1662 | */ | |
1663 | void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) | |
1664 | { | |
1665 | return radix_tree_delete_item(root, index, NULL); | |
1666 | } | |
1667 | EXPORT_SYMBOL(radix_tree_delete); | |
1668 | ||
1669 | void radix_tree_clear_tags(struct radix_tree_root *root, | |
1670 | struct radix_tree_node *node, | |
1671 | void **slot) | |
1672 | { | |
1673 | if (node) { | |
1674 | unsigned int tag, offset = get_slot_offset(node, slot); | |
1675 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) | |
1676 | node_tag_clear(root, node, tag, offset); | |
1677 | } else { | |
1678 | /* Clear root node tags */ | |
1679 | root->gfp_mask &= __GFP_BITS_MASK; | |
1680 | } | |
1681 | } | |
1682 | ||
1683 | /** | |
1684 | * radix_tree_tagged - test whether any items in the tree are tagged | |
1685 | * @root: radix tree root | |
1686 | * @tag: tag to test | |
1687 | */ | |
1688 | int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) | |
1689 | { | |
1690 | return root_tag_get(root, tag); | |
1691 | } | |
1692 | EXPORT_SYMBOL(radix_tree_tagged); | |
1693 | ||
1694 | static void | |
1695 | radix_tree_node_ctor(void *arg) | |
1696 | { | |
1697 | struct radix_tree_node *node = arg; | |
1698 | ||
1699 | memset(node, 0, sizeof(*node)); | |
1700 | INIT_LIST_HEAD(&node->private_list); | |
1701 | } | |
1702 | ||
1703 | static __init unsigned long __maxindex(unsigned int height) | |
1704 | { | |
1705 | unsigned int width = height * RADIX_TREE_MAP_SHIFT; | |
1706 | int shift = RADIX_TREE_INDEX_BITS - width; | |
1707 | ||
1708 | if (shift < 0) | |
1709 | return ~0UL; | |
1710 | if (shift >= BITS_PER_LONG) | |
1711 | return 0UL; | |
1712 | return ~0UL >> shift; | |
1713 | } | |
1714 | ||
1715 | static __init void radix_tree_init_maxnodes(void) | |
1716 | { | |
1717 | unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1]; | |
1718 | unsigned int i, j; | |
1719 | ||
1720 | for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++) | |
1721 | height_to_maxindex[i] = __maxindex(i); | |
1722 | for (i = 0; i < ARRAY_SIZE(height_to_maxnodes); i++) { | |
1723 | for (j = i; j > 0; j--) | |
1724 | height_to_maxnodes[i] += height_to_maxindex[j - 1] + 1; | |
1725 | } | |
1726 | } | |
1727 | ||
1728 | static int radix_tree_cpu_dead(unsigned int cpu) | |
1729 | { | |
1730 | struct radix_tree_preload *rtp; | |
1731 | struct radix_tree_node *node; | |
1732 | ||
1733 | /* Free per-cpu pool of preloaded nodes */ | |
1734 | rtp = &per_cpu(radix_tree_preloads, cpu); | |
1735 | while (rtp->nr) { | |
1736 | node = rtp->nodes; | |
1737 | rtp->nodes = node->private_data; | |
1738 | kmem_cache_free(radix_tree_node_cachep, node); | |
1739 | rtp->nr--; | |
1740 | } | |
1741 | return 0; | |
1742 | } | |
1743 | ||
1744 | void __init radix_tree_init(void) | |
1745 | { | |
1746 | int ret; | |
1747 | radix_tree_node_cachep = kmem_cache_create("radix_tree_node", | |
1748 | sizeof(struct radix_tree_node), 0, | |
1749 | SLAB_PANIC | SLAB_RECLAIM_ACCOUNT, | |
1750 | radix_tree_node_ctor); | |
1751 | radix_tree_init_maxnodes(); | |
1752 | ret = cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD, "lib/radix:dead", | |
1753 | NULL, radix_tree_cpu_dead); | |
1754 | WARN_ON(ret < 0); | |
1755 | } |