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1 | /* |
2 | * lib/btree.c - Simple In-memory B+Tree |
3 | * |
4 | * As should be obvious for Linux kernel code, license is GPLv2 |
5 | * |
6 | * Copyright (c) 2007-2008 Joern Engel <joern@logfs.org> |
7 | * Bits and pieces stolen from Peter Zijlstra's code, which is |
8 | * Copyright 2007, Red Hat Inc. Peter Zijlstra <pzijlstr@redhat.com> |
9 | * GPLv2 |
10 | * |
11 | * see http://programming.kicks-ass.net/kernel-patches/vma_lookup/btree.patch |
12 | * |
13 | * A relatively simple B+Tree implementation. I have written it as a learning |
14 | * exercise to understand how B+Trees work. Turned out to be useful as well. |
15 | * |
16 | * B+Trees can be used similar to Linux radix trees (which don't have anything |
17 | * in common with textbook radix trees, beware). Prerequisite for them working |
18 | * well is that access to a random tree node is much faster than a large number |
19 | * of operations within each node. |
20 | * |
21 | * Disks have fulfilled the prerequisite for a long time. More recently DRAM |
22 | * has gained similar properties, as memory access times, when measured in cpu |
23 | * cycles, have increased. Cacheline sizes have increased as well, which also |
24 | * helps B+Trees. |
25 | * |
26 | * Compared to radix trees, B+Trees are more efficient when dealing with a |
27 | * sparsely populated address space. Between 25% and 50% of the memory is |
28 | * occupied with valid pointers. When densely populated, radix trees contain |
29 | * ~98% pointers - hard to beat. Very sparse radix trees contain only ~2% |
30 | * pointers. |
31 | * |
32 | * This particular implementation stores pointers identified by a long value. |
33 | * Storing NULL pointers is illegal, lookup will return NULL when no entry |
34 | * was found. |
35 | * |
36 | * A tricks was used that is not commonly found in textbooks. The lowest |
37 | * values are to the right, not to the left. All used slots within a node |
38 | * are on the left, all unused slots contain NUL values. Most operations |
39 | * simply loop once over all slots and terminate on the first NUL. |
40 | */ |
41 | |
42 | #include <linux/btree.h> |
43 | #include <linux/cache.h> |
44 | #include <linux/kernel.h> |
45 | #include <linux/slab.h> |
46 | #include <linux/module.h> |
47 | |
48 | #define MAX(a, b) ((a) > (b) ? (a) : (b)) |
49 | #define NODESIZE MAX(L1_CACHE_BYTES, 128) |
50 | |
51 | struct btree_geo { |
52 | int keylen; |
53 | int no_pairs; |
54 | int no_longs; |
55 | }; |
56 | |
57 | struct btree_geo btree_geo32 = { |
58 | .keylen = 1, |
59 | .no_pairs = NODESIZE / sizeof(long) / 2, |
60 | .no_longs = NODESIZE / sizeof(long) / 2, |
61 | }; |
62 | EXPORT_SYMBOL_GPL(btree_geo32); |
63 | |
64 | #define LONG_PER_U64 (64 / BITS_PER_LONG) |
65 | struct btree_geo btree_geo64 = { |
66 | .keylen = LONG_PER_U64, |
67 | .no_pairs = NODESIZE / sizeof(long) / (1 + LONG_PER_U64), |
68 | .no_longs = LONG_PER_U64 * (NODESIZE / sizeof(long) / (1 + LONG_PER_U64)), |
69 | }; |
70 | EXPORT_SYMBOL_GPL(btree_geo64); |
71 | |
72 | struct btree_geo btree_geo128 = { |
73 | .keylen = 2 * LONG_PER_U64, |
74 | .no_pairs = NODESIZE / sizeof(long) / (1 + 2 * LONG_PER_U64), |
75 | .no_longs = 2 * LONG_PER_U64 * (NODESIZE / sizeof(long) / (1 + 2 * LONG_PER_U64)), |
76 | }; |
77 | EXPORT_SYMBOL_GPL(btree_geo128); |
78 | |
79 | static struct kmem_cache *btree_cachep; |
80 | |
81 | void *btree_alloc(gfp_t gfp_mask, void *pool_data) |
82 | { |
83 | return kmem_cache_alloc(btree_cachep, gfp_mask); |
84 | } |
85 | EXPORT_SYMBOL_GPL(btree_alloc); |
86 | |
87 | void btree_free(void *element, void *pool_data) |
88 | { |
89 | kmem_cache_free(btree_cachep, element); |
90 | } |
91 | EXPORT_SYMBOL_GPL(btree_free); |
92 | |
93 | static unsigned long *btree_node_alloc(struct btree_head *head, gfp_t gfp) |
94 | { |
95 | unsigned long *node; |
96 | |
97 | node = mempool_alloc(head->mempool, gfp); |
98 | if (likely(node)) |
99 | memset(node, 0, NODESIZE); |
100 | return node; |
101 | } |
102 | |
103 | static int longcmp(const unsigned long *l1, const unsigned long *l2, size_t n) |
104 | { |
105 | size_t i; |
106 | |
107 | for (i = 0; i < n; i++) { |
108 | if (l1[i] < l2[i]) |
109 | return -1; |
110 | if (l1[i] > l2[i]) |
111 | return 1; |
112 | } |
113 | return 0; |
114 | } |
115 | |
116 | static unsigned long *longcpy(unsigned long *dest, const unsigned long *src, |
117 | size_t n) |
118 | { |
119 | size_t i; |
120 | |
121 | for (i = 0; i < n; i++) |
122 | dest[i] = src[i]; |
123 | return dest; |
124 | } |
125 | |
126 | static unsigned long *longset(unsigned long *s, unsigned long c, size_t n) |
127 | { |
128 | size_t i; |
129 | |
130 | for (i = 0; i < n; i++) |
131 | s[i] = c; |
132 | return s; |
133 | } |
134 | |
135 | static void dec_key(struct btree_geo *geo, unsigned long *key) |
136 | { |
137 | unsigned long val; |
138 | int i; |
139 | |
140 | for (i = geo->keylen - 1; i >= 0; i--) { |
141 | val = key[i]; |
142 | key[i] = val - 1; |
143 | if (val) |
144 | break; |
145 | } |
146 | } |
147 | |
148 | static unsigned long *bkey(struct btree_geo *geo, unsigned long *node, int n) |
149 | { |
150 | return &node[n * geo->keylen]; |
151 | } |
152 | |
153 | static void *bval(struct btree_geo *geo, unsigned long *node, int n) |
154 | { |
155 | return (void *)node[geo->no_longs + n]; |
156 | } |
157 | |
158 | static void setkey(struct btree_geo *geo, unsigned long *node, int n, |
159 | unsigned long *key) |
160 | { |
161 | longcpy(bkey(geo, node, n), key, geo->keylen); |
162 | } |
163 | |
164 | static void setval(struct btree_geo *geo, unsigned long *node, int n, |
165 | void *val) |
166 | { |
167 | node[geo->no_longs + n] = (unsigned long) val; |
168 | } |
169 | |
170 | static void clearpair(struct btree_geo *geo, unsigned long *node, int n) |
171 | { |
172 | longset(bkey(geo, node, n), 0, geo->keylen); |
173 | node[geo->no_longs + n] = 0; |
174 | } |
175 | |
176 | static inline void __btree_init(struct btree_head *head) |
177 | { |
178 | head->node = NULL; |
179 | head->height = 0; |
180 | } |
181 | |
182 | void btree_init_mempool(struct btree_head *head, mempool_t *mempool) |
183 | { |
184 | __btree_init(head); |
185 | head->mempool = mempool; |
186 | } |
187 | EXPORT_SYMBOL_GPL(btree_init_mempool); |
188 | |
189 | int btree_init(struct btree_head *head) |
190 | { |
191 | __btree_init(head); |
192 | head->mempool = mempool_create(0, btree_alloc, btree_free, NULL); |
193 | if (!head->mempool) |
194 | return -ENOMEM; |
195 | return 0; |
196 | } |
197 | EXPORT_SYMBOL_GPL(btree_init); |
198 | |
199 | void btree_destroy(struct btree_head *head) |
200 | { |
201 | mempool_destroy(head->mempool); |
202 | head->mempool = NULL; |
203 | } |
204 | EXPORT_SYMBOL_GPL(btree_destroy); |
205 | |
206 | void *btree_last(struct btree_head *head, struct btree_geo *geo, |
207 | unsigned long *key) |
208 | { |
209 | int height = head->height; |
210 | unsigned long *node = head->node; |
211 | |
212 | if (height == 0) |
213 | return NULL; |
214 | |
215 | for ( ; height > 1; height--) |
216 | node = bval(geo, node, 0); |
217 | |
218 | longcpy(key, bkey(geo, node, 0), geo->keylen); |
219 | return bval(geo, node, 0); |
220 | } |
221 | EXPORT_SYMBOL_GPL(btree_last); |
222 | |
223 | static int keycmp(struct btree_geo *geo, unsigned long *node, int pos, |
224 | unsigned long *key) |
225 | { |
226 | return longcmp(bkey(geo, node, pos), key, geo->keylen); |
227 | } |
228 | |
229 | static int keyzero(struct btree_geo *geo, unsigned long *key) |
230 | { |
231 | int i; |
232 | |
233 | for (i = 0; i < geo->keylen; i++) |
234 | if (key[i]) |
235 | return 0; |
236 | |
237 | return 1; |
238 | } |
239 | |
240 | void *btree_lookup(struct btree_head *head, struct btree_geo *geo, |
241 | unsigned long *key) |
242 | { |
243 | int i, height = head->height; |
244 | unsigned long *node = head->node; |
245 | |
246 | if (height == 0) |
247 | return NULL; |
248 | |
249 | for ( ; height > 1; height--) { |
250 | for (i = 0; i < geo->no_pairs; i++) |
251 | if (keycmp(geo, node, i, key) <= 0) |
252 | break; |
253 | if (i == geo->no_pairs) |
254 | return NULL; |
255 | node = bval(geo, node, i); |
256 | if (!node) |
257 | return NULL; |
258 | } |
259 | |
260 | if (!node) |
261 | return NULL; |
262 | |
263 | for (i = 0; i < geo->no_pairs; i++) |
264 | if (keycmp(geo, node, i, key) == 0) |
265 | return bval(geo, node, i); |
266 | return NULL; |
267 | } |
268 | EXPORT_SYMBOL_GPL(btree_lookup); |
269 | |
270 | int btree_update(struct btree_head *head, struct btree_geo *geo, |
271 | unsigned long *key, void *val) |
272 | { |
273 | int i, height = head->height; |
274 | unsigned long *node = head->node; |
275 | |
276 | if (height == 0) |
277 | return -ENOENT; |
278 | |
279 | for ( ; height > 1; height--) { |
280 | for (i = 0; i < geo->no_pairs; i++) |
281 | if (keycmp(geo, node, i, key) <= 0) |
282 | break; |
283 | if (i == geo->no_pairs) |
284 | return -ENOENT; |
285 | node = bval(geo, node, i); |
286 | if (!node) |
287 | return -ENOENT; |
288 | } |
289 | |
290 | if (!node) |
291 | return -ENOENT; |
292 | |
293 | for (i = 0; i < geo->no_pairs; i++) |
294 | if (keycmp(geo, node, i, key) == 0) { |
295 | setval(geo, node, i, val); |
296 | return 0; |
297 | } |
298 | return -ENOENT; |
299 | } |
300 | EXPORT_SYMBOL_GPL(btree_update); |
301 | |
302 | /* |
303 | * Usually this function is quite similar to normal lookup. But the key of |
304 | * a parent node may be smaller than the smallest key of all its siblings. |
305 | * In such a case we cannot just return NULL, as we have only proven that no |
306 | * key smaller than __key, but larger than this parent key exists. |
307 | * So we set __key to the parent key and retry. We have to use the smallest |
308 | * such parent key, which is the last parent key we encountered. |
309 | */ |
310 | void *btree_get_prev(struct btree_head *head, struct btree_geo *geo, |
311 | unsigned long *__key) |
312 | { |
313 | int i, height; |
314 | unsigned long *node, *oldnode; |
315 | unsigned long *retry_key = NULL, key[geo->keylen]; |
316 | |
317 | if (keyzero(geo, __key)) |
318 | return NULL; |
319 | |
320 | if (head->height == 0) |
321 | return NULL; |
322 | retry: |
323 | longcpy(key, __key, geo->keylen); |
324 | dec_key(geo, key); |
325 | |
326 | node = head->node; |
327 | for (height = head->height ; height > 1; height--) { |
328 | for (i = 0; i < geo->no_pairs; i++) |
329 | if (keycmp(geo, node, i, key) <= 0) |
330 | break; |
331 | if (i == geo->no_pairs) |
332 | goto miss; |
333 | oldnode = node; |
334 | node = bval(geo, node, i); |
335 | if (!node) |
336 | goto miss; |
337 | retry_key = bkey(geo, oldnode, i); |
338 | } |
339 | |
340 | if (!node) |
341 | goto miss; |
342 | |
343 | for (i = 0; i < geo->no_pairs; i++) { |
344 | if (keycmp(geo, node, i, key) <= 0) { |
345 | if (bval(geo, node, i)) { |
346 | longcpy(__key, bkey(geo, node, i), geo->keylen); |
347 | return bval(geo, node, i); |
348 | } else |
349 | goto miss; |
350 | } |
351 | } |
352 | miss: |
353 | if (retry_key) { |
354 | __key = retry_key; |
355 | retry_key = NULL; |
356 | goto retry; |
357 | } |
358 | return NULL; |
359 | } |
360 | |
361 | static int getpos(struct btree_geo *geo, unsigned long *node, |
362 | unsigned long *key) |
363 | { |
364 | int i; |
365 | |
366 | for (i = 0; i < geo->no_pairs; i++) { |
367 | if (keycmp(geo, node, i, key) <= 0) |
368 | break; |
369 | } |
370 | return i; |
371 | } |
372 | |
373 | static int getfill(struct btree_geo *geo, unsigned long *node, int start) |
374 | { |
375 | int i; |
376 | |
377 | for (i = start; i < geo->no_pairs; i++) |
378 | if (!bval(geo, node, i)) |
379 | break; |
380 | return i; |
381 | } |
382 | |
383 | /* |
384 | * locate the correct leaf node in the btree |
385 | */ |
386 | static unsigned long *find_level(struct btree_head *head, struct btree_geo *geo, |
387 | unsigned long *key, int level) |
388 | { |
389 | unsigned long *node = head->node; |
390 | int i, height; |
391 | |
392 | for (height = head->height; height > level; height--) { |
393 | for (i = 0; i < geo->no_pairs; i++) |
394 | if (keycmp(geo, node, i, key) <= 0) |
395 | break; |
396 | |
397 | if ((i == geo->no_pairs) || !bval(geo, node, i)) { |
398 | /* right-most key is too large, update it */ |
399 | /* FIXME: If the right-most key on higher levels is |
400 | * always zero, this wouldn't be necessary. */ |
401 | i--; |
402 | setkey(geo, node, i, key); |
403 | } |
404 | BUG_ON(i < 0); |
405 | node = bval(geo, node, i); |
406 | } |
407 | BUG_ON(!node); |
408 | return node; |
409 | } |
410 | |
411 | static int btree_grow(struct btree_head *head, struct btree_geo *geo, |
412 | gfp_t gfp) |
413 | { |
414 | unsigned long *node; |
415 | int fill; |
416 | |
417 | node = btree_node_alloc(head, gfp); |
418 | if (!node) |
419 | return -ENOMEM; |
420 | if (head->node) { |
421 | fill = getfill(geo, head->node, 0); |
422 | setkey(geo, node, 0, bkey(geo, head->node, fill - 1)); |
423 | setval(geo, node, 0, head->node); |
424 | } |
425 | head->node = node; |
426 | head->height++; |
427 | return 0; |
428 | } |
429 | |
430 | static void btree_shrink(struct btree_head *head, struct btree_geo *geo) |
431 | { |
432 | unsigned long *node; |
433 | int fill; |
434 | |
435 | if (head->height <= 1) |
436 | return; |
437 | |
438 | node = head->node; |
439 | fill = getfill(geo, node, 0); |
440 | BUG_ON(fill > 1); |
441 | head->node = bval(geo, node, 0); |
442 | head->height--; |
443 | mempool_free(node, head->mempool); |
444 | } |
445 | |
446 | static int btree_insert_level(struct btree_head *head, struct btree_geo *geo, |
447 | unsigned long *key, void *val, int level, |
448 | gfp_t gfp) |
449 | { |
450 | unsigned long *node; |
451 | int i, pos, fill, err; |
452 | |
453 | BUG_ON(!val); |
454 | if (head->height < level) { |
455 | err = btree_grow(head, geo, gfp); |
456 | if (err) |
457 | return err; |
458 | } |
459 | |
460 | retry: |
461 | node = find_level(head, geo, key, level); |
462 | pos = getpos(geo, node, key); |
463 | fill = getfill(geo, node, pos); |
464 | /* two identical keys are not allowed */ |
465 | BUG_ON(pos < fill && keycmp(geo, node, pos, key) == 0); |
466 | |
467 | if (fill == geo->no_pairs) { |
468 | /* need to split node */ |
469 | unsigned long *new; |
470 | |
471 | new = btree_node_alloc(head, gfp); |
472 | if (!new) |
473 | return -ENOMEM; |
474 | err = btree_insert_level(head, geo, |
475 | bkey(geo, node, fill / 2 - 1), |
476 | new, level + 1, gfp); |
477 | if (err) { |
478 | mempool_free(new, head->mempool); |
479 | return err; |
480 | } |
481 | for (i = 0; i < fill / 2; i++) { |
482 | setkey(geo, new, i, bkey(geo, node, i)); |
483 | setval(geo, new, i, bval(geo, node, i)); |
484 | setkey(geo, node, i, bkey(geo, node, i + fill / 2)); |
485 | setval(geo, node, i, bval(geo, node, i + fill / 2)); |
486 | clearpair(geo, node, i + fill / 2); |
487 | } |
488 | if (fill & 1) { |
489 | setkey(geo, node, i, bkey(geo, node, fill - 1)); |
490 | setval(geo, node, i, bval(geo, node, fill - 1)); |
491 | clearpair(geo, node, fill - 1); |
492 | } |
493 | goto retry; |
494 | } |
495 | BUG_ON(fill >= geo->no_pairs); |
496 | |
497 | /* shift and insert */ |
498 | for (i = fill; i > pos; i--) { |
499 | setkey(geo, node, i, bkey(geo, node, i - 1)); |
500 | setval(geo, node, i, bval(geo, node, i - 1)); |
501 | } |
502 | setkey(geo, node, pos, key); |
503 | setval(geo, node, pos, val); |
504 | |
505 | return 0; |
506 | } |
507 | |
508 | int btree_insert(struct btree_head *head, struct btree_geo *geo, |
509 | unsigned long *key, void *val, gfp_t gfp) |
510 | { |
511 | return btree_insert_level(head, geo, key, val, 1, gfp); |
512 | } |
513 | EXPORT_SYMBOL_GPL(btree_insert); |
514 | |
515 | static void *btree_remove_level(struct btree_head *head, struct btree_geo *geo, |
516 | unsigned long *key, int level); |
517 | static void merge(struct btree_head *head, struct btree_geo *geo, int level, |
518 | unsigned long *left, int lfill, |
519 | unsigned long *right, int rfill, |
520 | unsigned long *parent, int lpos) |
521 | { |
522 | int i; |
523 | |
524 | for (i = 0; i < rfill; i++) { |
525 | /* Move all keys to the left */ |
526 | setkey(geo, left, lfill + i, bkey(geo, right, i)); |
527 | setval(geo, left, lfill + i, bval(geo, right, i)); |
528 | } |
529 | /* Exchange left and right child in parent */ |
530 | setval(geo, parent, lpos, right); |
531 | setval(geo, parent, lpos + 1, left); |
532 | /* Remove left (formerly right) child from parent */ |
533 | btree_remove_level(head, geo, bkey(geo, parent, lpos), level + 1); |
534 | mempool_free(right, head->mempool); |
535 | } |
536 | |
537 | static void rebalance(struct btree_head *head, struct btree_geo *geo, |
538 | unsigned long *key, int level, unsigned long *child, int fill) |
539 | { |
540 | unsigned long *parent, *left = NULL, *right = NULL; |
541 | int i, no_left, no_right; |
542 | |
543 | if (fill == 0) { |
544 | /* Because we don't steal entries from a neighbour, this case |
545 | * can happen. Parent node contains a single child, this |
546 | * node, so merging with a sibling never happens. |
547 | */ |
548 | btree_remove_level(head, geo, key, level + 1); |
549 | mempool_free(child, head->mempool); |
550 | return; |
551 | } |
552 | |
553 | parent = find_level(head, geo, key, level + 1); |
554 | i = getpos(geo, parent, key); |
555 | BUG_ON(bval(geo, parent, i) != child); |
556 | |
557 | if (i > 0) { |
558 | left = bval(geo, parent, i - 1); |
559 | no_left = getfill(geo, left, 0); |
560 | if (fill + no_left <= geo->no_pairs) { |
561 | merge(head, geo, level, |
562 | left, no_left, |
563 | child, fill, |
564 | parent, i - 1); |
565 | return; |
566 | } |
567 | } |
568 | if (i + 1 < getfill(geo, parent, i)) { |
569 | right = bval(geo, parent, i + 1); |
570 | no_right = getfill(geo, right, 0); |
571 | if (fill + no_right <= geo->no_pairs) { |
572 | merge(head, geo, level, |
573 | child, fill, |
574 | right, no_right, |
575 | parent, i); |
576 | return; |
577 | } |
578 | } |
579 | /* |
580 | * We could also try to steal one entry from the left or right |
581 | * neighbor. By not doing so we changed the invariant from |
582 | * "all nodes are at least half full" to "no two neighboring |
583 | * nodes can be merged". Which means that the average fill of |
584 | * all nodes is still half or better. |
585 | */ |
586 | } |
587 | |
588 | static void *btree_remove_level(struct btree_head *head, struct btree_geo *geo, |
589 | unsigned long *key, int level) |
590 | { |
591 | unsigned long *node; |
592 | int i, pos, fill; |
593 | void *ret; |
594 | |
595 | if (level > head->height) { |
596 | /* we recursed all the way up */ |
597 | head->height = 0; |
598 | head->node = NULL; |
599 | return NULL; |
600 | } |
601 | |
602 | node = find_level(head, geo, key, level); |
603 | pos = getpos(geo, node, key); |
604 | fill = getfill(geo, node, pos); |
605 | if ((level == 1) && (keycmp(geo, node, pos, key) != 0)) |
606 | return NULL; |
607 | ret = bval(geo, node, pos); |
608 | |
609 | /* remove and shift */ |
610 | for (i = pos; i < fill - 1; i++) { |
611 | setkey(geo, node, i, bkey(geo, node, i + 1)); |
612 | setval(geo, node, i, bval(geo, node, i + 1)); |
613 | } |
614 | clearpair(geo, node, fill - 1); |
615 | |
616 | if (fill - 1 < geo->no_pairs / 2) { |
617 | if (level < head->height) |
618 | rebalance(head, geo, key, level, node, fill - 1); |
619 | else if (fill - 1 == 1) |
620 | btree_shrink(head, geo); |
621 | } |
622 | |
623 | return ret; |
624 | } |
625 | |
626 | void *btree_remove(struct btree_head *head, struct btree_geo *geo, |
627 | unsigned long *key) |
628 | { |
629 | if (head->height == 0) |
630 | return NULL; |
631 | |
632 | return btree_remove_level(head, geo, key, 1); |
633 | } |
634 | EXPORT_SYMBOL_GPL(btree_remove); |
635 | |
636 | int btree_merge(struct btree_head *target, struct btree_head *victim, |
637 | struct btree_geo *geo, gfp_t gfp) |
638 | { |
639 | unsigned long key[geo->keylen]; |
640 | unsigned long dup[geo->keylen]; |
641 | void *val; |
642 | int err; |
643 | |
644 | BUG_ON(target == victim); |
645 | |
646 | if (!(target->node)) { |
647 | /* target is empty, just copy fields over */ |
648 | target->node = victim->node; |
649 | target->height = victim->height; |
650 | __btree_init(victim); |
651 | return 0; |
652 | } |
653 | |
654 | /* TODO: This needs some optimizations. Currently we do three tree |
655 | * walks to remove a single object from the victim. |
656 | */ |
657 | for (;;) { |
658 | if (!btree_last(victim, geo, key)) |
659 | break; |
660 | val = btree_lookup(victim, geo, key); |
661 | err = btree_insert(target, geo, key, val, gfp); |
662 | if (err) |
663 | return err; |
664 | /* We must make a copy of the key, as the original will get |
665 | * mangled inside btree_remove. */ |
666 | longcpy(dup, key, geo->keylen); |
667 | btree_remove(victim, geo, dup); |
668 | } |
669 | return 0; |
670 | } |
671 | EXPORT_SYMBOL_GPL(btree_merge); |
672 | |
673 | static size_t __btree_for_each(struct btree_head *head, struct btree_geo *geo, |
674 | unsigned long *node, unsigned long opaque, |
675 | void (*func)(void *elem, unsigned long opaque, |
676 | unsigned long *key, size_t index, |
677 | void *func2), |
678 | void *func2, int reap, int height, size_t count) |
679 | { |
680 | int i; |
681 | unsigned long *child; |
682 | |
683 | for (i = 0; i < geo->no_pairs; i++) { |
684 | child = bval(geo, node, i); |
685 | if (!child) |
686 | break; |
687 | if (height > 1) |
688 | count = __btree_for_each(head, geo, child, opaque, |
689 | func, func2, reap, height - 1, count); |
690 | else |
691 | func(child, opaque, bkey(geo, node, i), count++, |
692 | func2); |
693 | } |
694 | if (reap) |
695 | mempool_free(node, head->mempool); |
696 | return count; |
697 | } |
698 | |
699 | static void empty(void *elem, unsigned long opaque, unsigned long *key, |
700 | size_t index, void *func2) |
701 | { |
702 | } |
703 | |
704 | void visitorl(void *elem, unsigned long opaque, unsigned long *key, |
705 | size_t index, void *__func) |
706 | { |
707 | visitorl_t func = __func; |
708 | |
709 | func(elem, opaque, *key, index); |
710 | } |
711 | EXPORT_SYMBOL_GPL(visitorl); |
712 | |
713 | void visitor32(void *elem, unsigned long opaque, unsigned long *__key, |
714 | size_t index, void *__func) |
715 | { |
716 | visitor32_t func = __func; |
717 | u32 *key = (void *)__key; |
718 | |
719 | func(elem, opaque, *key, index); |
720 | } |
721 | EXPORT_SYMBOL_GPL(visitor32); |
722 | |
723 | void visitor64(void *elem, unsigned long opaque, unsigned long *__key, |
724 | size_t index, void *__func) |
725 | { |
726 | visitor64_t func = __func; |
727 | u64 *key = (void *)__key; |
728 | |
729 | func(elem, opaque, *key, index); |
730 | } |
731 | EXPORT_SYMBOL_GPL(visitor64); |
732 | |
733 | void visitor128(void *elem, unsigned long opaque, unsigned long *__key, |
734 | size_t index, void *__func) |
735 | { |
736 | visitor128_t func = __func; |
737 | u64 *key = (void *)__key; |
738 | |
739 | func(elem, opaque, key[0], key[1], index); |
740 | } |
741 | EXPORT_SYMBOL_GPL(visitor128); |
742 | |
743 | size_t btree_visitor(struct btree_head *head, struct btree_geo *geo, |
744 | unsigned long opaque, |
745 | void (*func)(void *elem, unsigned long opaque, |
746 | unsigned long *key, |
747 | size_t index, void *func2), |
748 | void *func2) |
749 | { |
750 | size_t count = 0; |
751 | |
752 | if (!func2) |
753 | func = empty; |
754 | if (head->node) |
755 | count = __btree_for_each(head, geo, head->node, opaque, func, |
756 | func2, 0, head->height, 0); |
757 | return count; |
758 | } |
759 | EXPORT_SYMBOL_GPL(btree_visitor); |
760 | |
761 | size_t btree_grim_visitor(struct btree_head *head, struct btree_geo *geo, |
762 | unsigned long opaque, |
763 | void (*func)(void *elem, unsigned long opaque, |
764 | unsigned long *key, |
765 | size_t index, void *func2), |
766 | void *func2) |
767 | { |
768 | size_t count = 0; |
769 | |
770 | if (!func2) |
771 | func = empty; |
772 | if (head->node) |
773 | count = __btree_for_each(head, geo, head->node, opaque, func, |
774 | func2, 1, head->height, 0); |
775 | __btree_init(head); |
776 | return count; |
777 | } |
778 | EXPORT_SYMBOL_GPL(btree_grim_visitor); |
779 | |
780 | static int __init btree_module_init(void) |
781 | { |
782 | btree_cachep = kmem_cache_create("btree_node", NODESIZE, 0, |
783 | SLAB_HWCACHE_ALIGN, NULL); |
784 | return 0; |
785 | } |
786 | |
787 | static void __exit btree_module_exit(void) |
788 | { |
789 | kmem_cache_destroy(btree_cachep); |
790 | } |
791 | |
792 | /* If core code starts using btree, initialization should happen even earlier */ |
793 | module_init(btree_module_init); |
794 | module_exit(btree_module_exit); |
795 | |
796 | MODULE_AUTHOR("Joern Engel <joern@logfs.org>"); |
797 | MODULE_AUTHOR("Johannes Berg <johannes@sipsolutions.net>"); |
798 | MODULE_LICENSE("GPL"); |
799 |
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v2.6.34-rc5
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