blob: f93a945274af12575f8fbbceb821552b2a13e61e
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 |
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_free(head->node, head->mempool); |
202 | mempool_destroy(head->mempool); |
203 | head->mempool = NULL; |
204 | } |
205 | EXPORT_SYMBOL_GPL(btree_destroy); |
206 | |
207 | void *btree_last(struct btree_head *head, struct btree_geo *geo, |
208 | unsigned long *key) |
209 | { |
210 | int height = head->height; |
211 | unsigned long *node = head->node; |
212 | |
213 | if (height == 0) |
214 | return NULL; |
215 | |
216 | for ( ; height > 1; height--) |
217 | node = bval(geo, node, 0); |
218 | |
219 | longcpy(key, bkey(geo, node, 0), geo->keylen); |
220 | return bval(geo, node, 0); |
221 | } |
222 | EXPORT_SYMBOL_GPL(btree_last); |
223 | |
224 | static int keycmp(struct btree_geo *geo, unsigned long *node, int pos, |
225 | unsigned long *key) |
226 | { |
227 | return longcmp(bkey(geo, node, pos), key, geo->keylen); |
228 | } |
229 | |
230 | static int keyzero(struct btree_geo *geo, unsigned long *key) |
231 | { |
232 | int i; |
233 | |
234 | for (i = 0; i < geo->keylen; i++) |
235 | if (key[i]) |
236 | return 0; |
237 | |
238 | return 1; |
239 | } |
240 | |
241 | void *btree_lookup(struct btree_head *head, struct btree_geo *geo, |
242 | unsigned long *key) |
243 | { |
244 | int i, height = head->height; |
245 | unsigned long *node = head->node; |
246 | |
247 | if (height == 0) |
248 | return NULL; |
249 | |
250 | for ( ; height > 1; height--) { |
251 | for (i = 0; i < geo->no_pairs; i++) |
252 | if (keycmp(geo, node, i, key) <= 0) |
253 | break; |
254 | if (i == geo->no_pairs) |
255 | return NULL; |
256 | node = bval(geo, node, i); |
257 | if (!node) |
258 | return NULL; |
259 | } |
260 | |
261 | if (!node) |
262 | return NULL; |
263 | |
264 | for (i = 0; i < geo->no_pairs; i++) |
265 | if (keycmp(geo, node, i, key) == 0) |
266 | return bval(geo, node, i); |
267 | return NULL; |
268 | } |
269 | EXPORT_SYMBOL_GPL(btree_lookup); |
270 | |
271 | int btree_update(struct btree_head *head, struct btree_geo *geo, |
272 | unsigned long *key, void *val) |
273 | { |
274 | int i, height = head->height; |
275 | unsigned long *node = head->node; |
276 | |
277 | if (height == 0) |
278 | return -ENOENT; |
279 | |
280 | for ( ; height > 1; height--) { |
281 | for (i = 0; i < geo->no_pairs; i++) |
282 | if (keycmp(geo, node, i, key) <= 0) |
283 | break; |
284 | if (i == geo->no_pairs) |
285 | return -ENOENT; |
286 | node = bval(geo, node, i); |
287 | if (!node) |
288 | return -ENOENT; |
289 | } |
290 | |
291 | if (!node) |
292 | return -ENOENT; |
293 | |
294 | for (i = 0; i < geo->no_pairs; i++) |
295 | if (keycmp(geo, node, i, key) == 0) { |
296 | setval(geo, node, i, val); |
297 | return 0; |
298 | } |
299 | return -ENOENT; |
300 | } |
301 | EXPORT_SYMBOL_GPL(btree_update); |
302 | |
303 | /* |
304 | * Usually this function is quite similar to normal lookup. But the key of |
305 | * a parent node may be smaller than the smallest key of all its siblings. |
306 | * In such a case we cannot just return NULL, as we have only proven that no |
307 | * key smaller than __key, but larger than this parent key exists. |
308 | * So we set __key to the parent key and retry. We have to use the smallest |
309 | * such parent key, which is the last parent key we encountered. |
310 | */ |
311 | void *btree_get_prev(struct btree_head *head, struct btree_geo *geo, |
312 | unsigned long *__key) |
313 | { |
314 | int i, height; |
315 | unsigned long *node, *oldnode; |
316 | unsigned long *retry_key = NULL, key[geo->keylen]; |
317 | |
318 | if (keyzero(geo, __key)) |
319 | return NULL; |
320 | |
321 | if (head->height == 0) |
322 | return NULL; |
323 | longcpy(key, __key, geo->keylen); |
324 | retry: |
325 | dec_key(geo, key); |
326 | |
327 | node = head->node; |
328 | for (height = head->height ; height > 1; height--) { |
329 | for (i = 0; i < geo->no_pairs; i++) |
330 | if (keycmp(geo, node, i, key) <= 0) |
331 | break; |
332 | if (i == geo->no_pairs) |
333 | goto miss; |
334 | oldnode = node; |
335 | node = bval(geo, node, i); |
336 | if (!node) |
337 | goto miss; |
338 | retry_key = bkey(geo, oldnode, i); |
339 | } |
340 | |
341 | if (!node) |
342 | goto miss; |
343 | |
344 | for (i = 0; i < geo->no_pairs; i++) { |
345 | if (keycmp(geo, node, i, key) <= 0) { |
346 | if (bval(geo, node, i)) { |
347 | longcpy(__key, bkey(geo, node, i), geo->keylen); |
348 | return bval(geo, node, i); |
349 | } else |
350 | goto miss; |
351 | } |
352 | } |
353 | miss: |
354 | if (retry_key) { |
355 | longcpy(key, retry_key, geo->keylen); |
356 | retry_key = NULL; |
357 | goto retry; |
358 | } |
359 | return NULL; |
360 | } |
361 | EXPORT_SYMBOL_GPL(btree_get_prev); |
362 | |
363 | static int getpos(struct btree_geo *geo, unsigned long *node, |
364 | unsigned long *key) |
365 | { |
366 | int i; |
367 | |
368 | for (i = 0; i < geo->no_pairs; i++) { |
369 | if (keycmp(geo, node, i, key) <= 0) |
370 | break; |
371 | } |
372 | return i; |
373 | } |
374 | |
375 | static int getfill(struct btree_geo *geo, unsigned long *node, int start) |
376 | { |
377 | int i; |
378 | |
379 | for (i = start; i < geo->no_pairs; i++) |
380 | if (!bval(geo, node, i)) |
381 | break; |
382 | return i; |
383 | } |
384 | |
385 | /* |
386 | * locate the correct leaf node in the btree |
387 | */ |
388 | static unsigned long *find_level(struct btree_head *head, struct btree_geo *geo, |
389 | unsigned long *key, int level) |
390 | { |
391 | unsigned long *node = head->node; |
392 | int i, height; |
393 | |
394 | for (height = head->height; height > level; height--) { |
395 | for (i = 0; i < geo->no_pairs; i++) |
396 | if (keycmp(geo, node, i, key) <= 0) |
397 | break; |
398 | |
399 | if ((i == geo->no_pairs) || !bval(geo, node, i)) { |
400 | /* right-most key is too large, update it */ |
401 | /* FIXME: If the right-most key on higher levels is |
402 | * always zero, this wouldn't be necessary. */ |
403 | i--; |
404 | setkey(geo, node, i, key); |
405 | } |
406 | BUG_ON(i < 0); |
407 | node = bval(geo, node, i); |
408 | } |
409 | BUG_ON(!node); |
410 | return node; |
411 | } |
412 | |
413 | static int btree_grow(struct btree_head *head, struct btree_geo *geo, |
414 | gfp_t gfp) |
415 | { |
416 | unsigned long *node; |
417 | int fill; |
418 | |
419 | node = btree_node_alloc(head, gfp); |
420 | if (!node) |
421 | return -ENOMEM; |
422 | if (head->node) { |
423 | fill = getfill(geo, head->node, 0); |
424 | setkey(geo, node, 0, bkey(geo, head->node, fill - 1)); |
425 | setval(geo, node, 0, head->node); |
426 | } |
427 | head->node = node; |
428 | head->height++; |
429 | return 0; |
430 | } |
431 | |
432 | static void btree_shrink(struct btree_head *head, struct btree_geo *geo) |
433 | { |
434 | unsigned long *node; |
435 | int fill; |
436 | |
437 | if (head->height <= 1) |
438 | return; |
439 | |
440 | node = head->node; |
441 | fill = getfill(geo, node, 0); |
442 | BUG_ON(fill > 1); |
443 | head->node = bval(geo, node, 0); |
444 | head->height--; |
445 | mempool_free(node, head->mempool); |
446 | } |
447 | |
448 | static int btree_insert_level(struct btree_head *head, struct btree_geo *geo, |
449 | unsigned long *key, void *val, int level, |
450 | gfp_t gfp) |
451 | { |
452 | unsigned long *node; |
453 | int i, pos, fill, err; |
454 | |
455 | BUG_ON(!val); |
456 | if (head->height < level) { |
457 | err = btree_grow(head, geo, gfp); |
458 | if (err) |
459 | return err; |
460 | } |
461 | |
462 | retry: |
463 | node = find_level(head, geo, key, level); |
464 | pos = getpos(geo, node, key); |
465 | fill = getfill(geo, node, pos); |
466 | /* two identical keys are not allowed */ |
467 | BUG_ON(pos < fill && keycmp(geo, node, pos, key) == 0); |
468 | |
469 | if (fill == geo->no_pairs) { |
470 | /* need to split node */ |
471 | unsigned long *new; |
472 | |
473 | new = btree_node_alloc(head, gfp); |
474 | if (!new) |
475 | return -ENOMEM; |
476 | err = btree_insert_level(head, geo, |
477 | bkey(geo, node, fill / 2 - 1), |
478 | new, level + 1, gfp); |
479 | if (err) { |
480 | mempool_free(new, head->mempool); |
481 | return err; |
482 | } |
483 | for (i = 0; i < fill / 2; i++) { |
484 | setkey(geo, new, i, bkey(geo, node, i)); |
485 | setval(geo, new, i, bval(geo, node, i)); |
486 | setkey(geo, node, i, bkey(geo, node, i + fill / 2)); |
487 | setval(geo, node, i, bval(geo, node, i + fill / 2)); |
488 | clearpair(geo, node, i + fill / 2); |
489 | } |
490 | if (fill & 1) { |
491 | setkey(geo, node, i, bkey(geo, node, fill - 1)); |
492 | setval(geo, node, i, bval(geo, node, fill - 1)); |
493 | clearpair(geo, node, fill - 1); |
494 | } |
495 | goto retry; |
496 | } |
497 | BUG_ON(fill >= geo->no_pairs); |
498 | |
499 | /* shift and insert */ |
500 | for (i = fill; i > pos; i--) { |
501 | setkey(geo, node, i, bkey(geo, node, i - 1)); |
502 | setval(geo, node, i, bval(geo, node, i - 1)); |
503 | } |
504 | setkey(geo, node, pos, key); |
505 | setval(geo, node, pos, val); |
506 | |
507 | return 0; |
508 | } |
509 | |
510 | int btree_insert(struct btree_head *head, struct btree_geo *geo, |
511 | unsigned long *key, void *val, gfp_t gfp) |
512 | { |
513 | BUG_ON(!val); |
514 | return btree_insert_level(head, geo, key, val, 1, gfp); |
515 | } |
516 | EXPORT_SYMBOL_GPL(btree_insert); |
517 | |
518 | static void *btree_remove_level(struct btree_head *head, struct btree_geo *geo, |
519 | unsigned long *key, int level); |
520 | static void merge(struct btree_head *head, struct btree_geo *geo, int level, |
521 | unsigned long *left, int lfill, |
522 | unsigned long *right, int rfill, |
523 | unsigned long *parent, int lpos) |
524 | { |
525 | int i; |
526 | |
527 | for (i = 0; i < rfill; i++) { |
528 | /* Move all keys to the left */ |
529 | setkey(geo, left, lfill + i, bkey(geo, right, i)); |
530 | setval(geo, left, lfill + i, bval(geo, right, i)); |
531 | } |
532 | /* Exchange left and right child in parent */ |
533 | setval(geo, parent, lpos, right); |
534 | setval(geo, parent, lpos + 1, left); |
535 | /* Remove left (formerly right) child from parent */ |
536 | btree_remove_level(head, geo, bkey(geo, parent, lpos), level + 1); |
537 | mempool_free(right, head->mempool); |
538 | } |
539 | |
540 | static void rebalance(struct btree_head *head, struct btree_geo *geo, |
541 | unsigned long *key, int level, unsigned long *child, int fill) |
542 | { |
543 | unsigned long *parent, *left = NULL, *right = NULL; |
544 | int i, no_left, no_right; |
545 | |
546 | if (fill == 0) { |
547 | /* Because we don't steal entries from a neighbour, this case |
548 | * can happen. Parent node contains a single child, this |
549 | * node, so merging with a sibling never happens. |
550 | */ |
551 | btree_remove_level(head, geo, key, level + 1); |
552 | mempool_free(child, head->mempool); |
553 | return; |
554 | } |
555 | |
556 | parent = find_level(head, geo, key, level + 1); |
557 | i = getpos(geo, parent, key); |
558 | BUG_ON(bval(geo, parent, i) != child); |
559 | |
560 | if (i > 0) { |
561 | left = bval(geo, parent, i - 1); |
562 | no_left = getfill(geo, left, 0); |
563 | if (fill + no_left <= geo->no_pairs) { |
564 | merge(head, geo, level, |
565 | left, no_left, |
566 | child, fill, |
567 | parent, i - 1); |
568 | return; |
569 | } |
570 | } |
571 | if (i + 1 < getfill(geo, parent, i)) { |
572 | right = bval(geo, parent, i + 1); |
573 | no_right = getfill(geo, right, 0); |
574 | if (fill + no_right <= geo->no_pairs) { |
575 | merge(head, geo, level, |
576 | child, fill, |
577 | right, no_right, |
578 | parent, i); |
579 | return; |
580 | } |
581 | } |
582 | /* |
583 | * We could also try to steal one entry from the left or right |
584 | * neighbor. By not doing so we changed the invariant from |
585 | * "all nodes are at least half full" to "no two neighboring |
586 | * nodes can be merged". Which means that the average fill of |
587 | * all nodes is still half or better. |
588 | */ |
589 | } |
590 | |
591 | static void *btree_remove_level(struct btree_head *head, struct btree_geo *geo, |
592 | unsigned long *key, int level) |
593 | { |
594 | unsigned long *node; |
595 | int i, pos, fill; |
596 | void *ret; |
597 | |
598 | if (level > head->height) { |
599 | /* we recursed all the way up */ |
600 | head->height = 0; |
601 | head->node = NULL; |
602 | return NULL; |
603 | } |
604 | |
605 | node = find_level(head, geo, key, level); |
606 | pos = getpos(geo, node, key); |
607 | fill = getfill(geo, node, pos); |
608 | if ((level == 1) && (keycmp(geo, node, pos, key) != 0)) |
609 | return NULL; |
610 | ret = bval(geo, node, pos); |
611 | |
612 | /* remove and shift */ |
613 | for (i = pos; i < fill - 1; i++) { |
614 | setkey(geo, node, i, bkey(geo, node, i + 1)); |
615 | setval(geo, node, i, bval(geo, node, i + 1)); |
616 | } |
617 | clearpair(geo, node, fill - 1); |
618 | |
619 | if (fill - 1 < geo->no_pairs / 2) { |
620 | if (level < head->height) |
621 | rebalance(head, geo, key, level, node, fill - 1); |
622 | else if (fill - 1 == 1) |
623 | btree_shrink(head, geo); |
624 | } |
625 | |
626 | return ret; |
627 | } |
628 | |
629 | void *btree_remove(struct btree_head *head, struct btree_geo *geo, |
630 | unsigned long *key) |
631 | { |
632 | if (head->height == 0) |
633 | return NULL; |
634 | |
635 | return btree_remove_level(head, geo, key, 1); |
636 | } |
637 | EXPORT_SYMBOL_GPL(btree_remove); |
638 | |
639 | int btree_merge(struct btree_head *target, struct btree_head *victim, |
640 | struct btree_geo *geo, gfp_t gfp) |
641 | { |
642 | unsigned long key[geo->keylen]; |
643 | unsigned long dup[geo->keylen]; |
644 | void *val; |
645 | int err; |
646 | |
647 | BUG_ON(target == victim); |
648 | |
649 | if (!(target->node)) { |
650 | /* target is empty, just copy fields over */ |
651 | target->node = victim->node; |
652 | target->height = victim->height; |
653 | __btree_init(victim); |
654 | return 0; |
655 | } |
656 | |
657 | /* TODO: This needs some optimizations. Currently we do three tree |
658 | * walks to remove a single object from the victim. |
659 | */ |
660 | for (;;) { |
661 | if (!btree_last(victim, geo, key)) |
662 | break; |
663 | val = btree_lookup(victim, geo, key); |
664 | err = btree_insert(target, geo, key, val, gfp); |
665 | if (err) |
666 | return err; |
667 | /* We must make a copy of the key, as the original will get |
668 | * mangled inside btree_remove. */ |
669 | longcpy(dup, key, geo->keylen); |
670 | btree_remove(victim, geo, dup); |
671 | } |
672 | return 0; |
673 | } |
674 | EXPORT_SYMBOL_GPL(btree_merge); |
675 | |
676 | static size_t __btree_for_each(struct btree_head *head, struct btree_geo *geo, |
677 | unsigned long *node, unsigned long opaque, |
678 | void (*func)(void *elem, unsigned long opaque, |
679 | unsigned long *key, size_t index, |
680 | void *func2), |
681 | void *func2, int reap, int height, size_t count) |
682 | { |
683 | int i; |
684 | unsigned long *child; |
685 | |
686 | for (i = 0; i < geo->no_pairs; i++) { |
687 | child = bval(geo, node, i); |
688 | if (!child) |
689 | break; |
690 | if (height > 1) |
691 | count = __btree_for_each(head, geo, child, opaque, |
692 | func, func2, reap, height - 1, count); |
693 | else |
694 | func(child, opaque, bkey(geo, node, i), count++, |
695 | func2); |
696 | } |
697 | if (reap) |
698 | mempool_free(node, head->mempool); |
699 | return count; |
700 | } |
701 | |
702 | static void empty(void *elem, unsigned long opaque, unsigned long *key, |
703 | size_t index, void *func2) |
704 | { |
705 | } |
706 | |
707 | void visitorl(void *elem, unsigned long opaque, unsigned long *key, |
708 | size_t index, void *__func) |
709 | { |
710 | visitorl_t func = __func; |
711 | |
712 | func(elem, opaque, *key, index); |
713 | } |
714 | EXPORT_SYMBOL_GPL(visitorl); |
715 | |
716 | void visitor32(void *elem, unsigned long opaque, unsigned long *__key, |
717 | size_t index, void *__func) |
718 | { |
719 | visitor32_t func = __func; |
720 | u32 *key = (void *)__key; |
721 | |
722 | func(elem, opaque, *key, index); |
723 | } |
724 | EXPORT_SYMBOL_GPL(visitor32); |
725 | |
726 | void visitor64(void *elem, unsigned long opaque, unsigned long *__key, |
727 | size_t index, void *__func) |
728 | { |
729 | visitor64_t func = __func; |
730 | u64 *key = (void *)__key; |
731 | |
732 | func(elem, opaque, *key, index); |
733 | } |
734 | EXPORT_SYMBOL_GPL(visitor64); |
735 | |
736 | void visitor128(void *elem, unsigned long opaque, unsigned long *__key, |
737 | size_t index, void *__func) |
738 | { |
739 | visitor128_t func = __func; |
740 | u64 *key = (void *)__key; |
741 | |
742 | func(elem, opaque, key[0], key[1], index); |
743 | } |
744 | EXPORT_SYMBOL_GPL(visitor128); |
745 | |
746 | size_t btree_visitor(struct btree_head *head, struct btree_geo *geo, |
747 | unsigned long opaque, |
748 | void (*func)(void *elem, unsigned long opaque, |
749 | unsigned long *key, |
750 | size_t index, void *func2), |
751 | void *func2) |
752 | { |
753 | size_t count = 0; |
754 | |
755 | if (!func2) |
756 | func = empty; |
757 | if (head->node) |
758 | count = __btree_for_each(head, geo, head->node, opaque, func, |
759 | func2, 0, head->height, 0); |
760 | return count; |
761 | } |
762 | EXPORT_SYMBOL_GPL(btree_visitor); |
763 | |
764 | size_t btree_grim_visitor(struct btree_head *head, struct btree_geo *geo, |
765 | unsigned long opaque, |
766 | void (*func)(void *elem, unsigned long opaque, |
767 | unsigned long *key, |
768 | size_t index, void *func2), |
769 | void *func2) |
770 | { |
771 | size_t count = 0; |
772 | |
773 | if (!func2) |
774 | func = empty; |
775 | if (head->node) |
776 | count = __btree_for_each(head, geo, head->node, opaque, func, |
777 | func2, 1, head->height, 0); |
778 | __btree_init(head); |
779 | return count; |
780 | } |
781 | EXPORT_SYMBOL_GPL(btree_grim_visitor); |
782 | |
783 | static int __init btree_module_init(void) |
784 | { |
785 | btree_cachep = kmem_cache_create("btree_node", NODESIZE, 0, |
786 | SLAB_HWCACHE_ALIGN, NULL); |
787 | return 0; |
788 | } |
789 | |
790 | static void __exit btree_module_exit(void) |
791 | { |
792 | kmem_cache_destroy(btree_cachep); |
793 | } |
794 | |
795 | /* If core code starts using btree, initialization should happen even earlier */ |
796 | module_init(btree_module_init); |
797 | module_exit(btree_module_exit); |
798 | |
799 | MODULE_AUTHOR("Joern Engel <joern@logfs.org>"); |
800 | MODULE_AUTHOR("Johannes Berg <johannes@sipsolutions.net>"); |
801 | MODULE_LICENSE("GPL"); |
802 |