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5db53f3e JE |
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 | * excercise 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 | memset(node, 0, NODESIZE); | |
99 | return node; | |
100 | } | |
101 | ||
102 | static int longcmp(const unsigned long *l1, const unsigned long *l2, size_t n) | |
103 | { | |
104 | size_t i; | |
105 | ||
106 | for (i = 0; i < n; i++) { | |
107 | if (l1[i] < l2[i]) | |
108 | return -1; | |
109 | if (l1[i] > l2[i]) | |
110 | return 1; | |
111 | } | |
112 | return 0; | |
113 | } | |
114 | ||
115 | static unsigned long *longcpy(unsigned long *dest, const unsigned long *src, | |
116 | size_t n) | |
117 | { | |
118 | size_t i; | |
119 | ||
120 | for (i = 0; i < n; i++) | |
121 | dest[i] = src[i]; | |
122 | return dest; | |
123 | } | |
124 | ||
125 | static unsigned long *longset(unsigned long *s, unsigned long c, size_t n) | |
126 | { | |
127 | size_t i; | |
128 | ||
129 | for (i = 0; i < n; i++) | |
130 | s[i] = c; | |
131 | return s; | |
132 | } | |
133 | ||
134 | static void dec_key(struct btree_geo *geo, unsigned long *key) | |
135 | { | |
136 | unsigned long val; | |
137 | int i; | |
138 | ||
139 | for (i = geo->keylen - 1; i >= 0; i--) { | |
140 | val = key[i]; | |
141 | key[i] = val - 1; | |
142 | if (val) | |
143 | break; | |
144 | } | |
145 | } | |
146 | ||
147 | static unsigned long *bkey(struct btree_geo *geo, unsigned long *node, int n) | |
148 | { | |
149 | return &node[n * geo->keylen]; | |
150 | } | |
151 | ||
152 | static void *bval(struct btree_geo *geo, unsigned long *node, int n) | |
153 | { | |
154 | return (void *)node[geo->no_longs + n]; | |
155 | } | |
156 | ||
157 | static void setkey(struct btree_geo *geo, unsigned long *node, int n, | |
158 | unsigned long *key) | |
159 | { | |
160 | longcpy(bkey(geo, node, n), key, geo->keylen); | |
161 | } | |
162 | ||
163 | static void setval(struct btree_geo *geo, unsigned long *node, int n, | |
164 | void *val) | |
165 | { | |
166 | node[geo->no_longs + n] = (unsigned long) val; | |
167 | } | |
168 | ||
169 | static void clearpair(struct btree_geo *geo, unsigned long *node, int n) | |
170 | { | |
171 | longset(bkey(geo, node, n), 0, geo->keylen); | |
172 | node[geo->no_longs + n] = 0; | |
173 | } | |
174 | ||
175 | static inline void __btree_init(struct btree_head *head) | |
176 | { | |
177 | head->node = NULL; | |
178 | head->height = 0; | |
179 | } | |
180 | ||
181 | void btree_init_mempool(struct btree_head *head, mempool_t *mempool) | |
182 | { | |
183 | __btree_init(head); | |
184 | head->mempool = mempool; | |
185 | } | |
186 | EXPORT_SYMBOL_GPL(btree_init_mempool); | |
187 | ||
188 | int btree_init(struct btree_head *head) | |
189 | { | |
190 | __btree_init(head); | |
191 | head->mempool = mempool_create(0, btree_alloc, btree_free, NULL); | |
192 | if (!head->mempool) | |
193 | return -ENOMEM; | |
194 | return 0; | |
195 | } | |
196 | EXPORT_SYMBOL_GPL(btree_init); | |
197 | ||
198 | void btree_destroy(struct btree_head *head) | |
199 | { | |
200 | mempool_destroy(head->mempool); | |
201 | head->mempool = NULL; | |
202 | } | |
203 | EXPORT_SYMBOL_GPL(btree_destroy); | |
204 | ||
205 | void *btree_last(struct btree_head *head, struct btree_geo *geo, | |
206 | unsigned long *key) | |
207 | { | |
208 | int height = head->height; | |
209 | unsigned long *node = head->node; | |
210 | ||
211 | if (height == 0) | |
212 | return NULL; | |
213 | ||
214 | for ( ; height > 1; height--) | |
215 | node = bval(geo, node, 0); | |
216 | ||
217 | longcpy(key, bkey(geo, node, 0), geo->keylen); | |
218 | return bval(geo, node, 0); | |
219 | } | |
220 | EXPORT_SYMBOL_GPL(btree_last); | |
221 | ||
222 | static int keycmp(struct btree_geo *geo, unsigned long *node, int pos, | |
223 | unsigned long *key) | |
224 | { | |
225 | return longcmp(bkey(geo, node, pos), key, geo->keylen); | |
226 | } | |
227 | ||
228 | static int keyzero(struct btree_geo *geo, unsigned long *key) | |
229 | { | |
230 | int i; | |
231 | ||
232 | for (i = 0; i < geo->keylen; i++) | |
233 | if (key[i]) | |
234 | return 0; | |
235 | ||
236 | return 1; | |
237 | } | |
238 | ||
239 | void *btree_lookup(struct btree_head *head, struct btree_geo *geo, | |
240 | unsigned long *key) | |
241 | { | |
242 | int i, height = head->height; | |
243 | unsigned long *node = head->node; | |
244 | ||
245 | if (height == 0) | |
246 | return NULL; | |
247 | ||
248 | for ( ; height > 1; height--) { | |
249 | for (i = 0; i < geo->no_pairs; i++) | |
250 | if (keycmp(geo, node, i, key) <= 0) | |
251 | break; | |
252 | if (i == geo->no_pairs) | |
253 | return NULL; | |
254 | node = bval(geo, node, i); | |
255 | if (!node) | |
256 | return NULL; | |
257 | } | |
258 | ||
259 | if (!node) | |
260 | return NULL; | |
261 | ||
262 | for (i = 0; i < geo->no_pairs; i++) | |
263 | if (keycmp(geo, node, i, key) == 0) | |
264 | return bval(geo, node, i); | |
265 | return NULL; | |
266 | } | |
267 | EXPORT_SYMBOL_GPL(btree_lookup); | |
268 | ||
269 | int btree_update(struct btree_head *head, struct btree_geo *geo, | |
270 | unsigned long *key, void *val) | |
271 | { | |
272 | int i, height = head->height; | |
273 | unsigned long *node = head->node; | |
274 | ||
275 | if (height == 0) | |
276 | return -ENOENT; | |
277 | ||
278 | for ( ; height > 1; height--) { | |
279 | for (i = 0; i < geo->no_pairs; i++) | |
280 | if (keycmp(geo, node, i, key) <= 0) | |
281 | break; | |
282 | if (i == geo->no_pairs) | |
283 | return -ENOENT; | |
284 | node = bval(geo, node, i); | |
285 | if (!node) | |
286 | return -ENOENT; | |
287 | } | |
288 | ||
289 | if (!node) | |
290 | return -ENOENT; | |
291 | ||
292 | for (i = 0; i < geo->no_pairs; i++) | |
293 | if (keycmp(geo, node, i, key) == 0) { | |
294 | setval(geo, node, i, val); | |
295 | return 0; | |
296 | } | |
297 | return -ENOENT; | |
298 | } | |
299 | EXPORT_SYMBOL_GPL(btree_update); | |
300 | ||
301 | /* | |
302 | * Usually this function is quite similar to normal lookup. But the key of | |
303 | * a parent node may be smaller than the smallest key of all its siblings. | |
304 | * In such a case we cannot just return NULL, as we have only proven that no | |
305 | * key smaller than __key, but larger than this parent key exists. | |
306 | * So we set __key to the parent key and retry. We have to use the smallest | |
307 | * such parent key, which is the last parent key we encountered. | |
308 | */ | |
309 | void *btree_get_prev(struct btree_head *head, struct btree_geo *geo, | |
310 | unsigned long *__key) | |
311 | { | |
312 | int i, height; | |
313 | unsigned long *node, *oldnode; | |
314 | unsigned long *retry_key = NULL, key[geo->keylen]; | |
315 | ||
316 | if (keyzero(geo, __key)) | |
317 | return NULL; | |
318 | ||
319 | if (head->height == 0) | |
320 | return NULL; | |
321 | retry: | |
322 | longcpy(key, __key, geo->keylen); | |
323 | dec_key(geo, key); | |
324 | ||
325 | node = head->node; | |
326 | for (height = head->height ; height > 1; height--) { | |
327 | for (i = 0; i < geo->no_pairs; i++) | |
328 | if (keycmp(geo, node, i, key) <= 0) | |
329 | break; | |
330 | if (i == geo->no_pairs) | |
331 | goto miss; | |
332 | oldnode = node; | |
333 | node = bval(geo, node, i); | |
334 | if (!node) | |
335 | goto miss; | |
336 | retry_key = bkey(geo, oldnode, i); | |
337 | } | |
338 | ||
339 | if (!node) | |
340 | goto miss; | |
341 | ||
342 | for (i = 0; i < geo->no_pairs; i++) { | |
343 | if (keycmp(geo, node, i, key) <= 0) { | |
344 | if (bval(geo, node, i)) { | |
345 | longcpy(__key, bkey(geo, node, i), geo->keylen); | |
346 | return bval(geo, node, i); | |
347 | } else | |
348 | goto miss; | |
349 | } | |
350 | } | |
351 | miss: | |
352 | if (retry_key) { | |
353 | __key = retry_key; | |
354 | retry_key = NULL; | |
355 | goto retry; | |
356 | } | |
357 | return NULL; | |
358 | } | |
359 | ||
360 | static int getpos(struct btree_geo *geo, unsigned long *node, | |
361 | unsigned long *key) | |
362 | { | |
363 | int i; | |
364 | ||
365 | for (i = 0; i < geo->no_pairs; i++) { | |
366 | if (keycmp(geo, node, i, key) <= 0) | |
367 | break; | |
368 | } | |
369 | return i; | |
370 | } | |
371 | ||
372 | static int getfill(struct btree_geo *geo, unsigned long *node, int start) | |
373 | { | |
374 | int i; | |
375 | ||
376 | for (i = start; i < geo->no_pairs; i++) | |
377 | if (!bval(geo, node, i)) | |
378 | break; | |
379 | return i; | |
380 | } | |
381 | ||
382 | /* | |
383 | * locate the correct leaf node in the btree | |
384 | */ | |
385 | static unsigned long *find_level(struct btree_head *head, struct btree_geo *geo, | |
386 | unsigned long *key, int level) | |
387 | { | |
388 | unsigned long *node = head->node; | |
389 | int i, height; | |
390 | ||
391 | for (height = head->height; height > level; height--) { | |
392 | for (i = 0; i < geo->no_pairs; i++) | |
393 | if (keycmp(geo, node, i, key) <= 0) | |
394 | break; | |
395 | ||
396 | if ((i == geo->no_pairs) || !bval(geo, node, i)) { | |
397 | /* right-most key is too large, update it */ | |
398 | /* FIXME: If the right-most key on higher levels is | |
399 | * always zero, this wouldn't be necessary. */ | |
400 | i--; | |
401 | setkey(geo, node, i, key); | |
402 | } | |
403 | BUG_ON(i < 0); | |
404 | node = bval(geo, node, i); | |
405 | } | |
406 | BUG_ON(!node); | |
407 | return node; | |
408 | } | |
409 | ||
410 | static int btree_grow(struct btree_head *head, struct btree_geo *geo, | |
411 | gfp_t gfp) | |
412 | { | |
413 | unsigned long *node; | |
414 | int fill; | |
415 | ||
416 | node = btree_node_alloc(head, gfp); | |
417 | if (!node) | |
418 | return -ENOMEM; | |
419 | if (head->node) { | |
420 | fill = getfill(geo, head->node, 0); | |
421 | setkey(geo, node, 0, bkey(geo, head->node, fill - 1)); | |
422 | setval(geo, node, 0, head->node); | |
423 | } | |
424 | head->node = node; | |
425 | head->height++; | |
426 | return 0; | |
427 | } | |
428 | ||
429 | static void btree_shrink(struct btree_head *head, struct btree_geo *geo) | |
430 | { | |
431 | unsigned long *node; | |
432 | int fill; | |
433 | ||
434 | if (head->height <= 1) | |
435 | return; | |
436 | ||
437 | node = head->node; | |
438 | fill = getfill(geo, node, 0); | |
439 | BUG_ON(fill > 1); | |
440 | head->node = bval(geo, node, 0); | |
441 | head->height--; | |
442 | mempool_free(node, head->mempool); | |
443 | } | |
444 | ||
445 | static int btree_insert_level(struct btree_head *head, struct btree_geo *geo, | |
446 | unsigned long *key, void *val, int level, | |
447 | gfp_t gfp) | |
448 | { | |
449 | unsigned long *node; | |
450 | int i, pos, fill, err; | |
451 | ||
452 | BUG_ON(!val); | |
453 | if (head->height < level) { | |
454 | err = btree_grow(head, geo, gfp); | |
455 | if (err) | |
456 | return err; | |
457 | } | |
458 | ||
459 | retry: | |
460 | node = find_level(head, geo, key, level); | |
461 | pos = getpos(geo, node, key); | |
462 | fill = getfill(geo, node, pos); | |
463 | /* two identical keys are not allowed */ | |
464 | BUG_ON(pos < fill && keycmp(geo, node, pos, key) == 0); | |
465 | ||
466 | if (fill == geo->no_pairs) { | |
467 | /* need to split node */ | |
468 | unsigned long *new; | |
469 | ||
470 | new = btree_node_alloc(head, gfp); | |
471 | if (!new) | |
472 | return -ENOMEM; | |
473 | err = btree_insert_level(head, geo, | |
474 | bkey(geo, node, fill / 2 - 1), | |
475 | new, level + 1, gfp); | |
476 | if (err) { | |
477 | mempool_free(new, head->mempool); | |
478 | return err; | |
479 | } | |
480 | for (i = 0; i < fill / 2; i++) { | |
481 | setkey(geo, new, i, bkey(geo, node, i)); | |
482 | setval(geo, new, i, bval(geo, node, i)); | |
483 | setkey(geo, node, i, bkey(geo, node, i + fill / 2)); | |
484 | setval(geo, node, i, bval(geo, node, i + fill / 2)); | |
485 | clearpair(geo, node, i + fill / 2); | |
486 | } | |
487 | if (fill & 1) { | |
488 | setkey(geo, node, i, bkey(geo, node, fill - 1)); | |
489 | setval(geo, node, i, bval(geo, node, fill - 1)); | |
490 | clearpair(geo, node, fill - 1); | |
491 | } | |
492 | goto retry; | |
493 | } | |
494 | BUG_ON(fill >= geo->no_pairs); | |
495 | ||
496 | /* shift and insert */ | |
497 | for (i = fill; i > pos; i--) { | |
498 | setkey(geo, node, i, bkey(geo, node, i - 1)); | |
499 | setval(geo, node, i, bval(geo, node, i - 1)); | |
500 | } | |
501 | setkey(geo, node, pos, key); | |
502 | setval(geo, node, pos, val); | |
503 | ||
504 | return 0; | |
505 | } | |
506 | ||
507 | int btree_insert(struct btree_head *head, struct btree_geo *geo, | |
508 | unsigned long *key, void *val, gfp_t gfp) | |
509 | { | |
510 | return btree_insert_level(head, geo, key, val, 1, gfp); | |
511 | } | |
512 | EXPORT_SYMBOL_GPL(btree_insert); | |
513 | ||
514 | static void *btree_remove_level(struct btree_head *head, struct btree_geo *geo, | |
515 | unsigned long *key, int level); | |
516 | static void merge(struct btree_head *head, struct btree_geo *geo, int level, | |
517 | unsigned long *left, int lfill, | |
518 | unsigned long *right, int rfill, | |
519 | unsigned long *parent, int lpos) | |
520 | { | |
521 | int i; | |
522 | ||
523 | for (i = 0; i < rfill; i++) { | |
524 | /* Move all keys to the left */ | |
525 | setkey(geo, left, lfill + i, bkey(geo, right, i)); | |
526 | setval(geo, left, lfill + i, bval(geo, right, i)); | |
527 | } | |
528 | /* Exchange left and right child in parent */ | |
529 | setval(geo, parent, lpos, right); | |
530 | setval(geo, parent, lpos + 1, left); | |
531 | /* Remove left (formerly right) child from parent */ | |
532 | btree_remove_level(head, geo, bkey(geo, parent, lpos), level + 1); | |
533 | mempool_free(right, head->mempool); | |
534 | } | |
535 | ||
536 | static void rebalance(struct btree_head *head, struct btree_geo *geo, | |
537 | unsigned long *key, int level, unsigned long *child, int fill) | |
538 | { | |
539 | unsigned long *parent, *left = NULL, *right = NULL; | |
540 | int i, no_left, no_right; | |
541 | ||
542 | if (fill == 0) { | |
543 | /* Because we don't steal entries from a neigbour, this case | |
544 | * can happen. Parent node contains a single child, this | |
545 | * node, so merging with a sibling never happens. | |
546 | */ | |
547 | btree_remove_level(head, geo, key, level + 1); | |
548 | mempool_free(child, head->mempool); | |
549 | return; | |
550 | } | |
551 | ||
552 | parent = find_level(head, geo, key, level + 1); | |
553 | i = getpos(geo, parent, key); | |
554 | BUG_ON(bval(geo, parent, i) != child); | |
555 | ||
556 | if (i > 0) { | |
557 | left = bval(geo, parent, i - 1); | |
558 | no_left = getfill(geo, left, 0); | |
559 | if (fill + no_left <= geo->no_pairs) { | |
560 | merge(head, geo, level, | |
561 | left, no_left, | |
562 | child, fill, | |
563 | parent, i - 1); | |
564 | return; | |
565 | } | |
566 | } | |
567 | if (i + 1 < getfill(geo, parent, i)) { | |
568 | right = bval(geo, parent, i + 1); | |
569 | no_right = getfill(geo, right, 0); | |
570 | if (fill + no_right <= geo->no_pairs) { | |
571 | merge(head, geo, level, | |
572 | child, fill, | |
573 | right, no_right, | |
574 | parent, i); | |
575 | return; | |
576 | } | |
577 | } | |
578 | /* | |
579 | * We could also try to steal one entry from the left or right | |
580 | * neighbor. By not doing so we changed the invariant from | |
581 | * "all nodes are at least half full" to "no two neighboring | |
582 | * nodes can be merged". Which means that the average fill of | |
583 | * all nodes is still half or better. | |
584 | */ | |
585 | } | |
586 | ||
587 | static void *btree_remove_level(struct btree_head *head, struct btree_geo *geo, | |
588 | unsigned long *key, int level) | |
589 | { | |
590 | unsigned long *node; | |
591 | int i, pos, fill; | |
592 | void *ret; | |
593 | ||
594 | if (level > head->height) { | |
595 | /* we recursed all the way up */ | |
596 | head->height = 0; | |
597 | head->node = NULL; | |
598 | return NULL; | |
599 | } | |
600 | ||
601 | node = find_level(head, geo, key, level); | |
602 | pos = getpos(geo, node, key); | |
603 | fill = getfill(geo, node, pos); | |
604 | if ((level == 1) && (keycmp(geo, node, pos, key) != 0)) | |
605 | return NULL; | |
606 | ret = bval(geo, node, pos); | |
607 | ||
608 | /* remove and shift */ | |
609 | for (i = pos; i < fill - 1; i++) { | |
610 | setkey(geo, node, i, bkey(geo, node, i + 1)); | |
611 | setval(geo, node, i, bval(geo, node, i + 1)); | |
612 | } | |
613 | clearpair(geo, node, fill - 1); | |
614 | ||
615 | if (fill - 1 < geo->no_pairs / 2) { | |
616 | if (level < head->height) | |
617 | rebalance(head, geo, key, level, node, fill - 1); | |
618 | else if (fill - 1 == 1) | |
619 | btree_shrink(head, geo); | |
620 | } | |
621 | ||
622 | return ret; | |
623 | } | |
624 | ||
625 | void *btree_remove(struct btree_head *head, struct btree_geo *geo, | |
626 | unsigned long *key) | |
627 | { | |
628 | if (head->height == 0) | |
629 | return NULL; | |
630 | ||
631 | return btree_remove_level(head, geo, key, 1); | |
632 | } | |
633 | EXPORT_SYMBOL_GPL(btree_remove); | |
634 | ||
635 | int btree_merge(struct btree_head *target, struct btree_head *victim, | |
636 | struct btree_geo *geo, gfp_t gfp) | |
637 | { | |
638 | unsigned long key[geo->keylen]; | |
639 | unsigned long dup[geo->keylen]; | |
640 | void *val; | |
641 | int err; | |
642 | ||
643 | BUG_ON(target == victim); | |
644 | ||
645 | if (!(target->node)) { | |
646 | /* target is empty, just copy fields over */ | |
647 | target->node = victim->node; | |
648 | target->height = victim->height; | |
649 | __btree_init(victim); | |
650 | return 0; | |
651 | } | |
652 | ||
653 | /* TODO: This needs some optimizations. Currently we do three tree | |
654 | * walks to remove a single object from the victim. | |
655 | */ | |
656 | for (;;) { | |
657 | if (!btree_last(victim, geo, key)) | |
658 | break; | |
659 | val = btree_lookup(victim, geo, key); | |
660 | err = btree_insert(target, geo, key, val, gfp); | |
661 | if (err) | |
662 | return err; | |
663 | /* We must make a copy of the key, as the original will get | |
664 | * mangled inside btree_remove. */ | |
665 | longcpy(dup, key, geo->keylen); | |
666 | btree_remove(victim, geo, dup); | |
667 | } | |
668 | return 0; | |
669 | } | |
670 | EXPORT_SYMBOL_GPL(btree_merge); | |
671 | ||
672 | static size_t __btree_for_each(struct btree_head *head, struct btree_geo *geo, | |
673 | unsigned long *node, unsigned long opaque, | |
674 | void (*func)(void *elem, unsigned long opaque, | |
675 | unsigned long *key, size_t index, | |
676 | void *func2), | |
677 | void *func2, int reap, int height, size_t count) | |
678 | { | |
679 | int i; | |
680 | unsigned long *child; | |
681 | ||
682 | for (i = 0; i < geo->no_pairs; i++) { | |
683 | child = bval(geo, node, i); | |
684 | if (!child) | |
685 | break; | |
686 | if (height > 1) | |
687 | count = __btree_for_each(head, geo, child, opaque, | |
688 | func, func2, reap, height - 1, count); | |
689 | else | |
690 | func(child, opaque, bkey(geo, node, i), count++, | |
691 | func2); | |
692 | } | |
693 | if (reap) | |
694 | mempool_free(node, head->mempool); | |
695 | return count; | |
696 | } | |
697 | ||
698 | static void empty(void *elem, unsigned long opaque, unsigned long *key, | |
699 | size_t index, void *func2) | |
700 | { | |
701 | } | |
702 | ||
703 | void visitorl(void *elem, unsigned long opaque, unsigned long *key, | |
704 | size_t index, void *__func) | |
705 | { | |
706 | visitorl_t func = __func; | |
707 | ||
708 | func(elem, opaque, *key, index); | |
709 | } | |
710 | EXPORT_SYMBOL_GPL(visitorl); | |
711 | ||
712 | void visitor32(void *elem, unsigned long opaque, unsigned long *__key, | |
713 | size_t index, void *__func) | |
714 | { | |
715 | visitor32_t func = __func; | |
716 | u32 *key = (void *)__key; | |
717 | ||
718 | func(elem, opaque, *key, index); | |
719 | } | |
720 | EXPORT_SYMBOL_GPL(visitor32); | |
721 | ||
722 | void visitor64(void *elem, unsigned long opaque, unsigned long *__key, | |
723 | size_t index, void *__func) | |
724 | { | |
725 | visitor64_t func = __func; | |
726 | u64 *key = (void *)__key; | |
727 | ||
728 | func(elem, opaque, *key, index); | |
729 | } | |
730 | EXPORT_SYMBOL_GPL(visitor64); | |
731 | ||
732 | void visitor128(void *elem, unsigned long opaque, unsigned long *__key, | |
733 | size_t index, void *__func) | |
734 | { | |
735 | visitor128_t func = __func; | |
736 | u64 *key = (void *)__key; | |
737 | ||
738 | func(elem, opaque, key[0], key[1], index); | |
739 | } | |
740 | EXPORT_SYMBOL_GPL(visitor128); | |
741 | ||
742 | size_t btree_visitor(struct btree_head *head, struct btree_geo *geo, | |
743 | unsigned long opaque, | |
744 | void (*func)(void *elem, unsigned long opaque, | |
745 | unsigned long *key, | |
746 | size_t index, void *func2), | |
747 | void *func2) | |
748 | { | |
749 | size_t count = 0; | |
750 | ||
751 | if (!func2) | |
752 | func = empty; | |
753 | if (head->node) | |
754 | count = __btree_for_each(head, geo, head->node, opaque, func, | |
755 | func2, 0, head->height, 0); | |
756 | return count; | |
757 | } | |
758 | EXPORT_SYMBOL_GPL(btree_visitor); | |
759 | ||
760 | size_t btree_grim_visitor(struct btree_head *head, struct btree_geo *geo, | |
761 | unsigned long opaque, | |
762 | void (*func)(void *elem, unsigned long opaque, | |
763 | unsigned long *key, | |
764 | size_t index, void *func2), | |
765 | void *func2) | |
766 | { | |
767 | size_t count = 0; | |
768 | ||
769 | if (!func2) | |
770 | func = empty; | |
771 | if (head->node) | |
772 | count = __btree_for_each(head, geo, head->node, opaque, func, | |
773 | func2, 1, head->height, 0); | |
774 | __btree_init(head); | |
775 | return count; | |
776 | } | |
777 | EXPORT_SYMBOL_GPL(btree_grim_visitor); | |
778 | ||
779 | static int __init btree_module_init(void) | |
780 | { | |
781 | btree_cachep = kmem_cache_create("btree_node", NODESIZE, 0, | |
782 | SLAB_HWCACHE_ALIGN, NULL); | |
783 | return 0; | |
784 | } | |
785 | ||
786 | static void __exit btree_module_exit(void) | |
787 | { | |
788 | kmem_cache_destroy(btree_cachep); | |
789 | } | |
790 | ||
791 | /* If core code starts using btree, initialization should happen even earlier */ | |
792 | module_init(btree_module_init); | |
793 | module_exit(btree_module_exit); | |
794 | ||
795 | MODULE_AUTHOR("Joern Engel <joern@logfs.org>"); | |
796 | MODULE_AUTHOR("Johannes Berg <johannes@sipsolutions.net>"); | |
797 | MODULE_LICENSE("GPL"); |