This source file includes following definitions.
- node_shift
- node_copy
- delete_at
- merge_threshold
- init_child
- exit_child
- shift
- __rebalance2
- rebalance2
- delete_center_node
- redistribute3
- __rebalance3
- rebalance3
- rebalance_children
- do_leaf
- remove_raw
- dm_btree_remove
- remove_nearest
- remove_one
- dm_btree_remove_leaves
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7 #include "dm-btree.h"
8 #include "dm-btree-internal.h"
9 #include "dm-transaction-manager.h"
10
11 #include <linux/export.h>
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55
56 static void node_shift(struct btree_node *n, int shift)
57 {
58 uint32_t nr_entries = le32_to_cpu(n->header.nr_entries);
59 uint32_t value_size = le32_to_cpu(n->header.value_size);
60
61 if (shift < 0) {
62 shift = -shift;
63 BUG_ON(shift > nr_entries);
64 BUG_ON((void *) key_ptr(n, shift) >= value_ptr(n, shift));
65 memmove(key_ptr(n, 0),
66 key_ptr(n, shift),
67 (nr_entries - shift) * sizeof(__le64));
68 memmove(value_ptr(n, 0),
69 value_ptr(n, shift),
70 (nr_entries - shift) * value_size);
71 } else {
72 BUG_ON(nr_entries + shift > le32_to_cpu(n->header.max_entries));
73 memmove(key_ptr(n, shift),
74 key_ptr(n, 0),
75 nr_entries * sizeof(__le64));
76 memmove(value_ptr(n, shift),
77 value_ptr(n, 0),
78 nr_entries * value_size);
79 }
80 }
81
82 static void node_copy(struct btree_node *left, struct btree_node *right, int shift)
83 {
84 uint32_t nr_left = le32_to_cpu(left->header.nr_entries);
85 uint32_t value_size = le32_to_cpu(left->header.value_size);
86 BUG_ON(value_size != le32_to_cpu(right->header.value_size));
87
88 if (shift < 0) {
89 shift = -shift;
90 BUG_ON(nr_left + shift > le32_to_cpu(left->header.max_entries));
91 memcpy(key_ptr(left, nr_left),
92 key_ptr(right, 0),
93 shift * sizeof(__le64));
94 memcpy(value_ptr(left, nr_left),
95 value_ptr(right, 0),
96 shift * value_size);
97 } else {
98 BUG_ON(shift > le32_to_cpu(right->header.max_entries));
99 memcpy(key_ptr(right, 0),
100 key_ptr(left, nr_left - shift),
101 shift * sizeof(__le64));
102 memcpy(value_ptr(right, 0),
103 value_ptr(left, nr_left - shift),
104 shift * value_size);
105 }
106 }
107
108
109
110
111 static void delete_at(struct btree_node *n, unsigned index)
112 {
113 unsigned nr_entries = le32_to_cpu(n->header.nr_entries);
114 unsigned nr_to_copy = nr_entries - (index + 1);
115 uint32_t value_size = le32_to_cpu(n->header.value_size);
116 BUG_ON(index >= nr_entries);
117
118 if (nr_to_copy) {
119 memmove(key_ptr(n, index),
120 key_ptr(n, index + 1),
121 nr_to_copy * sizeof(__le64));
122
123 memmove(value_ptr(n, index),
124 value_ptr(n, index + 1),
125 nr_to_copy * value_size);
126 }
127
128 n->header.nr_entries = cpu_to_le32(nr_entries - 1);
129 }
130
131 static unsigned merge_threshold(struct btree_node *n)
132 {
133 return le32_to_cpu(n->header.max_entries) / 3;
134 }
135
136 struct child {
137 unsigned index;
138 struct dm_block *block;
139 struct btree_node *n;
140 };
141
142 static int init_child(struct dm_btree_info *info, struct dm_btree_value_type *vt,
143 struct btree_node *parent,
144 unsigned index, struct child *result)
145 {
146 int r, inc;
147 dm_block_t root;
148
149 result->index = index;
150 root = value64(parent, index);
151
152 r = dm_tm_shadow_block(info->tm, root, &btree_node_validator,
153 &result->block, &inc);
154 if (r)
155 return r;
156
157 result->n = dm_block_data(result->block);
158
159 if (inc)
160 inc_children(info->tm, result->n, vt);
161
162 *((__le64 *) value_ptr(parent, index)) =
163 cpu_to_le64(dm_block_location(result->block));
164
165 return 0;
166 }
167
168 static void exit_child(struct dm_btree_info *info, struct child *c)
169 {
170 dm_tm_unlock(info->tm, c->block);
171 }
172
173 static void shift(struct btree_node *left, struct btree_node *right, int count)
174 {
175 uint32_t nr_left = le32_to_cpu(left->header.nr_entries);
176 uint32_t nr_right = le32_to_cpu(right->header.nr_entries);
177 uint32_t max_entries = le32_to_cpu(left->header.max_entries);
178 uint32_t r_max_entries = le32_to_cpu(right->header.max_entries);
179
180 BUG_ON(max_entries != r_max_entries);
181 BUG_ON(nr_left - count > max_entries);
182 BUG_ON(nr_right + count > max_entries);
183
184 if (!count)
185 return;
186
187 if (count > 0) {
188 node_shift(right, count);
189 node_copy(left, right, count);
190 } else {
191 node_copy(left, right, count);
192 node_shift(right, count);
193 }
194
195 left->header.nr_entries = cpu_to_le32(nr_left - count);
196 right->header.nr_entries = cpu_to_le32(nr_right + count);
197 }
198
199 static void __rebalance2(struct dm_btree_info *info, struct btree_node *parent,
200 struct child *l, struct child *r)
201 {
202 struct btree_node *left = l->n;
203 struct btree_node *right = r->n;
204 uint32_t nr_left = le32_to_cpu(left->header.nr_entries);
205 uint32_t nr_right = le32_to_cpu(right->header.nr_entries);
206
207
208
209
210
211
212 unsigned int threshold = 2 * (merge_threshold(left) + 1);
213
214 if (nr_left + nr_right < threshold) {
215
216
217
218 node_copy(left, right, -nr_right);
219 left->header.nr_entries = cpu_to_le32(nr_left + nr_right);
220 delete_at(parent, r->index);
221
222
223
224
225
226 dm_tm_dec(info->tm, dm_block_location(r->block));
227 } else {
228
229
230
231 unsigned target_left = (nr_left + nr_right) / 2;
232 shift(left, right, nr_left - target_left);
233 *key_ptr(parent, r->index) = right->keys[0];
234 }
235 }
236
237 static int rebalance2(struct shadow_spine *s, struct dm_btree_info *info,
238 struct dm_btree_value_type *vt, unsigned left_index)
239 {
240 int r;
241 struct btree_node *parent;
242 struct child left, right;
243
244 parent = dm_block_data(shadow_current(s));
245
246 r = init_child(info, vt, parent, left_index, &left);
247 if (r)
248 return r;
249
250 r = init_child(info, vt, parent, left_index + 1, &right);
251 if (r) {
252 exit_child(info, &left);
253 return r;
254 }
255
256 __rebalance2(info, parent, &left, &right);
257
258 exit_child(info, &left);
259 exit_child(info, &right);
260
261 return 0;
262 }
263
264
265
266
267
268
269 static void delete_center_node(struct dm_btree_info *info, struct btree_node *parent,
270 struct child *l, struct child *c, struct child *r,
271 struct btree_node *left, struct btree_node *center, struct btree_node *right,
272 uint32_t nr_left, uint32_t nr_center, uint32_t nr_right)
273 {
274 uint32_t max_entries = le32_to_cpu(left->header.max_entries);
275 unsigned shift = min(max_entries - nr_left, nr_center);
276
277 BUG_ON(nr_left + shift > max_entries);
278 node_copy(left, center, -shift);
279 left->header.nr_entries = cpu_to_le32(nr_left + shift);
280
281 if (shift != nr_center) {
282 shift = nr_center - shift;
283 BUG_ON((nr_right + shift) > max_entries);
284 node_shift(right, shift);
285 node_copy(center, right, shift);
286 right->header.nr_entries = cpu_to_le32(nr_right + shift);
287 }
288 *key_ptr(parent, r->index) = right->keys[0];
289
290 delete_at(parent, c->index);
291 r->index--;
292
293 dm_tm_dec(info->tm, dm_block_location(c->block));
294 __rebalance2(info, parent, l, r);
295 }
296
297
298
299
300 static void redistribute3(struct dm_btree_info *info, struct btree_node *parent,
301 struct child *l, struct child *c, struct child *r,
302 struct btree_node *left, struct btree_node *center, struct btree_node *right,
303 uint32_t nr_left, uint32_t nr_center, uint32_t nr_right)
304 {
305 int s;
306 uint32_t max_entries = le32_to_cpu(left->header.max_entries);
307 unsigned total = nr_left + nr_center + nr_right;
308 unsigned target_right = total / 3;
309 unsigned remainder = (target_right * 3) != total;
310 unsigned target_left = target_right + remainder;
311
312 BUG_ON(target_left > max_entries);
313 BUG_ON(target_right > max_entries);
314
315 if (nr_left < nr_right) {
316 s = nr_left - target_left;
317
318 if (s < 0 && nr_center < -s) {
319
320 shift(left, center, -nr_center);
321 s += nr_center;
322 shift(left, right, s);
323 nr_right += s;
324 } else
325 shift(left, center, s);
326
327 shift(center, right, target_right - nr_right);
328
329 } else {
330 s = target_right - nr_right;
331 if (s > 0 && nr_center < s) {
332
333 shift(center, right, nr_center);
334 s -= nr_center;
335 shift(left, right, s);
336 nr_left -= s;
337 } else
338 shift(center, right, s);
339
340 shift(left, center, nr_left - target_left);
341 }
342
343 *key_ptr(parent, c->index) = center->keys[0];
344 *key_ptr(parent, r->index) = right->keys[0];
345 }
346
347 static void __rebalance3(struct dm_btree_info *info, struct btree_node *parent,
348 struct child *l, struct child *c, struct child *r)
349 {
350 struct btree_node *left = l->n;
351 struct btree_node *center = c->n;
352 struct btree_node *right = r->n;
353
354 uint32_t nr_left = le32_to_cpu(left->header.nr_entries);
355 uint32_t nr_center = le32_to_cpu(center->header.nr_entries);
356 uint32_t nr_right = le32_to_cpu(right->header.nr_entries);
357
358 unsigned threshold = merge_threshold(left) * 4 + 1;
359
360 BUG_ON(left->header.max_entries != center->header.max_entries);
361 BUG_ON(center->header.max_entries != right->header.max_entries);
362
363 if ((nr_left + nr_center + nr_right) < threshold)
364 delete_center_node(info, parent, l, c, r, left, center, right,
365 nr_left, nr_center, nr_right);
366 else
367 redistribute3(info, parent, l, c, r, left, center, right,
368 nr_left, nr_center, nr_right);
369 }
370
371 static int rebalance3(struct shadow_spine *s, struct dm_btree_info *info,
372 struct dm_btree_value_type *vt, unsigned left_index)
373 {
374 int r;
375 struct btree_node *parent = dm_block_data(shadow_current(s));
376 struct child left, center, right;
377
378
379
380
381 r = init_child(info, vt, parent, left_index, &left);
382 if (r)
383 return r;
384
385 r = init_child(info, vt, parent, left_index + 1, ¢er);
386 if (r) {
387 exit_child(info, &left);
388 return r;
389 }
390
391 r = init_child(info, vt, parent, left_index + 2, &right);
392 if (r) {
393 exit_child(info, &left);
394 exit_child(info, ¢er);
395 return r;
396 }
397
398 __rebalance3(info, parent, &left, ¢er, &right);
399
400 exit_child(info, &left);
401 exit_child(info, ¢er);
402 exit_child(info, &right);
403
404 return 0;
405 }
406
407 static int rebalance_children(struct shadow_spine *s,
408 struct dm_btree_info *info,
409 struct dm_btree_value_type *vt, uint64_t key)
410 {
411 int i, r, has_left_sibling, has_right_sibling;
412 struct btree_node *n;
413
414 n = dm_block_data(shadow_current(s));
415
416 if (le32_to_cpu(n->header.nr_entries) == 1) {
417 struct dm_block *child;
418 dm_block_t b = value64(n, 0);
419
420 r = dm_tm_read_lock(info->tm, b, &btree_node_validator, &child);
421 if (r)
422 return r;
423
424 memcpy(n, dm_block_data(child),
425 dm_bm_block_size(dm_tm_get_bm(info->tm)));
426 dm_tm_unlock(info->tm, child);
427
428 dm_tm_dec(info->tm, dm_block_location(child));
429 return 0;
430 }
431
432 i = lower_bound(n, key);
433 if (i < 0)
434 return -ENODATA;
435
436 has_left_sibling = i > 0;
437 has_right_sibling = i < (le32_to_cpu(n->header.nr_entries) - 1);
438
439 if (!has_left_sibling)
440 r = rebalance2(s, info, vt, i);
441
442 else if (!has_right_sibling)
443 r = rebalance2(s, info, vt, i - 1);
444
445 else
446 r = rebalance3(s, info, vt, i - 1);
447
448 return r;
449 }
450
451 static int do_leaf(struct btree_node *n, uint64_t key, unsigned *index)
452 {
453 int i = lower_bound(n, key);
454
455 if ((i < 0) ||
456 (i >= le32_to_cpu(n->header.nr_entries)) ||
457 (le64_to_cpu(n->keys[i]) != key))
458 return -ENODATA;
459
460 *index = i;
461
462 return 0;
463 }
464
465
466
467
468
469 static int remove_raw(struct shadow_spine *s, struct dm_btree_info *info,
470 struct dm_btree_value_type *vt, dm_block_t root,
471 uint64_t key, unsigned *index)
472 {
473 int i = *index, r;
474 struct btree_node *n;
475
476 for (;;) {
477 r = shadow_step(s, root, vt);
478 if (r < 0)
479 break;
480
481
482
483
484
485
486 if (shadow_has_parent(s)) {
487 __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
488 memcpy(value_ptr(dm_block_data(shadow_parent(s)), i),
489 &location, sizeof(__le64));
490 }
491
492 n = dm_block_data(shadow_current(s));
493
494 if (le32_to_cpu(n->header.flags) & LEAF_NODE)
495 return do_leaf(n, key, index);
496
497 r = rebalance_children(s, info, vt, key);
498 if (r)
499 break;
500
501 n = dm_block_data(shadow_current(s));
502 if (le32_to_cpu(n->header.flags) & LEAF_NODE)
503 return do_leaf(n, key, index);
504
505 i = lower_bound(n, key);
506
507
508
509
510
511
512 root = value64(n, i);
513 }
514
515 return r;
516 }
517
518 int dm_btree_remove(struct dm_btree_info *info, dm_block_t root,
519 uint64_t *keys, dm_block_t *new_root)
520 {
521 unsigned level, last_level = info->levels - 1;
522 int index = 0, r = 0;
523 struct shadow_spine spine;
524 struct btree_node *n;
525 struct dm_btree_value_type le64_vt;
526
527 init_le64_type(info->tm, &le64_vt);
528 init_shadow_spine(&spine, info);
529 for (level = 0; level < info->levels; level++) {
530 r = remove_raw(&spine, info,
531 (level == last_level ?
532 &info->value_type : &le64_vt),
533 root, keys[level], (unsigned *)&index);
534 if (r < 0)
535 break;
536
537 n = dm_block_data(shadow_current(&spine));
538 if (level != last_level) {
539 root = value64(n, index);
540 continue;
541 }
542
543 BUG_ON(index < 0 || index >= le32_to_cpu(n->header.nr_entries));
544
545 if (info->value_type.dec)
546 info->value_type.dec(info->value_type.context,
547 value_ptr(n, index));
548
549 delete_at(n, index);
550 }
551
552 *new_root = shadow_root(&spine);
553 exit_shadow_spine(&spine);
554
555 return r;
556 }
557 EXPORT_SYMBOL_GPL(dm_btree_remove);
558
559
560
561 static int remove_nearest(struct shadow_spine *s, struct dm_btree_info *info,
562 struct dm_btree_value_type *vt, dm_block_t root,
563 uint64_t key, int *index)
564 {
565 int i = *index, r;
566 struct btree_node *n;
567
568 for (;;) {
569 r = shadow_step(s, root, vt);
570 if (r < 0)
571 break;
572
573
574
575
576
577
578 if (shadow_has_parent(s)) {
579 __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
580 memcpy(value_ptr(dm_block_data(shadow_parent(s)), i),
581 &location, sizeof(__le64));
582 }
583
584 n = dm_block_data(shadow_current(s));
585
586 if (le32_to_cpu(n->header.flags) & LEAF_NODE) {
587 *index = lower_bound(n, key);
588 return 0;
589 }
590
591 r = rebalance_children(s, info, vt, key);
592 if (r)
593 break;
594
595 n = dm_block_data(shadow_current(s));
596 if (le32_to_cpu(n->header.flags) & LEAF_NODE) {
597 *index = lower_bound(n, key);
598 return 0;
599 }
600
601 i = lower_bound(n, key);
602
603
604
605
606
607
608 root = value64(n, i);
609 }
610
611 return r;
612 }
613
614 static int remove_one(struct dm_btree_info *info, dm_block_t root,
615 uint64_t *keys, uint64_t end_key,
616 dm_block_t *new_root, unsigned *nr_removed)
617 {
618 unsigned level, last_level = info->levels - 1;
619 int index = 0, r = 0;
620 struct shadow_spine spine;
621 struct btree_node *n;
622 struct dm_btree_value_type le64_vt;
623 uint64_t k;
624
625 init_le64_type(info->tm, &le64_vt);
626 init_shadow_spine(&spine, info);
627 for (level = 0; level < last_level; level++) {
628 r = remove_raw(&spine, info, &le64_vt,
629 root, keys[level], (unsigned *) &index);
630 if (r < 0)
631 goto out;
632
633 n = dm_block_data(shadow_current(&spine));
634 root = value64(n, index);
635 }
636
637 r = remove_nearest(&spine, info, &info->value_type,
638 root, keys[last_level], &index);
639 if (r < 0)
640 goto out;
641
642 n = dm_block_data(shadow_current(&spine));
643
644 if (index < 0)
645 index = 0;
646
647 if (index >= le32_to_cpu(n->header.nr_entries)) {
648 r = -ENODATA;
649 goto out;
650 }
651
652 k = le64_to_cpu(n->keys[index]);
653 if (k >= keys[last_level] && k < end_key) {
654 if (info->value_type.dec)
655 info->value_type.dec(info->value_type.context,
656 value_ptr(n, index));
657
658 delete_at(n, index);
659 keys[last_level] = k + 1ull;
660
661 } else
662 r = -ENODATA;
663
664 out:
665 *new_root = shadow_root(&spine);
666 exit_shadow_spine(&spine);
667
668 return r;
669 }
670
671 int dm_btree_remove_leaves(struct dm_btree_info *info, dm_block_t root,
672 uint64_t *first_key, uint64_t end_key,
673 dm_block_t *new_root, unsigned *nr_removed)
674 {
675 int r;
676
677 *nr_removed = 0;
678 do {
679 r = remove_one(info, root, first_key, end_key, &root, nr_removed);
680 if (!r)
681 (*nr_removed)++;
682 } while (!r);
683
684 *new_root = root;
685 return r == -ENODATA ? 0 : r;
686 }
687 EXPORT_SYMBOL_GPL(dm_btree_remove_leaves);