1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright (C) 2011 Red Hat, Inc. |
4 | * |
5 | * This file is released under the GPL. |
6 | */ |
7 | |
8 | #include "dm-btree.h" |
9 | #include "dm-btree-internal.h" |
10 | #include "dm-transaction-manager.h" |
11 | |
12 | #include <linux/export.h> |
13 | #include <linux/device-mapper.h> |
14 | |
15 | #define DM_MSG_PREFIX "btree" |
16 | |
17 | /* |
18 | * Removing an entry from a btree |
19 | * ============================== |
20 | * |
21 | * A very important constraint for our btree is that no node, except the |
22 | * root, may have fewer than a certain number of entries. |
23 | * (MIN_ENTRIES <= nr_entries <= MAX_ENTRIES). |
24 | * |
25 | * Ensuring this is complicated by the way we want to only ever hold the |
26 | * locks on 2 nodes concurrently, and only change nodes in a top to bottom |
27 | * fashion. |
28 | * |
29 | * Each node may have a left or right sibling. When decending the spine, |
30 | * if a node contains only MIN_ENTRIES then we try and increase this to at |
31 | * least MIN_ENTRIES + 1. We do this in the following ways: |
32 | * |
33 | * [A] No siblings => this can only happen if the node is the root, in which |
34 | * case we copy the childs contents over the root. |
35 | * |
36 | * [B] No left sibling |
37 | * ==> rebalance(node, right sibling) |
38 | * |
39 | * [C] No right sibling |
40 | * ==> rebalance(left sibling, node) |
41 | * |
42 | * [D] Both siblings, total_entries(left, node, right) <= DEL_THRESHOLD |
43 | * ==> delete node adding it's contents to left and right |
44 | * |
45 | * [E] Both siblings, total_entries(left, node, right) > DEL_THRESHOLD |
46 | * ==> rebalance(left, node, right) |
47 | * |
48 | * After these operations it's possible that the our original node no |
49 | * longer contains the desired sub tree. For this reason this rebalancing |
50 | * is performed on the children of the current node. This also avoids |
51 | * having a special case for the root. |
52 | * |
53 | * Once this rebalancing has occurred we can then step into the child node |
54 | * for internal nodes. Or delete the entry for leaf nodes. |
55 | */ |
56 | |
57 | /* |
58 | * Some little utilities for moving node data around. |
59 | */ |
60 | static void node_shift(struct btree_node *n, int shift) |
61 | { |
62 | uint32_t nr_entries = le32_to_cpu(n->header.nr_entries); |
63 | uint32_t value_size = le32_to_cpu(n->header.value_size); |
64 | |
65 | if (shift < 0) { |
66 | shift = -shift; |
67 | BUG_ON(shift > nr_entries); |
68 | BUG_ON((void *) key_ptr(n, shift) >= value_ptr(n, shift)); |
69 | memmove(key_ptr(n, 0), |
70 | key_ptr(n, shift), |
71 | (nr_entries - shift) * sizeof(__le64)); |
72 | memmove(value_ptr(n, 0), |
73 | value_ptr(n, shift), |
74 | (nr_entries - shift) * value_size); |
75 | } else { |
76 | BUG_ON(nr_entries + shift > le32_to_cpu(n->header.max_entries)); |
77 | memmove(key_ptr(n, shift), |
78 | key_ptr(n, 0), |
79 | nr_entries * sizeof(__le64)); |
80 | memmove(value_ptr(n, shift), |
81 | value_ptr(n, 0), |
82 | nr_entries * value_size); |
83 | } |
84 | } |
85 | |
86 | static int node_copy(struct btree_node *left, struct btree_node *right, int shift) |
87 | { |
88 | uint32_t nr_left = le32_to_cpu(left->header.nr_entries); |
89 | uint32_t value_size = le32_to_cpu(left->header.value_size); |
90 | |
91 | if (value_size != le32_to_cpu(right->header.value_size)) { |
92 | DMERR("mismatched value size" ); |
93 | return -EILSEQ; |
94 | } |
95 | |
96 | if (shift < 0) { |
97 | shift = -shift; |
98 | |
99 | if (nr_left + shift > le32_to_cpu(left->header.max_entries)) { |
100 | DMERR("bad shift" ); |
101 | return -EINVAL; |
102 | } |
103 | |
104 | memcpy(key_ptr(left, nr_left), |
105 | key_ptr(right, 0), |
106 | shift * sizeof(__le64)); |
107 | memcpy(value_ptr(left, nr_left), |
108 | value_ptr(right, 0), |
109 | shift * value_size); |
110 | } else { |
111 | if (shift > le32_to_cpu(right->header.max_entries)) { |
112 | DMERR("bad shift" ); |
113 | return -EINVAL; |
114 | } |
115 | |
116 | memcpy(key_ptr(right, 0), |
117 | key_ptr(left, nr_left - shift), |
118 | shift * sizeof(__le64)); |
119 | memcpy(value_ptr(right, 0), |
120 | value_ptr(left, nr_left - shift), |
121 | shift * value_size); |
122 | } |
123 | return 0; |
124 | } |
125 | |
126 | /* |
127 | * Delete a specific entry from a leaf node. |
128 | */ |
129 | static void delete_at(struct btree_node *n, unsigned int index) |
130 | { |
131 | unsigned int nr_entries = le32_to_cpu(n->header.nr_entries); |
132 | unsigned int nr_to_copy = nr_entries - (index + 1); |
133 | uint32_t value_size = le32_to_cpu(n->header.value_size); |
134 | |
135 | BUG_ON(index >= nr_entries); |
136 | |
137 | if (nr_to_copy) { |
138 | memmove(key_ptr(n, index), |
139 | key_ptr(n, index + 1), |
140 | nr_to_copy * sizeof(__le64)); |
141 | |
142 | memmove(value_ptr(n, index), |
143 | value_ptr(n, index + 1), |
144 | nr_to_copy * value_size); |
145 | } |
146 | |
147 | n->header.nr_entries = cpu_to_le32(nr_entries - 1); |
148 | } |
149 | |
150 | static unsigned int merge_threshold(struct btree_node *n) |
151 | { |
152 | return le32_to_cpu(n->header.max_entries) / 3; |
153 | } |
154 | |
155 | struct child { |
156 | unsigned int index; |
157 | struct dm_block *block; |
158 | struct btree_node *n; |
159 | }; |
160 | |
161 | static int init_child(struct dm_btree_info *info, struct dm_btree_value_type *vt, |
162 | struct btree_node *parent, |
163 | unsigned int index, struct child *result) |
164 | { |
165 | int r, inc; |
166 | dm_block_t root; |
167 | |
168 | result->index = index; |
169 | root = value64(n: parent, index); |
170 | |
171 | r = dm_tm_shadow_block(tm: info->tm, orig: root, v: &btree_node_validator, |
172 | result: &result->block, inc_children: &inc); |
173 | if (r) |
174 | return r; |
175 | |
176 | result->n = dm_block_data(b: result->block); |
177 | |
178 | if (inc) |
179 | inc_children(tm: info->tm, n: result->n, vt); |
180 | |
181 | *((__le64 *) value_ptr(n: parent, index)) = |
182 | cpu_to_le64(dm_block_location(result->block)); |
183 | |
184 | return 0; |
185 | } |
186 | |
187 | static void exit_child(struct dm_btree_info *info, struct child *c) |
188 | { |
189 | dm_tm_unlock(tm: info->tm, b: c->block); |
190 | } |
191 | |
192 | static int shift(struct btree_node *left, struct btree_node *right, int count) |
193 | { |
194 | int r; |
195 | uint32_t nr_left = le32_to_cpu(left->header.nr_entries); |
196 | uint32_t nr_right = le32_to_cpu(right->header.nr_entries); |
197 | uint32_t max_entries = le32_to_cpu(left->header.max_entries); |
198 | uint32_t r_max_entries = le32_to_cpu(right->header.max_entries); |
199 | |
200 | if (max_entries != r_max_entries) { |
201 | DMERR("node max_entries mismatch" ); |
202 | return -EILSEQ; |
203 | } |
204 | |
205 | if (nr_left - count > max_entries) { |
206 | DMERR("node shift out of bounds" ); |
207 | return -EINVAL; |
208 | } |
209 | |
210 | if (nr_right + count > max_entries) { |
211 | DMERR("node shift out of bounds" ); |
212 | return -EINVAL; |
213 | } |
214 | |
215 | if (!count) |
216 | return 0; |
217 | |
218 | if (count > 0) { |
219 | node_shift(n: right, shift: count); |
220 | r = node_copy(left, right, shift: count); |
221 | if (r) |
222 | return r; |
223 | } else { |
224 | r = node_copy(left, right, shift: count); |
225 | if (r) |
226 | return r; |
227 | node_shift(n: right, shift: count); |
228 | } |
229 | |
230 | left->header.nr_entries = cpu_to_le32(nr_left - count); |
231 | right->header.nr_entries = cpu_to_le32(nr_right + count); |
232 | |
233 | return 0; |
234 | } |
235 | |
236 | static int __rebalance2(struct dm_btree_info *info, struct btree_node *parent, |
237 | struct child *l, struct child *r) |
238 | { |
239 | int ret; |
240 | struct btree_node *left = l->n; |
241 | struct btree_node *right = r->n; |
242 | uint32_t nr_left = le32_to_cpu(left->header.nr_entries); |
243 | uint32_t nr_right = le32_to_cpu(right->header.nr_entries); |
244 | /* |
245 | * Ensure the number of entries in each child will be greater |
246 | * than or equal to (max_entries / 3 + 1), so no matter which |
247 | * child is used for removal, the number will still be not |
248 | * less than (max_entries / 3). |
249 | */ |
250 | unsigned int threshold = 2 * (merge_threshold(n: left) + 1); |
251 | |
252 | if (nr_left + nr_right < threshold) { |
253 | /* |
254 | * Merge |
255 | */ |
256 | node_copy(left, right, shift: -nr_right); |
257 | left->header.nr_entries = cpu_to_le32(nr_left + nr_right); |
258 | delete_at(n: parent, index: r->index); |
259 | |
260 | /* |
261 | * We need to decrement the right block, but not it's |
262 | * children, since they're still referenced by left. |
263 | */ |
264 | dm_tm_dec(tm: info->tm, b: dm_block_location(b: r->block)); |
265 | } else { |
266 | /* |
267 | * Rebalance. |
268 | */ |
269 | unsigned int target_left = (nr_left + nr_right) / 2; |
270 | |
271 | ret = shift(left, right, count: nr_left - target_left); |
272 | if (ret) |
273 | return ret; |
274 | *key_ptr(n: parent, index: r->index) = right->keys[0]; |
275 | } |
276 | return 0; |
277 | } |
278 | |
279 | static int rebalance2(struct shadow_spine *s, struct dm_btree_info *info, |
280 | struct dm_btree_value_type *vt, unsigned int left_index) |
281 | { |
282 | int r; |
283 | struct btree_node *parent; |
284 | struct child left, right; |
285 | |
286 | parent = dm_block_data(b: shadow_current(s)); |
287 | |
288 | r = init_child(info, vt, parent, index: left_index, result: &left); |
289 | if (r) |
290 | return r; |
291 | |
292 | r = init_child(info, vt, parent, index: left_index + 1, result: &right); |
293 | if (r) { |
294 | exit_child(info, c: &left); |
295 | return r; |
296 | } |
297 | |
298 | r = __rebalance2(info, parent, l: &left, r: &right); |
299 | |
300 | exit_child(info, c: &left); |
301 | exit_child(info, c: &right); |
302 | |
303 | return r; |
304 | } |
305 | |
306 | /* |
307 | * We dump as many entries from center as possible into left, then the rest |
308 | * in right, then rebalance2. This wastes some cpu, but I want something |
309 | * simple atm. |
310 | */ |
311 | static int delete_center_node(struct dm_btree_info *info, struct btree_node *parent, |
312 | struct child *l, struct child *c, struct child *r, |
313 | struct btree_node *left, struct btree_node *center, struct btree_node *right, |
314 | uint32_t nr_left, uint32_t nr_center, uint32_t nr_right) |
315 | { |
316 | uint32_t max_entries = le32_to_cpu(left->header.max_entries); |
317 | unsigned int shift = min(max_entries - nr_left, nr_center); |
318 | |
319 | if (nr_left + shift > max_entries) { |
320 | DMERR("node shift out of bounds" ); |
321 | return -EINVAL; |
322 | } |
323 | |
324 | node_copy(left, right: center, shift: -shift); |
325 | left->header.nr_entries = cpu_to_le32(nr_left + shift); |
326 | |
327 | if (shift != nr_center) { |
328 | shift = nr_center - shift; |
329 | |
330 | if ((nr_right + shift) > max_entries) { |
331 | DMERR("node shift out of bounds" ); |
332 | return -EINVAL; |
333 | } |
334 | |
335 | node_shift(n: right, shift); |
336 | node_copy(left: center, right, shift); |
337 | right->header.nr_entries = cpu_to_le32(nr_right + shift); |
338 | } |
339 | *key_ptr(n: parent, index: r->index) = right->keys[0]; |
340 | |
341 | delete_at(n: parent, index: c->index); |
342 | r->index--; |
343 | |
344 | dm_tm_dec(tm: info->tm, b: dm_block_location(b: c->block)); |
345 | return __rebalance2(info, parent, l, r); |
346 | } |
347 | |
348 | /* |
349 | * Redistributes entries among 3 sibling nodes. |
350 | */ |
351 | static int redistribute3(struct dm_btree_info *info, struct btree_node *parent, |
352 | struct child *l, struct child *c, struct child *r, |
353 | struct btree_node *left, struct btree_node *center, struct btree_node *right, |
354 | uint32_t nr_left, uint32_t nr_center, uint32_t nr_right) |
355 | { |
356 | int s, ret; |
357 | uint32_t max_entries = le32_to_cpu(left->header.max_entries); |
358 | unsigned int total = nr_left + nr_center + nr_right; |
359 | unsigned int target_right = total / 3; |
360 | unsigned int remainder = (target_right * 3) != total; |
361 | unsigned int target_left = target_right + remainder; |
362 | |
363 | BUG_ON(target_left > max_entries); |
364 | BUG_ON(target_right > max_entries); |
365 | |
366 | if (nr_left < nr_right) { |
367 | s = nr_left - target_left; |
368 | |
369 | if (s < 0 && nr_center < -s) { |
370 | /* not enough in central node */ |
371 | ret = shift(left, right: center, count: -nr_center); |
372 | if (ret) |
373 | return ret; |
374 | |
375 | s += nr_center; |
376 | ret = shift(left, right, count: s); |
377 | if (ret) |
378 | return ret; |
379 | |
380 | nr_right += s; |
381 | } else { |
382 | ret = shift(left, right: center, count: s); |
383 | if (ret) |
384 | return ret; |
385 | } |
386 | |
387 | ret = shift(left: center, right, count: target_right - nr_right); |
388 | if (ret) |
389 | return ret; |
390 | } else { |
391 | s = target_right - nr_right; |
392 | if (s > 0 && nr_center < s) { |
393 | /* not enough in central node */ |
394 | ret = shift(left: center, right, count: nr_center); |
395 | if (ret) |
396 | return ret; |
397 | s -= nr_center; |
398 | ret = shift(left, right, count: s); |
399 | if (ret) |
400 | return ret; |
401 | nr_left -= s; |
402 | } else { |
403 | ret = shift(left: center, right, count: s); |
404 | if (ret) |
405 | return ret; |
406 | } |
407 | |
408 | ret = shift(left, right: center, count: nr_left - target_left); |
409 | if (ret) |
410 | return ret; |
411 | } |
412 | |
413 | *key_ptr(n: parent, index: c->index) = center->keys[0]; |
414 | *key_ptr(n: parent, index: r->index) = right->keys[0]; |
415 | return 0; |
416 | } |
417 | |
418 | static int __rebalance3(struct dm_btree_info *info, struct btree_node *parent, |
419 | struct child *l, struct child *c, struct child *r) |
420 | { |
421 | struct btree_node *left = l->n; |
422 | struct btree_node *center = c->n; |
423 | struct btree_node *right = r->n; |
424 | |
425 | uint32_t nr_left = le32_to_cpu(left->header.nr_entries); |
426 | uint32_t nr_center = le32_to_cpu(center->header.nr_entries); |
427 | uint32_t nr_right = le32_to_cpu(right->header.nr_entries); |
428 | |
429 | unsigned int threshold = merge_threshold(n: left) * 4 + 1; |
430 | |
431 | if ((left->header.max_entries != center->header.max_entries) || |
432 | (center->header.max_entries != right->header.max_entries)) { |
433 | DMERR("bad btree metadata, max_entries differ" ); |
434 | return -EILSEQ; |
435 | } |
436 | |
437 | if ((nr_left + nr_center + nr_right) < threshold) { |
438 | return delete_center_node(info, parent, l, c, r, left, center, right, |
439 | nr_left, nr_center, nr_right); |
440 | } |
441 | |
442 | return redistribute3(info, parent, l, c, r, left, center, right, |
443 | nr_left, nr_center, nr_right); |
444 | } |
445 | |
446 | static int rebalance3(struct shadow_spine *s, struct dm_btree_info *info, |
447 | struct dm_btree_value_type *vt, unsigned int left_index) |
448 | { |
449 | int r; |
450 | struct btree_node *parent = dm_block_data(b: shadow_current(s)); |
451 | struct child left, center, right; |
452 | |
453 | /* |
454 | * FIXME: fill out an array? |
455 | */ |
456 | r = init_child(info, vt, parent, index: left_index, result: &left); |
457 | if (r) |
458 | return r; |
459 | |
460 | r = init_child(info, vt, parent, index: left_index + 1, result: ¢er); |
461 | if (r) { |
462 | exit_child(info, c: &left); |
463 | return r; |
464 | } |
465 | |
466 | r = init_child(info, vt, parent, index: left_index + 2, result: &right); |
467 | if (r) { |
468 | exit_child(info, c: &left); |
469 | exit_child(info, c: ¢er); |
470 | return r; |
471 | } |
472 | |
473 | r = __rebalance3(info, parent, l: &left, c: ¢er, r: &right); |
474 | |
475 | exit_child(info, c: &left); |
476 | exit_child(info, c: ¢er); |
477 | exit_child(info, c: &right); |
478 | |
479 | return r; |
480 | } |
481 | |
482 | static int rebalance_children(struct shadow_spine *s, |
483 | struct dm_btree_info *info, |
484 | struct dm_btree_value_type *vt, uint64_t key) |
485 | { |
486 | int i, r, has_left_sibling, has_right_sibling; |
487 | struct btree_node *n; |
488 | |
489 | n = dm_block_data(b: shadow_current(s)); |
490 | |
491 | if (le32_to_cpu(n->header.nr_entries) == 1) { |
492 | struct dm_block *child; |
493 | dm_block_t b = value64(n, index: 0); |
494 | |
495 | r = dm_tm_read_lock(tm: info->tm, b, v: &btree_node_validator, result: &child); |
496 | if (r) |
497 | return r; |
498 | |
499 | memcpy(n, dm_block_data(child), |
500 | dm_bm_block_size(dm_tm_get_bm(info->tm))); |
501 | |
502 | dm_tm_dec(tm: info->tm, b: dm_block_location(b: child)); |
503 | dm_tm_unlock(tm: info->tm, b: child); |
504 | return 0; |
505 | } |
506 | |
507 | i = lower_bound(n, key); |
508 | if (i < 0) |
509 | return -ENODATA; |
510 | |
511 | has_left_sibling = i > 0; |
512 | has_right_sibling = i < (le32_to_cpu(n->header.nr_entries) - 1); |
513 | |
514 | if (!has_left_sibling) |
515 | r = rebalance2(s, info, vt, left_index: i); |
516 | |
517 | else if (!has_right_sibling) |
518 | r = rebalance2(s, info, vt, left_index: i - 1); |
519 | |
520 | else |
521 | r = rebalance3(s, info, vt, left_index: i - 1); |
522 | |
523 | return r; |
524 | } |
525 | |
526 | static int do_leaf(struct btree_node *n, uint64_t key, unsigned int *index) |
527 | { |
528 | int i = lower_bound(n, key); |
529 | |
530 | if ((i < 0) || |
531 | (i >= le32_to_cpu(n->header.nr_entries)) || |
532 | (le64_to_cpu(n->keys[i]) != key)) |
533 | return -ENODATA; |
534 | |
535 | *index = i; |
536 | |
537 | return 0; |
538 | } |
539 | |
540 | /* |
541 | * Prepares for removal from one level of the hierarchy. The caller must |
542 | * call delete_at() to remove the entry at index. |
543 | */ |
544 | static int remove_raw(struct shadow_spine *s, struct dm_btree_info *info, |
545 | struct dm_btree_value_type *vt, dm_block_t root, |
546 | uint64_t key, unsigned int *index) |
547 | { |
548 | int i = *index, r; |
549 | struct btree_node *n; |
550 | |
551 | for (;;) { |
552 | r = shadow_step(s, b: root, vt); |
553 | if (r < 0) |
554 | break; |
555 | |
556 | /* |
557 | * We have to patch up the parent node, ugly, but I don't |
558 | * see a way to do this automatically as part of the spine |
559 | * op. |
560 | */ |
561 | if (shadow_has_parent(s)) { |
562 | __le64 location = cpu_to_le64(dm_block_location(shadow_current(s))); |
563 | |
564 | memcpy(value_ptr(dm_block_data(shadow_parent(s)), i), |
565 | &location, sizeof(__le64)); |
566 | } |
567 | |
568 | n = dm_block_data(b: shadow_current(s)); |
569 | |
570 | if (le32_to_cpu(n->header.flags) & LEAF_NODE) |
571 | return do_leaf(n, key, index); |
572 | |
573 | r = rebalance_children(s, info, vt, key); |
574 | if (r) |
575 | break; |
576 | |
577 | n = dm_block_data(b: shadow_current(s)); |
578 | if (le32_to_cpu(n->header.flags) & LEAF_NODE) |
579 | return do_leaf(n, key, index); |
580 | |
581 | i = lower_bound(n, key); |
582 | |
583 | /* |
584 | * We know the key is present, or else |
585 | * rebalance_children would have returned |
586 | * -ENODATA |
587 | */ |
588 | root = value64(n, index: i); |
589 | } |
590 | |
591 | return r; |
592 | } |
593 | |
594 | int dm_btree_remove(struct dm_btree_info *info, dm_block_t root, |
595 | uint64_t *keys, dm_block_t *new_root) |
596 | { |
597 | unsigned int level, last_level = info->levels - 1; |
598 | int index = 0, r = 0; |
599 | struct shadow_spine spine; |
600 | struct btree_node *n; |
601 | struct dm_btree_value_type le64_vt; |
602 | |
603 | init_le64_type(tm: info->tm, vt: &le64_vt); |
604 | init_shadow_spine(s: &spine, info); |
605 | for (level = 0; level < info->levels; level++) { |
606 | r = remove_raw(s: &spine, info, |
607 | vt: (level == last_level ? |
608 | &info->value_type : &le64_vt), |
609 | root, key: keys[level], index: (unsigned int *)&index); |
610 | if (r < 0) |
611 | break; |
612 | |
613 | n = dm_block_data(b: shadow_current(s: &spine)); |
614 | if (level != last_level) { |
615 | root = value64(n, index); |
616 | continue; |
617 | } |
618 | |
619 | BUG_ON(index < 0 || index >= le32_to_cpu(n->header.nr_entries)); |
620 | |
621 | if (info->value_type.dec) |
622 | info->value_type.dec(info->value_type.context, |
623 | value_ptr(n, index), 1); |
624 | |
625 | delete_at(n, index); |
626 | } |
627 | |
628 | if (!r) |
629 | *new_root = shadow_root(s: &spine); |
630 | exit_shadow_spine(s: &spine); |
631 | |
632 | return r; |
633 | } |
634 | EXPORT_SYMBOL_GPL(dm_btree_remove); |
635 | |
636 | /*----------------------------------------------------------------*/ |
637 | |
638 | static int remove_nearest(struct shadow_spine *s, struct dm_btree_info *info, |
639 | struct dm_btree_value_type *vt, dm_block_t root, |
640 | uint64_t key, int *index) |
641 | { |
642 | int i = *index, r; |
643 | struct btree_node *n; |
644 | |
645 | for (;;) { |
646 | r = shadow_step(s, b: root, vt); |
647 | if (r < 0) |
648 | break; |
649 | |
650 | /* |
651 | * We have to patch up the parent node, ugly, but I don't |
652 | * see a way to do this automatically as part of the spine |
653 | * op. |
654 | */ |
655 | if (shadow_has_parent(s)) { |
656 | __le64 location = cpu_to_le64(dm_block_location(shadow_current(s))); |
657 | |
658 | memcpy(value_ptr(dm_block_data(shadow_parent(s)), i), |
659 | &location, sizeof(__le64)); |
660 | } |
661 | |
662 | n = dm_block_data(b: shadow_current(s)); |
663 | |
664 | if (le32_to_cpu(n->header.flags) & LEAF_NODE) { |
665 | *index = lower_bound(n, key); |
666 | return 0; |
667 | } |
668 | |
669 | r = rebalance_children(s, info, vt, key); |
670 | if (r) |
671 | break; |
672 | |
673 | n = dm_block_data(b: shadow_current(s)); |
674 | if (le32_to_cpu(n->header.flags) & LEAF_NODE) { |
675 | *index = lower_bound(n, key); |
676 | return 0; |
677 | } |
678 | |
679 | i = lower_bound(n, key); |
680 | |
681 | /* |
682 | * We know the key is present, or else |
683 | * rebalance_children would have returned |
684 | * -ENODATA |
685 | */ |
686 | root = value64(n, index: i); |
687 | } |
688 | |
689 | return r; |
690 | } |
691 | |
692 | static int remove_one(struct dm_btree_info *info, dm_block_t root, |
693 | uint64_t *keys, uint64_t end_key, |
694 | dm_block_t *new_root, unsigned int *nr_removed) |
695 | { |
696 | unsigned int level, last_level = info->levels - 1; |
697 | int index = 0, r = 0; |
698 | struct shadow_spine spine; |
699 | struct btree_node *n; |
700 | struct dm_btree_value_type le64_vt; |
701 | uint64_t k; |
702 | |
703 | init_le64_type(tm: info->tm, vt: &le64_vt); |
704 | init_shadow_spine(s: &spine, info); |
705 | for (level = 0; level < last_level; level++) { |
706 | r = remove_raw(s: &spine, info, vt: &le64_vt, |
707 | root, key: keys[level], index: (unsigned int *) &index); |
708 | if (r < 0) |
709 | goto out; |
710 | |
711 | n = dm_block_data(b: shadow_current(s: &spine)); |
712 | root = value64(n, index); |
713 | } |
714 | |
715 | r = remove_nearest(s: &spine, info, vt: &info->value_type, |
716 | root, key: keys[last_level], index: &index); |
717 | if (r < 0) |
718 | goto out; |
719 | |
720 | n = dm_block_data(b: shadow_current(s: &spine)); |
721 | |
722 | if (index < 0) |
723 | index = 0; |
724 | |
725 | if (index >= le32_to_cpu(n->header.nr_entries)) { |
726 | r = -ENODATA; |
727 | goto out; |
728 | } |
729 | |
730 | k = le64_to_cpu(n->keys[index]); |
731 | if (k >= keys[last_level] && k < end_key) { |
732 | if (info->value_type.dec) |
733 | info->value_type.dec(info->value_type.context, |
734 | value_ptr(n, index), 1); |
735 | |
736 | delete_at(n, index); |
737 | keys[last_level] = k + 1ull; |
738 | |
739 | } else |
740 | r = -ENODATA; |
741 | |
742 | out: |
743 | *new_root = shadow_root(s: &spine); |
744 | exit_shadow_spine(s: &spine); |
745 | |
746 | return r; |
747 | } |
748 | |
749 | int dm_btree_remove_leaves(struct dm_btree_info *info, dm_block_t root, |
750 | uint64_t *first_key, uint64_t end_key, |
751 | dm_block_t *new_root, unsigned int *nr_removed) |
752 | { |
753 | int r; |
754 | |
755 | *nr_removed = 0; |
756 | do { |
757 | r = remove_one(info, root, keys: first_key, end_key, new_root: &root, nr_removed); |
758 | if (!r) |
759 | (*nr_removed)++; |
760 | } while (!r); |
761 | |
762 | *new_root = root; |
763 | return r == -ENODATA ? 0 : r; |
764 | } |
765 | EXPORT_SYMBOL_GPL(dm_btree_remove_leaves); |
766 | |