Commit | Line | Data |
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3241b1d3 JT |
1 | /* |
2 | * Copyright (C) 2011 Red Hat, Inc. | |
3 | * | |
4 | * This file is released under the GPL. | |
5 | */ | |
6 | ||
7 | #include "dm-btree.h" | |
8 | #include "dm-btree-internal.h" | |
9 | #include "dm-transaction-manager.h" | |
10 | ||
1944ce60 | 11 | #include <linux/export.h> |
3241b1d3 JT |
12 | |
13 | /* | |
14 | * Removing an entry from a btree | |
15 | * ============================== | |
16 | * | |
17 | * A very important constraint for our btree is that no node, except the | |
18 | * root, may have fewer than a certain number of entries. | |
19 | * (MIN_ENTRIES <= nr_entries <= MAX_ENTRIES). | |
20 | * | |
21 | * Ensuring this is complicated by the way we want to only ever hold the | |
22 | * locks on 2 nodes concurrently, and only change nodes in a top to bottom | |
23 | * fashion. | |
24 | * | |
25 | * Each node may have a left or right sibling. When decending the spine, | |
26 | * if a node contains only MIN_ENTRIES then we try and increase this to at | |
27 | * least MIN_ENTRIES + 1. We do this in the following ways: | |
28 | * | |
29 | * [A] No siblings => this can only happen if the node is the root, in which | |
30 | * case we copy the childs contents over the root. | |
31 | * | |
32 | * [B] No left sibling | |
33 | * ==> rebalance(node, right sibling) | |
34 | * | |
35 | * [C] No right sibling | |
36 | * ==> rebalance(left sibling, node) | |
37 | * | |
38 | * [D] Both siblings, total_entries(left, node, right) <= DEL_THRESHOLD | |
39 | * ==> delete node adding it's contents to left and right | |
40 | * | |
41 | * [E] Both siblings, total_entries(left, node, right) > DEL_THRESHOLD | |
42 | * ==> rebalance(left, node, right) | |
43 | * | |
44 | * After these operations it's possible that the our original node no | |
45 | * longer contains the desired sub tree. For this reason this rebalancing | |
46 | * is performed on the children of the current node. This also avoids | |
47 | * having a special case for the root. | |
48 | * | |
49 | * Once this rebalancing has occurred we can then step into the child node | |
50 | * for internal nodes. Or delete the entry for leaf nodes. | |
51 | */ | |
52 | ||
53 | /* | |
54 | * Some little utilities for moving node data around. | |
55 | */ | |
550929fa | 56 | static void node_shift(struct btree_node *n, int shift) |
3241b1d3 JT |
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); | |
a3aefb39 | 64 | BUG_ON((void *) key_ptr(n, shift) >= value_ptr(n, shift)); |
3241b1d3 JT |
65 | memmove(key_ptr(n, 0), |
66 | key_ptr(n, shift), | |
67 | (nr_entries - shift) * sizeof(__le64)); | |
a3aefb39 JT |
68 | memmove(value_ptr(n, 0), |
69 | value_ptr(n, shift), | |
3241b1d3 JT |
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)); | |
a3aefb39 JT |
76 | memmove(value_ptr(n, shift), |
77 | value_ptr(n, 0), | |
3241b1d3 JT |
78 | nr_entries * value_size); |
79 | } | |
80 | } | |
81 | ||
550929fa | 82 | static void node_copy(struct btree_node *left, struct btree_node *right, int shift) |
3241b1d3 JT |
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)); | |
a3aefb39 JT |
94 | memcpy(value_ptr(left, nr_left), |
95 | value_ptr(right, 0), | |
3241b1d3 JT |
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)); | |
a3aefb39 JT |
102 | memcpy(value_ptr(right, 0), |
103 | value_ptr(left, nr_left - shift), | |
3241b1d3 JT |
104 | shift * value_size); |
105 | } | |
106 | } | |
107 | ||
108 | /* | |
109 | * Delete a specific entry from a leaf node. | |
110 | */ | |
550929fa | 111 | static void delete_at(struct btree_node *n, unsigned index) |
3241b1d3 JT |
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 | ||
a3aefb39 JT |
123 | memmove(value_ptr(n, index), |
124 | value_ptr(n, index + 1), | |
3241b1d3 JT |
125 | nr_to_copy * value_size); |
126 | } | |
127 | ||
128 | n->header.nr_entries = cpu_to_le32(nr_entries - 1); | |
129 | } | |
130 | ||
550929fa | 131 | static unsigned merge_threshold(struct btree_node *n) |
3241b1d3 | 132 | { |
b0988900 | 133 | return le32_to_cpu(n->header.max_entries) / 3; |
3241b1d3 JT |
134 | } |
135 | ||
136 | struct child { | |
137 | unsigned index; | |
138 | struct dm_block *block; | |
550929fa | 139 | struct btree_node *n; |
3241b1d3 JT |
140 | }; |
141 | ||
142 | static struct dm_btree_value_type le64_type = { | |
143 | .context = NULL, | |
144 | .size = sizeof(__le64), | |
145 | .inc = NULL, | |
146 | .dec = NULL, | |
147 | .equal = NULL | |
148 | }; | |
149 | ||
550929fa | 150 | static int init_child(struct dm_btree_info *info, struct btree_node *parent, |
3241b1d3 JT |
151 | unsigned index, struct child *result) |
152 | { | |
153 | int r, inc; | |
154 | dm_block_t root; | |
155 | ||
156 | result->index = index; | |
157 | root = value64(parent, index); | |
158 | ||
159 | r = dm_tm_shadow_block(info->tm, root, &btree_node_validator, | |
160 | &result->block, &inc); | |
161 | if (r) | |
162 | return r; | |
163 | ||
164 | result->n = dm_block_data(result->block); | |
165 | ||
166 | if (inc) | |
167 | inc_children(info->tm, result->n, &le64_type); | |
168 | ||
a3aefb39 | 169 | *((__le64 *) value_ptr(parent, index)) = |
3241b1d3 JT |
170 | cpu_to_le64(dm_block_location(result->block)); |
171 | ||
172 | return 0; | |
173 | } | |
174 | ||
175 | static int exit_child(struct dm_btree_info *info, struct child *c) | |
176 | { | |
177 | return dm_tm_unlock(info->tm, c->block); | |
178 | } | |
179 | ||
550929fa | 180 | static void shift(struct btree_node *left, struct btree_node *right, int count) |
3241b1d3 | 181 | { |
b0988900 JT |
182 | uint32_t nr_left = le32_to_cpu(left->header.nr_entries); |
183 | uint32_t nr_right = le32_to_cpu(right->header.nr_entries); | |
184 | uint32_t max_entries = le32_to_cpu(left->header.max_entries); | |
185 | uint32_t r_max_entries = le32_to_cpu(right->header.max_entries); | |
186 | ||
187 | BUG_ON(max_entries != r_max_entries); | |
188 | BUG_ON(nr_left - count > max_entries); | |
189 | BUG_ON(nr_right + count > max_entries); | |
190 | ||
3241b1d3 JT |
191 | if (!count) |
192 | return; | |
193 | ||
194 | if (count > 0) { | |
195 | node_shift(right, count); | |
196 | node_copy(left, right, count); | |
197 | } else { | |
198 | node_copy(left, right, count); | |
199 | node_shift(right, count); | |
200 | } | |
201 | ||
b0988900 JT |
202 | left->header.nr_entries = cpu_to_le32(nr_left - count); |
203 | right->header.nr_entries = cpu_to_le32(nr_right + count); | |
3241b1d3 JT |
204 | } |
205 | ||
550929fa | 206 | static void __rebalance2(struct dm_btree_info *info, struct btree_node *parent, |
3241b1d3 JT |
207 | struct child *l, struct child *r) |
208 | { | |
550929fa MP |
209 | struct btree_node *left = l->n; |
210 | struct btree_node *right = r->n; | |
3241b1d3 JT |
211 | uint32_t nr_left = le32_to_cpu(left->header.nr_entries); |
212 | uint32_t nr_right = le32_to_cpu(right->header.nr_entries); | |
b0988900 | 213 | unsigned threshold = 2 * merge_threshold(left) + 1; |
3241b1d3 | 214 | |
b0988900 | 215 | if (nr_left + nr_right < threshold) { |
3241b1d3 JT |
216 | /* |
217 | * Merge | |
218 | */ | |
219 | node_copy(left, right, -nr_right); | |
220 | left->header.nr_entries = cpu_to_le32(nr_left + nr_right); | |
221 | delete_at(parent, r->index); | |
222 | ||
223 | /* | |
224 | * We need to decrement the right block, but not it's | |
225 | * children, since they're still referenced by left. | |
226 | */ | |
227 | dm_tm_dec(info->tm, dm_block_location(r->block)); | |
228 | } else { | |
229 | /* | |
230 | * Rebalance. | |
231 | */ | |
232 | unsigned target_left = (nr_left + nr_right) / 2; | |
3241b1d3 JT |
233 | shift(left, right, nr_left - target_left); |
234 | *key_ptr(parent, r->index) = right->keys[0]; | |
235 | } | |
236 | } | |
237 | ||
238 | static int rebalance2(struct shadow_spine *s, struct dm_btree_info *info, | |
239 | unsigned left_index) | |
240 | { | |
241 | int r; | |
550929fa | 242 | struct btree_node *parent; |
3241b1d3 JT |
243 | struct child left, right; |
244 | ||
245 | parent = dm_block_data(shadow_current(s)); | |
246 | ||
247 | r = init_child(info, parent, left_index, &left); | |
248 | if (r) | |
249 | return r; | |
250 | ||
251 | r = init_child(info, parent, left_index + 1, &right); | |
252 | if (r) { | |
253 | exit_child(info, &left); | |
254 | return r; | |
255 | } | |
256 | ||
257 | __rebalance2(info, parent, &left, &right); | |
258 | ||
259 | r = exit_child(info, &left); | |
260 | if (r) { | |
261 | exit_child(info, &right); | |
262 | return r; | |
263 | } | |
264 | ||
265 | return exit_child(info, &right); | |
266 | } | |
267 | ||
b0988900 JT |
268 | /* |
269 | * We dump as many entries from center as possible into left, then the rest | |
270 | * in right, then rebalance2. This wastes some cpu, but I want something | |
271 | * simple atm. | |
272 | */ | |
550929fa | 273 | static void delete_center_node(struct dm_btree_info *info, struct btree_node *parent, |
b0988900 | 274 | struct child *l, struct child *c, struct child *r, |
550929fa | 275 | struct btree_node *left, struct btree_node *center, struct btree_node *right, |
b0988900 JT |
276 | uint32_t nr_left, uint32_t nr_center, uint32_t nr_right) |
277 | { | |
278 | uint32_t max_entries = le32_to_cpu(left->header.max_entries); | |
279 | unsigned shift = min(max_entries - nr_left, nr_center); | |
280 | ||
281 | BUG_ON(nr_left + shift > max_entries); | |
282 | node_copy(left, center, -shift); | |
283 | left->header.nr_entries = cpu_to_le32(nr_left + shift); | |
284 | ||
285 | if (shift != nr_center) { | |
286 | shift = nr_center - shift; | |
287 | BUG_ON((nr_right + shift) > max_entries); | |
288 | node_shift(right, shift); | |
289 | node_copy(center, right, shift); | |
290 | right->header.nr_entries = cpu_to_le32(nr_right + shift); | |
291 | } | |
292 | *key_ptr(parent, r->index) = right->keys[0]; | |
293 | ||
294 | delete_at(parent, c->index); | |
295 | r->index--; | |
296 | ||
297 | dm_tm_dec(info->tm, dm_block_location(c->block)); | |
298 | __rebalance2(info, parent, l, r); | |
299 | } | |
300 | ||
301 | /* | |
302 | * Redistributes entries among 3 sibling nodes. | |
303 | */ | |
550929fa | 304 | static void redistribute3(struct dm_btree_info *info, struct btree_node *parent, |
b0988900 | 305 | struct child *l, struct child *c, struct child *r, |
550929fa | 306 | struct btree_node *left, struct btree_node *center, struct btree_node *right, |
b0988900 JT |
307 | uint32_t nr_left, uint32_t nr_center, uint32_t nr_right) |
308 | { | |
309 | int s; | |
310 | uint32_t max_entries = le32_to_cpu(left->header.max_entries); | |
311 | unsigned target = (nr_left + nr_center + nr_right) / 3; | |
312 | BUG_ON(target > max_entries); | |
313 | ||
314 | if (nr_left < nr_right) { | |
315 | s = nr_left - target; | |
316 | ||
317 | if (s < 0 && nr_center < -s) { | |
318 | /* not enough in central node */ | |
319 | shift(left, center, nr_center); | |
320 | s = nr_center - target; | |
321 | shift(left, right, s); | |
322 | nr_right += s; | |
323 | } else | |
324 | shift(left, center, s); | |
325 | ||
326 | shift(center, right, target - nr_right); | |
327 | ||
328 | } else { | |
329 | s = target - nr_right; | |
330 | if (s > 0 && nr_center < s) { | |
331 | /* not enough in central node */ | |
332 | shift(center, right, nr_center); | |
333 | s = target - nr_center; | |
334 | shift(left, right, s); | |
335 | nr_left -= s; | |
336 | } else | |
337 | shift(center, right, s); | |
338 | ||
339 | shift(left, center, nr_left - target); | |
340 | } | |
341 | ||
342 | *key_ptr(parent, c->index) = center->keys[0]; | |
343 | *key_ptr(parent, r->index) = right->keys[0]; | |
344 | } | |
345 | ||
550929fa | 346 | static void __rebalance3(struct dm_btree_info *info, struct btree_node *parent, |
3241b1d3 JT |
347 | struct child *l, struct child *c, struct child *r) |
348 | { | |
550929fa MP |
349 | struct btree_node *left = l->n; |
350 | struct btree_node *center = c->n; | |
351 | struct btree_node *right = r->n; | |
3241b1d3 JT |
352 | |
353 | uint32_t nr_left = le32_to_cpu(left->header.nr_entries); | |
354 | uint32_t nr_center = le32_to_cpu(center->header.nr_entries); | |
355 | uint32_t nr_right = le32_to_cpu(right->header.nr_entries); | |
3241b1d3 | 356 | |
b0988900 | 357 | unsigned threshold = merge_threshold(left) * 4 + 1; |
3241b1d3 JT |
358 | |
359 | BUG_ON(left->header.max_entries != center->header.max_entries); | |
360 | BUG_ON(center->header.max_entries != right->header.max_entries); | |
361 | ||
b0988900 JT |
362 | if ((nr_left + nr_center + nr_right) < threshold) |
363 | delete_center_node(info, parent, l, c, r, left, center, right, | |
364 | nr_left, nr_center, nr_right); | |
365 | else | |
366 | redistribute3(info, parent, l, c, r, left, center, right, | |
367 | nr_left, nr_center, nr_right); | |
3241b1d3 JT |
368 | } |
369 | ||
370 | static int rebalance3(struct shadow_spine *s, struct dm_btree_info *info, | |
371 | unsigned left_index) | |
372 | { | |
373 | int r; | |
550929fa | 374 | struct btree_node *parent = dm_block_data(shadow_current(s)); |
3241b1d3 JT |
375 | struct child left, center, right; |
376 | ||
377 | /* | |
378 | * FIXME: fill out an array? | |
379 | */ | |
380 | r = init_child(info, parent, left_index, &left); | |
381 | if (r) | |
382 | return r; | |
383 | ||
384 | r = init_child(info, parent, left_index + 1, ¢er); | |
385 | if (r) { | |
386 | exit_child(info, &left); | |
387 | return r; | |
388 | } | |
389 | ||
390 | r = init_child(info, parent, left_index + 2, &right); | |
391 | if (r) { | |
392 | exit_child(info, &left); | |
393 | exit_child(info, ¢er); | |
394 | return r; | |
395 | } | |
396 | ||
397 | __rebalance3(info, parent, &left, ¢er, &right); | |
398 | ||
399 | r = exit_child(info, &left); | |
400 | if (r) { | |
401 | exit_child(info, ¢er); | |
402 | exit_child(info, &right); | |
403 | return r; | |
404 | } | |
405 | ||
406 | r = exit_child(info, ¢er); | |
407 | if (r) { | |
408 | exit_child(info, &right); | |
409 | return r; | |
410 | } | |
411 | ||
412 | r = exit_child(info, &right); | |
413 | if (r) | |
414 | return r; | |
415 | ||
416 | return 0; | |
417 | } | |
418 | ||
419 | static int get_nr_entries(struct dm_transaction_manager *tm, | |
420 | dm_block_t b, uint32_t *result) | |
421 | { | |
422 | int r; | |
423 | struct dm_block *block; | |
550929fa | 424 | struct btree_node *n; |
3241b1d3 JT |
425 | |
426 | r = dm_tm_read_lock(tm, b, &btree_node_validator, &block); | |
427 | if (r) | |
428 | return r; | |
429 | ||
430 | n = dm_block_data(block); | |
431 | *result = le32_to_cpu(n->header.nr_entries); | |
432 | ||
433 | return dm_tm_unlock(tm, block); | |
434 | } | |
435 | ||
436 | static int rebalance_children(struct shadow_spine *s, | |
437 | struct dm_btree_info *info, uint64_t key) | |
438 | { | |
439 | int i, r, has_left_sibling, has_right_sibling; | |
440 | uint32_t child_entries; | |
550929fa | 441 | struct btree_node *n; |
3241b1d3 JT |
442 | |
443 | n = dm_block_data(shadow_current(s)); | |
444 | ||
445 | if (le32_to_cpu(n->header.nr_entries) == 1) { | |
446 | struct dm_block *child; | |
447 | dm_block_t b = value64(n, 0); | |
448 | ||
449 | r = dm_tm_read_lock(info->tm, b, &btree_node_validator, &child); | |
450 | if (r) | |
451 | return r; | |
452 | ||
453 | memcpy(n, dm_block_data(child), | |
454 | dm_bm_block_size(dm_tm_get_bm(info->tm))); | |
455 | r = dm_tm_unlock(info->tm, child); | |
456 | if (r) | |
457 | return r; | |
458 | ||
459 | dm_tm_dec(info->tm, dm_block_location(child)); | |
460 | return 0; | |
461 | } | |
462 | ||
463 | i = lower_bound(n, key); | |
464 | if (i < 0) | |
465 | return -ENODATA; | |
466 | ||
467 | r = get_nr_entries(info->tm, value64(n, i), &child_entries); | |
468 | if (r) | |
469 | return r; | |
470 | ||
3241b1d3 JT |
471 | has_left_sibling = i > 0; |
472 | has_right_sibling = i < (le32_to_cpu(n->header.nr_entries) - 1); | |
473 | ||
474 | if (!has_left_sibling) | |
475 | r = rebalance2(s, info, i); | |
476 | ||
477 | else if (!has_right_sibling) | |
478 | r = rebalance2(s, info, i - 1); | |
479 | ||
480 | else | |
481 | r = rebalance3(s, info, i - 1); | |
482 | ||
483 | return r; | |
484 | } | |
485 | ||
550929fa | 486 | static int do_leaf(struct btree_node *n, uint64_t key, unsigned *index) |
3241b1d3 JT |
487 | { |
488 | int i = lower_bound(n, key); | |
489 | ||
490 | if ((i < 0) || | |
491 | (i >= le32_to_cpu(n->header.nr_entries)) || | |
492 | (le64_to_cpu(n->keys[i]) != key)) | |
493 | return -ENODATA; | |
494 | ||
495 | *index = i; | |
496 | ||
497 | return 0; | |
498 | } | |
499 | ||
500 | /* | |
501 | * Prepares for removal from one level of the hierarchy. The caller must | |
502 | * call delete_at() to remove the entry at index. | |
503 | */ | |
504 | static int remove_raw(struct shadow_spine *s, struct dm_btree_info *info, | |
505 | struct dm_btree_value_type *vt, dm_block_t root, | |
506 | uint64_t key, unsigned *index) | |
507 | { | |
508 | int i = *index, r; | |
550929fa | 509 | struct btree_node *n; |
3241b1d3 JT |
510 | |
511 | for (;;) { | |
512 | r = shadow_step(s, root, vt); | |
513 | if (r < 0) | |
514 | break; | |
515 | ||
516 | /* | |
517 | * We have to patch up the parent node, ugly, but I don't | |
518 | * see a way to do this automatically as part of the spine | |
519 | * op. | |
520 | */ | |
521 | if (shadow_has_parent(s)) { | |
522 | __le64 location = cpu_to_le64(dm_block_location(shadow_current(s))); | |
a3aefb39 | 523 | memcpy(value_ptr(dm_block_data(shadow_parent(s)), i), |
3241b1d3 JT |
524 | &location, sizeof(__le64)); |
525 | } | |
526 | ||
527 | n = dm_block_data(shadow_current(s)); | |
528 | ||
529 | if (le32_to_cpu(n->header.flags) & LEAF_NODE) | |
530 | return do_leaf(n, key, index); | |
531 | ||
532 | r = rebalance_children(s, info, key); | |
533 | if (r) | |
534 | break; | |
535 | ||
536 | n = dm_block_data(shadow_current(s)); | |
537 | if (le32_to_cpu(n->header.flags) & LEAF_NODE) | |
538 | return do_leaf(n, key, index); | |
539 | ||
540 | i = lower_bound(n, key); | |
541 | ||
542 | /* | |
543 | * We know the key is present, or else | |
544 | * rebalance_children would have returned | |
545 | * -ENODATA | |
546 | */ | |
547 | root = value64(n, i); | |
548 | } | |
549 | ||
550 | return r; | |
551 | } | |
552 | ||
553 | int dm_btree_remove(struct dm_btree_info *info, dm_block_t root, | |
554 | uint64_t *keys, dm_block_t *new_root) | |
555 | { | |
556 | unsigned level, last_level = info->levels - 1; | |
557 | int index = 0, r = 0; | |
558 | struct shadow_spine spine; | |
550929fa | 559 | struct btree_node *n; |
3241b1d3 JT |
560 | |
561 | init_shadow_spine(&spine, info); | |
562 | for (level = 0; level < info->levels; level++) { | |
563 | r = remove_raw(&spine, info, | |
564 | (level == last_level ? | |
565 | &info->value_type : &le64_type), | |
566 | root, keys[level], (unsigned *)&index); | |
567 | if (r < 0) | |
568 | break; | |
569 | ||
570 | n = dm_block_data(shadow_current(&spine)); | |
571 | if (level != last_level) { | |
572 | root = value64(n, index); | |
573 | continue; | |
574 | } | |
575 | ||
576 | BUG_ON(index < 0 || index >= le32_to_cpu(n->header.nr_entries)); | |
577 | ||
578 | if (info->value_type.dec) | |
579 | info->value_type.dec(info->value_type.context, | |
a3aefb39 | 580 | value_ptr(n, index)); |
3241b1d3 JT |
581 | |
582 | delete_at(n, index); | |
583 | } | |
584 | ||
585 | *new_root = shadow_root(&spine); | |
586 | exit_shadow_spine(&spine); | |
587 | ||
588 | return r; | |
589 | } | |
590 | EXPORT_SYMBOL_GPL(dm_btree_remove); |