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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-internal.h"
9#include "dm-space-map.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 *--------------------------------------------------------------
19 * Array manipulation
20 *--------------------------------------------------------------
21 */
22static void memcpy_disk(void *dest, const void *src, size_t len)
23 __dm_written_to_disk(src)
24{
25 memcpy(dest, src, len);
26 __dm_unbless_for_disk(src);
27}
28
29static void array_insert(void *base, size_t elt_size, unsigned int nr_elts,
30 unsigned int index, void *elt)
31 __dm_written_to_disk(elt)
32{
33 if (index < nr_elts)
34 memmove(base + (elt_size * (index + 1)),
35 base + (elt_size * index),
36 (nr_elts - index) * elt_size);
37
38 memcpy_disk(base + (elt_size * index), elt, elt_size);
39}
40
41/*----------------------------------------------------------------*/
42
43/* makes the assumption that no two keys are the same. */
44static int bsearch(struct btree_node *n, uint64_t key, int want_hi)
45{
46 int lo = -1, hi = le32_to_cpu(n->header.nr_entries);
47
48 while (hi - lo > 1) {
49 int mid = lo + ((hi - lo) / 2);
50 uint64_t mid_key = le64_to_cpu(n->keys[mid]);
51
52 if (mid_key == key)
53 return mid;
54
55 if (mid_key < key)
56 lo = mid;
57 else
58 hi = mid;
59 }
60
61 return want_hi ? hi : lo;
62}
63
64int lower_bound(struct btree_node *n, uint64_t key)
65{
66 return bsearch(n, key, 0);
67}
68
69static int upper_bound(struct btree_node *n, uint64_t key)
70{
71 return bsearch(n, key, 1);
72}
73
74void inc_children(struct dm_transaction_manager *tm, struct btree_node *n,
75 struct dm_btree_value_type *vt)
76{
77 uint32_t nr_entries = le32_to_cpu(n->header.nr_entries);
78
79 if (le32_to_cpu(n->header.flags) & INTERNAL_NODE)
80 dm_tm_with_runs(tm, value_ptr(n, 0), nr_entries, dm_tm_inc_range);
81
82 else if (vt->inc)
83 vt->inc(vt->context, value_ptr(n, 0), nr_entries);
84}
85
86static int insert_at(size_t value_size, struct btree_node *node, unsigned int index,
87 uint64_t key, void *value)
88 __dm_written_to_disk(value)
89{
90 uint32_t nr_entries = le32_to_cpu(node->header.nr_entries);
91 uint32_t max_entries = le32_to_cpu(node->header.max_entries);
92 __le64 key_le = cpu_to_le64(key);
93
94 if (index > nr_entries ||
95 index >= max_entries ||
96 nr_entries >= max_entries) {
97 DMERR("too many entries in btree node for insert");
98 __dm_unbless_for_disk(value);
99 return -ENOMEM;
100 }
101
102 __dm_bless_for_disk(&key_le);
103
104 array_insert(node->keys, sizeof(*node->keys), nr_entries, index, &key_le);
105 array_insert(value_base(node), value_size, nr_entries, index, value);
106 node->header.nr_entries = cpu_to_le32(nr_entries + 1);
107
108 return 0;
109}
110
111/*----------------------------------------------------------------*/
112
113/*
114 * We want 3n entries (for some n). This works more nicely for repeated
115 * insert remove loops than (2n + 1).
116 */
117static uint32_t calc_max_entries(size_t value_size, size_t block_size)
118{
119 uint32_t total, n;
120 size_t elt_size = sizeof(uint64_t) + value_size; /* key + value */
121
122 block_size -= sizeof(struct node_header);
123 total = block_size / elt_size;
124 n = total / 3; /* rounds down */
125
126 return 3 * n;
127}
128
129int dm_btree_empty(struct dm_btree_info *info, dm_block_t *root)
130{
131 int r;
132 struct dm_block *b;
133 struct btree_node *n;
134 size_t block_size;
135 uint32_t max_entries;
136
137 r = new_block(info, &b);
138 if (r < 0)
139 return r;
140
141 block_size = dm_bm_block_size(dm_tm_get_bm(info->tm));
142 max_entries = calc_max_entries(info->value_type.size, block_size);
143
144 n = dm_block_data(b);
145 memset(n, 0, block_size);
146 n->header.flags = cpu_to_le32(LEAF_NODE);
147 n->header.nr_entries = cpu_to_le32(0);
148 n->header.max_entries = cpu_to_le32(max_entries);
149 n->header.value_size = cpu_to_le32(info->value_type.size);
150
151 *root = dm_block_location(b);
152 unlock_block(info, b);
153
154 return 0;
155}
156EXPORT_SYMBOL_GPL(dm_btree_empty);
157
158/*----------------------------------------------------------------*/
159
160/*
161 * Deletion uses a recursive algorithm, since we have limited stack space
162 * we explicitly manage our own stack on the heap.
163 */
164#define MAX_SPINE_DEPTH 64
165struct frame {
166 struct dm_block *b;
167 struct btree_node *n;
168 unsigned int level;
169 unsigned int nr_children;
170 unsigned int current_child;
171};
172
173struct del_stack {
174 struct dm_btree_info *info;
175 struct dm_transaction_manager *tm;
176 int top;
177 struct frame spine[MAX_SPINE_DEPTH];
178};
179
180static int top_frame(struct del_stack *s, struct frame **f)
181{
182 if (s->top < 0) {
183 DMERR("btree deletion stack empty");
184 return -EINVAL;
185 }
186
187 *f = s->spine + s->top;
188
189 return 0;
190}
191
192static int unprocessed_frames(struct del_stack *s)
193{
194 return s->top >= 0;
195}
196
197static void prefetch_children(struct del_stack *s, struct frame *f)
198{
199 unsigned int i;
200 struct dm_block_manager *bm = dm_tm_get_bm(s->tm);
201
202 for (i = 0; i < f->nr_children; i++)
203 dm_bm_prefetch(bm, value64(f->n, i));
204}
205
206static bool is_internal_level(struct dm_btree_info *info, struct frame *f)
207{
208 return f->level < (info->levels - 1);
209}
210
211static int push_frame(struct del_stack *s, dm_block_t b, unsigned int level)
212{
213 int r;
214 uint32_t ref_count;
215
216 if (s->top >= MAX_SPINE_DEPTH - 1) {
217 DMERR("btree deletion stack out of memory");
218 return -ENOMEM;
219 }
220
221 r = dm_tm_ref(s->tm, b, &ref_count);
222 if (r)
223 return r;
224
225 if (ref_count > 1)
226 /*
227 * This is a shared node, so we can just decrement it's
228 * reference counter and leave the children.
229 */
230 dm_tm_dec(s->tm, b);
231
232 else {
233 uint32_t flags;
234 struct frame *f = s->spine + ++s->top;
235
236 r = dm_tm_read_lock(s->tm, b, &btree_node_validator, &f->b);
237 if (r) {
238 s->top--;
239 return r;
240 }
241
242 f->n = dm_block_data(f->b);
243 f->level = level;
244 f->nr_children = le32_to_cpu(f->n->header.nr_entries);
245 f->current_child = 0;
246
247 flags = le32_to_cpu(f->n->header.flags);
248 if (flags & INTERNAL_NODE || is_internal_level(s->info, f))
249 prefetch_children(s, f);
250 }
251
252 return 0;
253}
254
255static void pop_frame(struct del_stack *s)
256{
257 struct frame *f = s->spine + s->top--;
258
259 dm_tm_dec(s->tm, dm_block_location(f->b));
260 dm_tm_unlock(s->tm, f->b);
261}
262
263static void unlock_all_frames(struct del_stack *s)
264{
265 struct frame *f;
266
267 while (unprocessed_frames(s)) {
268 f = s->spine + s->top--;
269 dm_tm_unlock(s->tm, f->b);
270 }
271}
272
273int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
274{
275 int r;
276 struct del_stack *s;
277
278 /*
279 * dm_btree_del() is called via an ioctl, as such should be
280 * considered an FS op. We can't recurse back into the FS, so we
281 * allocate GFP_NOFS.
282 */
283 s = kmalloc(sizeof(*s), GFP_NOFS);
284 if (!s)
285 return -ENOMEM;
286 s->info = info;
287 s->tm = info->tm;
288 s->top = -1;
289
290 r = push_frame(s, root, 0);
291 if (r)
292 goto out;
293
294 while (unprocessed_frames(s)) {
295 uint32_t flags;
296 struct frame *f;
297 dm_block_t b;
298
299 r = top_frame(s, &f);
300 if (r)
301 goto out;
302
303 if (f->current_child >= f->nr_children) {
304 pop_frame(s);
305 continue;
306 }
307
308 flags = le32_to_cpu(f->n->header.flags);
309 if (flags & INTERNAL_NODE) {
310 b = value64(f->n, f->current_child);
311 f->current_child++;
312 r = push_frame(s, b, f->level);
313 if (r)
314 goto out;
315
316 } else if (is_internal_level(info, f)) {
317 b = value64(f->n, f->current_child);
318 f->current_child++;
319 r = push_frame(s, b, f->level + 1);
320 if (r)
321 goto out;
322
323 } else {
324 if (info->value_type.dec)
325 info->value_type.dec(info->value_type.context,
326 value_ptr(f->n, 0), f->nr_children);
327 pop_frame(s);
328 }
329 }
330out:
331 if (r) {
332 /* cleanup all frames of del_stack */
333 unlock_all_frames(s);
334 }
335 kfree(s);
336
337 return r;
338}
339EXPORT_SYMBOL_GPL(dm_btree_del);
340
341/*----------------------------------------------------------------*/
342
343static int btree_lookup_raw(struct ro_spine *s, dm_block_t block, uint64_t key,
344 int (*search_fn)(struct btree_node *, uint64_t),
345 uint64_t *result_key, void *v, size_t value_size)
346{
347 int i, r;
348 uint32_t flags, nr_entries;
349
350 do {
351 r = ro_step(s, block);
352 if (r < 0)
353 return r;
354
355 i = search_fn(ro_node(s), key);
356
357 flags = le32_to_cpu(ro_node(s)->header.flags);
358 nr_entries = le32_to_cpu(ro_node(s)->header.nr_entries);
359 if (i < 0 || i >= nr_entries)
360 return -ENODATA;
361
362 if (flags & INTERNAL_NODE)
363 block = value64(ro_node(s), i);
364
365 } while (!(flags & LEAF_NODE));
366
367 *result_key = le64_to_cpu(ro_node(s)->keys[i]);
368 if (v)
369 memcpy(v, value_ptr(ro_node(s), i), value_size);
370
371 return 0;
372}
373
374int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
375 uint64_t *keys, void *value_le)
376{
377 unsigned int level, last_level = info->levels - 1;
378 int r = -ENODATA;
379 uint64_t rkey;
380 __le64 internal_value_le;
381 struct ro_spine spine;
382
383 init_ro_spine(&spine, info);
384 for (level = 0; level < info->levels; level++) {
385 size_t size;
386 void *value_p;
387
388 if (level == last_level) {
389 value_p = value_le;
390 size = info->value_type.size;
391
392 } else {
393 value_p = &internal_value_le;
394 size = sizeof(uint64_t);
395 }
396
397 r = btree_lookup_raw(&spine, root, keys[level],
398 lower_bound, &rkey,
399 value_p, size);
400
401 if (!r) {
402 if (rkey != keys[level]) {
403 exit_ro_spine(&spine);
404 return -ENODATA;
405 }
406 } else {
407 exit_ro_spine(&spine);
408 return r;
409 }
410
411 root = le64_to_cpu(internal_value_le);
412 }
413 exit_ro_spine(&spine);
414
415 return r;
416}
417EXPORT_SYMBOL_GPL(dm_btree_lookup);
418
419static int dm_btree_lookup_next_single(struct dm_btree_info *info, dm_block_t root,
420 uint64_t key, uint64_t *rkey, void *value_le)
421{
422 int r, i;
423 uint32_t flags, nr_entries;
424 struct dm_block *node;
425 struct btree_node *n;
426
427 r = bn_read_lock(info, root, &node);
428 if (r)
429 return r;
430
431 n = dm_block_data(node);
432 flags = le32_to_cpu(n->header.flags);
433 nr_entries = le32_to_cpu(n->header.nr_entries);
434
435 if (flags & INTERNAL_NODE) {
436 i = lower_bound(n, key);
437 if (i < 0) {
438 /*
439 * avoid early -ENODATA return when all entries are
440 * higher than the search @key.
441 */
442 i = 0;
443 }
444 if (i >= nr_entries) {
445 r = -ENODATA;
446 goto out;
447 }
448
449 r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
450 if (r == -ENODATA && i < (nr_entries - 1)) {
451 i++;
452 r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
453 }
454
455 } else {
456 i = upper_bound(n, key);
457 if (i < 0 || i >= nr_entries) {
458 r = -ENODATA;
459 goto out;
460 }
461
462 *rkey = le64_to_cpu(n->keys[i]);
463 memcpy(value_le, value_ptr(n, i), info->value_type.size);
464 }
465out:
466 dm_tm_unlock(info->tm, node);
467 return r;
468}
469
470int dm_btree_lookup_next(struct dm_btree_info *info, dm_block_t root,
471 uint64_t *keys, uint64_t *rkey, void *value_le)
472{
473 unsigned int level;
474 int r = -ENODATA;
475 __le64 internal_value_le;
476 struct ro_spine spine;
477
478 init_ro_spine(&spine, info);
479 for (level = 0; level < info->levels - 1u; level++) {
480 r = btree_lookup_raw(&spine, root, keys[level],
481 lower_bound, rkey,
482 &internal_value_le, sizeof(uint64_t));
483 if (r)
484 goto out;
485
486 if (*rkey != keys[level]) {
487 r = -ENODATA;
488 goto out;
489 }
490
491 root = le64_to_cpu(internal_value_le);
492 }
493
494 r = dm_btree_lookup_next_single(info, root, keys[level], rkey, value_le);
495out:
496 exit_ro_spine(&spine);
497 return r;
498}
499EXPORT_SYMBOL_GPL(dm_btree_lookup_next);
500
501/*----------------------------------------------------------------*/
502
503/*
504 * Copies entries from one region of a btree node to another. The regions
505 * must not overlap.
506 */
507static void copy_entries(struct btree_node *dest, unsigned int dest_offset,
508 struct btree_node *src, unsigned int src_offset,
509 unsigned int count)
510{
511 size_t value_size = le32_to_cpu(dest->header.value_size);
512
513 memcpy(dest->keys + dest_offset, src->keys + src_offset, count * sizeof(uint64_t));
514 memcpy(value_ptr(dest, dest_offset), value_ptr(src, src_offset), count * value_size);
515}
516
517/*
518 * Moves entries from one region fo a btree node to another. The regions
519 * may overlap.
520 */
521static void move_entries(struct btree_node *dest, unsigned int dest_offset,
522 struct btree_node *src, unsigned int src_offset,
523 unsigned int count)
524{
525 size_t value_size = le32_to_cpu(dest->header.value_size);
526
527 memmove(dest->keys + dest_offset, src->keys + src_offset, count * sizeof(uint64_t));
528 memmove(value_ptr(dest, dest_offset), value_ptr(src, src_offset), count * value_size);
529}
530
531/*
532 * Erases the first 'count' entries of a btree node, shifting following
533 * entries down into their place.
534 */
535static void shift_down(struct btree_node *n, unsigned int count)
536{
537 move_entries(n, 0, n, count, le32_to_cpu(n->header.nr_entries) - count);
538}
539
540/*
541 * Moves entries in a btree node up 'count' places, making space for
542 * new entries at the start of the node.
543 */
544static void shift_up(struct btree_node *n, unsigned int count)
545{
546 move_entries(n, count, n, 0, le32_to_cpu(n->header.nr_entries));
547}
548
549/*
550 * Redistributes entries between two btree nodes to make them
551 * have similar numbers of entries.
552 */
553static void redistribute2(struct btree_node *left, struct btree_node *right)
554{
555 unsigned int nr_left = le32_to_cpu(left->header.nr_entries);
556 unsigned int nr_right = le32_to_cpu(right->header.nr_entries);
557 unsigned int total = nr_left + nr_right;
558 unsigned int target_left = total / 2;
559 unsigned int target_right = total - target_left;
560
561 if (nr_left < target_left) {
562 unsigned int delta = target_left - nr_left;
563
564 copy_entries(left, nr_left, right, 0, delta);
565 shift_down(right, delta);
566 } else if (nr_left > target_left) {
567 unsigned int delta = nr_left - target_left;
568
569 if (nr_right)
570 shift_up(right, delta);
571 copy_entries(right, 0, left, target_left, delta);
572 }
573
574 left->header.nr_entries = cpu_to_le32(target_left);
575 right->header.nr_entries = cpu_to_le32(target_right);
576}
577
578/*
579 * Redistribute entries between three nodes. Assumes the central
580 * node is empty.
581 */
582static void redistribute3(struct btree_node *left, struct btree_node *center,
583 struct btree_node *right)
584{
585 unsigned int nr_left = le32_to_cpu(left->header.nr_entries);
586 unsigned int nr_center = le32_to_cpu(center->header.nr_entries);
587 unsigned int nr_right = le32_to_cpu(right->header.nr_entries);
588 unsigned int total, target_left, target_center, target_right;
589
590 BUG_ON(nr_center);
591
592 total = nr_left + nr_right;
593 target_left = total / 3;
594 target_center = (total - target_left) / 2;
595 target_right = (total - target_left - target_center);
596
597 if (nr_left < target_left) {
598 unsigned int left_short = target_left - nr_left;
599
600 copy_entries(left, nr_left, right, 0, left_short);
601 copy_entries(center, 0, right, left_short, target_center);
602 shift_down(right, nr_right - target_right);
603
604 } else if (nr_left < (target_left + target_center)) {
605 unsigned int left_to_center = nr_left - target_left;
606
607 copy_entries(center, 0, left, target_left, left_to_center);
608 copy_entries(center, left_to_center, right, 0, target_center - left_to_center);
609 shift_down(right, nr_right - target_right);
610
611 } else {
612 unsigned int right_short = target_right - nr_right;
613
614 shift_up(right, right_short);
615 copy_entries(right, 0, left, nr_left - right_short, right_short);
616 copy_entries(center, 0, left, target_left, nr_left - target_left);
617 }
618
619 left->header.nr_entries = cpu_to_le32(target_left);
620 center->header.nr_entries = cpu_to_le32(target_center);
621 right->header.nr_entries = cpu_to_le32(target_right);
622}
623
624/*
625 * Splits a node by creating a sibling node and shifting half the nodes
626 * contents across. Assumes there is a parent node, and it has room for
627 * another child.
628 *
629 * Before:
630 * +--------+
631 * | Parent |
632 * +--------+
633 * |
634 * v
635 * +----------+
636 * | A ++++++ |
637 * +----------+
638 *
639 *
640 * After:
641 * +--------+
642 * | Parent |
643 * +--------+
644 * | |
645 * v +------+
646 * +---------+ |
647 * | A* +++ | v
648 * +---------+ +-------+
649 * | B +++ |
650 * +-------+
651 *
652 * Where A* is a shadow of A.
653 */
654static int split_one_into_two(struct shadow_spine *s, unsigned int parent_index,
655 struct dm_btree_value_type *vt, uint64_t key)
656{
657 int r;
658 struct dm_block *left, *right, *parent;
659 struct btree_node *ln, *rn, *pn;
660 __le64 location;
661
662 left = shadow_current(s);
663
664 r = new_block(s->info, &right);
665 if (r < 0)
666 return r;
667
668 ln = dm_block_data(left);
669 rn = dm_block_data(right);
670
671 rn->header.flags = ln->header.flags;
672 rn->header.nr_entries = cpu_to_le32(0);
673 rn->header.max_entries = ln->header.max_entries;
674 rn->header.value_size = ln->header.value_size;
675 redistribute2(ln, rn);
676
677 /* patch up the parent */
678 parent = shadow_parent(s);
679 pn = dm_block_data(parent);
680
681 location = cpu_to_le64(dm_block_location(right));
682 __dm_bless_for_disk(&location);
683 r = insert_at(sizeof(__le64), pn, parent_index + 1,
684 le64_to_cpu(rn->keys[0]), &location);
685 if (r) {
686 unlock_block(s->info, right);
687 return r;
688 }
689
690 /* patch up the spine */
691 if (key < le64_to_cpu(rn->keys[0])) {
692 unlock_block(s->info, right);
693 s->nodes[1] = left;
694 } else {
695 unlock_block(s->info, left);
696 s->nodes[1] = right;
697 }
698
699 return 0;
700}
701
702/*
703 * We often need to modify a sibling node. This function shadows a particular
704 * child of the given parent node. Making sure to update the parent to point
705 * to the new shadow.
706 */
707static int shadow_child(struct dm_btree_info *info, struct dm_btree_value_type *vt,
708 struct btree_node *parent, unsigned int index,
709 struct dm_block **result)
710{
711 int r, inc;
712 dm_block_t root;
713 struct btree_node *node;
714
715 root = value64(parent, index);
716
717 r = dm_tm_shadow_block(info->tm, root, &btree_node_validator,
718 result, &inc);
719 if (r)
720 return r;
721
722 node = dm_block_data(*result);
723
724 if (inc)
725 inc_children(info->tm, node, vt);
726
727 *((__le64 *) value_ptr(parent, index)) =
728 cpu_to_le64(dm_block_location(*result));
729
730 return 0;
731}
732
733/*
734 * Splits two nodes into three. This is more work, but results in fuller
735 * nodes, so saves metadata space.
736 */
737static int split_two_into_three(struct shadow_spine *s, unsigned int parent_index,
738 struct dm_btree_value_type *vt, uint64_t key)
739{
740 int r;
741 unsigned int middle_index;
742 struct dm_block *left, *middle, *right, *parent;
743 struct btree_node *ln, *rn, *mn, *pn;
744 __le64 location;
745
746 parent = shadow_parent(s);
747 pn = dm_block_data(parent);
748
749 if (parent_index == 0) {
750 middle_index = 1;
751 left = shadow_current(s);
752 r = shadow_child(s->info, vt, pn, parent_index + 1, &right);
753 if (r)
754 return r;
755 } else {
756 middle_index = parent_index;
757 right = shadow_current(s);
758 r = shadow_child(s->info, vt, pn, parent_index - 1, &left);
759 if (r)
760 return r;
761 }
762
763 r = new_block(s->info, &middle);
764 if (r < 0)
765 return r;
766
767 ln = dm_block_data(left);
768 mn = dm_block_data(middle);
769 rn = dm_block_data(right);
770
771 mn->header.nr_entries = cpu_to_le32(0);
772 mn->header.flags = ln->header.flags;
773 mn->header.max_entries = ln->header.max_entries;
774 mn->header.value_size = ln->header.value_size;
775
776 redistribute3(ln, mn, rn);
777
778 /* patch up the parent */
779 pn->keys[middle_index] = rn->keys[0];
780 location = cpu_to_le64(dm_block_location(middle));
781 __dm_bless_for_disk(&location);
782 r = insert_at(sizeof(__le64), pn, middle_index,
783 le64_to_cpu(mn->keys[0]), &location);
784 if (r) {
785 if (shadow_current(s) != left)
786 unlock_block(s->info, left);
787
788 unlock_block(s->info, middle);
789
790 if (shadow_current(s) != right)
791 unlock_block(s->info, right);
792
793 return r;
794 }
795
796
797 /* patch up the spine */
798 if (key < le64_to_cpu(mn->keys[0])) {
799 unlock_block(s->info, middle);
800 unlock_block(s->info, right);
801 s->nodes[1] = left;
802 } else if (key < le64_to_cpu(rn->keys[0])) {
803 unlock_block(s->info, left);
804 unlock_block(s->info, right);
805 s->nodes[1] = middle;
806 } else {
807 unlock_block(s->info, left);
808 unlock_block(s->info, middle);
809 s->nodes[1] = right;
810 }
811
812 return 0;
813}
814
815/*----------------------------------------------------------------*/
816
817/*
818 * Splits a node by creating two new children beneath the given node.
819 *
820 * Before:
821 * +----------+
822 * | A ++++++ |
823 * +----------+
824 *
825 *
826 * After:
827 * +------------+
828 * | A (shadow) |
829 * +------------+
830 * | |
831 * +------+ +----+
832 * | |
833 * v v
834 * +-------+ +-------+
835 * | B +++ | | C +++ |
836 * +-------+ +-------+
837 */
838static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
839{
840 int r;
841 size_t size;
842 unsigned int nr_left, nr_right;
843 struct dm_block *left, *right, *new_parent;
844 struct btree_node *pn, *ln, *rn;
845 __le64 val;
846
847 new_parent = shadow_current(s);
848
849 pn = dm_block_data(new_parent);
850 size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
851 sizeof(__le64) : s->info->value_type.size;
852
853 /* create & init the left block */
854 r = new_block(s->info, &left);
855 if (r < 0)
856 return r;
857
858 ln = dm_block_data(left);
859 nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
860
861 ln->header.flags = pn->header.flags;
862 ln->header.nr_entries = cpu_to_le32(nr_left);
863 ln->header.max_entries = pn->header.max_entries;
864 ln->header.value_size = pn->header.value_size;
865 memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
866 memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
867
868 /* create & init the right block */
869 r = new_block(s->info, &right);
870 if (r < 0) {
871 unlock_block(s->info, left);
872 return r;
873 }
874
875 rn = dm_block_data(right);
876 nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
877
878 rn->header.flags = pn->header.flags;
879 rn->header.nr_entries = cpu_to_le32(nr_right);
880 rn->header.max_entries = pn->header.max_entries;
881 rn->header.value_size = pn->header.value_size;
882 memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
883 memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left),
884 nr_right * size);
885
886 /* new_parent should just point to l and r now */
887 pn->header.flags = cpu_to_le32(INTERNAL_NODE);
888 pn->header.nr_entries = cpu_to_le32(2);
889 pn->header.max_entries = cpu_to_le32(
890 calc_max_entries(sizeof(__le64),
891 dm_bm_block_size(
892 dm_tm_get_bm(s->info->tm))));
893 pn->header.value_size = cpu_to_le32(sizeof(__le64));
894
895 val = cpu_to_le64(dm_block_location(left));
896 __dm_bless_for_disk(&val);
897 pn->keys[0] = ln->keys[0];
898 memcpy_disk(value_ptr(pn, 0), &val, sizeof(__le64));
899
900 val = cpu_to_le64(dm_block_location(right));
901 __dm_bless_for_disk(&val);
902 pn->keys[1] = rn->keys[0];
903 memcpy_disk(value_ptr(pn, 1), &val, sizeof(__le64));
904
905 unlock_block(s->info, left);
906 unlock_block(s->info, right);
907 return 0;
908}
909
910/*----------------------------------------------------------------*/
911
912/*
913 * Redistributes a node's entries with its left sibling.
914 */
915static int rebalance_left(struct shadow_spine *s, struct dm_btree_value_type *vt,
916 unsigned int parent_index, uint64_t key)
917{
918 int r;
919 struct dm_block *sib;
920 struct btree_node *left, *right, *parent = dm_block_data(shadow_parent(s));
921
922 r = shadow_child(s->info, vt, parent, parent_index - 1, &sib);
923 if (r)
924 return r;
925
926 left = dm_block_data(sib);
927 right = dm_block_data(shadow_current(s));
928 redistribute2(left, right);
929 *key_ptr(parent, parent_index) = right->keys[0];
930
931 if (key < le64_to_cpu(right->keys[0])) {
932 unlock_block(s->info, s->nodes[1]);
933 s->nodes[1] = sib;
934 } else {
935 unlock_block(s->info, sib);
936 }
937
938 return 0;
939}
940
941/*
942 * Redistributes a nodes entries with its right sibling.
943 */
944static int rebalance_right(struct shadow_spine *s, struct dm_btree_value_type *vt,
945 unsigned int parent_index, uint64_t key)
946{
947 int r;
948 struct dm_block *sib;
949 struct btree_node *left, *right, *parent = dm_block_data(shadow_parent(s));
950
951 r = shadow_child(s->info, vt, parent, parent_index + 1, &sib);
952 if (r)
953 return r;
954
955 left = dm_block_data(shadow_current(s));
956 right = dm_block_data(sib);
957 redistribute2(left, right);
958 *key_ptr(parent, parent_index + 1) = right->keys[0];
959
960 if (key < le64_to_cpu(right->keys[0])) {
961 unlock_block(s->info, sib);
962 } else {
963 unlock_block(s->info, s->nodes[1]);
964 s->nodes[1] = sib;
965 }
966
967 return 0;
968}
969
970/*
971 * Returns the number of spare entries in a node.
972 */
973static int get_node_free_space(struct dm_btree_info *info, dm_block_t b, unsigned int *space)
974{
975 int r;
976 unsigned int nr_entries;
977 struct dm_block *block;
978 struct btree_node *node;
979
980 r = bn_read_lock(info, b, &block);
981 if (r)
982 return r;
983
984 node = dm_block_data(block);
985 nr_entries = le32_to_cpu(node->header.nr_entries);
986 *space = le32_to_cpu(node->header.max_entries) - nr_entries;
987
988 unlock_block(info, block);
989 return 0;
990}
991
992/*
993 * Make space in a node, either by moving some entries to a sibling,
994 * or creating a new sibling node. SPACE_THRESHOLD defines the minimum
995 * number of free entries that must be in the sibling to make the move
996 * worth while. If the siblings are shared (eg, part of a snapshot),
997 * then they are not touched, since this break sharing and so consume
998 * more space than we save.
999 */
1000#define SPACE_THRESHOLD 8
1001static int rebalance_or_split(struct shadow_spine *s, struct dm_btree_value_type *vt,
1002 unsigned int parent_index, uint64_t key)
1003{
1004 int r;
1005 struct btree_node *parent = dm_block_data(shadow_parent(s));
1006 unsigned int nr_parent = le32_to_cpu(parent->header.nr_entries);
1007 unsigned int free_space;
1008 int left_shared = 0, right_shared = 0;
1009
1010 /* Should we move entries to the left sibling? */
1011 if (parent_index > 0) {
1012 dm_block_t left_b = value64(parent, parent_index - 1);
1013
1014 r = dm_tm_block_is_shared(s->info->tm, left_b, &left_shared);
1015 if (r)
1016 return r;
1017
1018 if (!left_shared) {
1019 r = get_node_free_space(s->info, left_b, &free_space);
1020 if (r)
1021 return r;
1022
1023 if (free_space >= SPACE_THRESHOLD)
1024 return rebalance_left(s, vt, parent_index, key);
1025 }
1026 }
1027
1028 /* Should we move entries to the right sibling? */
1029 if (parent_index < (nr_parent - 1)) {
1030 dm_block_t right_b = value64(parent, parent_index + 1);
1031
1032 r = dm_tm_block_is_shared(s->info->tm, right_b, &right_shared);
1033 if (r)
1034 return r;
1035
1036 if (!right_shared) {
1037 r = get_node_free_space(s->info, right_b, &free_space);
1038 if (r)
1039 return r;
1040
1041 if (free_space >= SPACE_THRESHOLD)
1042 return rebalance_right(s, vt, parent_index, key);
1043 }
1044 }
1045
1046 /*
1047 * We need to split the node, normally we split two nodes
1048 * into three. But when inserting a sequence that is either
1049 * monotonically increasing or decreasing it's better to split
1050 * a single node into two.
1051 */
1052 if (left_shared || right_shared || (nr_parent <= 2) ||
1053 (parent_index == 0) || (parent_index + 1 == nr_parent)) {
1054 return split_one_into_two(s, parent_index, vt, key);
1055 } else {
1056 return split_two_into_three(s, parent_index, vt, key);
1057 }
1058}
1059
1060/*
1061 * Does the node contain a particular key?
1062 */
1063static bool contains_key(struct btree_node *node, uint64_t key)
1064{
1065 int i = lower_bound(node, key);
1066
1067 if (i >= 0 && le64_to_cpu(node->keys[i]) == key)
1068 return true;
1069
1070 return false;
1071}
1072
1073/*
1074 * In general we preemptively make sure there's a free entry in every
1075 * node on the spine when doing an insert. But we can avoid that with
1076 * leaf nodes if we know it's an overwrite.
1077 */
1078static bool has_space_for_insert(struct btree_node *node, uint64_t key)
1079{
1080 if (node->header.nr_entries == node->header.max_entries) {
1081 if (le32_to_cpu(node->header.flags) & LEAF_NODE) {
1082 /* we don't need space if it's an overwrite */
1083 return contains_key(node, key);
1084 }
1085
1086 return false;
1087 }
1088
1089 return true;
1090}
1091
1092static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
1093 struct dm_btree_value_type *vt,
1094 uint64_t key, unsigned int *index)
1095{
1096 int r, i = *index, top = 1;
1097 struct btree_node *node;
1098
1099 for (;;) {
1100 r = shadow_step(s, root, vt);
1101 if (r < 0)
1102 return r;
1103
1104 node = dm_block_data(shadow_current(s));
1105
1106 /*
1107 * We have to patch up the parent node, ugly, but I don't
1108 * see a way to do this automatically as part of the spine
1109 * op.
1110 */
1111 if (shadow_has_parent(s) && i >= 0) { /* FIXME: second clause unness. */
1112 __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
1113
1114 __dm_bless_for_disk(&location);
1115 memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
1116 &location, sizeof(__le64));
1117 }
1118
1119 node = dm_block_data(shadow_current(s));
1120
1121 if (!has_space_for_insert(node, key)) {
1122 if (top)
1123 r = btree_split_beneath(s, key);
1124 else
1125 r = rebalance_or_split(s, vt, i, key);
1126
1127 if (r < 0)
1128 return r;
1129
1130 /* making space can cause the current node to change */
1131 node = dm_block_data(shadow_current(s));
1132 }
1133
1134 i = lower_bound(node, key);
1135
1136 if (le32_to_cpu(node->header.flags) & LEAF_NODE)
1137 break;
1138
1139 if (i < 0) {
1140 /* change the bounds on the lowest key */
1141 node->keys[0] = cpu_to_le64(key);
1142 i = 0;
1143 }
1144
1145 root = value64(node, i);
1146 top = 0;
1147 }
1148
1149 if (i < 0 || le64_to_cpu(node->keys[i]) != key)
1150 i++;
1151
1152 *index = i;
1153 return 0;
1154}
1155
1156static int __btree_get_overwrite_leaf(struct shadow_spine *s, dm_block_t root,
1157 uint64_t key, int *index)
1158{
1159 int r, i = -1;
1160 struct btree_node *node;
1161
1162 *index = 0;
1163 for (;;) {
1164 r = shadow_step(s, root, &s->info->value_type);
1165 if (r < 0)
1166 return r;
1167
1168 node = dm_block_data(shadow_current(s));
1169
1170 /*
1171 * We have to patch up the parent node, ugly, but I don't
1172 * see a way to do this automatically as part of the spine
1173 * op.
1174 */
1175 if (shadow_has_parent(s) && i >= 0) {
1176 __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
1177
1178 __dm_bless_for_disk(&location);
1179 memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
1180 &location, sizeof(__le64));
1181 }
1182
1183 node = dm_block_data(shadow_current(s));
1184 i = lower_bound(node, key);
1185
1186 BUG_ON(i < 0);
1187 BUG_ON(i >= le32_to_cpu(node->header.nr_entries));
1188
1189 if (le32_to_cpu(node->header.flags) & LEAF_NODE) {
1190 if (key != le64_to_cpu(node->keys[i]))
1191 return -EINVAL;
1192 break;
1193 }
1194
1195 root = value64(node, i);
1196 }
1197
1198 *index = i;
1199 return 0;
1200}
1201
1202int btree_get_overwrite_leaf(struct dm_btree_info *info, dm_block_t root,
1203 uint64_t key, int *index,
1204 dm_block_t *new_root, struct dm_block **leaf)
1205{
1206 int r;
1207 struct shadow_spine spine;
1208
1209 BUG_ON(info->levels > 1);
1210 init_shadow_spine(&spine, info);
1211 r = __btree_get_overwrite_leaf(&spine, root, key, index);
1212 if (!r) {
1213 *new_root = shadow_root(&spine);
1214 *leaf = shadow_current(&spine);
1215
1216 /*
1217 * Decrement the count so exit_shadow_spine() doesn't
1218 * unlock the leaf.
1219 */
1220 spine.count--;
1221 }
1222 exit_shadow_spine(&spine);
1223
1224 return r;
1225}
1226
1227static bool need_insert(struct btree_node *node, uint64_t *keys,
1228 unsigned int level, unsigned int index)
1229{
1230 return ((index >= le32_to_cpu(node->header.nr_entries)) ||
1231 (le64_to_cpu(node->keys[index]) != keys[level]));
1232}
1233
1234static int insert(struct dm_btree_info *info, dm_block_t root,
1235 uint64_t *keys, void *value, dm_block_t *new_root,
1236 int *inserted)
1237 __dm_written_to_disk(value)
1238{
1239 int r;
1240 unsigned int level, index = -1, last_level = info->levels - 1;
1241 dm_block_t block = root;
1242 struct shadow_spine spine;
1243 struct btree_node *n;
1244 struct dm_btree_value_type le64_type;
1245
1246 init_le64_type(info->tm, &le64_type);
1247 init_shadow_spine(&spine, info);
1248
1249 for (level = 0; level < (info->levels - 1); level++) {
1250 r = btree_insert_raw(&spine, block, &le64_type, keys[level], &index);
1251 if (r < 0)
1252 goto bad;
1253
1254 n = dm_block_data(shadow_current(&spine));
1255
1256 if (need_insert(n, keys, level, index)) {
1257 dm_block_t new_tree;
1258 __le64 new_le;
1259
1260 r = dm_btree_empty(info, &new_tree);
1261 if (r < 0)
1262 goto bad;
1263
1264 new_le = cpu_to_le64(new_tree);
1265 __dm_bless_for_disk(&new_le);
1266
1267 r = insert_at(sizeof(uint64_t), n, index,
1268 keys[level], &new_le);
1269 if (r)
1270 goto bad;
1271 }
1272
1273 if (level < last_level)
1274 block = value64(n, index);
1275 }
1276
1277 r = btree_insert_raw(&spine, block, &info->value_type,
1278 keys[level], &index);
1279 if (r < 0)
1280 goto bad;
1281
1282 n = dm_block_data(shadow_current(&spine));
1283
1284 if (need_insert(n, keys, level, index)) {
1285 if (inserted)
1286 *inserted = 1;
1287
1288 r = insert_at(info->value_type.size, n, index,
1289 keys[level], value);
1290 if (r)
1291 goto bad_unblessed;
1292 } else {
1293 if (inserted)
1294 *inserted = 0;
1295
1296 if (info->value_type.dec &&
1297 (!info->value_type.equal ||
1298 !info->value_type.equal(
1299 info->value_type.context,
1300 value_ptr(n, index),
1301 value))) {
1302 info->value_type.dec(info->value_type.context,
1303 value_ptr(n, index), 1);
1304 }
1305 memcpy_disk(value_ptr(n, index),
1306 value, info->value_type.size);
1307 }
1308
1309 *new_root = shadow_root(&spine);
1310 exit_shadow_spine(&spine);
1311
1312 return 0;
1313
1314bad:
1315 __dm_unbless_for_disk(value);
1316bad_unblessed:
1317 exit_shadow_spine(&spine);
1318 return r;
1319}
1320
1321int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
1322 uint64_t *keys, void *value, dm_block_t *new_root)
1323 __dm_written_to_disk(value)
1324{
1325 return insert(info, root, keys, value, new_root, NULL);
1326}
1327EXPORT_SYMBOL_GPL(dm_btree_insert);
1328
1329int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
1330 uint64_t *keys, void *value, dm_block_t *new_root,
1331 int *inserted)
1332 __dm_written_to_disk(value)
1333{
1334 return insert(info, root, keys, value, new_root, inserted);
1335}
1336EXPORT_SYMBOL_GPL(dm_btree_insert_notify);
1337
1338/*----------------------------------------------------------------*/
1339
1340static int find_key(struct ro_spine *s, dm_block_t block, bool find_highest,
1341 uint64_t *result_key, dm_block_t *next_block)
1342{
1343 int i, r;
1344 uint32_t flags;
1345
1346 do {
1347 r = ro_step(s, block);
1348 if (r < 0)
1349 return r;
1350
1351 flags = le32_to_cpu(ro_node(s)->header.flags);
1352 i = le32_to_cpu(ro_node(s)->header.nr_entries);
1353 if (!i)
1354 return -ENODATA;
1355
1356 i--;
1357
1358 if (find_highest)
1359 *result_key = le64_to_cpu(ro_node(s)->keys[i]);
1360 else
1361 *result_key = le64_to_cpu(ro_node(s)->keys[0]);
1362
1363 if (next_block || flags & INTERNAL_NODE) {
1364 if (find_highest)
1365 block = value64(ro_node(s), i);
1366 else
1367 block = value64(ro_node(s), 0);
1368 }
1369
1370 } while (flags & INTERNAL_NODE);
1371
1372 if (next_block)
1373 *next_block = block;
1374 return 0;
1375}
1376
1377static int dm_btree_find_key(struct dm_btree_info *info, dm_block_t root,
1378 bool find_highest, uint64_t *result_keys)
1379{
1380 int r = 0, count = 0, level;
1381 struct ro_spine spine;
1382
1383 init_ro_spine(&spine, info);
1384 for (level = 0; level < info->levels; level++) {
1385 r = find_key(&spine, root, find_highest, result_keys + level,
1386 level == info->levels - 1 ? NULL : &root);
1387 if (r == -ENODATA) {
1388 r = 0;
1389 break;
1390
1391 } else if (r)
1392 break;
1393
1394 count++;
1395 }
1396 exit_ro_spine(&spine);
1397
1398 return r ? r : count;
1399}
1400
1401int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
1402 uint64_t *result_keys)
1403{
1404 return dm_btree_find_key(info, root, true, result_keys);
1405}
1406EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);
1407
1408int dm_btree_find_lowest_key(struct dm_btree_info *info, dm_block_t root,
1409 uint64_t *result_keys)
1410{
1411 return dm_btree_find_key(info, root, false, result_keys);
1412}
1413EXPORT_SYMBOL_GPL(dm_btree_find_lowest_key);
1414
1415/*----------------------------------------------------------------*/
1416
1417/*
1418 * FIXME: We shouldn't use a recursive algorithm when we have limited stack
1419 * space. Also this only works for single level trees.
1420 */
1421static int walk_node(struct dm_btree_info *info, dm_block_t block,
1422 int (*fn)(void *context, uint64_t *keys, void *leaf),
1423 void *context)
1424{
1425 int r;
1426 unsigned int i, nr;
1427 struct dm_block *node;
1428 struct btree_node *n;
1429 uint64_t keys;
1430
1431 r = bn_read_lock(info, block, &node);
1432 if (r)
1433 return r;
1434
1435 n = dm_block_data(node);
1436
1437 nr = le32_to_cpu(n->header.nr_entries);
1438 for (i = 0; i < nr; i++) {
1439 if (le32_to_cpu(n->header.flags) & INTERNAL_NODE) {
1440 r = walk_node(info, value64(n, i), fn, context);
1441 if (r)
1442 goto out;
1443 } else {
1444 keys = le64_to_cpu(*key_ptr(n, i));
1445 r = fn(context, &keys, value_ptr(n, i));
1446 if (r)
1447 goto out;
1448 }
1449 }
1450
1451out:
1452 dm_tm_unlock(info->tm, node);
1453 return r;
1454}
1455
1456int dm_btree_walk(struct dm_btree_info *info, dm_block_t root,
1457 int (*fn)(void *context, uint64_t *keys, void *leaf),
1458 void *context)
1459{
1460 BUG_ON(info->levels > 1);
1461 return walk_node(info, root, fn, context);
1462}
1463EXPORT_SYMBOL_GPL(dm_btree_walk);
1464
1465/*----------------------------------------------------------------*/
1466
1467static void prefetch_values(struct dm_btree_cursor *c)
1468{
1469 unsigned int i, nr;
1470 __le64 value_le;
1471 struct cursor_node *n = c->nodes + c->depth - 1;
1472 struct btree_node *bn = dm_block_data(n->b);
1473 struct dm_block_manager *bm = dm_tm_get_bm(c->info->tm);
1474
1475 BUG_ON(c->info->value_type.size != sizeof(value_le));
1476
1477 nr = le32_to_cpu(bn->header.nr_entries);
1478 for (i = 0; i < nr; i++) {
1479 memcpy(&value_le, value_ptr(bn, i), sizeof(value_le));
1480 dm_bm_prefetch(bm, le64_to_cpu(value_le));
1481 }
1482}
1483
1484static bool leaf_node(struct dm_btree_cursor *c)
1485{
1486 struct cursor_node *n = c->nodes + c->depth - 1;
1487 struct btree_node *bn = dm_block_data(n->b);
1488
1489 return le32_to_cpu(bn->header.flags) & LEAF_NODE;
1490}
1491
1492static int push_node(struct dm_btree_cursor *c, dm_block_t b)
1493{
1494 int r;
1495 struct cursor_node *n = c->nodes + c->depth;
1496
1497 if (c->depth >= DM_BTREE_CURSOR_MAX_DEPTH - 1) {
1498 DMERR("couldn't push cursor node, stack depth too high");
1499 return -EINVAL;
1500 }
1501
1502 r = bn_read_lock(c->info, b, &n->b);
1503 if (r)
1504 return r;
1505
1506 n->index = 0;
1507 c->depth++;
1508
1509 if (c->prefetch_leaves || !leaf_node(c))
1510 prefetch_values(c);
1511
1512 return 0;
1513}
1514
1515static void pop_node(struct dm_btree_cursor *c)
1516{
1517 c->depth--;
1518 unlock_block(c->info, c->nodes[c->depth].b);
1519}
1520
1521static int inc_or_backtrack(struct dm_btree_cursor *c)
1522{
1523 struct cursor_node *n;
1524 struct btree_node *bn;
1525
1526 for (;;) {
1527 if (!c->depth)
1528 return -ENODATA;
1529
1530 n = c->nodes + c->depth - 1;
1531 bn = dm_block_data(n->b);
1532
1533 n->index++;
1534 if (n->index < le32_to_cpu(bn->header.nr_entries))
1535 break;
1536
1537 pop_node(c);
1538 }
1539
1540 return 0;
1541}
1542
1543static int find_leaf(struct dm_btree_cursor *c)
1544{
1545 int r = 0;
1546 struct cursor_node *n;
1547 struct btree_node *bn;
1548 __le64 value_le;
1549
1550 for (;;) {
1551 n = c->nodes + c->depth - 1;
1552 bn = dm_block_data(n->b);
1553
1554 if (le32_to_cpu(bn->header.flags) & LEAF_NODE)
1555 break;
1556
1557 memcpy(&value_le, value_ptr(bn, n->index), sizeof(value_le));
1558 r = push_node(c, le64_to_cpu(value_le));
1559 if (r) {
1560 DMERR("push_node failed");
1561 break;
1562 }
1563 }
1564
1565 if (!r && (le32_to_cpu(bn->header.nr_entries) == 0))
1566 return -ENODATA;
1567
1568 return r;
1569}
1570
1571int dm_btree_cursor_begin(struct dm_btree_info *info, dm_block_t root,
1572 bool prefetch_leaves, struct dm_btree_cursor *c)
1573{
1574 int r;
1575
1576 c->info = info;
1577 c->root = root;
1578 c->depth = 0;
1579 c->prefetch_leaves = prefetch_leaves;
1580
1581 r = push_node(c, root);
1582 if (r)
1583 return r;
1584
1585 return find_leaf(c);
1586}
1587EXPORT_SYMBOL_GPL(dm_btree_cursor_begin);
1588
1589void dm_btree_cursor_end(struct dm_btree_cursor *c)
1590{
1591 while (c->depth)
1592 pop_node(c);
1593}
1594EXPORT_SYMBOL_GPL(dm_btree_cursor_end);
1595
1596int dm_btree_cursor_next(struct dm_btree_cursor *c)
1597{
1598 int r = inc_or_backtrack(c);
1599
1600 if (!r) {
1601 r = find_leaf(c);
1602 if (r)
1603 DMERR("find_leaf failed");
1604 }
1605
1606 return r;
1607}
1608EXPORT_SYMBOL_GPL(dm_btree_cursor_next);
1609
1610int dm_btree_cursor_skip(struct dm_btree_cursor *c, uint32_t count)
1611{
1612 int r = 0;
1613
1614 while (count-- && !r)
1615 r = dm_btree_cursor_next(c);
1616
1617 return r;
1618}
1619EXPORT_SYMBOL_GPL(dm_btree_cursor_skip);
1620
1621int dm_btree_cursor_get_value(struct dm_btree_cursor *c, uint64_t *key, void *value_le)
1622{
1623 if (c->depth) {
1624 struct cursor_node *n = c->nodes + c->depth - 1;
1625 struct btree_node *bn = dm_block_data(n->b);
1626
1627 if (le32_to_cpu(bn->header.flags) & INTERNAL_NODE)
1628 return -EINVAL;
1629
1630 *key = le64_to_cpu(*key_ptr(bn, n->index));
1631 memcpy(value_le, value_ptr(bn, n->index), c->info->value_type.size);
1632 return 0;
1633
1634 } else
1635 return -ENODATA;
1636}
1637EXPORT_SYMBOL_GPL(dm_btree_cursor_get_value);
1/*
2 * Copyright (C) 2011 Red Hat, Inc.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm-btree-internal.h"
8#include "dm-space-map.h"
9#include "dm-transaction-manager.h"
10
11#include <linux/export.h>
12#include <linux/device-mapper.h>
13
14#define DM_MSG_PREFIX "btree"
15
16/*----------------------------------------------------------------
17 * Array manipulation
18 *--------------------------------------------------------------*/
19static void memcpy_disk(void *dest, const void *src, size_t len)
20 __dm_written_to_disk(src)
21{
22 memcpy(dest, src, len);
23 __dm_unbless_for_disk(src);
24}
25
26static void array_insert(void *base, size_t elt_size, unsigned nr_elts,
27 unsigned index, void *elt)
28 __dm_written_to_disk(elt)
29{
30 if (index < nr_elts)
31 memmove(base + (elt_size * (index + 1)),
32 base + (elt_size * index),
33 (nr_elts - index) * elt_size);
34
35 memcpy_disk(base + (elt_size * index), elt, elt_size);
36}
37
38/*----------------------------------------------------------------*/
39
40/* makes the assumption that no two keys are the same. */
41static int bsearch(struct node *n, uint64_t key, int want_hi)
42{
43 int lo = -1, hi = le32_to_cpu(n->header.nr_entries);
44
45 while (hi - lo > 1) {
46 int mid = lo + ((hi - lo) / 2);
47 uint64_t mid_key = le64_to_cpu(n->keys[mid]);
48
49 if (mid_key == key)
50 return mid;
51
52 if (mid_key < key)
53 lo = mid;
54 else
55 hi = mid;
56 }
57
58 return want_hi ? hi : lo;
59}
60
61int lower_bound(struct node *n, uint64_t key)
62{
63 return bsearch(n, key, 0);
64}
65
66void inc_children(struct dm_transaction_manager *tm, struct node *n,
67 struct dm_btree_value_type *vt)
68{
69 unsigned i;
70 uint32_t nr_entries = le32_to_cpu(n->header.nr_entries);
71
72 if (le32_to_cpu(n->header.flags) & INTERNAL_NODE)
73 for (i = 0; i < nr_entries; i++)
74 dm_tm_inc(tm, value64(n, i));
75 else if (vt->inc)
76 for (i = 0; i < nr_entries; i++)
77 vt->inc(vt->context, value_ptr(n, i));
78}
79
80static int insert_at(size_t value_size, struct node *node, unsigned index,
81 uint64_t key, void *value)
82 __dm_written_to_disk(value)
83{
84 uint32_t nr_entries = le32_to_cpu(node->header.nr_entries);
85 __le64 key_le = cpu_to_le64(key);
86
87 if (index > nr_entries ||
88 index >= le32_to_cpu(node->header.max_entries)) {
89 DMERR("too many entries in btree node for insert");
90 __dm_unbless_for_disk(value);
91 return -ENOMEM;
92 }
93
94 __dm_bless_for_disk(&key_le);
95
96 array_insert(node->keys, sizeof(*node->keys), nr_entries, index, &key_le);
97 array_insert(value_base(node), value_size, nr_entries, index, value);
98 node->header.nr_entries = cpu_to_le32(nr_entries + 1);
99
100 return 0;
101}
102
103/*----------------------------------------------------------------*/
104
105/*
106 * We want 3n entries (for some n). This works more nicely for repeated
107 * insert remove loops than (2n + 1).
108 */
109static uint32_t calc_max_entries(size_t value_size, size_t block_size)
110{
111 uint32_t total, n;
112 size_t elt_size = sizeof(uint64_t) + value_size; /* key + value */
113
114 block_size -= sizeof(struct node_header);
115 total = block_size / elt_size;
116 n = total / 3; /* rounds down */
117
118 return 3 * n;
119}
120
121int dm_btree_empty(struct dm_btree_info *info, dm_block_t *root)
122{
123 int r;
124 struct dm_block *b;
125 struct node *n;
126 size_t block_size;
127 uint32_t max_entries;
128
129 r = new_block(info, &b);
130 if (r < 0)
131 return r;
132
133 block_size = dm_bm_block_size(dm_tm_get_bm(info->tm));
134 max_entries = calc_max_entries(info->value_type.size, block_size);
135
136 n = dm_block_data(b);
137 memset(n, 0, block_size);
138 n->header.flags = cpu_to_le32(LEAF_NODE);
139 n->header.nr_entries = cpu_to_le32(0);
140 n->header.max_entries = cpu_to_le32(max_entries);
141 n->header.value_size = cpu_to_le32(info->value_type.size);
142
143 *root = dm_block_location(b);
144 return unlock_block(info, b);
145}
146EXPORT_SYMBOL_GPL(dm_btree_empty);
147
148/*----------------------------------------------------------------*/
149
150/*
151 * Deletion uses a recursive algorithm, since we have limited stack space
152 * we explicitly manage our own stack on the heap.
153 */
154#define MAX_SPINE_DEPTH 64
155struct frame {
156 struct dm_block *b;
157 struct node *n;
158 unsigned level;
159 unsigned nr_children;
160 unsigned current_child;
161};
162
163struct del_stack {
164 struct dm_transaction_manager *tm;
165 int top;
166 struct frame spine[MAX_SPINE_DEPTH];
167};
168
169static int top_frame(struct del_stack *s, struct frame **f)
170{
171 if (s->top < 0) {
172 DMERR("btree deletion stack empty");
173 return -EINVAL;
174 }
175
176 *f = s->spine + s->top;
177
178 return 0;
179}
180
181static int unprocessed_frames(struct del_stack *s)
182{
183 return s->top >= 0;
184}
185
186static int push_frame(struct del_stack *s, dm_block_t b, unsigned level)
187{
188 int r;
189 uint32_t ref_count;
190
191 if (s->top >= MAX_SPINE_DEPTH - 1) {
192 DMERR("btree deletion stack out of memory");
193 return -ENOMEM;
194 }
195
196 r = dm_tm_ref(s->tm, b, &ref_count);
197 if (r)
198 return r;
199
200 if (ref_count > 1)
201 /*
202 * This is a shared node, so we can just decrement it's
203 * reference counter and leave the children.
204 */
205 dm_tm_dec(s->tm, b);
206
207 else {
208 struct frame *f = s->spine + ++s->top;
209
210 r = dm_tm_read_lock(s->tm, b, &btree_node_validator, &f->b);
211 if (r) {
212 s->top--;
213 return r;
214 }
215
216 f->n = dm_block_data(f->b);
217 f->level = level;
218 f->nr_children = le32_to_cpu(f->n->header.nr_entries);
219 f->current_child = 0;
220 }
221
222 return 0;
223}
224
225static void pop_frame(struct del_stack *s)
226{
227 struct frame *f = s->spine + s->top--;
228
229 dm_tm_dec(s->tm, dm_block_location(f->b));
230 dm_tm_unlock(s->tm, f->b);
231}
232
233int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
234{
235 int r;
236 struct del_stack *s;
237
238 s = kmalloc(sizeof(*s), GFP_KERNEL);
239 if (!s)
240 return -ENOMEM;
241 s->tm = info->tm;
242 s->top = -1;
243
244 r = push_frame(s, root, 1);
245 if (r)
246 goto out;
247
248 while (unprocessed_frames(s)) {
249 uint32_t flags;
250 struct frame *f;
251 dm_block_t b;
252
253 r = top_frame(s, &f);
254 if (r)
255 goto out;
256
257 if (f->current_child >= f->nr_children) {
258 pop_frame(s);
259 continue;
260 }
261
262 flags = le32_to_cpu(f->n->header.flags);
263 if (flags & INTERNAL_NODE) {
264 b = value64(f->n, f->current_child);
265 f->current_child++;
266 r = push_frame(s, b, f->level);
267 if (r)
268 goto out;
269
270 } else if (f->level != (info->levels - 1)) {
271 b = value64(f->n, f->current_child);
272 f->current_child++;
273 r = push_frame(s, b, f->level + 1);
274 if (r)
275 goto out;
276
277 } else {
278 if (info->value_type.dec) {
279 unsigned i;
280
281 for (i = 0; i < f->nr_children; i++)
282 info->value_type.dec(info->value_type.context,
283 value_ptr(f->n, i));
284 }
285 f->current_child = f->nr_children;
286 }
287 }
288
289out:
290 kfree(s);
291 return r;
292}
293EXPORT_SYMBOL_GPL(dm_btree_del);
294
295/*----------------------------------------------------------------*/
296
297static int btree_lookup_raw(struct ro_spine *s, dm_block_t block, uint64_t key,
298 int (*search_fn)(struct node *, uint64_t),
299 uint64_t *result_key, void *v, size_t value_size)
300{
301 int i, r;
302 uint32_t flags, nr_entries;
303
304 do {
305 r = ro_step(s, block);
306 if (r < 0)
307 return r;
308
309 i = search_fn(ro_node(s), key);
310
311 flags = le32_to_cpu(ro_node(s)->header.flags);
312 nr_entries = le32_to_cpu(ro_node(s)->header.nr_entries);
313 if (i < 0 || i >= nr_entries)
314 return -ENODATA;
315
316 if (flags & INTERNAL_NODE)
317 block = value64(ro_node(s), i);
318
319 } while (!(flags & LEAF_NODE));
320
321 *result_key = le64_to_cpu(ro_node(s)->keys[i]);
322 memcpy(v, value_ptr(ro_node(s), i), value_size);
323
324 return 0;
325}
326
327int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
328 uint64_t *keys, void *value_le)
329{
330 unsigned level, last_level = info->levels - 1;
331 int r = -ENODATA;
332 uint64_t rkey;
333 __le64 internal_value_le;
334 struct ro_spine spine;
335
336 init_ro_spine(&spine, info);
337 for (level = 0; level < info->levels; level++) {
338 size_t size;
339 void *value_p;
340
341 if (level == last_level) {
342 value_p = value_le;
343 size = info->value_type.size;
344
345 } else {
346 value_p = &internal_value_le;
347 size = sizeof(uint64_t);
348 }
349
350 r = btree_lookup_raw(&spine, root, keys[level],
351 lower_bound, &rkey,
352 value_p, size);
353
354 if (!r) {
355 if (rkey != keys[level]) {
356 exit_ro_spine(&spine);
357 return -ENODATA;
358 }
359 } else {
360 exit_ro_spine(&spine);
361 return r;
362 }
363
364 root = le64_to_cpu(internal_value_le);
365 }
366 exit_ro_spine(&spine);
367
368 return r;
369}
370EXPORT_SYMBOL_GPL(dm_btree_lookup);
371
372/*
373 * Splits a node by creating a sibling node and shifting half the nodes
374 * contents across. Assumes there is a parent node, and it has room for
375 * another child.
376 *
377 * Before:
378 * +--------+
379 * | Parent |
380 * +--------+
381 * |
382 * v
383 * +----------+
384 * | A ++++++ |
385 * +----------+
386 *
387 *
388 * After:
389 * +--------+
390 * | Parent |
391 * +--------+
392 * | |
393 * v +------+
394 * +---------+ |
395 * | A* +++ | v
396 * +---------+ +-------+
397 * | B +++ |
398 * +-------+
399 *
400 * Where A* is a shadow of A.
401 */
402static int btree_split_sibling(struct shadow_spine *s, dm_block_t root,
403 unsigned parent_index, uint64_t key)
404{
405 int r;
406 size_t size;
407 unsigned nr_left, nr_right;
408 struct dm_block *left, *right, *parent;
409 struct node *ln, *rn, *pn;
410 __le64 location;
411
412 left = shadow_current(s);
413
414 r = new_block(s->info, &right);
415 if (r < 0)
416 return r;
417
418 ln = dm_block_data(left);
419 rn = dm_block_data(right);
420
421 nr_left = le32_to_cpu(ln->header.nr_entries) / 2;
422 nr_right = le32_to_cpu(ln->header.nr_entries) - nr_left;
423
424 ln->header.nr_entries = cpu_to_le32(nr_left);
425
426 rn->header.flags = ln->header.flags;
427 rn->header.nr_entries = cpu_to_le32(nr_right);
428 rn->header.max_entries = ln->header.max_entries;
429 rn->header.value_size = ln->header.value_size;
430 memcpy(rn->keys, ln->keys + nr_left, nr_right * sizeof(rn->keys[0]));
431
432 size = le32_to_cpu(ln->header.flags) & INTERNAL_NODE ?
433 sizeof(uint64_t) : s->info->value_type.size;
434 memcpy(value_ptr(rn, 0), value_ptr(ln, nr_left),
435 size * nr_right);
436
437 /*
438 * Patch up the parent
439 */
440 parent = shadow_parent(s);
441
442 pn = dm_block_data(parent);
443 location = cpu_to_le64(dm_block_location(left));
444 __dm_bless_for_disk(&location);
445 memcpy_disk(value_ptr(pn, parent_index),
446 &location, sizeof(__le64));
447
448 location = cpu_to_le64(dm_block_location(right));
449 __dm_bless_for_disk(&location);
450
451 r = insert_at(sizeof(__le64), pn, parent_index + 1,
452 le64_to_cpu(rn->keys[0]), &location);
453 if (r)
454 return r;
455
456 if (key < le64_to_cpu(rn->keys[0])) {
457 unlock_block(s->info, right);
458 s->nodes[1] = left;
459 } else {
460 unlock_block(s->info, left);
461 s->nodes[1] = right;
462 }
463
464 return 0;
465}
466
467/*
468 * Splits a node by creating two new children beneath the given node.
469 *
470 * Before:
471 * +----------+
472 * | A ++++++ |
473 * +----------+
474 *
475 *
476 * After:
477 * +------------+
478 * | A (shadow) |
479 * +------------+
480 * | |
481 * +------+ +----+
482 * | |
483 * v v
484 * +-------+ +-------+
485 * | B +++ | | C +++ |
486 * +-------+ +-------+
487 */
488static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
489{
490 int r;
491 size_t size;
492 unsigned nr_left, nr_right;
493 struct dm_block *left, *right, *new_parent;
494 struct node *pn, *ln, *rn;
495 __le64 val;
496
497 new_parent = shadow_current(s);
498
499 r = new_block(s->info, &left);
500 if (r < 0)
501 return r;
502
503 r = new_block(s->info, &right);
504 if (r < 0) {
505 /* FIXME: put left */
506 return r;
507 }
508
509 pn = dm_block_data(new_parent);
510 ln = dm_block_data(left);
511 rn = dm_block_data(right);
512
513 nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
514 nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
515
516 ln->header.flags = pn->header.flags;
517 ln->header.nr_entries = cpu_to_le32(nr_left);
518 ln->header.max_entries = pn->header.max_entries;
519 ln->header.value_size = pn->header.value_size;
520
521 rn->header.flags = pn->header.flags;
522 rn->header.nr_entries = cpu_to_le32(nr_right);
523 rn->header.max_entries = pn->header.max_entries;
524 rn->header.value_size = pn->header.value_size;
525
526 memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
527 memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
528
529 size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
530 sizeof(__le64) : s->info->value_type.size;
531 memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
532 memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left),
533 nr_right * size);
534
535 /* new_parent should just point to l and r now */
536 pn->header.flags = cpu_to_le32(INTERNAL_NODE);
537 pn->header.nr_entries = cpu_to_le32(2);
538 pn->header.max_entries = cpu_to_le32(
539 calc_max_entries(sizeof(__le64),
540 dm_bm_block_size(
541 dm_tm_get_bm(s->info->tm))));
542 pn->header.value_size = cpu_to_le32(sizeof(__le64));
543
544 val = cpu_to_le64(dm_block_location(left));
545 __dm_bless_for_disk(&val);
546 pn->keys[0] = ln->keys[0];
547 memcpy_disk(value_ptr(pn, 0), &val, sizeof(__le64));
548
549 val = cpu_to_le64(dm_block_location(right));
550 __dm_bless_for_disk(&val);
551 pn->keys[1] = rn->keys[0];
552 memcpy_disk(value_ptr(pn, 1), &val, sizeof(__le64));
553
554 /*
555 * rejig the spine. This is ugly, since it knows too
556 * much about the spine
557 */
558 if (s->nodes[0] != new_parent) {
559 unlock_block(s->info, s->nodes[0]);
560 s->nodes[0] = new_parent;
561 }
562 if (key < le64_to_cpu(rn->keys[0])) {
563 unlock_block(s->info, right);
564 s->nodes[1] = left;
565 } else {
566 unlock_block(s->info, left);
567 s->nodes[1] = right;
568 }
569 s->count = 2;
570
571 return 0;
572}
573
574static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
575 struct dm_btree_value_type *vt,
576 uint64_t key, unsigned *index)
577{
578 int r, i = *index, top = 1;
579 struct node *node;
580
581 for (;;) {
582 r = shadow_step(s, root, vt);
583 if (r < 0)
584 return r;
585
586 node = dm_block_data(shadow_current(s));
587
588 /*
589 * We have to patch up the parent node, ugly, but I don't
590 * see a way to do this automatically as part of the spine
591 * op.
592 */
593 if (shadow_has_parent(s) && i >= 0) { /* FIXME: second clause unness. */
594 __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
595
596 __dm_bless_for_disk(&location);
597 memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
598 &location, sizeof(__le64));
599 }
600
601 node = dm_block_data(shadow_current(s));
602
603 if (node->header.nr_entries == node->header.max_entries) {
604 if (top)
605 r = btree_split_beneath(s, key);
606 else
607 r = btree_split_sibling(s, root, i, key);
608
609 if (r < 0)
610 return r;
611 }
612
613 node = dm_block_data(shadow_current(s));
614
615 i = lower_bound(node, key);
616
617 if (le32_to_cpu(node->header.flags) & LEAF_NODE)
618 break;
619
620 if (i < 0) {
621 /* change the bounds on the lowest key */
622 node->keys[0] = cpu_to_le64(key);
623 i = 0;
624 }
625
626 root = value64(node, i);
627 top = 0;
628 }
629
630 if (i < 0 || le64_to_cpu(node->keys[i]) != key)
631 i++;
632
633 *index = i;
634 return 0;
635}
636
637static int insert(struct dm_btree_info *info, dm_block_t root,
638 uint64_t *keys, void *value, dm_block_t *new_root,
639 int *inserted)
640 __dm_written_to_disk(value)
641{
642 int r, need_insert;
643 unsigned level, index = -1, last_level = info->levels - 1;
644 dm_block_t block = root;
645 struct shadow_spine spine;
646 struct node *n;
647 struct dm_btree_value_type le64_type;
648
649 le64_type.context = NULL;
650 le64_type.size = sizeof(__le64);
651 le64_type.inc = NULL;
652 le64_type.dec = NULL;
653 le64_type.equal = NULL;
654
655 init_shadow_spine(&spine, info);
656
657 for (level = 0; level < (info->levels - 1); level++) {
658 r = btree_insert_raw(&spine, block, &le64_type, keys[level], &index);
659 if (r < 0)
660 goto bad;
661
662 n = dm_block_data(shadow_current(&spine));
663 need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) ||
664 (le64_to_cpu(n->keys[index]) != keys[level]));
665
666 if (need_insert) {
667 dm_block_t new_tree;
668 __le64 new_le;
669
670 r = dm_btree_empty(info, &new_tree);
671 if (r < 0)
672 goto bad;
673
674 new_le = cpu_to_le64(new_tree);
675 __dm_bless_for_disk(&new_le);
676
677 r = insert_at(sizeof(uint64_t), n, index,
678 keys[level], &new_le);
679 if (r)
680 goto bad;
681 }
682
683 if (level < last_level)
684 block = value64(n, index);
685 }
686
687 r = btree_insert_raw(&spine, block, &info->value_type,
688 keys[level], &index);
689 if (r < 0)
690 goto bad;
691
692 n = dm_block_data(shadow_current(&spine));
693 need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) ||
694 (le64_to_cpu(n->keys[index]) != keys[level]));
695
696 if (need_insert) {
697 if (inserted)
698 *inserted = 1;
699
700 r = insert_at(info->value_type.size, n, index,
701 keys[level], value);
702 if (r)
703 goto bad_unblessed;
704 } else {
705 if (inserted)
706 *inserted = 0;
707
708 if (info->value_type.dec &&
709 (!info->value_type.equal ||
710 !info->value_type.equal(
711 info->value_type.context,
712 value_ptr(n, index),
713 value))) {
714 info->value_type.dec(info->value_type.context,
715 value_ptr(n, index));
716 }
717 memcpy_disk(value_ptr(n, index),
718 value, info->value_type.size);
719 }
720
721 *new_root = shadow_root(&spine);
722 exit_shadow_spine(&spine);
723
724 return 0;
725
726bad:
727 __dm_unbless_for_disk(value);
728bad_unblessed:
729 exit_shadow_spine(&spine);
730 return r;
731}
732
733int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
734 uint64_t *keys, void *value, dm_block_t *new_root)
735 __dm_written_to_disk(value)
736{
737 return insert(info, root, keys, value, new_root, NULL);
738}
739EXPORT_SYMBOL_GPL(dm_btree_insert);
740
741int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
742 uint64_t *keys, void *value, dm_block_t *new_root,
743 int *inserted)
744 __dm_written_to_disk(value)
745{
746 return insert(info, root, keys, value, new_root, inserted);
747}
748EXPORT_SYMBOL_GPL(dm_btree_insert_notify);
749
750/*----------------------------------------------------------------*/
751
752static int find_highest_key(struct ro_spine *s, dm_block_t block,
753 uint64_t *result_key, dm_block_t *next_block)
754{
755 int i, r;
756 uint32_t flags;
757
758 do {
759 r = ro_step(s, block);
760 if (r < 0)
761 return r;
762
763 flags = le32_to_cpu(ro_node(s)->header.flags);
764 i = le32_to_cpu(ro_node(s)->header.nr_entries);
765 if (!i)
766 return -ENODATA;
767 else
768 i--;
769
770 *result_key = le64_to_cpu(ro_node(s)->keys[i]);
771 if (next_block || flags & INTERNAL_NODE)
772 block = value64(ro_node(s), i);
773
774 } while (flags & INTERNAL_NODE);
775
776 if (next_block)
777 *next_block = block;
778 return 0;
779}
780
781int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
782 uint64_t *result_keys)
783{
784 int r = 0, count = 0, level;
785 struct ro_spine spine;
786
787 init_ro_spine(&spine, info);
788 for (level = 0; level < info->levels; level++) {
789 r = find_highest_key(&spine, root, result_keys + level,
790 level == info->levels - 1 ? NULL : &root);
791 if (r == -ENODATA) {
792 r = 0;
793 break;
794
795 } else if (r)
796 break;
797
798 count++;
799 }
800 exit_ro_spine(&spine);
801
802 return r ? r : count;
803}
804EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);