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