drivers/md/persistent-data/dm-btree.c

   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  *--------------------------------------------------------------*/
  19 static 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
  26 static 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. */
  41 static 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
  61 int lower_bound(struct btree_node *n, uint64_t key)
  62 {
  63         return bsearch(n, key, 0);
  64 }
  65
  66 void inc_children(struct dm_transaction_manager *tm, struct btree_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
  80 static int insert_at(size_t value_size, struct btree_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  */
 109 static 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
 121 int dm_btree_empty(struct dm_btree_info *info, dm_block_t *root)
 122 {
 123         int r;
 124         struct dm_block *b;
 125         struct btree_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 }
 146 EXPORT_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
 155 struct frame {
 156         struct dm_block *b;
 157         struct btree_node *n;
 158         unsigned level;
 159         unsigned nr_children;
 160         unsigned current_child;
 161 };
 162
 163 struct del_stack {
 164         struct dm_transaction_manager *tm;
 165         int top;
 166         struct frame spine[MAX_SPINE_DEPTH];
 167 };
 168
 169 static 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
 181 static int unprocessed_frames(struct del_stack *s)
 182 {
 183         return s->top >= 0;
 184 }
 185
 186 static 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
 225 static 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
 233 static bool is_internal_level(struct dm_btree_info *info, struct frame *f)
 234 {
 235         return f->level < (info->levels - 1);
 236 }
 237
 238 int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
 239 {
 240         int r;
 241         struct del_stack *s;
 242
 243         s = kmalloc(sizeof(*s), GFP_KERNEL);
 244         if (!s)
 245                 return -ENOMEM;
 246         s->tm = info->tm;
 247         s->top = -1;
 248
 249         r = push_frame(s, root, 0);
 250         if (r)
 251                 goto out;
 252
 253         while (unprocessed_frames(s)) {
 254                 uint32_t flags;
 255                 struct frame *f;
 256                 dm_block_t b;
 257
 258                 r = top_frame(s, &f);
 259                 if (r)
 260                         goto out;
 261
 262                 if (f->current_child >= f->nr_children) {
 263                         pop_frame(s);
 264                         continue;
 265                 }
 266
 267                 flags = le32_to_cpu(f->n->header.flags);
 268                 if (flags & INTERNAL_NODE) {
 269                         b = value64(f->n, f->current_child);
 270                         f->current_child++;
 271                         r = push_frame(s, b, f->level);
 272                         if (r)
 273                                 goto out;
 274
 275                 } else if (is_internal_level(info, f)) {
 276                         b = value64(f->n, f->current_child);
 277                         f->current_child++;
 278                         r = push_frame(s, b, f->level + 1);
 279                         if (r)
 280                                 goto out;
 281
 282                 } else {
 283                         if (info->value_type.dec) {
 284                                 unsigned i;
 285
 286                                 for (i = 0; i < f->nr_children; i++)
 287                                         info->value_type.dec(info->value_type.context,
 288                                                              value_ptr(f->n, i));
 289                         }
 290                         f->current_child = f->nr_children;
 291                 }
 292         }
 293
 294 out:
 295         kfree(s);
 296         return r;
 297 }
 298 EXPORT_SYMBOL_GPL(dm_btree_del);
 299
 300 /*----------------------------------------------------------------*/
 301
 302 static int btree_lookup_raw(struct ro_spine *s, dm_block_t block, uint64_t key,
 303                             int (*search_fn)(struct btree_node *, uint64_t),
 304                             uint64_t *result_key, void *v, size_t value_size)
 305 {
 306         int i, r;
 307         uint32_t flags, nr_entries;
 308
 309         do {
 310                 r = ro_step(s, block);
 311                 if (r < 0)
 312                         return r;
 313
 314                 i = search_fn(ro_node(s), key);
 315
 316                 flags = le32_to_cpu(ro_node(s)->header.flags);
 317                 nr_entries = le32_to_cpu(ro_node(s)->header.nr_entries);
 318                 if (i < 0 || i >= nr_entries)
 319                         return -ENODATA;
 320
 321                 if (flags & INTERNAL_NODE)
 322                         block = value64(ro_node(s), i);
 323
 324         } while (!(flags & LEAF_NODE));
 325
 326         *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 327         memcpy(v, value_ptr(ro_node(s), i), value_size);
 328
 329         return 0;
 330 }
 331
 332 int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
 333                     uint64_t *keys, void *value_le)
 334 {
 335         unsigned level, last_level = info->levels - 1;
 336         int r = -ENODATA;
 337         uint64_t rkey;
 338         __le64 internal_value_le;
 339         struct ro_spine spine;
 340
 341         init_ro_spine(&spine, info);
 342         for (level = 0; level < info->levels; level++) {
 343                 size_t size;
 344                 void *value_p;
 345
 346                 if (level == last_level) {
 347                         value_p = value_le;
 348                         size = info->value_type.size;
 349
 350                 } else {
 351                         value_p = &internal_value_le;
 352                         size = sizeof(uint64_t);
 353                 }
 354
 355                 r = btree_lookup_raw(&spine, root, keys[level],
 356                                      lower_bound, &rkey,
 357                                      value_p, size);
 358
 359                 if (!r) {
 360                         if (rkey != keys[level]) {
 361                                 exit_ro_spine(&spine);
 362                                 return -ENODATA;
 363                         }
 364                 } else {
 365                         exit_ro_spine(&spine);
 366                         return r;
 367                 }
 368
 369                 root = le64_to_cpu(internal_value_le);
 370         }
 371         exit_ro_spine(&spine);
 372
 373         return r;
 374 }
 375 EXPORT_SYMBOL_GPL(dm_btree_lookup);
 376
 377 /*
 378  * Splits a node by creating a sibling node and shifting half the nodes
 379  * contents across.  Assumes there is a parent node, and it has room for
 380  * another child.
 381  *
 382  * Before:
 383  *        +--------+
 384  *        | Parent |
 385  *        +--------+
 386  *           |
 387  *           v
 388  *      +----------+
 389  *      | A ++++++ |
 390  *      +----------+
 391  *
 392  *
 393  * After:
 394  *              +--------+
 395  *              | Parent |
 396  *              +--------+
 397  *                |     |
 398  *                v     +------+
 399  *          +---------+        |
 400  *          | A* +++  |        v
 401  *          +---------+   +-------+
 402  *                        | B +++ |
 403  *                        +-------+
 404  *
 405  * Where A* is a shadow of A.
 406  */
 407 static int btree_split_sibling(struct shadow_spine *s, dm_block_t root,
 408                                unsigned parent_index, uint64_t key)
 409 {
 410         int r;
 411         size_t size;
 412         unsigned nr_left, nr_right;
 413         struct dm_block *left, *right, *parent;
 414         struct btree_node *ln, *rn, *pn;
 415         __le64 location;
 416
 417         left = shadow_current(s);
 418
 419         r = new_block(s->info, &right);
 420         if (r < 0)
 421                 return r;
 422
 423         ln = dm_block_data(left);
 424         rn = dm_block_data(right);
 425
 426         nr_left = le32_to_cpu(ln->header.nr_entries) / 2;
 427         nr_right = le32_to_cpu(ln->header.nr_entries) - nr_left;
 428
 429         ln->header.nr_entries = cpu_to_le32(nr_left);
 430
 431         rn->header.flags = ln->header.flags;
 432         rn->header.nr_entries = cpu_to_le32(nr_right);
 433         rn->header.max_entries = ln->header.max_entries;
 434         rn->header.value_size = ln->header.value_size;
 435         memcpy(rn->keys, ln->keys + nr_left, nr_right * sizeof(rn->keys[0]));
 436
 437         size = le32_to_cpu(ln->header.flags) & INTERNAL_NODE ?
 438                 sizeof(uint64_t) : s->info->value_type.size;
 439         memcpy(value_ptr(rn, 0), value_ptr(ln, nr_left),
 440                size * nr_right);
 441
 442         /*
 443          * Patch up the parent
 444          */
 445         parent = shadow_parent(s);
 446
 447         pn = dm_block_data(parent);
 448         location = cpu_to_le64(dm_block_location(left));
 449         __dm_bless_for_disk(&location);
 450         memcpy_disk(value_ptr(pn, parent_index),
 451                     &location, sizeof(__le64));
 452
 453         location = cpu_to_le64(dm_block_location(right));
 454         __dm_bless_for_disk(&location);
 455
 456         r = insert_at(sizeof(__le64), pn, parent_index + 1,
 457                       le64_to_cpu(rn->keys[0]), &location);
 458         if (r)
 459                 return r;
 460
 461         if (key < le64_to_cpu(rn->keys[0])) {
 462                 unlock_block(s->info, right);
 463                 s->nodes[1] = left;
 464         } else {
 465                 unlock_block(s->info, left);
 466                 s->nodes[1] = right;
 467         }
 468
 469         return 0;
 470 }
 471
 472 /*
 473  * Splits a node by creating two new children beneath the given node.
 474  *
 475  * Before:
 476  *        +----------+
 477  *        | A ++++++ |
 478  *        +----------+
 479  *
 480  *
 481  * After:
 482  *      +------------+
 483  *      | A (shadow) |
 484  *      +------------+
 485  *          |   |
 486  *   +------+   +----+
 487  *   |               |
 488  *   v               v
 489  * +-------+     +-------+
 490  * | B +++ |     | C +++ |
 491  * +-------+     +-------+
 492  */
 493 static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
 494 {
 495         int r;
 496         size_t size;
 497         unsigned nr_left, nr_right;
 498         struct dm_block *left, *right, *new_parent;
 499         struct btree_node *pn, *ln, *rn;
 500         __le64 val;
 501
 502         new_parent = shadow_current(s);
 503
 504         r = new_block(s->info, &left);
 505         if (r < 0)
 506                 return r;
 507
 508         r = new_block(s->info, &right);
 509         if (r < 0) {
 510                 /* FIXME: put left */
 511                 return r;
 512         }
 513
 514         pn = dm_block_data(new_parent);
 515         ln = dm_block_data(left);
 516         rn = dm_block_data(right);
 517
 518         nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
 519         nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
 520
 521         ln->header.flags = pn->header.flags;
 522         ln->header.nr_entries = cpu_to_le32(nr_left);
 523         ln->header.max_entries = pn->header.max_entries;
 524         ln->header.value_size = pn->header.value_size;
 525
 526         rn->header.flags = pn->header.flags;
 527         rn->header.nr_entries = cpu_to_le32(nr_right);
 528         rn->header.max_entries = pn->header.max_entries;
 529         rn->header.value_size = pn->header.value_size;
 530
 531         memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
 532         memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
 533
 534         size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
 535                 sizeof(__le64) : s->info->value_type.size;
 536         memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
 537         memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left),
 538                nr_right * size);
 539
 540         /* new_parent should just point to l and r now */
 541         pn->header.flags = cpu_to_le32(INTERNAL_NODE);
 542         pn->header.nr_entries = cpu_to_le32(2);
 543         pn->header.max_entries = cpu_to_le32(
 544                 calc_max_entries(sizeof(__le64),
 545                                  dm_bm_block_size(
 546                                          dm_tm_get_bm(s->info->tm))));
 547         pn->header.value_size = cpu_to_le32(sizeof(__le64));
 548
 549         val = cpu_to_le64(dm_block_location(left));
 550         __dm_bless_for_disk(&val);
 551         pn->keys[0] = ln->keys[0];
 552         memcpy_disk(value_ptr(pn, 0), &val, sizeof(__le64));
 553
 554         val = cpu_to_le64(dm_block_location(right));
 555         __dm_bless_for_disk(&val);
 556         pn->keys[1] = rn->keys[0];
 557         memcpy_disk(value_ptr(pn, 1), &val, sizeof(__le64));
 558
 559         /*
 560          * rejig the spine.  This is ugly, since it knows too
 561          * much about the spine
 562          */
 563         if (s->nodes[0] != new_parent) {
 564                 unlock_block(s->info, s->nodes[0]);
 565                 s->nodes[0] = new_parent;
 566         }
 567         if (key < le64_to_cpu(rn->keys[0])) {
 568                 unlock_block(s->info, right);
 569                 s->nodes[1] = left;
 570         } else {
 571                 unlock_block(s->info, left);
 572                 s->nodes[1] = right;
 573         }
 574         s->count = 2;
 575
 576         return 0;
 577 }
 578
 579 static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
 580                             struct dm_btree_value_type *vt,
 581                             uint64_t key, unsigned *index)
 582 {
 583         int r, i = *index, top = 1;
 584         struct btree_node *node;
 585
 586         for (;;) {
 587                 r = shadow_step(s, root, vt);
 588                 if (r < 0)
 589                         return r;
 590
 591                 node = dm_block_data(shadow_current(s));
 592
 593                 /*
 594                  * We have to patch up the parent node, ugly, but I don't
 595                  * see a way to do this automatically as part of the spine
 596                  * op.
 597                  */
 598                 if (shadow_has_parent(s) && i >= 0) { /* FIXME: second clause unness. */
 599                         __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
 600
 601                         __dm_bless_for_disk(&location);
 602                         memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
 603                                     &location, sizeof(__le64));
 604                 }
 605
 606                 node = dm_block_data(shadow_current(s));
 607
 608                 if (node->header.nr_entries == node->header.max_entries) {
 609                         if (top)
 610                                 r = btree_split_beneath(s, key);
 611                         else
 612                                 r = btree_split_sibling(s, root, i, key);
 613
 614                         if (r < 0)
 615                                 return r;
 616                 }
 617
 618                 node = dm_block_data(shadow_current(s));
 619
 620                 i = lower_bound(node, key);
 621
 622                 if (le32_to_cpu(node->header.flags) & LEAF_NODE)
 623                         break;
 624
 625                 if (i < 0) {
 626                         /* change the bounds on the lowest key */
 627                         node->keys[0] = cpu_to_le64(key);
 628                         i = 0;
 629                 }
 630
 631                 root = value64(node, i);
 632                 top = 0;
 633         }
 634
 635         if (i < 0 || le64_to_cpu(node->keys[i]) != key)
 636                 i++;
 637
 638         *index = i;
 639         return 0;
 640 }
 641
 642 static int insert(struct dm_btree_info *info, dm_block_t root,
 643                   uint64_t *keys, void *value, dm_block_t *new_root,
 644                   int *inserted)
 645                   __dm_written_to_disk(value)
 646 {
 647         int r, need_insert;
 648         unsigned level, index = -1, last_level = info->levels - 1;
 649         dm_block_t block = root;
 650         struct shadow_spine spine;
 651         struct btree_node *n;
 652         struct dm_btree_value_type le64_type;
 653
 654         le64_type.context = NULL;
 655         le64_type.size = sizeof(__le64);
 656         le64_type.inc = NULL;
 657         le64_type.dec = NULL;
 658         le64_type.equal = NULL;
 659
 660         init_shadow_spine(&spine, info);
 661
 662         for (level = 0; level < (info->levels - 1); level++) {
 663                 r = btree_insert_raw(&spine, block, &le64_type, keys[level], &index);
 664                 if (r < 0)
 665                         goto bad;
 666
 667                 n = dm_block_data(shadow_current(&spine));
 668                 need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) ||
 669                                (le64_to_cpu(n->keys[index]) != keys[level]));
 670
 671                 if (need_insert) {
 672                         dm_block_t new_tree;
 673                         __le64 new_le;
 674
 675                         r = dm_btree_empty(info, &new_tree);
 676                         if (r < 0)
 677                                 goto bad;
 678
 679                         new_le = cpu_to_le64(new_tree);
 680                         __dm_bless_for_disk(&new_le);
 681
 682                         r = insert_at(sizeof(uint64_t), n, index,
 683                                       keys[level], &new_le);
 684                         if (r)
 685                                 goto bad;
 686                 }
 687
 688                 if (level < last_level)
 689                         block = value64(n, index);
 690         }
 691
 692         r = btree_insert_raw(&spine, block, &info->value_type,
 693                              keys[level], &index);
 694         if (r < 0)
 695                 goto bad;
 696
 697         n = dm_block_data(shadow_current(&spine));
 698         need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) ||
 699                        (le64_to_cpu(n->keys[index]) != keys[level]));
 700
 701         if (need_insert) {
 702                 if (inserted)
 703                         *inserted = 1;
 704
 705                 r = insert_at(info->value_type.size, n, index,
 706                               keys[level], value);
 707                 if (r)
 708                         goto bad_unblessed;
 709         } else {
 710                 if (inserted)
 711                         *inserted = 0;
 712
 713                 if (info->value_type.dec &&
 714                     (!info->value_type.equal ||
 715                      !info->value_type.equal(
 716                              info->value_type.context,
 717                              value_ptr(n, index),
 718                              value))) {
 719                         info->value_type.dec(info->value_type.context,
 720                                              value_ptr(n, index));
 721                 }
 722                 memcpy_disk(value_ptr(n, index),
 723                             value, info->value_type.size);
 724         }
 725
 726         *new_root = shadow_root(&spine);
 727         exit_shadow_spine(&spine);
 728
 729         return 0;
 730
 731 bad:
 732         __dm_unbless_for_disk(value);
 733 bad_unblessed:
 734         exit_shadow_spine(&spine);
 735         return r;
 736 }
 737
 738 int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
 739                     uint64_t *keys, void *value, dm_block_t *new_root)
 740                     __dm_written_to_disk(value)
 741 {
 742         return insert(info, root, keys, value, new_root, NULL);
 743 }
 744 EXPORT_SYMBOL_GPL(dm_btree_insert);
 745
 746 int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
 747                            uint64_t *keys, void *value, dm_block_t *new_root,
 748                            int *inserted)
 749                            __dm_written_to_disk(value)
 750 {
 751         return insert(info, root, keys, value, new_root, inserted);
 752 }
 753 EXPORT_SYMBOL_GPL(dm_btree_insert_notify);
 754
 755 /*----------------------------------------------------------------*/
 756
 757 static int find_highest_key(struct ro_spine *s, dm_block_t block,
 758                             uint64_t *result_key, dm_block_t *next_block)
 759 {
 760         int i, r;
 761         uint32_t flags;
 762
 763         do {
 764                 r = ro_step(s, block);
 765                 if (r < 0)
 766                         return r;
 767
 768                 flags = le32_to_cpu(ro_node(s)->header.flags);
 769                 i = le32_to_cpu(ro_node(s)->header.nr_entries);
 770                 if (!i)
 771                         return -ENODATA;
 772                 else
 773                         i--;
 774
 775                 *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 776                 if (next_block || flags & INTERNAL_NODE)
 777                         block = value64(ro_node(s), i);
 778
 779         } while (flags & INTERNAL_NODE);
 780
 781         if (next_block)
 782                 *next_block = block;
 783         return 0;
 784 }
 785
 786 int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
 787                               uint64_t *result_keys)
 788 {
 789         int r = 0, count = 0, level;
 790         struct ro_spine spine;
 791
 792         init_ro_spine(&spine, info);
 793         for (level = 0; level < info->levels; level++) {
 794                 r = find_highest_key(&spine, root, result_keys + level,
 795                                      level == info->levels - 1 ? NULL : &root);
 796                 if (r == -ENODATA) {
 797                         r = 0;
 798                         break;
 799
 800                 } else if (r)
 801                         break;
 802
 803                 count++;
 804         }
 805         exit_ro_spine(&spine);
 806
 807         return r ? r : count;
 808 }
 809 EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);
 810
 811 /*
 812  * FIXME: We shouldn't use a recursive algorithm when we have limited stack
 813  * space.  Also this only works for single level trees.
 814  */
 815 static int walk_node(struct ro_spine *s, dm_block_t block,
 816                      int (*fn)(void *context, uint64_t *keys, void *leaf),
 817                      void *context)
 818 {
 819         int r;
 820         unsigned i, nr;
 821         struct btree_node *n;
 822         uint64_t keys;
 823
 824         r = ro_step(s, block);
 825         n = ro_node(s);
 826
 827         nr = le32_to_cpu(n->header.nr_entries);
 828         for (i = 0; i < nr; i++) {
 829                 if (le32_to_cpu(n->header.flags) & INTERNAL_NODE) {
 830                         r = walk_node(s, value64(n, i), fn, context);
 831                         if (r)
 832                                 goto out;
 833                 } else {
 834                         keys = le64_to_cpu(*key_ptr(n, i));
 835                         r = fn(context, &keys, value_ptr(n, i));
 836                         if (r)
 837                                 goto out;
 838                 }
 839         }
 840
 841 out:
 842         ro_pop(s);
 843         return r;
 844 }
 845
 846 int dm_btree_walk(struct dm_btree_info *info, dm_block_t root,
 847                   int (*fn)(void *context, uint64_t *keys, void *leaf),
 848                   void *context)
 849 {
 850         int r;
 851         struct ro_spine spine;
 852
 853         BUG_ON(info->levels > 1);
 854
 855         init_ro_spine(&spine, info);
 856         r = walk_node(&spine, root, fn, context);
 857         exit_ro_spine(&spine);
 858
 859         return r;
 860 }
 861 EXPORT_SYMBOL_GPL(dm_btree_walk);