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         unlock_block(info, b);
 145
 146         return 0;
 147 }
 148 EXPORT_SYMBOL_GPL(dm_btree_empty);
 149
 150 /*----------------------------------------------------------------*/
 151
 152 /*
 153  * Deletion uses a recursive algorithm, since we have limited stack space
 154  * we explicitly manage our own stack on the heap.
 155  */
 156 #define MAX_SPINE_DEPTH 64
 157 struct frame {
 158         struct dm_block *b;
 159         struct btree_node *n;
 160         unsigned level;
 161         unsigned nr_children;
 162         unsigned current_child;
 163 };
 164
 165 struct del_stack {
 166         struct dm_btree_info *info;
 167         struct dm_transaction_manager *tm;
 168         int top;
 169         struct frame spine[MAX_SPINE_DEPTH];
 170 };
 171
 172 static int top_frame(struct del_stack *s, struct frame **f)
 173 {
 174         if (s->top < 0) {
 175                 DMERR("btree deletion stack empty");
 176                 return -EINVAL;
 177         }
 178
 179         *f = s->spine + s->top;
 180
 181         return 0;
 182 }
 183
 184 static int unprocessed_frames(struct del_stack *s)
 185 {
 186         return s->top >= 0;
 187 }
 188
 189 static void prefetch_children(struct del_stack *s, struct frame *f)
 190 {
 191         unsigned i;
 192         struct dm_block_manager *bm = dm_tm_get_bm(s->tm);
 193
 194         for (i = 0; i < f->nr_children; i++)
 195                 dm_bm_prefetch(bm, value64(f->n, i));
 196 }
 197
 198 static bool is_internal_level(struct dm_btree_info *info, struct frame *f)
 199 {
 200         return f->level < (info->levels - 1);
 201 }
 202
 203 static int push_frame(struct del_stack *s, dm_block_t b, unsigned level)
 204 {
 205         int r;
 206         uint32_t ref_count;
 207
 208         if (s->top >= MAX_SPINE_DEPTH - 1) {
 209                 DMERR("btree deletion stack out of memory");
 210                 return -ENOMEM;
 211         }
 212
 213         r = dm_tm_ref(s->tm, b, &ref_count);
 214         if (r)
 215                 return r;
 216
 217         if (ref_count > 1)
 218                 /*
 219                  * This is a shared node, so we can just decrement it's
 220                  * reference counter and leave the children.
 221                  */
 222                 dm_tm_dec(s->tm, b);
 223
 224         else {
 225                 uint32_t flags;
 226                 struct frame *f = s->spine + ++s->top;
 227
 228                 r = dm_tm_read_lock(s->tm, b, &btree_node_validator, &f->b);
 229                 if (r) {
 230                         s->top--;
 231                         return r;
 232                 }
 233
 234                 f->n = dm_block_data(f->b);
 235                 f->level = level;
 236                 f->nr_children = le32_to_cpu(f->n->header.nr_entries);
 237                 f->current_child = 0;
 238
 239                 flags = le32_to_cpu(f->n->header.flags);
 240                 if (flags & INTERNAL_NODE || is_internal_level(s->info, f))
 241                         prefetch_children(s, f);
 242         }
 243
 244         return 0;
 245 }
 246
 247 static void pop_frame(struct del_stack *s)
 248 {
 249         struct frame *f = s->spine + s->top--;
 250
 251         dm_tm_dec(s->tm, dm_block_location(f->b));
 252         dm_tm_unlock(s->tm, f->b);
 253 }
 254
 255 int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
 256 {
 257         int r;
 258         struct del_stack *s;
 259
 260         s = kmalloc(sizeof(*s), GFP_NOIO);
 261         if (!s)
 262                 return -ENOMEM;
 263         s->info = info;
 264         s->tm = info->tm;
 265         s->top = -1;
 266
 267         r = push_frame(s, root, 0);
 268         if (r)
 269                 goto out;
 270
 271         while (unprocessed_frames(s)) {
 272                 uint32_t flags;
 273                 struct frame *f;
 274                 dm_block_t b;
 275
 276                 r = top_frame(s, &f);
 277                 if (r)
 278                         goto out;
 279
 280                 if (f->current_child >= f->nr_children) {
 281                         pop_frame(s);
 282                         continue;
 283                 }
 284
 285                 flags = le32_to_cpu(f->n->header.flags);
 286                 if (flags & INTERNAL_NODE) {
 287                         b = value64(f->n, f->current_child);
 288                         f->current_child++;
 289                         r = push_frame(s, b, f->level);
 290                         if (r)
 291                                 goto out;
 292
 293                 } else if (is_internal_level(info, f)) {
 294                         b = value64(f->n, f->current_child);
 295                         f->current_child++;
 296                         r = push_frame(s, b, f->level + 1);
 297                         if (r)
 298                                 goto out;
 299
 300                 } else {
 301                         if (info->value_type.dec) {
 302                                 unsigned i;
 303
 304                                 for (i = 0; i < f->nr_children; i++)
 305                                         info->value_type.dec(info->value_type.context,
 306                                                              value_ptr(f->n, i));
 307                         }
 308                         pop_frame(s);
 309                 }
 310         }
 311
 312 out:
 313         kfree(s);
 314         return r;
 315 }
 316 EXPORT_SYMBOL_GPL(dm_btree_del);
 317
 318 /*----------------------------------------------------------------*/
 319
 320 static int btree_lookup_raw(struct ro_spine *s, dm_block_t block, uint64_t key,
 321                             int (*search_fn)(struct btree_node *, uint64_t),
 322                             uint64_t *result_key, void *v, size_t value_size)
 323 {
 324         int i, r;
 325         uint32_t flags, nr_entries;
 326
 327         do {
 328                 r = ro_step(s, block);
 329                 if (r < 0)
 330                         return r;
 331
 332                 i = search_fn(ro_node(s), key);
 333
 334                 flags = le32_to_cpu(ro_node(s)->header.flags);
 335                 nr_entries = le32_to_cpu(ro_node(s)->header.nr_entries);
 336                 if (i < 0 || i >= nr_entries)
 337                         return -ENODATA;
 338
 339                 if (flags & INTERNAL_NODE)
 340                         block = value64(ro_node(s), i);
 341
 342         } while (!(flags & LEAF_NODE));
 343
 344         *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 345         memcpy(v, value_ptr(ro_node(s), i), value_size);
 346
 347         return 0;
 348 }
 349
 350 int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
 351                     uint64_t *keys, void *value_le)
 352 {
 353         unsigned level, last_level = info->levels - 1;
 354         int r = -ENODATA;
 355         uint64_t rkey;
 356         __le64 internal_value_le;
 357         struct ro_spine spine;
 358
 359         init_ro_spine(&spine, info);
 360         for (level = 0; level < info->levels; level++) {
 361                 size_t size;
 362                 void *value_p;
 363
 364                 if (level == last_level) {
 365                         value_p = value_le;
 366                         size = info->value_type.size;
 367
 368                 } else {
 369                         value_p = &internal_value_le;
 370                         size = sizeof(uint64_t);
 371                 }
 372
 373                 r = btree_lookup_raw(&spine, root, keys[level],
 374                                      lower_bound, &rkey,
 375                                      value_p, size);
 376
 377                 if (!r) {
 378                         if (rkey != keys[level]) {
 379                                 exit_ro_spine(&spine);
 380                                 return -ENODATA;
 381                         }
 382                 } else {
 383                         exit_ro_spine(&spine);
 384                         return r;
 385                 }
 386
 387                 root = le64_to_cpu(internal_value_le);
 388         }
 389         exit_ro_spine(&spine);
 390
 391         return r;
 392 }
 393 EXPORT_SYMBOL_GPL(dm_btree_lookup);
 394
 395 /*
 396  * Splits a node by creating a sibling node and shifting half the nodes
 397  * contents across.  Assumes there is a parent node, and it has room for
 398  * another child.
 399  *
 400  * Before:
 401  *        +--------+
 402  *        | Parent |
 403  *        +--------+
 404  *           |
 405  *           v
 406  *      +----------+
 407  *      | A ++++++ |
 408  *      +----------+
 409  *
 410  *
 411  * After:
 412  *              +--------+
 413  *              | Parent |
 414  *              +--------+
 415  *                |     |
 416  *                v     +------+
 417  *          +---------+        |
 418  *          | A* +++  |        v
 419  *          +---------+   +-------+
 420  *                        | B +++ |
 421  *                        +-------+
 422  *
 423  * Where A* is a shadow of A.
 424  */
 425 static int btree_split_sibling(struct shadow_spine *s, unsigned parent_index,
 426                                uint64_t key)
 427 {
 428         int r;
 429         size_t size;
 430         unsigned nr_left, nr_right;
 431         struct dm_block *left, *right, *parent;
 432         struct btree_node *ln, *rn, *pn;
 433         __le64 location;
 434
 435         left = shadow_current(s);
 436
 437         r = new_block(s->info, &right);
 438         if (r < 0)
 439                 return r;
 440
 441         ln = dm_block_data(left);
 442         rn = dm_block_data(right);
 443
 444         nr_left = le32_to_cpu(ln->header.nr_entries) / 2;
 445         nr_right = le32_to_cpu(ln->header.nr_entries) - nr_left;
 446
 447         ln->header.nr_entries = cpu_to_le32(nr_left);
 448
 449         rn->header.flags = ln->header.flags;
 450         rn->header.nr_entries = cpu_to_le32(nr_right);
 451         rn->header.max_entries = ln->header.max_entries;
 452         rn->header.value_size = ln->header.value_size;
 453         memcpy(rn->keys, ln->keys + nr_left, nr_right * sizeof(rn->keys[0]));
 454
 455         size = le32_to_cpu(ln->header.flags) & INTERNAL_NODE ?
 456                 sizeof(uint64_t) : s->info->value_type.size;
 457         memcpy(value_ptr(rn, 0), value_ptr(ln, nr_left),
 458                size * nr_right);
 459
 460         /*
 461          * Patch up the parent
 462          */
 463         parent = shadow_parent(s);
 464
 465         pn = dm_block_data(parent);
 466         location = cpu_to_le64(dm_block_location(left));
 467         __dm_bless_for_disk(&location);
 468         memcpy_disk(value_ptr(pn, parent_index),
 469                     &location, sizeof(__le64));
 470
 471         location = cpu_to_le64(dm_block_location(right));
 472         __dm_bless_for_disk(&location);
 473
 474         r = insert_at(sizeof(__le64), pn, parent_index + 1,
 475                       le64_to_cpu(rn->keys[0]), &location);
 476         if (r)
 477                 return r;
 478
 479         if (key < le64_to_cpu(rn->keys[0])) {
 480                 unlock_block(s->info, right);
 481                 s->nodes[1] = left;
 482         } else {
 483                 unlock_block(s->info, left);
 484                 s->nodes[1] = right;
 485         }
 486
 487         return 0;
 488 }
 489
 490 /*
 491  * Splits a node by creating two new children beneath the given node.
 492  *
 493  * Before:
 494  *        +----------+
 495  *        | A ++++++ |
 496  *        +----------+
 497  *
 498  *
 499  * After:
 500  *      +------------+
 501  *      | A (shadow) |
 502  *      +------------+
 503  *          |   |
 504  *   +------+   +----+
 505  *   |               |
 506  *   v               v
 507  * +-------+     +-------+
 508  * | B +++ |     | C +++ |
 509  * +-------+     +-------+
 510  */
 511 static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
 512 {
 513         int r;
 514         size_t size;
 515         unsigned nr_left, nr_right;
 516         struct dm_block *left, *right, *new_parent;
 517         struct btree_node *pn, *ln, *rn;
 518         __le64 val;
 519
 520         new_parent = shadow_current(s);
 521
 522         r = new_block(s->info, &left);
 523         if (r < 0)
 524                 return r;
 525
 526         r = new_block(s->info, &right);
 527         if (r < 0) {
 528                 unlock_block(s->info, left);
 529                 return r;
 530         }
 531
 532         pn = dm_block_data(new_parent);
 533         ln = dm_block_data(left);
 534         rn = dm_block_data(right);
 535
 536         nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
 537         nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
 538
 539         ln->header.flags = pn->header.flags;
 540         ln->header.nr_entries = cpu_to_le32(nr_left);
 541         ln->header.max_entries = pn->header.max_entries;
 542         ln->header.value_size = pn->header.value_size;
 543
 544         rn->header.flags = pn->header.flags;
 545         rn->header.nr_entries = cpu_to_le32(nr_right);
 546         rn->header.max_entries = pn->header.max_entries;
 547         rn->header.value_size = pn->header.value_size;
 548
 549         memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
 550         memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
 551
 552         size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
 553                 sizeof(__le64) : s->info->value_type.size;
 554         memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
 555         memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left),
 556                nr_right * size);
 557
 558         /* new_parent should just point to l and r now */
 559         pn->header.flags = cpu_to_le32(INTERNAL_NODE);
 560         pn->header.nr_entries = cpu_to_le32(2);
 561         pn->header.max_entries = cpu_to_le32(
 562                 calc_max_entries(sizeof(__le64),
 563                                  dm_bm_block_size(
 564                                          dm_tm_get_bm(s->info->tm))));
 565         pn->header.value_size = cpu_to_le32(sizeof(__le64));
 566
 567         val = cpu_to_le64(dm_block_location(left));
 568         __dm_bless_for_disk(&val);
 569         pn->keys[0] = ln->keys[0];
 570         memcpy_disk(value_ptr(pn, 0), &val, sizeof(__le64));
 571
 572         val = cpu_to_le64(dm_block_location(right));
 573         __dm_bless_for_disk(&val);
 574         pn->keys[1] = rn->keys[0];
 575         memcpy_disk(value_ptr(pn, 1), &val, sizeof(__le64));
 576
 577         /*
 578          * rejig the spine.  This is ugly, since it knows too
 579          * much about the spine
 580          */
 581         if (s->nodes[0] != new_parent) {
 582                 unlock_block(s->info, s->nodes[0]);
 583                 s->nodes[0] = new_parent;
 584         }
 585         if (key < le64_to_cpu(rn->keys[0])) {
 586                 unlock_block(s->info, right);
 587                 s->nodes[1] = left;
 588         } else {
 589                 unlock_block(s->info, left);
 590                 s->nodes[1] = right;
 591         }
 592         s->count = 2;
 593
 594         return 0;
 595 }
 596
 597 static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
 598                             struct dm_btree_value_type *vt,
 599                             uint64_t key, unsigned *index)
 600 {
 601         int r, i = *index, top = 1;
 602         struct btree_node *node;
 603
 604         for (;;) {
 605                 r = shadow_step(s, root, vt);
 606                 if (r < 0)
 607                         return r;
 608
 609                 node = dm_block_data(shadow_current(s));
 610
 611                 /*
 612                  * We have to patch up the parent node, ugly, but I don't
 613                  * see a way to do this automatically as part of the spine
 614                  * op.
 615                  */
 616                 if (shadow_has_parent(s) && i >= 0) { /* FIXME: second clause unness. */
 617                         __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
 618
 619                         __dm_bless_for_disk(&location);
 620                         memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
 621                                     &location, sizeof(__le64));
 622                 }
 623
 624                 node = dm_block_data(shadow_current(s));
 625
 626                 if (node->header.nr_entries == node->header.max_entries) {
 627                         if (top)
 628                                 r = btree_split_beneath(s, key);
 629                         else
 630                                 r = btree_split_sibling(s, i, key);
 631
 632                         if (r < 0)
 633                                 return r;
 634                 }
 635
 636                 node = dm_block_data(shadow_current(s));
 637
 638                 i = lower_bound(node, key);
 639
 640                 if (le32_to_cpu(node->header.flags) & LEAF_NODE)
 641                         break;
 642
 643                 if (i < 0) {
 644                         /* change the bounds on the lowest key */
 645                         node->keys[0] = cpu_to_le64(key);
 646                         i = 0;
 647                 }
 648
 649                 root = value64(node, i);
 650                 top = 0;
 651         }
 652
 653         if (i < 0 || le64_to_cpu(node->keys[i]) != key)
 654                 i++;
 655
 656         *index = i;
 657         return 0;
 658 }
 659
 660 static int insert(struct dm_btree_info *info, dm_block_t root,
 661                   uint64_t *keys, void *value, dm_block_t *new_root,
 662                   int *inserted)
 663                   __dm_written_to_disk(value)
 664 {
 665         int r, need_insert;
 666         unsigned level, index = -1, last_level = info->levels - 1;
 667         dm_block_t block = root;
 668         struct shadow_spine spine;
 669         struct btree_node *n;
 670         struct dm_btree_value_type le64_type;
 671
 672         init_le64_type(info->tm, &le64_type);
 673         init_shadow_spine(&spine, info);
 674
 675         for (level = 0; level < (info->levels - 1); level++) {
 676                 r = btree_insert_raw(&spine, block, &le64_type, keys[level], &index);
 677                 if (r < 0)
 678                         goto bad;
 679
 680                 n = dm_block_data(shadow_current(&spine));
 681                 need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) ||
 682                                (le64_to_cpu(n->keys[index]) != keys[level]));
 683
 684                 if (need_insert) {
 685                         dm_block_t new_tree;
 686                         __le64 new_le;
 687
 688                         r = dm_btree_empty(info, &new_tree);
 689                         if (r < 0)
 690                                 goto bad;
 691
 692                         new_le = cpu_to_le64(new_tree);
 693                         __dm_bless_for_disk(&new_le);
 694
 695                         r = insert_at(sizeof(uint64_t), n, index,
 696                                       keys[level], &new_le);
 697                         if (r)
 698                                 goto bad;
 699                 }
 700
 701                 if (level < last_level)
 702                         block = value64(n, index);
 703         }
 704
 705         r = btree_insert_raw(&spine, block, &info->value_type,
 706                              keys[level], &index);
 707         if (r < 0)
 708                 goto bad;
 709
 710         n = dm_block_data(shadow_current(&spine));
 711         need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) ||
 712                        (le64_to_cpu(n->keys[index]) != keys[level]));
 713
 714         if (need_insert) {
 715                 if (inserted)
 716                         *inserted = 1;
 717
 718                 r = insert_at(info->value_type.size, n, index,
 719                               keys[level], value);
 720                 if (r)
 721                         goto bad_unblessed;
 722         } else {
 723                 if (inserted)
 724                         *inserted = 0;
 725
 726                 if (info->value_type.dec &&
 727                     (!info->value_type.equal ||
 728                      !info->value_type.equal(
 729                              info->value_type.context,
 730                              value_ptr(n, index),
 731                              value))) {
 732                         info->value_type.dec(info->value_type.context,
 733                                              value_ptr(n, index));
 734                 }
 735                 memcpy_disk(value_ptr(n, index),
 736                             value, info->value_type.size);
 737         }
 738
 739         *new_root = shadow_root(&spine);
 740         exit_shadow_spine(&spine);
 741
 742         return 0;
 743
 744 bad:
 745         __dm_unbless_for_disk(value);
 746 bad_unblessed:
 747         exit_shadow_spine(&spine);
 748         return r;
 749 }
 750
 751 int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
 752                     uint64_t *keys, void *value, dm_block_t *new_root)
 753                     __dm_written_to_disk(value)
 754 {
 755         return insert(info, root, keys, value, new_root, NULL);
 756 }
 757 EXPORT_SYMBOL_GPL(dm_btree_insert);
 758
 759 int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
 760                            uint64_t *keys, void *value, dm_block_t *new_root,
 761                            int *inserted)
 762                            __dm_written_to_disk(value)
 763 {
 764         return insert(info, root, keys, value, new_root, inserted);
 765 }
 766 EXPORT_SYMBOL_GPL(dm_btree_insert_notify);
 767
 768 /*----------------------------------------------------------------*/
 769
 770 static int find_key(struct ro_spine *s, dm_block_t block, bool find_highest,
 771                     uint64_t *result_key, dm_block_t *next_block)
 772 {
 773         int i, r;
 774         uint32_t flags;
 775
 776         do {
 777                 r = ro_step(s, block);
 778                 if (r < 0)
 779                         return r;
 780
 781                 flags = le32_to_cpu(ro_node(s)->header.flags);
 782                 i = le32_to_cpu(ro_node(s)->header.nr_entries);
 783                 if (!i)
 784                         return -ENODATA;
 785                 else
 786                         i--;
 787
 788                 if (find_highest)
 789                         *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 790                 else
 791                         *result_key = le64_to_cpu(ro_node(s)->keys[0]);
 792
 793                 if (next_block || flags & INTERNAL_NODE)
 794                         block = value64(ro_node(s), i);
 795
 796         } while (flags & INTERNAL_NODE);
 797
 798         if (next_block)
 799                 *next_block = block;
 800         return 0;
 801 }
 802
 803 static int dm_btree_find_key(struct dm_btree_info *info, dm_block_t root,
 804                              bool find_highest, uint64_t *result_keys)
 805 {
 806         int r = 0, count = 0, level;
 807         struct ro_spine spine;
 808
 809         init_ro_spine(&spine, info);
 810         for (level = 0; level < info->levels; level++) {
 811                 r = find_key(&spine, root, find_highest, result_keys + level,
 812                              level == info->levels - 1 ? NULL : &root);
 813                 if (r == -ENODATA) {
 814                         r = 0;
 815                         break;
 816
 817                 } else if (r)
 818                         break;
 819
 820                 count++;
 821         }
 822         exit_ro_spine(&spine);
 823
 824         return r ? r : count;
 825 }
 826
 827 int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
 828                               uint64_t *result_keys)
 829 {
 830         return dm_btree_find_key(info, root, true, result_keys);
 831 }
 832 EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);
 833
 834 int dm_btree_find_lowest_key(struct dm_btree_info *info, dm_block_t root,
 835                              uint64_t *result_keys)
 836 {
 837         return dm_btree_find_key(info, root, false, result_keys);
 838 }
 839 EXPORT_SYMBOL_GPL(dm_btree_find_lowest_key);
 840
 841 /*----------------------------------------------------------------*/
 842
 843 /*
 844  * FIXME: We shouldn't use a recursive algorithm when we have limited stack
 845  * space.  Also this only works for single level trees.
 846  */
 847 static int walk_node(struct dm_btree_info *info, dm_block_t block,
 848                      int (*fn)(void *context, uint64_t *keys, void *leaf),
 849                      void *context)
 850 {
 851         int r;
 852         unsigned i, nr;
 853         struct dm_block *node;
 854         struct btree_node *n;
 855         uint64_t keys;
 856
 857         r = bn_read_lock(info, block, &node);
 858         if (r)
 859                 return r;
 860
 861         n = dm_block_data(node);
 862
 863         nr = le32_to_cpu(n->header.nr_entries);
 864         for (i = 0; i < nr; i++) {
 865                 if (le32_to_cpu(n->header.flags) & INTERNAL_NODE) {
 866                         r = walk_node(info, value64(n, i), fn, context);
 867                         if (r)
 868                                 goto out;
 869                 } else {
 870                         keys = le64_to_cpu(*key_ptr(n, i));
 871                         r = fn(context, &keys, value_ptr(n, i));
 872                         if (r)
 873                                 goto out;
 874                 }
 875         }
 876
 877 out:
 878         dm_tm_unlock(info->tm, node);
 879         return r;
 880 }
 881
 882 int dm_btree_walk(struct dm_btree_info *info, dm_block_t root,
 883                   int (*fn)(void *context, uint64_t *keys, void *leaf),
 884                   void *context)
 885 {
 886         BUG_ON(info->levels > 1);
 887         return walk_node(info, root, fn, context);
 888 }
 889 EXPORT_SYMBOL_GPL(dm_btree_walk);