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_btree_info *info;
 165         struct dm_transaction_manager *tm;
 166         int top;
 167         struct frame spine[MAX_SPINE_DEPTH];
 168 };
 169
 170 static int top_frame(struct del_stack *s, struct frame **f)
 171 {
 172         if (s->top < 0) {
 173                 DMERR("btree deletion stack empty");
 174                 return -EINVAL;
 175         }
 176
 177         *f = s->spine + s->top;
 178
 179         return 0;
 180 }
 181
 182 static int unprocessed_frames(struct del_stack *s)
 183 {
 184         return s->top >= 0;
 185 }
 186
 187 static void prefetch_children(struct del_stack *s, struct frame *f)
 188 {
 189         unsigned i;
 190         struct dm_block_manager *bm = dm_tm_get_bm(s->tm);
 191
 192         for (i = 0; i < f->nr_children; i++)
 193                 dm_bm_prefetch(bm, value64(f->n, i));
 194 }
 195
 196 static bool is_internal_level(struct dm_btree_info *info, struct frame *f)
 197 {
 198         return f->level < (info->levels - 1);
 199 }
 200
 201 static int push_frame(struct del_stack *s, dm_block_t b, unsigned level)
 202 {
 203         int r;
 204         uint32_t ref_count;
 205
 206         if (s->top >= MAX_SPINE_DEPTH - 1) {
 207                 DMERR("btree deletion stack out of memory");
 208                 return -ENOMEM;
 209         }
 210
 211         r = dm_tm_ref(s->tm, b, &ref_count);
 212         if (r)
 213                 return r;
 214
 215         if (ref_count > 1)
 216                 /*
 217                  * This is a shared node, so we can just decrement it's
 218                  * reference counter and leave the children.
 219                  */
 220                 dm_tm_dec(s->tm, b);
 221
 222         else {
 223                 uint32_t flags;
 224                 struct frame *f = s->spine + ++s->top;
 225
 226                 r = dm_tm_read_lock(s->tm, b, &btree_node_validator, &f->b);
 227                 if (r) {
 228                         s->top--;
 229                         return r;
 230                 }
 231
 232                 f->n = dm_block_data(f->b);
 233                 f->level = level;
 234                 f->nr_children = le32_to_cpu(f->n->header.nr_entries);
 235                 f->current_child = 0;
 236
 237                 flags = le32_to_cpu(f->n->header.flags);
 238                 if (flags & INTERNAL_NODE || is_internal_level(s->info, f))
 239                         prefetch_children(s, f);
 240         }
 241
 242         return 0;
 243 }
 244
 245 static void pop_frame(struct del_stack *s)
 246 {
 247         struct frame *f = s->spine + s->top--;
 248
 249         dm_tm_dec(s->tm, dm_block_location(f->b));
 250         dm_tm_unlock(s->tm, f->b);
 251 }
 252
 253 int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
 254 {
 255         int r;
 256         struct del_stack *s;
 257
 258         s = kmalloc(sizeof(*s), GFP_KERNEL);
 259         if (!s)
 260                 return -ENOMEM;
 261         s->info = info;
 262         s->tm = info->tm;
 263         s->top = -1;
 264
 265         r = push_frame(s, root, 0);
 266         if (r)
 267                 goto out;
 268
 269         while (unprocessed_frames(s)) {
 270                 uint32_t flags;
 271                 struct frame *f;
 272                 dm_block_t b;
 273
 274                 r = top_frame(s, &f);
 275                 if (r)
 276                         goto out;
 277
 278                 if (f->current_child >= f->nr_children) {
 279                         pop_frame(s);
 280                         continue;
 281                 }
 282
 283                 flags = le32_to_cpu(f->n->header.flags);
 284                 if (flags & INTERNAL_NODE) {
 285                         b = value64(f->n, f->current_child);
 286                         f->current_child++;
 287                         r = push_frame(s, b, f->level);
 288                         if (r)
 289                                 goto out;
 290
 291                 } else if (is_internal_level(info, f)) {
 292                         b = value64(f->n, f->current_child);
 293                         f->current_child++;
 294                         r = push_frame(s, b, f->level + 1);
 295                         if (r)
 296                                 goto out;
 297
 298                 } else {
 299                         if (info->value_type.dec) {
 300                                 unsigned i;
 301
 302                                 for (i = 0; i < f->nr_children; i++)
 303                                         info->value_type.dec(info->value_type.context,
 304                                                              value_ptr(f->n, i));
 305                         }
 306                         pop_frame(s);
 307                 }
 308         }
 309
 310 out:
 311         kfree(s);
 312         return r;
 313 }
 314 EXPORT_SYMBOL_GPL(dm_btree_del);
 315
 316 /*----------------------------------------------------------------*/
 317
 318 static int btree_lookup_raw(struct ro_spine *s, dm_block_t block, uint64_t key,
 319                             int (*search_fn)(struct btree_node *, uint64_t),
 320                             uint64_t *result_key, void *v, size_t value_size)
 321 {
 322         int i, r;
 323         uint32_t flags, nr_entries;
 324
 325         do {
 326                 r = ro_step(s, block);
 327                 if (r < 0)
 328                         return r;
 329
 330                 i = search_fn(ro_node(s), key);
 331
 332                 flags = le32_to_cpu(ro_node(s)->header.flags);
 333                 nr_entries = le32_to_cpu(ro_node(s)->header.nr_entries);
 334                 if (i < 0 || i >= nr_entries)
 335                         return -ENODATA;
 336
 337                 if (flags & INTERNAL_NODE)
 338                         block = value64(ro_node(s), i);
 339
 340         } while (!(flags & LEAF_NODE));
 341
 342         *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 343         memcpy(v, value_ptr(ro_node(s), i), value_size);
 344
 345         return 0;
 346 }
 347
 348 int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
 349                     uint64_t *keys, void *value_le)
 350 {
 351         unsigned level, last_level = info->levels - 1;
 352         int r = -ENODATA;
 353         uint64_t rkey;
 354         __le64 internal_value_le;
 355         struct ro_spine spine;
 356
 357         init_ro_spine(&spine, info);
 358         for (level = 0; level < info->levels; level++) {
 359                 size_t size;
 360                 void *value_p;
 361
 362                 if (level == last_level) {
 363                         value_p = value_le;
 364                         size = info->value_type.size;
 365
 366                 } else {
 367                         value_p = &internal_value_le;
 368                         size = sizeof(uint64_t);
 369                 }
 370
 371                 r = btree_lookup_raw(&spine, root, keys[level],
 372                                      lower_bound, &rkey,
 373                                      value_p, size);
 374
 375                 if (!r) {
 376                         if (rkey != keys[level]) {
 377                                 exit_ro_spine(&spine);
 378                                 return -ENODATA;
 379                         }
 380                 } else {
 381                         exit_ro_spine(&spine);
 382                         return r;
 383                 }
 384
 385                 root = le64_to_cpu(internal_value_le);
 386         }
 387         exit_ro_spine(&spine);
 388
 389         return r;
 390 }
 391 EXPORT_SYMBOL_GPL(dm_btree_lookup);
 392
 393 /*
 394  * Splits a node by creating a sibling node and shifting half the nodes
 395  * contents across.  Assumes there is a parent node, and it has room for
 396  * another child.
 397  *
 398  * Before:
 399  *        +--------+
 400  *        | Parent |
 401  *        +--------+
 402  *           |
 403  *           v
 404  *      +----------+
 405  *      | A ++++++ |
 406  *      +----------+
 407  *
 408  *
 409  * After:
 410  *              +--------+
 411  *              | Parent |
 412  *              +--------+
 413  *                |     |
 414  *                v     +------+
 415  *          +---------+        |
 416  *          | A* +++  |        v
 417  *          +---------+   +-------+
 418  *                        | B +++ |
 419  *                        +-------+
 420  *
 421  * Where A* is a shadow of A.
 422  */
 423 static int btree_split_sibling(struct shadow_spine *s, dm_block_t root,
 424                                unsigned parent_index, uint64_t key)
 425 {
 426         int r;
 427         size_t size;
 428         unsigned nr_left, nr_right;
 429         struct dm_block *left, *right, *parent;
 430         struct btree_node *ln, *rn, *pn;
 431         __le64 location;
 432
 433         left = shadow_current(s);
 434
 435         r = new_block(s->info, &right);
 436         if (r < 0)
 437                 return r;
 438
 439         ln = dm_block_data(left);
 440         rn = dm_block_data(right);
 441
 442         nr_left = le32_to_cpu(ln->header.nr_entries) / 2;
 443         nr_right = le32_to_cpu(ln->header.nr_entries) - nr_left;
 444
 445         ln->header.nr_entries = cpu_to_le32(nr_left);
 446
 447         rn->header.flags = ln->header.flags;
 448         rn->header.nr_entries = cpu_to_le32(nr_right);
 449         rn->header.max_entries = ln->header.max_entries;
 450         rn->header.value_size = ln->header.value_size;
 451         memcpy(rn->keys, ln->keys + nr_left, nr_right * sizeof(rn->keys[0]));
 452
 453         size = le32_to_cpu(ln->header.flags) & INTERNAL_NODE ?
 454                 sizeof(uint64_t) : s->info->value_type.size;
 455         memcpy(value_ptr(rn, 0), value_ptr(ln, nr_left),
 456                size * nr_right);
 457
 458         /*
 459          * Patch up the parent
 460          */
 461         parent = shadow_parent(s);
 462
 463         pn = dm_block_data(parent);
 464         location = cpu_to_le64(dm_block_location(left));
 465         __dm_bless_for_disk(&location);
 466         memcpy_disk(value_ptr(pn, parent_index),
 467                     &location, sizeof(__le64));
 468
 469         location = cpu_to_le64(dm_block_location(right));
 470         __dm_bless_for_disk(&location);
 471
 472         r = insert_at(sizeof(__le64), pn, parent_index + 1,
 473                       le64_to_cpu(rn->keys[0]), &location);
 474         if (r)
 475                 return r;
 476
 477         if (key < le64_to_cpu(rn->keys[0])) {
 478                 unlock_block(s->info, right);
 479                 s->nodes[1] = left;
 480         } else {
 481                 unlock_block(s->info, left);
 482                 s->nodes[1] = right;
 483         }
 484
 485         return 0;
 486 }
 487
 488 /*
 489  * Splits a node by creating two new children beneath the given node.
 490  *
 491  * Before:
 492  *        +----------+
 493  *        | A ++++++ |
 494  *        +----------+
 495  *
 496  *
 497  * After:
 498  *      +------------+
 499  *      | A (shadow) |
 500  *      +------------+
 501  *          |   |
 502  *   +------+   +----+
 503  *   |               |
 504  *   v               v
 505  * +-------+     +-------+
 506  * | B +++ |     | C +++ |
 507  * +-------+     +-------+
 508  */
 509 static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
 510 {
 511         int r;
 512         size_t size;
 513         unsigned nr_left, nr_right;
 514         struct dm_block *left, *right, *new_parent;
 515         struct btree_node *pn, *ln, *rn;
 516         __le64 val;
 517
 518         new_parent = shadow_current(s);
 519
 520         r = new_block(s->info, &left);
 521         if (r < 0)
 522                 return r;
 523
 524         r = new_block(s->info, &right);
 525         if (r < 0) {
 526                 /* FIXME: put left */
 527                 return r;
 528         }
 529
 530         pn = dm_block_data(new_parent);
 531         ln = dm_block_data(left);
 532         rn = dm_block_data(right);
 533
 534         nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
 535         nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
 536
 537         ln->header.flags = pn->header.flags;
 538         ln->header.nr_entries = cpu_to_le32(nr_left);
 539         ln->header.max_entries = pn->header.max_entries;
 540         ln->header.value_size = pn->header.value_size;
 541
 542         rn->header.flags = pn->header.flags;
 543         rn->header.nr_entries = cpu_to_le32(nr_right);
 544         rn->header.max_entries = pn->header.max_entries;
 545         rn->header.value_size = pn->header.value_size;
 546
 547         memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
 548         memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
 549
 550         size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
 551                 sizeof(__le64) : s->info->value_type.size;
 552         memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
 553         memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left),
 554                nr_right * size);
 555
 556         /* new_parent should just point to l and r now */
 557         pn->header.flags = cpu_to_le32(INTERNAL_NODE);
 558         pn->header.nr_entries = cpu_to_le32(2);
 559         pn->header.max_entries = cpu_to_le32(
 560                 calc_max_entries(sizeof(__le64),
 561                                  dm_bm_block_size(
 562                                          dm_tm_get_bm(s->info->tm))));
 563         pn->header.value_size = cpu_to_le32(sizeof(__le64));
 564
 565         val = cpu_to_le64(dm_block_location(left));
 566         __dm_bless_for_disk(&val);
 567         pn->keys[0] = ln->keys[0];
 568         memcpy_disk(value_ptr(pn, 0), &val, sizeof(__le64));
 569
 570         val = cpu_to_le64(dm_block_location(right));
 571         __dm_bless_for_disk(&val);
 572         pn->keys[1] = rn->keys[0];
 573         memcpy_disk(value_ptr(pn, 1), &val, sizeof(__le64));
 574
 575         /*
 576          * rejig the spine.  This is ugly, since it knows too
 577          * much about the spine
 578          */
 579         if (s->nodes[0] != new_parent) {
 580                 unlock_block(s->info, s->nodes[0]);
 581                 s->nodes[0] = new_parent;
 582         }
 583         if (key < le64_to_cpu(rn->keys[0])) {
 584                 unlock_block(s->info, right);
 585                 s->nodes[1] = left;
 586         } else {
 587                 unlock_block(s->info, left);
 588                 s->nodes[1] = right;
 589         }
 590         s->count = 2;
 591
 592         return 0;
 593 }
 594
 595 static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
 596                             struct dm_btree_value_type *vt,
 597                             uint64_t key, unsigned *index)
 598 {
 599         int r, i = *index, top = 1;
 600         struct btree_node *node;
 601
 602         for (;;) {
 603                 r = shadow_step(s, root, vt);
 604                 if (r < 0)
 605                         return r;
 606
 607                 node = dm_block_data(shadow_current(s));
 608
 609                 /*
 610                  * We have to patch up the parent node, ugly, but I don't
 611                  * see a way to do this automatically as part of the spine
 612                  * op.
 613                  */
 614                 if (shadow_has_parent(s) && i >= 0) { /* FIXME: second clause unness. */
 615                         __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
 616
 617                         __dm_bless_for_disk(&location);
 618                         memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
 619                                     &location, sizeof(__le64));
 620                 }
 621
 622                 node = dm_block_data(shadow_current(s));
 623
 624                 if (node->header.nr_entries == node->header.max_entries) {
 625                         if (top)
 626                                 r = btree_split_beneath(s, key);
 627                         else
 628                                 r = btree_split_sibling(s, root, i, key);
 629
 630                         if (r < 0)
 631                                 return r;
 632                 }
 633
 634                 node = dm_block_data(shadow_current(s));
 635
 636                 i = lower_bound(node, key);
 637
 638                 if (le32_to_cpu(node->header.flags) & LEAF_NODE)
 639                         break;
 640
 641                 if (i < 0) {
 642                         /* change the bounds on the lowest key */
 643                         node->keys[0] = cpu_to_le64(key);
 644                         i = 0;
 645                 }
 646
 647                 root = value64(node, i);
 648                 top = 0;
 649         }
 650
 651         if (i < 0 || le64_to_cpu(node->keys[i]) != key)
 652                 i++;
 653
 654         *index = i;
 655         return 0;
 656 }
 657
 658 static int insert(struct dm_btree_info *info, dm_block_t root,
 659                   uint64_t *keys, void *value, dm_block_t *new_root,
 660                   int *inserted)
 661                   __dm_written_to_disk(value)
 662 {
 663         int r, need_insert;
 664         unsigned level, index = -1, last_level = info->levels - 1;
 665         dm_block_t block = root;
 666         struct shadow_spine spine;
 667         struct btree_node *n;
 668         struct dm_btree_value_type le64_type;
 669
 670         le64_type.context = NULL;
 671         le64_type.size = sizeof(__le64);
 672         le64_type.inc = NULL;
 673         le64_type.dec = NULL;
 674         le64_type.equal = NULL;
 675
 676         init_shadow_spine(&spine, info);
 677
 678         for (level = 0; level < (info->levels - 1); level++) {
 679                 r = btree_insert_raw(&spine, block, &le64_type, keys[level], &index);
 680                 if (r < 0)
 681                         goto bad;
 682
 683                 n = dm_block_data(shadow_current(&spine));
 684                 need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) ||
 685                                (le64_to_cpu(n->keys[index]) != keys[level]));
 686
 687                 if (need_insert) {
 688                         dm_block_t new_tree;
 689                         __le64 new_le;
 690
 691                         r = dm_btree_empty(info, &new_tree);
 692                         if (r < 0)
 693                                 goto bad;
 694
 695                         new_le = cpu_to_le64(new_tree);
 696                         __dm_bless_for_disk(&new_le);
 697
 698                         r = insert_at(sizeof(uint64_t), n, index,
 699                                       keys[level], &new_le);
 700                         if (r)
 701                                 goto bad;
 702                 }
 703
 704                 if (level < last_level)
 705                         block = value64(n, index);
 706         }
 707
 708         r = btree_insert_raw(&spine, block, &info->value_type,
 709                              keys[level], &index);
 710         if (r < 0)
 711                 goto bad;
 712
 713         n = dm_block_data(shadow_current(&spine));
 714         need_insert = ((index >= le32_to_cpu(n->header.nr_entries)) ||
 715                        (le64_to_cpu(n->keys[index]) != keys[level]));
 716
 717         if (need_insert) {
 718                 if (inserted)
 719                         *inserted = 1;
 720
 721                 r = insert_at(info->value_type.size, n, index,
 722                               keys[level], value);
 723                 if (r)
 724                         goto bad_unblessed;
 725         } else {
 726                 if (inserted)
 727                         *inserted = 0;
 728
 729                 if (info->value_type.dec &&
 730                     (!info->value_type.equal ||
 731                      !info->value_type.equal(
 732                              info->value_type.context,
 733                              value_ptr(n, index),
 734                              value))) {
 735                         info->value_type.dec(info->value_type.context,
 736                                              value_ptr(n, index));
 737                 }
 738                 memcpy_disk(value_ptr(n, index),
 739                             value, info->value_type.size);
 740         }
 741
 742         *new_root = shadow_root(&spine);
 743         exit_shadow_spine(&spine);
 744
 745         return 0;
 746
 747 bad:
 748         __dm_unbless_for_disk(value);
 749 bad_unblessed:
 750         exit_shadow_spine(&spine);
 751         return r;
 752 }
 753
 754 int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
 755                     uint64_t *keys, void *value, dm_block_t *new_root)
 756                     __dm_written_to_disk(value)
 757 {
 758         return insert(info, root, keys, value, new_root, NULL);
 759 }
 760 EXPORT_SYMBOL_GPL(dm_btree_insert);
 761
 762 int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
 763                            uint64_t *keys, void *value, dm_block_t *new_root,
 764                            int *inserted)
 765                            __dm_written_to_disk(value)
 766 {
 767         return insert(info, root, keys, value, new_root, inserted);
 768 }
 769 EXPORT_SYMBOL_GPL(dm_btree_insert_notify);
 770
 771 /*----------------------------------------------------------------*/
 772
 773 static int find_key(struct ro_spine *s, dm_block_t block, bool find_highest,
 774                     uint64_t *result_key, dm_block_t *next_block)
 775 {
 776         int i, r;
 777         uint32_t flags;
 778
 779         do {
 780                 r = ro_step(s, block);
 781                 if (r < 0)
 782                         return r;
 783
 784                 flags = le32_to_cpu(ro_node(s)->header.flags);
 785                 i = le32_to_cpu(ro_node(s)->header.nr_entries);
 786                 if (!i)
 787                         return -ENODATA;
 788                 else
 789                         i--;
 790
 791                 if (find_highest)
 792                         *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 793                 else
 794                         *result_key = le64_to_cpu(ro_node(s)->keys[0]);
 795
 796                 if (next_block || flags & INTERNAL_NODE)
 797                         block = value64(ro_node(s), i);
 798
 799         } while (flags & INTERNAL_NODE);
 800
 801         if (next_block)
 802                 *next_block = block;
 803         return 0;
 804 }
 805
 806 static int dm_btree_find_key(struct dm_btree_info *info, dm_block_t root,
 807                              bool find_highest, uint64_t *result_keys)
 808 {
 809         int r = 0, count = 0, level;
 810         struct ro_spine spine;
 811
 812         init_ro_spine(&spine, info);
 813         for (level = 0; level < info->levels; level++) {
 814                 r = find_key(&spine, root, find_highest, result_keys + level,
 815                              level == info->levels - 1 ? NULL : &root);
 816                 if (r == -ENODATA) {
 817                         r = 0;
 818                         break;
 819
 820                 } else if (r)
 821                         break;
 822
 823                 count++;
 824         }
 825         exit_ro_spine(&spine);
 826
 827         return r ? r : count;
 828 }
 829
 830 int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
 831                               uint64_t *result_keys)
 832 {
 833         return dm_btree_find_key(info, root, true, result_keys);
 834 }
 835 EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);
 836
 837 int dm_btree_find_lowest_key(struct dm_btree_info *info, dm_block_t root,
 838                              uint64_t *result_keys)
 839 {
 840         return dm_btree_find_key(info, root, false, result_keys);
 841 }
 842 EXPORT_SYMBOL_GPL(dm_btree_find_lowest_key);
 843
 844 /*----------------------------------------------------------------*/
 845
 846 /*
 847  * FIXME: We shouldn't use a recursive algorithm when we have limited stack
 848  * space.  Also this only works for single level trees.
 849  */
 850 static int walk_node(struct ro_spine *s, dm_block_t block,
 851                      int (*fn)(void *context, uint64_t *keys, void *leaf),
 852                      void *context)
 853 {
 854         int r;
 855         unsigned i, nr;
 856         struct btree_node *n;
 857         uint64_t keys;
 858
 859         r = ro_step(s, block);
 860         n = ro_node(s);
 861
 862         nr = le32_to_cpu(n->header.nr_entries);
 863         for (i = 0; i < nr; i++) {
 864                 if (le32_to_cpu(n->header.flags) & INTERNAL_NODE) {
 865                         r = walk_node(s, value64(n, i), fn, context);
 866                         if (r)
 867                                 goto out;
 868                 } else {
 869                         keys = le64_to_cpu(*key_ptr(n, i));
 870                         r = fn(context, &keys, value_ptr(n, i));
 871                         if (r)
 872                                 goto out;
 873                 }
 874         }
 875
 876 out:
 877         ro_pop(s);
 878         return r;
 879 }
 880
 881 int dm_btree_walk(struct dm_btree_info *info, dm_block_t root,
 882                   int (*fn)(void *context, uint64_t *keys, void *leaf),
 883                   void *context)
 884 {
 885         int r;
 886         struct ro_spine spine;
 887
 888         BUG_ON(info->levels > 1);
 889
 890         init_ro_spine(&spine, info);
 891         r = walk_node(&spine, root, fn, context);
 892         exit_ro_spine(&spine);
 893
 894         return r;
 895 }
 896 EXPORT_SYMBOL_GPL(dm_btree_walk);