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 static int upper_bound(struct btree_node *n, uint64_t key)
  67 {
  68         return bsearch(n, key, 1);
  69 }
  70
  71 void inc_children(struct dm_transaction_manager *tm, struct btree_node *n,
  72                   struct dm_btree_value_type *vt)
  73 {
  74         unsigned i;
  75         uint32_t nr_entries = le32_to_cpu(n->header.nr_entries);
  76
  77         if (le32_to_cpu(n->header.flags) & INTERNAL_NODE)
  78                 for (i = 0; i < nr_entries; i++)
  79                         dm_tm_inc(tm, value64(n, i));
  80         else if (vt->inc)
  81                 for (i = 0; i < nr_entries; i++)
  82                         vt->inc(vt->context, value_ptr(n, i));
  83 }
  84
  85 static int insert_at(size_t value_size, struct btree_node *node, unsigned index,
  86                       uint64_t key, void *value)
  87                       __dm_written_to_disk(value)
  88 {
  89         uint32_t nr_entries = le32_to_cpu(node->header.nr_entries);
  90         __le64 key_le = cpu_to_le64(key);
  91
  92         if (index > nr_entries ||
  93             index >= le32_to_cpu(node->header.max_entries)) {
  94                 DMERR("too many entries in btree node for insert");
  95                 __dm_unbless_for_disk(value);
  96                 return -ENOMEM;
  97         }
  98
  99         __dm_bless_for_disk(&key_le);
 100
 101         array_insert(node->keys, sizeof(*node->keys), nr_entries, index, &key_le);
 102         array_insert(value_base(node), value_size, nr_entries, index, value);
 103         node->header.nr_entries = cpu_to_le32(nr_entries + 1);
 104
 105         return 0;
 106 }
 107
 108 /*----------------------------------------------------------------*/
 109
 110 /*
 111  * We want 3n entries (for some n).  This works more nicely for repeated
 112  * insert remove loops than (2n + 1).
 113  */
 114 static uint32_t calc_max_entries(size_t value_size, size_t block_size)
 115 {
 116         uint32_t total, n;
 117         size_t elt_size = sizeof(uint64_t) + value_size; /* key + value */
 118
 119         block_size -= sizeof(struct node_header);
 120         total = block_size / elt_size;
 121         n = total / 3;          /* rounds down */
 122
 123         return 3 * n;
 124 }
 125
 126 int dm_btree_empty(struct dm_btree_info *info, dm_block_t *root)
 127 {
 128         int r;
 129         struct dm_block *b;
 130         struct btree_node *n;
 131         size_t block_size;
 132         uint32_t max_entries;
 133
 134         r = new_block(info, &b);
 135         if (r < 0)
 136                 return r;
 137
 138         block_size = dm_bm_block_size(dm_tm_get_bm(info->tm));
 139         max_entries = calc_max_entries(info->value_type.size, block_size);
 140
 141         n = dm_block_data(b);
 142         memset(n, 0, block_size);
 143         n->header.flags = cpu_to_le32(LEAF_NODE);
 144         n->header.nr_entries = cpu_to_le32(0);
 145         n->header.max_entries = cpu_to_le32(max_entries);
 146         n->header.value_size = cpu_to_le32(info->value_type.size);
 147
 148         *root = dm_block_location(b);
 149         unlock_block(info, b);
 150
 151         return 0;
 152 }
 153 EXPORT_SYMBOL_GPL(dm_btree_empty);
 154
 155 /*----------------------------------------------------------------*/
 156
 157 /*
 158  * Deletion uses a recursive algorithm, since we have limited stack space
 159  * we explicitly manage our own stack on the heap.
 160  */
 161 #define MAX_SPINE_DEPTH 64
 162 struct frame {
 163         struct dm_block *b;
 164         struct btree_node *n;
 165         unsigned level;
 166         unsigned nr_children;
 167         unsigned current_child;
 168 };
 169
 170 struct del_stack {
 171         struct dm_btree_info *info;
 172         struct dm_transaction_manager *tm;
 173         int top;
 174         struct frame spine[MAX_SPINE_DEPTH];
 175 };
 176
 177 static int top_frame(struct del_stack *s, struct frame **f)
 178 {
 179         if (s->top < 0) {
 180                 DMERR("btree deletion stack empty");
 181                 return -EINVAL;
 182         }
 183
 184         *f = s->spine + s->top;
 185
 186         return 0;
 187 }
 188
 189 static int unprocessed_frames(struct del_stack *s)
 190 {
 191         return s->top >= 0;
 192 }
 193
 194 static void prefetch_children(struct del_stack *s, struct frame *f)
 195 {
 196         unsigned i;
 197         struct dm_block_manager *bm = dm_tm_get_bm(s->tm);
 198
 199         for (i = 0; i < f->nr_children; i++)
 200                 dm_bm_prefetch(bm, value64(f->n, i));
 201 }
 202
 203 static bool is_internal_level(struct dm_btree_info *info, struct frame *f)
 204 {
 205         return f->level < (info->levels - 1);
 206 }
 207
 208 static int push_frame(struct del_stack *s, dm_block_t b, unsigned level)
 209 {
 210         int r;
 211         uint32_t ref_count;
 212
 213         if (s->top >= MAX_SPINE_DEPTH - 1) {
 214                 DMERR("btree deletion stack out of memory");
 215                 return -ENOMEM;
 216         }
 217
 218         r = dm_tm_ref(s->tm, b, &ref_count);
 219         if (r)
 220                 return r;
 221
 222         if (ref_count > 1)
 223                 /*
 224                  * This is a shared node, so we can just decrement it's
 225                  * reference counter and leave the children.
 226                  */
 227                 dm_tm_dec(s->tm, b);
 228
 229         else {
 230                 uint32_t flags;
 231                 struct frame *f = s->spine + ++s->top;
 232
 233                 r = dm_tm_read_lock(s->tm, b, &btree_node_validator, &f->b);
 234                 if (r) {
 235                         s->top--;
 236                         return r;
 237                 }
 238
 239                 f->n = dm_block_data(f->b);
 240                 f->level = level;
 241                 f->nr_children = le32_to_cpu(f->n->header.nr_entries);
 242                 f->current_child = 0;
 243
 244                 flags = le32_to_cpu(f->n->header.flags);
 245                 if (flags & INTERNAL_NODE || is_internal_level(s->info, f))
 246                         prefetch_children(s, f);
 247         }
 248
 249         return 0;
 250 }
 251
 252 static void pop_frame(struct del_stack *s)
 253 {
 254         struct frame *f = s->spine + s->top--;
 255
 256         dm_tm_dec(s->tm, dm_block_location(f->b));
 257         dm_tm_unlock(s->tm, f->b);
 258 }
 259
 260 static void unlock_all_frames(struct del_stack *s)
 261 {
 262         struct frame *f;
 263
 264         while (unprocessed_frames(s)) {
 265                 f = s->spine + s->top--;
 266                 dm_tm_unlock(s->tm, f->b);
 267         }
 268 }
 269
 270 int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
 271 {
 272         int r;
 273         struct del_stack *s;
 274
 275         s = kmalloc(sizeof(*s), GFP_NOIO);
 276         if (!s)
 277                 return -ENOMEM;
 278         s->info = info;
 279         s->tm = info->tm;
 280         s->top = -1;
 281
 282         r = push_frame(s, root, 0);
 283         if (r)
 284                 goto out;
 285
 286         while (unprocessed_frames(s)) {
 287                 uint32_t flags;
 288                 struct frame *f;
 289                 dm_block_t b;
 290
 291                 r = top_frame(s, &f);
 292                 if (r)
 293                         goto out;
 294
 295                 if (f->current_child >= f->nr_children) {
 296                         pop_frame(s);
 297                         continue;
 298                 }
 299
 300                 flags = le32_to_cpu(f->n->header.flags);
 301                 if (flags & INTERNAL_NODE) {
 302                         b = value64(f->n, f->current_child);
 303                         f->current_child++;
 304                         r = push_frame(s, b, f->level);
 305                         if (r)
 306                                 goto out;
 307
 308                 } else if (is_internal_level(info, f)) {
 309                         b = value64(f->n, f->current_child);
 310                         f->current_child++;
 311                         r = push_frame(s, b, f->level + 1);
 312                         if (r)
 313                                 goto out;
 314
 315                 } else {
 316                         if (info->value_type.dec) {
 317                                 unsigned i;
 318
 319                                 for (i = 0; i < f->nr_children; i++)
 320                                         info->value_type.dec(info->value_type.context,
 321                                                              value_ptr(f->n, i));
 322                         }
 323                         pop_frame(s);
 324                 }
 325         }
 326 out:
 327         if (r) {
 328                 /* cleanup all frames of del_stack */
 329                 unlock_all_frames(s);
 330         }
 331         kfree(s);
 332
 333         return r;
 334 }
 335 EXPORT_SYMBOL_GPL(dm_btree_del);
 336
 337 /*----------------------------------------------------------------*/
 338
 339 static int btree_lookup_raw(struct ro_spine *s, dm_block_t block, uint64_t key,
 340                             int (*search_fn)(struct btree_node *, uint64_t),
 341                             uint64_t *result_key, void *v, size_t value_size)
 342 {
 343         int i, r;
 344         uint32_t flags, nr_entries;
 345
 346         do {
 347                 r = ro_step(s, block);
 348                 if (r < 0)
 349                         return r;
 350
 351                 i = search_fn(ro_node(s), key);
 352
 353                 flags = le32_to_cpu(ro_node(s)->header.flags);
 354                 nr_entries = le32_to_cpu(ro_node(s)->header.nr_entries);
 355                 if (i < 0 || i >= nr_entries)
 356                         return -ENODATA;
 357
 358                 if (flags & INTERNAL_NODE)
 359                         block = value64(ro_node(s), i);
 360
 361         } while (!(flags & LEAF_NODE));
 362
 363         *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 364         memcpy(v, value_ptr(ro_node(s), i), value_size);
 365
 366         return 0;
 367 }
 368
 369 int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
 370                     uint64_t *keys, void *value_le)
 371 {
 372         unsigned level, last_level = info->levels - 1;
 373         int r = -ENODATA;
 374         uint64_t rkey;
 375         __le64 internal_value_le;
 376         struct ro_spine spine;
 377
 378         init_ro_spine(&spine, info);
 379         for (level = 0; level < info->levels; level++) {
 380                 size_t size;
 381                 void *value_p;
 382
 383                 if (level == last_level) {
 384                         value_p = value_le;
 385                         size = info->value_type.size;
 386
 387                 } else {
 388                         value_p = &internal_value_le;
 389                         size = sizeof(uint64_t);
 390                 }
 391
 392                 r = btree_lookup_raw(&spine, root, keys[level],
 393                                      lower_bound, &rkey,
 394                                      value_p, size);
 395
 396                 if (!r) {
 397                         if (rkey != keys[level]) {
 398                                 exit_ro_spine(&spine);
 399                                 return -ENODATA;
 400                         }
 401                 } else {
 402                         exit_ro_spine(&spine);
 403                         return r;
 404                 }
 405
 406                 root = le64_to_cpu(internal_value_le);
 407         }
 408         exit_ro_spine(&spine);
 409
 410         return r;
 411 }
 412 EXPORT_SYMBOL_GPL(dm_btree_lookup);
 413
 414 static int dm_btree_lookup_next_single(struct dm_btree_info *info, dm_block_t root,
 415                                        uint64_t key, uint64_t *rkey, void *value_le)
 416 {
 417         int r, i;
 418         uint32_t flags, nr_entries;
 419         struct dm_block *node;
 420         struct btree_node *n;
 421
 422         r = bn_read_lock(info, root, &node);
 423         if (r)
 424                 return r;
 425
 426         n = dm_block_data(node);
 427         flags = le32_to_cpu(n->header.flags);
 428         nr_entries = le32_to_cpu(n->header.nr_entries);
 429
 430         if (flags & INTERNAL_NODE) {
 431                 i = lower_bound(n, key);
 432                 if (i < 0 || i >= nr_entries) {
 433                         r = -ENODATA;
 434                         goto out;
 435                 }
 436
 437                 r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
 438                 if (r == -ENODATA && i < (nr_entries - 1)) {
 439                         i++;
 440                         r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
 441                 }
 442
 443         } else {
 444                 i = upper_bound(n, key);
 445                 if (i < 0 || i >= nr_entries) {
 446                         r = -ENODATA;
 447                         goto out;
 448                 }
 449
 450                 *rkey = le64_to_cpu(n->keys[i]);
 451                 memcpy(value_le, value_ptr(n, i), info->value_type.size);
 452         }
 453 out:
 454         dm_tm_unlock(info->tm, node);
 455         return r;
 456 }
 457
 458 int dm_btree_lookup_next(struct dm_btree_info *info, dm_block_t root,
 459                          uint64_t *keys, uint64_t *rkey, void *value_le)
 460 {
 461         unsigned level;
 462         int r = -ENODATA;
 463         __le64 internal_value_le;
 464         struct ro_spine spine;
 465
 466         init_ro_spine(&spine, info);
 467         for (level = 0; level < info->levels - 1u; level++) {
 468                 r = btree_lookup_raw(&spine, root, keys[level],
 469                                      lower_bound, rkey,
 470                                      &internal_value_le, sizeof(uint64_t));
 471                 if (r)
 472                         goto out;
 473
 474                 if (*rkey != keys[level]) {
 475                         r = -ENODATA;
 476                         goto out;
 477                 }
 478
 479                 root = le64_to_cpu(internal_value_le);
 480         }
 481
 482         r = dm_btree_lookup_next_single(info, root, keys[level], rkey, value_le);
 483 out:
 484         exit_ro_spine(&spine);
 485         return r;
 486 }
 487
 488 EXPORT_SYMBOL_GPL(dm_btree_lookup_next);
 489
 490 /*
 491  * Splits a node by creating a sibling node and shifting half the nodes
 492  * contents across.  Assumes there is a parent node, and it has room for
 493  * another child.
 494  *
 495  * Before:
 496  *        +--------+
 497  *        | Parent |
 498  *        +--------+
 499  *           |
 500  *           v
 501  *      +----------+
 502  *      | A ++++++ |
 503  *      +----------+
 504  *
 505  *
 506  * After:
 507  *              +--------+
 508  *              | Parent |
 509  *              +--------+
 510  *                |     |
 511  *                v     +------+
 512  *          +---------+        |
 513  *          | A* +++  |        v
 514  *          +---------+   +-------+
 515  *                        | B +++ |
 516  *                        +-------+
 517  *
 518  * Where A* is a shadow of A.
 519  */
 520 static int btree_split_sibling(struct shadow_spine *s, unsigned parent_index,
 521                                uint64_t key)
 522 {
 523         int r;
 524         size_t size;
 525         unsigned nr_left, nr_right;
 526         struct dm_block *left, *right, *parent;
 527         struct btree_node *ln, *rn, *pn;
 528         __le64 location;
 529
 530         left = shadow_current(s);
 531
 532         r = new_block(s->info, &right);
 533         if (r < 0)
 534                 return r;
 535
 536         ln = dm_block_data(left);
 537         rn = dm_block_data(right);
 538
 539         nr_left = le32_to_cpu(ln->header.nr_entries) / 2;
 540         nr_right = le32_to_cpu(ln->header.nr_entries) - nr_left;
 541
 542         ln->header.nr_entries = cpu_to_le32(nr_left);
 543
 544         rn->header.flags = ln->header.flags;
 545         rn->header.nr_entries = cpu_to_le32(nr_right);
 546         rn->header.max_entries = ln->header.max_entries;
 547         rn->header.value_size = ln->header.value_size;
 548         memcpy(rn->keys, ln->keys + nr_left, nr_right * sizeof(rn->keys[0]));
 549
 550         size = le32_to_cpu(ln->header.flags) & INTERNAL_NODE ?
 551                 sizeof(uint64_t) : s->info->value_type.size;
 552         memcpy(value_ptr(rn, 0), value_ptr(ln, nr_left),
 553                size * nr_right);
 554
 555         /*
 556          * Patch up the parent
 557          */
 558         parent = shadow_parent(s);
 559
 560         pn = dm_block_data(parent);
 561         location = cpu_to_le64(dm_block_location(left));
 562         __dm_bless_for_disk(&location);
 563         memcpy_disk(value_ptr(pn, parent_index),
 564                     &location, sizeof(__le64));
 565
 566         location = cpu_to_le64(dm_block_location(right));
 567         __dm_bless_for_disk(&location);
 568
 569         r = insert_at(sizeof(__le64), pn, parent_index + 1,
 570                       le64_to_cpu(rn->keys[0]), &location);
 571         if (r) {
 572                 unlock_block(s->info, right);
 573                 return r;
 574         }
 575
 576         if (key < le64_to_cpu(rn->keys[0])) {
 577                 unlock_block(s->info, right);
 578                 s->nodes[1] = left;
 579         } else {
 580                 unlock_block(s->info, left);
 581                 s->nodes[1] = right;
 582         }
 583
 584         return 0;
 585 }
 586
 587 /*
 588  * Splits a node by creating two new children beneath the given node.
 589  *
 590  * Before:
 591  *        +----------+
 592  *        | A ++++++ |
 593  *        +----------+
 594  *
 595  *
 596  * After:
 597  *      +------------+
 598  *      | A (shadow) |
 599  *      +------------+
 600  *          |   |
 601  *   +------+   +----+
 602  *   |               |
 603  *   v               v
 604  * +-------+     +-------+
 605  * | B +++ |     | C +++ |
 606  * +-------+     +-------+
 607  */
 608 static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
 609 {
 610         int r;
 611         size_t size;
 612         unsigned nr_left, nr_right;
 613         struct dm_block *left, *right, *new_parent;
 614         struct btree_node *pn, *ln, *rn;
 615         __le64 val;
 616
 617         new_parent = shadow_current(s);
 618
 619         r = new_block(s->info, &left);
 620         if (r < 0)
 621                 return r;
 622
 623         r = new_block(s->info, &right);
 624         if (r < 0) {
 625                 unlock_block(s->info, left);
 626                 return r;
 627         }
 628
 629         pn = dm_block_data(new_parent);
 630         ln = dm_block_data(left);
 631         rn = dm_block_data(right);
 632
 633         nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
 634         nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
 635
 636         ln->header.flags = pn->header.flags;
 637         ln->header.nr_entries = cpu_to_le32(nr_left);
 638         ln->header.max_entries = pn->header.max_entries;
 639         ln->header.value_size = pn->header.value_size;
 640
 641         rn->header.flags = pn->header.flags;
 642         rn->header.nr_entries = cpu_to_le32(nr_right);
 643         rn->header.max_entries = pn->header.max_entries;
 644         rn->header.value_size = pn->header.value_size;
 645
 646         memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
 647         memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
 648
 649         size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
 650                 sizeof(__le64) : s->info->value_type.size;
 651         memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
 652         memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left),
 653                nr_right * size);
 654
 655         /* new_parent should just point to l and r now */
 656         pn->header.flags = cpu_to_le32(INTERNAL_NODE);
 657         pn->header.nr_entries = cpu_to_le32(2);
 658         pn->header.max_entries = cpu_to_le32(
 659                 calc_max_entries(sizeof(__le64),
 660                                  dm_bm_block_size(
 661                                          dm_tm_get_bm(s->info->tm))));
 662         pn->header.value_size = cpu_to_le32(sizeof(__le64));
 663
 664         val = cpu_to_le64(dm_block_location(left));
 665         __dm_bless_for_disk(&val);
 666         pn->keys[0] = ln->keys[0];
 667         memcpy_disk(value_ptr(pn, 0), &val, sizeof(__le64));
 668
 669         val = cpu_to_le64(dm_block_location(right));
 670         __dm_bless_for_disk(&val);
 671         pn->keys[1] = rn->keys[0];
 672         memcpy_disk(value_ptr(pn, 1), &val, sizeof(__le64));
 673
 674         /*
 675          * rejig the spine.  This is ugly, since it knows too
 676          * much about the spine
 677          */
 678         if (s->nodes[0] != new_parent) {
 679                 unlock_block(s->info, s->nodes[0]);
 680                 s->nodes[0] = new_parent;
 681         }
 682         if (key < le64_to_cpu(rn->keys[0])) {
 683                 unlock_block(s->info, right);
 684                 s->nodes[1] = left;
 685         } else {
 686                 unlock_block(s->info, left);
 687                 s->nodes[1] = right;
 688         }
 689         s->count = 2;
 690
 691         return 0;
 692 }
 693
 694 static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
 695                             struct dm_btree_value_type *vt,
 696                             uint64_t key, unsigned *index)
 697 {
 698         int r, i = *index, top = 1;
 699         struct btree_node *node;
 700
 701         for (;;) {
 702                 r = shadow_step(s, root, vt);
 703                 if (r < 0)
 704                         return r;
 705
 706                 node = dm_block_data(shadow_current(s));
 707
 708                 /*
 709                  * We have to patch up the parent node, ugly, but I don't
 710                  * see a way to do this automatically as part of the spine
 711                  * op.
 712                  */
 713                 if (shadow_has_parent(s) && i >= 0) { /* FIXME: second clause unness. */
 714                         __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
 715
 716                         __dm_bless_for_disk(&location);
 717                         memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
 718                                     &location, sizeof(__le64));
 719                 }
 720
 721                 node = dm_block_data(shadow_current(s));
 722
 723                 if (node->header.nr_entries == node->header.max_entries) {
 724                         if (top)
 725                                 r = btree_split_beneath(s, key);
 726                         else
 727                                 r = btree_split_sibling(s, i, key);
 728
 729                         if (r < 0)
 730                                 return r;
 731                 }
 732
 733                 node = dm_block_data(shadow_current(s));
 734
 735                 i = lower_bound(node, key);
 736
 737                 if (le32_to_cpu(node->header.flags) & LEAF_NODE)
 738                         break;
 739
 740                 if (i < 0) {
 741                         /* change the bounds on the lowest key */
 742                         node->keys[0] = cpu_to_le64(key);
 743                         i = 0;
 744                 }
 745
 746                 root = value64(node, i);
 747                 top = 0;
 748         }
 749
 750         if (i < 0 || le64_to_cpu(node->keys[i]) != key)
 751                 i++;
 752
 753         *index = i;
 754         return 0;
 755 }
 756
 757 static bool need_insert(struct btree_node *node, uint64_t *keys,
 758                         unsigned level, unsigned index)
 759 {
 760         return ((index >= le32_to_cpu(node->header.nr_entries)) ||
 761                 (le64_to_cpu(node->keys[index]) != keys[level]));
 762 }
 763
 764 static int insert(struct dm_btree_info *info, dm_block_t root,
 765                   uint64_t *keys, void *value, dm_block_t *new_root,
 766                   int *inserted)
 767                   __dm_written_to_disk(value)
 768 {
 769         int r;
 770         unsigned level, index = -1, last_level = info->levels - 1;
 771         dm_block_t block = root;
 772         struct shadow_spine spine;
 773         struct btree_node *n;
 774         struct dm_btree_value_type le64_type;
 775
 776         init_le64_type(info->tm, &le64_type);
 777         init_shadow_spine(&spine, info);
 778
 779         for (level = 0; level < (info->levels - 1); level++) {
 780                 r = btree_insert_raw(&spine, block, &le64_type, keys[level], &index);
 781                 if (r < 0)
 782                         goto bad;
 783
 784                 n = dm_block_data(shadow_current(&spine));
 785
 786                 if (need_insert(n, keys, level, index)) {
 787                         dm_block_t new_tree;
 788                         __le64 new_le;
 789
 790                         r = dm_btree_empty(info, &new_tree);
 791                         if (r < 0)
 792                                 goto bad;
 793
 794                         new_le = cpu_to_le64(new_tree);
 795                         __dm_bless_for_disk(&new_le);
 796
 797                         r = insert_at(sizeof(uint64_t), n, index,
 798                                       keys[level], &new_le);
 799                         if (r)
 800                                 goto bad;
 801                 }
 802
 803                 if (level < last_level)
 804                         block = value64(n, index);
 805         }
 806
 807         r = btree_insert_raw(&spine, block, &info->value_type,
 808                              keys[level], &index);
 809         if (r < 0)
 810                 goto bad;
 811
 812         n = dm_block_data(shadow_current(&spine));
 813
 814         if (need_insert(n, keys, level, index)) {
 815                 if (inserted)
 816                         *inserted = 1;
 817
 818                 r = insert_at(info->value_type.size, n, index,
 819                               keys[level], value);
 820                 if (r)
 821                         goto bad_unblessed;
 822         } else {
 823                 if (inserted)
 824                         *inserted = 0;
 825
 826                 if (info->value_type.dec &&
 827                     (!info->value_type.equal ||
 828                      !info->value_type.equal(
 829                              info->value_type.context,
 830                              value_ptr(n, index),
 831                              value))) {
 832                         info->value_type.dec(info->value_type.context,
 833                                              value_ptr(n, index));
 834                 }
 835                 memcpy_disk(value_ptr(n, index),
 836                             value, info->value_type.size);
 837         }
 838
 839         *new_root = shadow_root(&spine);
 840         exit_shadow_spine(&spine);
 841
 842         return 0;
 843
 844 bad:
 845         __dm_unbless_for_disk(value);
 846 bad_unblessed:
 847         exit_shadow_spine(&spine);
 848         return r;
 849 }
 850
 851 int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
 852                     uint64_t *keys, void *value, dm_block_t *new_root)
 853                     __dm_written_to_disk(value)
 854 {
 855         return insert(info, root, keys, value, new_root, NULL);
 856 }
 857 EXPORT_SYMBOL_GPL(dm_btree_insert);
 858
 859 int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
 860                            uint64_t *keys, void *value, dm_block_t *new_root,
 861                            int *inserted)
 862                            __dm_written_to_disk(value)
 863 {
 864         return insert(info, root, keys, value, new_root, inserted);
 865 }
 866 EXPORT_SYMBOL_GPL(dm_btree_insert_notify);
 867
 868 /*----------------------------------------------------------------*/
 869
 870 static int find_key(struct ro_spine *s, dm_block_t block, bool find_highest,
 871                     uint64_t *result_key, dm_block_t *next_block)
 872 {
 873         int i, r;
 874         uint32_t flags;
 875
 876         do {
 877                 r = ro_step(s, block);
 878                 if (r < 0)
 879                         return r;
 880
 881                 flags = le32_to_cpu(ro_node(s)->header.flags);
 882                 i = le32_to_cpu(ro_node(s)->header.nr_entries);
 883                 if (!i)
 884                         return -ENODATA;
 885                 else
 886                         i--;
 887
 888                 if (find_highest)
 889                         *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 890                 else
 891                         *result_key = le64_to_cpu(ro_node(s)->keys[0]);
 892
 893                 if (next_block || flags & INTERNAL_NODE)
 894                         block = value64(ro_node(s), i);
 895
 896         } while (flags & INTERNAL_NODE);
 897
 898         if (next_block)
 899                 *next_block = block;
 900         return 0;
 901 }
 902
 903 static int dm_btree_find_key(struct dm_btree_info *info, dm_block_t root,
 904                              bool find_highest, uint64_t *result_keys)
 905 {
 906         int r = 0, count = 0, level;
 907         struct ro_spine spine;
 908
 909         init_ro_spine(&spine, info);
 910         for (level = 0; level < info->levels; level++) {
 911                 r = find_key(&spine, root, find_highest, result_keys + level,
 912                              level == info->levels - 1 ? NULL : &root);
 913                 if (r == -ENODATA) {
 914                         r = 0;
 915                         break;
 916
 917                 } else if (r)
 918                         break;
 919
 920                 count++;
 921         }
 922         exit_ro_spine(&spine);
 923
 924         return r ? r : count;
 925 }
 926
 927 int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
 928                               uint64_t *result_keys)
 929 {
 930         return dm_btree_find_key(info, root, true, result_keys);
 931 }
 932 EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);
 933
 934 int dm_btree_find_lowest_key(struct dm_btree_info *info, dm_block_t root,
 935                              uint64_t *result_keys)
 936 {
 937         return dm_btree_find_key(info, root, false, result_keys);
 938 }
 939 EXPORT_SYMBOL_GPL(dm_btree_find_lowest_key);
 940
 941 /*----------------------------------------------------------------*/
 942
 943 /*
 944  * FIXME: We shouldn't use a recursive algorithm when we have limited stack
 945  * space.  Also this only works for single level trees.
 946  */
 947 static int walk_node(struct dm_btree_info *info, dm_block_t block,
 948                      int (*fn)(void *context, uint64_t *keys, void *leaf),
 949                      void *context)
 950 {
 951         int r;
 952         unsigned i, nr;
 953         struct dm_block *node;
 954         struct btree_node *n;
 955         uint64_t keys;
 956
 957         r = bn_read_lock(info, block, &node);
 958         if (r)
 959                 return r;
 960
 961         n = dm_block_data(node);
 962
 963         nr = le32_to_cpu(n->header.nr_entries);
 964         for (i = 0; i < nr; i++) {
 965                 if (le32_to_cpu(n->header.flags) & INTERNAL_NODE) {
 966                         r = walk_node(info, value64(n, i), fn, context);
 967                         if (r)
 968                                 goto out;
 969                 } else {
 970                         keys = le64_to_cpu(*key_ptr(n, i));
 971                         r = fn(context, &keys, value_ptr(n, i));
 972                         if (r)
 973                                 goto out;
 974                 }
 975         }
 976
 977 out:
 978         dm_tm_unlock(info->tm, node);
 979         return r;
 980 }
 981
 982 int dm_btree_walk(struct dm_btree_info *info, dm_block_t root,
 983                   int (*fn)(void *context, uint64_t *keys, void *leaf),
 984                   void *context)
 985 {
 986         BUG_ON(info->levels > 1);
 987         return walk_node(info, root, fn, context);
 988 }
 989 EXPORT_SYMBOL_GPL(dm_btree_walk);