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) {
 433                         /*
 434                          * avoid early -ENODATA return when all entries are
 435                          * higher than the search @key.
 436                          */
 437                         i = 0;
 438                 }
 439                 if (i >= nr_entries) {
 440                         r = -ENODATA;
 441                         goto out;
 442                 }
 443
 444                 r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
 445                 if (r == -ENODATA && i < (nr_entries - 1)) {
 446                         i++;
 447                         r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
 448                 }
 449
 450         } else {
 451                 i = upper_bound(n, key);
 452                 if (i < 0 || i >= nr_entries) {
 453                         r = -ENODATA;
 454                         goto out;
 455                 }
 456
 457                 *rkey = le64_to_cpu(n->keys[i]);
 458                 memcpy(value_le, value_ptr(n, i), info->value_type.size);
 459         }
 460 out:
 461         dm_tm_unlock(info->tm, node);
 462         return r;
 463 }
 464
 465 int dm_btree_lookup_next(struct dm_btree_info *info, dm_block_t root,
 466                          uint64_t *keys, uint64_t *rkey, void *value_le)
 467 {
 468         unsigned level;
 469         int r = -ENODATA;
 470         __le64 internal_value_le;
 471         struct ro_spine spine;
 472
 473         init_ro_spine(&spine, info);
 474         for (level = 0; level < info->levels - 1u; level++) {
 475                 r = btree_lookup_raw(&spine, root, keys[level],
 476                                      lower_bound, rkey,
 477                                      &internal_value_le, sizeof(uint64_t));
 478                 if (r)
 479                         goto out;
 480
 481                 if (*rkey != keys[level]) {
 482                         r = -ENODATA;
 483                         goto out;
 484                 }
 485
 486                 root = le64_to_cpu(internal_value_le);
 487         }
 488
 489         r = dm_btree_lookup_next_single(info, root, keys[level], rkey, value_le);
 490 out:
 491         exit_ro_spine(&spine);
 492         return r;
 493 }
 494
 495 EXPORT_SYMBOL_GPL(dm_btree_lookup_next);
 496
 497 /*
 498  * Splits a node by creating a sibling node and shifting half the nodes
 499  * contents across.  Assumes there is a parent node, and it has room for
 500  * another child.
 501  *
 502  * Before:
 503  *        +--------+
 504  *        | Parent |
 505  *        +--------+
 506  *           |
 507  *           v
 508  *      +----------+
 509  *      | A ++++++ |
 510  *      +----------+
 511  *
 512  *
 513  * After:
 514  *              +--------+
 515  *              | Parent |
 516  *              +--------+
 517  *                |     |
 518  *                v     +------+
 519  *          +---------+        |
 520  *          | A* +++  |        v
 521  *          +---------+   +-------+
 522  *                        | B +++ |
 523  *                        +-------+
 524  *
 525  * Where A* is a shadow of A.
 526  */
 527 static int btree_split_sibling(struct shadow_spine *s, unsigned parent_index,
 528                                uint64_t key)
 529 {
 530         int r;
 531         size_t size;
 532         unsigned nr_left, nr_right;
 533         struct dm_block *left, *right, *parent;
 534         struct btree_node *ln, *rn, *pn;
 535         __le64 location;
 536
 537         left = shadow_current(s);
 538
 539         r = new_block(s->info, &right);
 540         if (r < 0)
 541                 return r;
 542
 543         ln = dm_block_data(left);
 544         rn = dm_block_data(right);
 545
 546         nr_left = le32_to_cpu(ln->header.nr_entries) / 2;
 547         nr_right = le32_to_cpu(ln->header.nr_entries) - nr_left;
 548
 549         ln->header.nr_entries = cpu_to_le32(nr_left);
 550
 551         rn->header.flags = ln->header.flags;
 552         rn->header.nr_entries = cpu_to_le32(nr_right);
 553         rn->header.max_entries = ln->header.max_entries;
 554         rn->header.value_size = ln->header.value_size;
 555         memcpy(rn->keys, ln->keys + nr_left, nr_right * sizeof(rn->keys[0]));
 556
 557         size = le32_to_cpu(ln->header.flags) & INTERNAL_NODE ?
 558                 sizeof(uint64_t) : s->info->value_type.size;
 559         memcpy(value_ptr(rn, 0), value_ptr(ln, nr_left),
 560                size * nr_right);
 561
 562         /*
 563          * Patch up the parent
 564          */
 565         parent = shadow_parent(s);
 566
 567         pn = dm_block_data(parent);
 568         location = cpu_to_le64(dm_block_location(left));
 569         __dm_bless_for_disk(&location);
 570         memcpy_disk(value_ptr(pn, parent_index),
 571                     &location, sizeof(__le64));
 572
 573         location = cpu_to_le64(dm_block_location(right));
 574         __dm_bless_for_disk(&location);
 575
 576         r = insert_at(sizeof(__le64), pn, parent_index + 1,
 577                       le64_to_cpu(rn->keys[0]), &location);
 578         if (r) {
 579                 unlock_block(s->info, right);
 580                 return r;
 581         }
 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
 591         return 0;
 592 }
 593
 594 /*
 595  * Splits a node by creating two new children beneath the given node.
 596  *
 597  * Before:
 598  *        +----------+
 599  *        | A ++++++ |
 600  *        +----------+
 601  *
 602  *
 603  * After:
 604  *      +------------+
 605  *      | A (shadow) |
 606  *      +------------+
 607  *          |   |
 608  *   +------+   +----+
 609  *   |               |
 610  *   v               v
 611  * +-------+     +-------+
 612  * | B +++ |     | C +++ |
 613  * +-------+     +-------+
 614  */
 615 static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
 616 {
 617         int r;
 618         size_t size;
 619         unsigned nr_left, nr_right;
 620         struct dm_block *left, *right, *new_parent;
 621         struct btree_node *pn, *ln, *rn;
 622         __le64 val;
 623
 624         new_parent = shadow_current(s);
 625
 626         pn = dm_block_data(new_parent);
 627         size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
 628                 sizeof(__le64) : s->info->value_type.size;
 629
 630         /* create & init the left block */
 631         r = new_block(s->info, &left);
 632         if (r < 0)
 633                 return r;
 634
 635         ln = dm_block_data(left);
 636         nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
 637
 638         ln->header.flags = pn->header.flags;
 639         ln->header.nr_entries = cpu_to_le32(nr_left);
 640         ln->header.max_entries = pn->header.max_entries;
 641         ln->header.value_size = pn->header.value_size;
 642         memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
 643         memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
 644
 645         /* create & init the right block */
 646         r = new_block(s->info, &right);
 647         if (r < 0) {
 648                 unlock_block(s->info, left);
 649                 return r;
 650         }
 651
 652         rn = dm_block_data(right);
 653         nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
 654
 655         rn->header.flags = pn->header.flags;
 656         rn->header.nr_entries = cpu_to_le32(nr_right);
 657         rn->header.max_entries = pn->header.max_entries;
 658         rn->header.value_size = pn->header.value_size;
 659         memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
 660         memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left),
 661                nr_right * size);
 662
 663         /* new_parent should just point to l and r now */
 664         pn->header.flags = cpu_to_le32(INTERNAL_NODE);
 665         pn->header.nr_entries = cpu_to_le32(2);
 666         pn->header.max_entries = cpu_to_le32(
 667                 calc_max_entries(sizeof(__le64),
 668                                  dm_bm_block_size(
 669                                          dm_tm_get_bm(s->info->tm))));
 670         pn->header.value_size = cpu_to_le32(sizeof(__le64));
 671
 672         val = cpu_to_le64(dm_block_location(left));
 673         __dm_bless_for_disk(&val);
 674         pn->keys[0] = ln->keys[0];
 675         memcpy_disk(value_ptr(pn, 0), &val, sizeof(__le64));
 676
 677         val = cpu_to_le64(dm_block_location(right));
 678         __dm_bless_for_disk(&val);
 679         pn->keys[1] = rn->keys[0];
 680         memcpy_disk(value_ptr(pn, 1), &val, sizeof(__le64));
 681
 682         unlock_block(s->info, left);
 683         unlock_block(s->info, right);
 684         return 0;
 685 }
 686
 687 static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
 688                             struct dm_btree_value_type *vt,
 689                             uint64_t key, unsigned *index)
 690 {
 691         int r, i = *index, top = 1;
 692         struct btree_node *node;
 693
 694         for (;;) {
 695                 r = shadow_step(s, root, vt);
 696                 if (r < 0)
 697                         return r;
 698
 699                 node = dm_block_data(shadow_current(s));
 700
 701                 /*
 702                  * We have to patch up the parent node, ugly, but I don't
 703                  * see a way to do this automatically as part of the spine
 704                  * op.
 705                  */
 706                 if (shadow_has_parent(s) && i >= 0) { /* FIXME: second clause unness. */
 707                         __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
 708
 709                         __dm_bless_for_disk(&location);
 710                         memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
 711                                     &location, sizeof(__le64));
 712                 }
 713
 714                 node = dm_block_data(shadow_current(s));
 715
 716                 if (node->header.nr_entries == node->header.max_entries) {
 717                         if (top)
 718                                 r = btree_split_beneath(s, key);
 719                         else
 720                                 r = btree_split_sibling(s, i, key);
 721
 722                         if (r < 0)
 723                                 return r;
 724                 }
 725
 726                 node = dm_block_data(shadow_current(s));
 727
 728                 i = lower_bound(node, key);
 729
 730                 if (le32_to_cpu(node->header.flags) & LEAF_NODE)
 731                         break;
 732
 733                 if (i < 0) {
 734                         /* change the bounds on the lowest key */
 735                         node->keys[0] = cpu_to_le64(key);
 736                         i = 0;
 737                 }
 738
 739                 root = value64(node, i);
 740                 top = 0;
 741         }
 742
 743         if (i < 0 || le64_to_cpu(node->keys[i]) != key)
 744                 i++;
 745
 746         *index = i;
 747         return 0;
 748 }
 749
 750 static bool need_insert(struct btree_node *node, uint64_t *keys,
 751                         unsigned level, unsigned index)
 752 {
 753         return ((index >= le32_to_cpu(node->header.nr_entries)) ||
 754                 (le64_to_cpu(node->keys[index]) != keys[level]));
 755 }
 756
 757 static int insert(struct dm_btree_info *info, dm_block_t root,
 758                   uint64_t *keys, void *value, dm_block_t *new_root,
 759                   int *inserted)
 760                   __dm_written_to_disk(value)
 761 {
 762         int r;
 763         unsigned level, index = -1, last_level = info->levels - 1;
 764         dm_block_t block = root;
 765         struct shadow_spine spine;
 766         struct btree_node *n;
 767         struct dm_btree_value_type le64_type;
 768
 769         init_le64_type(info->tm, &le64_type);
 770         init_shadow_spine(&spine, info);
 771
 772         for (level = 0; level < (info->levels - 1); level++) {
 773                 r = btree_insert_raw(&spine, block, &le64_type, keys[level], &index);
 774                 if (r < 0)
 775                         goto bad;
 776
 777                 n = dm_block_data(shadow_current(&spine));
 778
 779                 if (need_insert(n, keys, level, index)) {
 780                         dm_block_t new_tree;
 781                         __le64 new_le;
 782
 783                         r = dm_btree_empty(info, &new_tree);
 784                         if (r < 0)
 785                                 goto bad;
 786
 787                         new_le = cpu_to_le64(new_tree);
 788                         __dm_bless_for_disk(&new_le);
 789
 790                         r = insert_at(sizeof(uint64_t), n, index,
 791                                       keys[level], &new_le);
 792                         if (r)
 793                                 goto bad;
 794                 }
 795
 796                 if (level < last_level)
 797                         block = value64(n, index);
 798         }
 799
 800         r = btree_insert_raw(&spine, block, &info->value_type,
 801                              keys[level], &index);
 802         if (r < 0)
 803                 goto bad;
 804
 805         n = dm_block_data(shadow_current(&spine));
 806
 807         if (need_insert(n, keys, level, index)) {
 808                 if (inserted)
 809                         *inserted = 1;
 810
 811                 r = insert_at(info->value_type.size, n, index,
 812                               keys[level], value);
 813                 if (r)
 814                         goto bad_unblessed;
 815         } else {
 816                 if (inserted)
 817                         *inserted = 0;
 818
 819                 if (info->value_type.dec &&
 820                     (!info->value_type.equal ||
 821                      !info->value_type.equal(
 822                              info->value_type.context,
 823                              value_ptr(n, index),
 824                              value))) {
 825                         info->value_type.dec(info->value_type.context,
 826                                              value_ptr(n, index));
 827                 }
 828                 memcpy_disk(value_ptr(n, index),
 829                             value, info->value_type.size);
 830         }
 831
 832         *new_root = shadow_root(&spine);
 833         exit_shadow_spine(&spine);
 834
 835         return 0;
 836
 837 bad:
 838         __dm_unbless_for_disk(value);
 839 bad_unblessed:
 840         exit_shadow_spine(&spine);
 841         return r;
 842 }
 843
 844 int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
 845                     uint64_t *keys, void *value, dm_block_t *new_root)
 846                     __dm_written_to_disk(value)
 847 {
 848         return insert(info, root, keys, value, new_root, NULL);
 849 }
 850 EXPORT_SYMBOL_GPL(dm_btree_insert);
 851
 852 int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
 853                            uint64_t *keys, void *value, dm_block_t *new_root,
 854                            int *inserted)
 855                            __dm_written_to_disk(value)
 856 {
 857         return insert(info, root, keys, value, new_root, inserted);
 858 }
 859 EXPORT_SYMBOL_GPL(dm_btree_insert_notify);
 860
 861 /*----------------------------------------------------------------*/
 862
 863 static int find_key(struct ro_spine *s, dm_block_t block, bool find_highest,
 864                     uint64_t *result_key, dm_block_t *next_block)
 865 {
 866         int i, r;
 867         uint32_t flags;
 868
 869         do {
 870                 r = ro_step(s, block);
 871                 if (r < 0)
 872                         return r;
 873
 874                 flags = le32_to_cpu(ro_node(s)->header.flags);
 875                 i = le32_to_cpu(ro_node(s)->header.nr_entries);
 876                 if (!i)
 877                         return -ENODATA;
 878                 else
 879                         i--;
 880
 881                 if (find_highest)
 882                         *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 883                 else
 884                         *result_key = le64_to_cpu(ro_node(s)->keys[0]);
 885
 886                 if (next_block || flags & INTERNAL_NODE) {
 887                         if (find_highest)
 888                                 block = value64(ro_node(s), i);
 889                         else
 890                                 block = value64(ro_node(s), 0);
 891                 }
 892
 893         } while (flags & INTERNAL_NODE);
 894
 895         if (next_block)
 896                 *next_block = block;
 897         return 0;
 898 }
 899
 900 static int dm_btree_find_key(struct dm_btree_info *info, dm_block_t root,
 901                              bool find_highest, uint64_t *result_keys)
 902 {
 903         int r = 0, count = 0, level;
 904         struct ro_spine spine;
 905
 906         init_ro_spine(&spine, info);
 907         for (level = 0; level < info->levels; level++) {
 908                 r = find_key(&spine, root, find_highest, result_keys + level,
 909                              level == info->levels - 1 ? NULL : &root);
 910                 if (r == -ENODATA) {
 911                         r = 0;
 912                         break;
 913
 914                 } else if (r)
 915                         break;
 916
 917                 count++;
 918         }
 919         exit_ro_spine(&spine);
 920
 921         return r ? r : count;
 922 }
 923
 924 int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
 925                               uint64_t *result_keys)
 926 {
 927         return dm_btree_find_key(info, root, true, result_keys);
 928 }
 929 EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);
 930
 931 int dm_btree_find_lowest_key(struct dm_btree_info *info, dm_block_t root,
 932                              uint64_t *result_keys)
 933 {
 934         return dm_btree_find_key(info, root, false, result_keys);
 935 }
 936 EXPORT_SYMBOL_GPL(dm_btree_find_lowest_key);
 937
 938 /*----------------------------------------------------------------*/
 939
 940 /*
 941  * FIXME: We shouldn't use a recursive algorithm when we have limited stack
 942  * space.  Also this only works for single level trees.
 943  */
 944 static int walk_node(struct dm_btree_info *info, dm_block_t block,
 945                      int (*fn)(void *context, uint64_t *keys, void *leaf),
 946                      void *context)
 947 {
 948         int r;
 949         unsigned i, nr;
 950         struct dm_block *node;
 951         struct btree_node *n;
 952         uint64_t keys;
 953
 954         r = bn_read_lock(info, block, &node);
 955         if (r)
 956                 return r;
 957
 958         n = dm_block_data(node);
 959
 960         nr = le32_to_cpu(n->header.nr_entries);
 961         for (i = 0; i < nr; i++) {
 962                 if (le32_to_cpu(n->header.flags) & INTERNAL_NODE) {
 963                         r = walk_node(info, value64(n, i), fn, context);
 964                         if (r)
 965                                 goto out;
 966                 } else {
 967                         keys = le64_to_cpu(*key_ptr(n, i));
 968                         r = fn(context, &keys, value_ptr(n, i));
 969                         if (r)
 970                                 goto out;
 971                 }
 972         }
 973
 974 out:
 975         dm_tm_unlock(info->tm, node);
 976         return r;
 977 }
 978
 979 int dm_btree_walk(struct dm_btree_info *info, dm_block_t root,
 980                   int (*fn)(void *context, uint64_t *keys, void *leaf),
 981                   void *context)
 982 {
 983         BUG_ON(info->levels > 1);
 984         return walk_node(info, root, fn, context);
 985 }
 986 EXPORT_SYMBOL_GPL(dm_btree_walk);
 987
 988 /*----------------------------------------------------------------*/
 989
 990 static void prefetch_values(struct dm_btree_cursor *c)
 991 {
 992         unsigned i, nr;
 993         __le64 value_le;
 994         struct cursor_node *n = c->nodes + c->depth - 1;
 995         struct btree_node *bn = dm_block_data(n->b);
 996         struct dm_block_manager *bm = dm_tm_get_bm(c->info->tm);
 997
 998         BUG_ON(c->info->value_type.size != sizeof(value_le));
 999
1000         nr = le32_to_cpu(bn->header.nr_entries);
1001         for (i = 0; i < nr; i++) {
1002                 memcpy(&value_le, value_ptr(bn, i), sizeof(value_le));
1003                 dm_bm_prefetch(bm, le64_to_cpu(value_le));
1004         }
1005 }
1006
1007 static bool leaf_node(struct dm_btree_cursor *c)
1008 {
1009         struct cursor_node *n = c->nodes + c->depth - 1;
1010         struct btree_node *bn = dm_block_data(n->b);
1011
1012         return le32_to_cpu(bn->header.flags) & LEAF_NODE;
1013 }
1014
1015 static int push_node(struct dm_btree_cursor *c, dm_block_t b)
1016 {
1017         int r;
1018         struct cursor_node *n = c->nodes + c->depth;
1019
1020         if (c->depth >= DM_BTREE_CURSOR_MAX_DEPTH - 1) {
1021                 DMERR("couldn't push cursor node, stack depth too high");
1022                 return -EINVAL;
1023         }
1024
1025         r = bn_read_lock(c->info, b, &n->b);
1026         if (r)
1027                 return r;
1028
1029         n->index = 0;
1030         c->depth++;
1031
1032         if (c->prefetch_leaves || !leaf_node(c))
1033                 prefetch_values(c);
1034
1035         return 0;
1036 }
1037
1038 static void pop_node(struct dm_btree_cursor *c)
1039 {
1040         c->depth--;
1041         unlock_block(c->info, c->nodes[c->depth].b);
1042 }
1043
1044 static int inc_or_backtrack(struct dm_btree_cursor *c)
1045 {
1046         struct cursor_node *n;
1047         struct btree_node *bn;
1048
1049         for (;;) {
1050                 if (!c->depth)
1051                         return -ENODATA;
1052
1053                 n = c->nodes + c->depth - 1;
1054                 bn = dm_block_data(n->b);
1055
1056                 n->index++;
1057                 if (n->index < le32_to_cpu(bn->header.nr_entries))
1058                         break;
1059
1060                 pop_node(c);
1061         }
1062
1063         return 0;
1064 }
1065
1066 static int find_leaf(struct dm_btree_cursor *c)
1067 {
1068         int r = 0;
1069         struct cursor_node *n;
1070         struct btree_node *bn;
1071         __le64 value_le;
1072
1073         for (;;) {
1074                 n = c->nodes + c->depth - 1;
1075                 bn = dm_block_data(n->b);
1076
1077                 if (le32_to_cpu(bn->header.flags) & LEAF_NODE)
1078                         break;
1079
1080                 memcpy(&value_le, value_ptr(bn, n->index), sizeof(value_le));
1081                 r = push_node(c, le64_to_cpu(value_le));
1082                 if (r) {
1083                         DMERR("push_node failed");
1084                         break;
1085                 }
1086         }
1087
1088         if (!r && (le32_to_cpu(bn->header.nr_entries) == 0))
1089                 return -ENODATA;
1090
1091         return r;
1092 }
1093
1094 int dm_btree_cursor_begin(struct dm_btree_info *info, dm_block_t root,
1095                           bool prefetch_leaves, struct dm_btree_cursor *c)
1096 {
1097         int r;
1098
1099         c->info = info;
1100         c->root = root;
1101         c->depth = 0;
1102         c->prefetch_leaves = prefetch_leaves;
1103
1104         r = push_node(c, root);
1105         if (r)
1106                 return r;
1107
1108         return find_leaf(c);
1109 }
1110 EXPORT_SYMBOL_GPL(dm_btree_cursor_begin);
1111
1112 void dm_btree_cursor_end(struct dm_btree_cursor *c)
1113 {
1114         while (c->depth)
1115                 pop_node(c);
1116 }
1117 EXPORT_SYMBOL_GPL(dm_btree_cursor_end);
1118
1119 int dm_btree_cursor_next(struct dm_btree_cursor *c)
1120 {
1121         int r = inc_or_backtrack(c);
1122         if (!r) {
1123                 r = find_leaf(c);
1124                 if (r)
1125                         DMERR("find_leaf failed");
1126         }
1127
1128         return r;
1129 }
1130 EXPORT_SYMBOL_GPL(dm_btree_cursor_next);
1131
1132 int dm_btree_cursor_get_value(struct dm_btree_cursor *c, uint64_t *key, void *value_le)
1133 {
1134         if (c->depth) {
1135                 struct cursor_node *n = c->nodes + c->depth - 1;
1136                 struct btree_node *bn = dm_block_data(n->b);
1137
1138                 if (le32_to_cpu(bn->header.flags) & INTERNAL_NODE)
1139                         return -EINVAL;
1140
1141                 *key = le64_to_cpu(*key_ptr(bn, n->index));
1142                 memcpy(value_le, value_ptr(bn, n->index), c->info->value_type.size);
1143                 return 0;
1144
1145         } else
1146                 return -ENODATA;
1147 }
1148 EXPORT_SYMBOL_GPL(dm_btree_cursor_get_value);