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         uint32_t max_entries = le32_to_cpu(node->header.max_entries);
  91         __le64 key_le = cpu_to_le64(key);
  92
  93         if (index > nr_entries ||
  94             index >= max_entries ||
  95             nr_entries >= max_entries) {
  96                 DMERR("too many entries in btree node for insert");
  97                 __dm_unbless_for_disk(value);
  98                 return -ENOMEM;
  99         }
 100
 101         __dm_bless_for_disk(&key_le);
 102
 103         array_insert(node->keys, sizeof(*node->keys), nr_entries, index, &key_le);
 104         array_insert(value_base(node), value_size, nr_entries, index, value);
 105         node->header.nr_entries = cpu_to_le32(nr_entries + 1);
 106
 107         return 0;
 108 }
 109
 110 /*----------------------------------------------------------------*/
 111
 112 /*
 113  * We want 3n entries (for some n).  This works more nicely for repeated
 114  * insert remove loops than (2n + 1).
 115  */
 116 static uint32_t calc_max_entries(size_t value_size, size_t block_size)
 117 {
 118         uint32_t total, n;
 119         size_t elt_size = sizeof(uint64_t) + value_size; /* key + value */
 120
 121         block_size -= sizeof(struct node_header);
 122         total = block_size / elt_size;
 123         n = total / 3;          /* rounds down */
 124
 125         return 3 * n;
 126 }
 127
 128 int dm_btree_empty(struct dm_btree_info *info, dm_block_t *root)
 129 {
 130         int r;
 131         struct dm_block *b;
 132         struct btree_node *n;
 133         size_t block_size;
 134         uint32_t max_entries;
 135
 136         r = new_block(info, &b);
 137         if (r < 0)
 138                 return r;
 139
 140         block_size = dm_bm_block_size(dm_tm_get_bm(info->tm));
 141         max_entries = calc_max_entries(info->value_type.size, block_size);
 142
 143         n = dm_block_data(b);
 144         memset(n, 0, block_size);
 145         n->header.flags = cpu_to_le32(LEAF_NODE);
 146         n->header.nr_entries = cpu_to_le32(0);
 147         n->header.max_entries = cpu_to_le32(max_entries);
 148         n->header.value_size = cpu_to_le32(info->value_type.size);
 149
 150         *root = dm_block_location(b);
 151         unlock_block(info, b);
 152
 153         return 0;
 154 }
 155 EXPORT_SYMBOL_GPL(dm_btree_empty);
 156
 157 /*----------------------------------------------------------------*/
 158
 159 /*
 160  * Deletion uses a recursive algorithm, since we have limited stack space
 161  * we explicitly manage our own stack on the heap.
 162  */
 163 #define MAX_SPINE_DEPTH 64
 164 struct frame {
 165         struct dm_block *b;
 166         struct btree_node *n;
 167         unsigned level;
 168         unsigned nr_children;
 169         unsigned current_child;
 170 };
 171
 172 struct del_stack {
 173         struct dm_btree_info *info;
 174         struct dm_transaction_manager *tm;
 175         int top;
 176         struct frame spine[MAX_SPINE_DEPTH];
 177 };
 178
 179 static int top_frame(struct del_stack *s, struct frame **f)
 180 {
 181         if (s->top < 0) {
 182                 DMERR("btree deletion stack empty");
 183                 return -EINVAL;
 184         }
 185
 186         *f = s->spine + s->top;
 187
 188         return 0;
 189 }
 190
 191 static int unprocessed_frames(struct del_stack *s)
 192 {
 193         return s->top >= 0;
 194 }
 195
 196 static void prefetch_children(struct del_stack *s, struct frame *f)
 197 {
 198         unsigned i;
 199         struct dm_block_manager *bm = dm_tm_get_bm(s->tm);
 200
 201         for (i = 0; i < f->nr_children; i++)
 202                 dm_bm_prefetch(bm, value64(f->n, i));
 203 }
 204
 205 static bool is_internal_level(struct dm_btree_info *info, struct frame *f)
 206 {
 207         return f->level < (info->levels - 1);
 208 }
 209
 210 static int push_frame(struct del_stack *s, dm_block_t b, unsigned level)
 211 {
 212         int r;
 213         uint32_t ref_count;
 214
 215         if (s->top >= MAX_SPINE_DEPTH - 1) {
 216                 DMERR("btree deletion stack out of memory");
 217                 return -ENOMEM;
 218         }
 219
 220         r = dm_tm_ref(s->tm, b, &ref_count);
 221         if (r)
 222                 return r;
 223
 224         if (ref_count > 1)
 225                 /*
 226                  * This is a shared node, so we can just decrement it's
 227                  * reference counter and leave the children.
 228                  */
 229                 dm_tm_dec(s->tm, b);
 230
 231         else {
 232                 uint32_t flags;
 233                 struct frame *f = s->spine + ++s->top;
 234
 235                 r = dm_tm_read_lock(s->tm, b, &btree_node_validator, &f->b);
 236                 if (r) {
 237                         s->top--;
 238                         return r;
 239                 }
 240
 241                 f->n = dm_block_data(f->b);
 242                 f->level = level;
 243                 f->nr_children = le32_to_cpu(f->n->header.nr_entries);
 244                 f->current_child = 0;
 245
 246                 flags = le32_to_cpu(f->n->header.flags);
 247                 if (flags & INTERNAL_NODE || is_internal_level(s->info, f))
 248                         prefetch_children(s, f);
 249         }
 250
 251         return 0;
 252 }
 253
 254 static void pop_frame(struct del_stack *s)
 255 {
 256         struct frame *f = s->spine + s->top--;
 257
 258         dm_tm_dec(s->tm, dm_block_location(f->b));
 259         dm_tm_unlock(s->tm, f->b);
 260 }
 261
 262 static void unlock_all_frames(struct del_stack *s)
 263 {
 264         struct frame *f;
 265
 266         while (unprocessed_frames(s)) {
 267                 f = s->spine + s->top--;
 268                 dm_tm_unlock(s->tm, f->b);
 269         }
 270 }
 271
 272 int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
 273 {
 274         int r;
 275         struct del_stack *s;
 276
 277         /*
 278          * dm_btree_del() is called via an ioctl, as such should be
 279          * considered an FS op.  We can't recurse back into the FS, so we
 280          * allocate GFP_NOFS.
 281          */
 282         s = kmalloc(sizeof(*s), GFP_NOFS);
 283         if (!s)
 284                 return -ENOMEM;
 285         s->info = info;
 286         s->tm = info->tm;
 287         s->top = -1;
 288
 289         r = push_frame(s, root, 0);
 290         if (r)
 291                 goto out;
 292
 293         while (unprocessed_frames(s)) {
 294                 uint32_t flags;
 295                 struct frame *f;
 296                 dm_block_t b;
 297
 298                 r = top_frame(s, &f);
 299                 if (r)
 300                         goto out;
 301
 302                 if (f->current_child >= f->nr_children) {
 303                         pop_frame(s);
 304                         continue;
 305                 }
 306
 307                 flags = le32_to_cpu(f->n->header.flags);
 308                 if (flags & INTERNAL_NODE) {
 309                         b = value64(f->n, f->current_child);
 310                         f->current_child++;
 311                         r = push_frame(s, b, f->level);
 312                         if (r)
 313                                 goto out;
 314
 315                 } else if (is_internal_level(info, f)) {
 316                         b = value64(f->n, f->current_child);
 317                         f->current_child++;
 318                         r = push_frame(s, b, f->level + 1);
 319                         if (r)
 320                                 goto out;
 321
 322                 } else {
 323                         if (info->value_type.dec) {
 324                                 unsigned i;
 325
 326                                 for (i = 0; i < f->nr_children; i++)
 327                                         info->value_type.dec(info->value_type.context,
 328                                                              value_ptr(f->n, i));
 329                         }
 330                         pop_frame(s);
 331                 }
 332         }
 333 out:
 334         if (r) {
 335                 /* cleanup all frames of del_stack */
 336                 unlock_all_frames(s);
 337         }
 338         kfree(s);
 339
 340         return r;
 341 }
 342 EXPORT_SYMBOL_GPL(dm_btree_del);
 343
 344 /*----------------------------------------------------------------*/
 345
 346 static int btree_lookup_raw(struct ro_spine *s, dm_block_t block, uint64_t key,
 347                             int (*search_fn)(struct btree_node *, uint64_t),
 348                             uint64_t *result_key, void *v, size_t value_size)
 349 {
 350         int i, r;
 351         uint32_t flags, nr_entries;
 352
 353         do {
 354                 r = ro_step(s, block);
 355                 if (r < 0)
 356                         return r;
 357
 358                 i = search_fn(ro_node(s), key);
 359
 360                 flags = le32_to_cpu(ro_node(s)->header.flags);
 361                 nr_entries = le32_to_cpu(ro_node(s)->header.nr_entries);
 362                 if (i < 0 || i >= nr_entries)
 363                         return -ENODATA;
 364
 365                 if (flags & INTERNAL_NODE)
 366                         block = value64(ro_node(s), i);
 367
 368         } while (!(flags & LEAF_NODE));
 369
 370         *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 371         if (v)
 372                 memcpy(v, value_ptr(ro_node(s), i), value_size);
 373
 374         return 0;
 375 }
 376
 377 int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
 378                     uint64_t *keys, void *value_le)
 379 {
 380         unsigned level, last_level = info->levels - 1;
 381         int r = -ENODATA;
 382         uint64_t rkey;
 383         __le64 internal_value_le;
 384         struct ro_spine spine;
 385
 386         init_ro_spine(&spine, info);
 387         for (level = 0; level < info->levels; level++) {
 388                 size_t size;
 389                 void *value_p;
 390
 391                 if (level == last_level) {
 392                         value_p = value_le;
 393                         size = info->value_type.size;
 394
 395                 } else {
 396                         value_p = &internal_value_le;
 397                         size = sizeof(uint64_t);
 398                 }
 399
 400                 r = btree_lookup_raw(&spine, root, keys[level],
 401                                      lower_bound, &rkey,
 402                                      value_p, size);
 403
 404                 if (!r) {
 405                         if (rkey != keys[level]) {
 406                                 exit_ro_spine(&spine);
 407                                 return -ENODATA;
 408                         }
 409                 } else {
 410                         exit_ro_spine(&spine);
 411                         return r;
 412                 }
 413
 414                 root = le64_to_cpu(internal_value_le);
 415         }
 416         exit_ro_spine(&spine);
 417
 418         return r;
 419 }
 420 EXPORT_SYMBOL_GPL(dm_btree_lookup);
 421
 422 static int dm_btree_lookup_next_single(struct dm_btree_info *info, dm_block_t root,
 423                                        uint64_t key, uint64_t *rkey, void *value_le)
 424 {
 425         int r, i;
 426         uint32_t flags, nr_entries;
 427         struct dm_block *node;
 428         struct btree_node *n;
 429
 430         r = bn_read_lock(info, root, &node);
 431         if (r)
 432                 return r;
 433
 434         n = dm_block_data(node);
 435         flags = le32_to_cpu(n->header.flags);
 436         nr_entries = le32_to_cpu(n->header.nr_entries);
 437
 438         if (flags & INTERNAL_NODE) {
 439                 i = lower_bound(n, key);
 440                 if (i < 0) {
 441                         /*
 442                          * avoid early -ENODATA return when all entries are
 443                          * higher than the search @key.
 444                          */
 445                         i = 0;
 446                 }
 447                 if (i >= nr_entries) {
 448                         r = -ENODATA;
 449                         goto out;
 450                 }
 451
 452                 r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
 453                 if (r == -ENODATA && i < (nr_entries - 1)) {
 454                         i++;
 455                         r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
 456                 }
 457
 458         } else {
 459                 i = upper_bound(n, key);
 460                 if (i < 0 || i >= nr_entries) {
 461                         r = -ENODATA;
 462                         goto out;
 463                 }
 464
 465                 *rkey = le64_to_cpu(n->keys[i]);
 466                 memcpy(value_le, value_ptr(n, i), info->value_type.size);
 467         }
 468 out:
 469         dm_tm_unlock(info->tm, node);
 470         return r;
 471 }
 472
 473 int dm_btree_lookup_next(struct dm_btree_info *info, dm_block_t root,
 474                          uint64_t *keys, uint64_t *rkey, void *value_le)
 475 {
 476         unsigned level;
 477         int r = -ENODATA;
 478         __le64 internal_value_le;
 479         struct ro_spine spine;
 480
 481         init_ro_spine(&spine, info);
 482         for (level = 0; level < info->levels - 1u; level++) {
 483                 r = btree_lookup_raw(&spine, root, keys[level],
 484                                      lower_bound, rkey,
 485                                      &internal_value_le, sizeof(uint64_t));
 486                 if (r)
 487                         goto out;
 488
 489                 if (*rkey != keys[level]) {
 490                         r = -ENODATA;
 491                         goto out;
 492                 }
 493
 494                 root = le64_to_cpu(internal_value_le);
 495         }
 496
 497         r = dm_btree_lookup_next_single(info, root, keys[level], rkey, value_le);
 498 out:
 499         exit_ro_spine(&spine);
 500         return r;
 501 }
 502
 503 EXPORT_SYMBOL_GPL(dm_btree_lookup_next);
 504
 505 /*
 506  * Splits a node by creating a sibling node and shifting half the nodes
 507  * contents across.  Assumes there is a parent node, and it has room for
 508  * another child.
 509  *
 510  * Before:
 511  *        +--------+
 512  *        | Parent |
 513  *        +--------+
 514  *           |
 515  *           v
 516  *      +----------+
 517  *      | A ++++++ |
 518  *      +----------+
 519  *
 520  *
 521  * After:
 522  *              +--------+
 523  *              | Parent |
 524  *              +--------+
 525  *                |     |
 526  *                v     +------+
 527  *          +---------+        |
 528  *          | A* +++  |        v
 529  *          +---------+   +-------+
 530  *                        | B +++ |
 531  *                        +-------+
 532  *
 533  * Where A* is a shadow of A.
 534  */
 535 static int btree_split_sibling(struct shadow_spine *s, unsigned parent_index,
 536                                uint64_t key)
 537 {
 538         int r;
 539         size_t size;
 540         unsigned nr_left, nr_right;
 541         struct dm_block *left, *right, *parent;
 542         struct btree_node *ln, *rn, *pn;
 543         __le64 location;
 544
 545         left = shadow_current(s);
 546
 547         r = new_block(s->info, &right);
 548         if (r < 0)
 549                 return r;
 550
 551         ln = dm_block_data(left);
 552         rn = dm_block_data(right);
 553
 554         nr_left = le32_to_cpu(ln->header.nr_entries) / 2;
 555         nr_right = le32_to_cpu(ln->header.nr_entries) - nr_left;
 556
 557         ln->header.nr_entries = cpu_to_le32(nr_left);
 558
 559         rn->header.flags = ln->header.flags;
 560         rn->header.nr_entries = cpu_to_le32(nr_right);
 561         rn->header.max_entries = ln->header.max_entries;
 562         rn->header.value_size = ln->header.value_size;
 563         memcpy(rn->keys, ln->keys + nr_left, nr_right * sizeof(rn->keys[0]));
 564
 565         size = le32_to_cpu(ln->header.flags) & INTERNAL_NODE ?
 566                 sizeof(uint64_t) : s->info->value_type.size;
 567         memcpy(value_ptr(rn, 0), value_ptr(ln, nr_left),
 568                size * nr_right);
 569
 570         /*
 571          * Patch up the parent
 572          */
 573         parent = shadow_parent(s);
 574
 575         pn = dm_block_data(parent);
 576         location = cpu_to_le64(dm_block_location(left));
 577         __dm_bless_for_disk(&location);
 578         memcpy_disk(value_ptr(pn, parent_index),
 579                     &location, sizeof(__le64));
 580
 581         location = cpu_to_le64(dm_block_location(right));
 582         __dm_bless_for_disk(&location);
 583
 584         r = insert_at(sizeof(__le64), pn, parent_index + 1,
 585                       le64_to_cpu(rn->keys[0]), &location);
 586         if (r) {
 587                 unlock_block(s->info, right);
 588                 return r;
 589         }
 590
 591         if (key < le64_to_cpu(rn->keys[0])) {
 592                 unlock_block(s->info, right);
 593                 s->nodes[1] = left;
 594         } else {
 595                 unlock_block(s->info, left);
 596                 s->nodes[1] = right;
 597         }
 598
 599         return 0;
 600 }
 601
 602 /*
 603  * Splits a node by creating two new children beneath the given node.
 604  *
 605  * Before:
 606  *        +----------+
 607  *        | A ++++++ |
 608  *        +----------+
 609  *
 610  *
 611  * After:
 612  *      +------------+
 613  *      | A (shadow) |
 614  *      +------------+
 615  *          |   |
 616  *   +------+   +----+
 617  *   |               |
 618  *   v               v
 619  * +-------+     +-------+
 620  * | B +++ |     | C +++ |
 621  * +-------+     +-------+
 622  */
 623 static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
 624 {
 625         int r;
 626         size_t size;
 627         unsigned nr_left, nr_right;
 628         struct dm_block *left, *right, *new_parent;
 629         struct btree_node *pn, *ln, *rn;
 630         __le64 val;
 631
 632         new_parent = shadow_current(s);
 633
 634         pn = dm_block_data(new_parent);
 635         size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
 636                 sizeof(__le64) : s->info->value_type.size;
 637
 638         /* create & init the left block */
 639         r = new_block(s->info, &left);
 640         if (r < 0)
 641                 return r;
 642
 643         ln = dm_block_data(left);
 644         nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
 645
 646         ln->header.flags = pn->header.flags;
 647         ln->header.nr_entries = cpu_to_le32(nr_left);
 648         ln->header.max_entries = pn->header.max_entries;
 649         ln->header.value_size = pn->header.value_size;
 650         memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
 651         memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
 652
 653         /* create & init the right block */
 654         r = new_block(s->info, &right);
 655         if (r < 0) {
 656                 unlock_block(s->info, left);
 657                 return r;
 658         }
 659
 660         rn = dm_block_data(right);
 661         nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
 662
 663         rn->header.flags = pn->header.flags;
 664         rn->header.nr_entries = cpu_to_le32(nr_right);
 665         rn->header.max_entries = pn->header.max_entries;
 666         rn->header.value_size = pn->header.value_size;
 667         memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
 668         memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left),
 669                nr_right * size);
 670
 671         /* new_parent should just point to l and r now */
 672         pn->header.flags = cpu_to_le32(INTERNAL_NODE);
 673         pn->header.nr_entries = cpu_to_le32(2);
 674         pn->header.max_entries = cpu_to_le32(
 675                 calc_max_entries(sizeof(__le64),
 676                                  dm_bm_block_size(
 677                                          dm_tm_get_bm(s->info->tm))));
 678         pn->header.value_size = cpu_to_le32(sizeof(__le64));
 679
 680         val = cpu_to_le64(dm_block_location(left));
 681         __dm_bless_for_disk(&val);
 682         pn->keys[0] = ln->keys[0];
 683         memcpy_disk(value_ptr(pn, 0), &val, sizeof(__le64));
 684
 685         val = cpu_to_le64(dm_block_location(right));
 686         __dm_bless_for_disk(&val);
 687         pn->keys[1] = rn->keys[0];
 688         memcpy_disk(value_ptr(pn, 1), &val, sizeof(__le64));
 689
 690         unlock_block(s->info, left);
 691         unlock_block(s->info, right);
 692         return 0;
 693 }
 694
 695 static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
 696                             struct dm_btree_value_type *vt,
 697                             uint64_t key, unsigned *index)
 698 {
 699         int r, i = *index, top = 1;
 700         struct btree_node *node;
 701
 702         for (;;) {
 703                 r = shadow_step(s, root, vt);
 704                 if (r < 0)
 705                         return r;
 706
 707                 node = dm_block_data(shadow_current(s));
 708
 709                 /*
 710                  * We have to patch up the parent node, ugly, but I don't
 711                  * see a way to do this automatically as part of the spine
 712                  * op.
 713                  */
 714                 if (shadow_has_parent(s) && i >= 0) { /* FIXME: second clause unness. */
 715                         __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
 716
 717                         __dm_bless_for_disk(&location);
 718                         memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
 719                                     &location, sizeof(__le64));
 720                 }
 721
 722                 node = dm_block_data(shadow_current(s));
 723
 724                 if (node->header.nr_entries == node->header.max_entries) {
 725                         if (top)
 726                                 r = btree_split_beneath(s, key);
 727                         else
 728                                 r = btree_split_sibling(s, i, key);
 729
 730                         if (r < 0)
 731                                 return r;
 732                 }
 733
 734                 node = dm_block_data(shadow_current(s));
 735
 736                 i = lower_bound(node, key);
 737
 738                 if (le32_to_cpu(node->header.flags) & LEAF_NODE)
 739                         break;
 740
 741                 if (i < 0) {
 742                         /* change the bounds on the lowest key */
 743                         node->keys[0] = cpu_to_le64(key);
 744                         i = 0;
 745                 }
 746
 747                 root = value64(node, i);
 748                 top = 0;
 749         }
 750
 751         if (i < 0 || le64_to_cpu(node->keys[i]) != key)
 752                 i++;
 753
 754         *index = i;
 755         return 0;
 756 }
 757
 758 static bool need_insert(struct btree_node *node, uint64_t *keys,
 759                         unsigned level, unsigned index)
 760 {
 761         return ((index >= le32_to_cpu(node->header.nr_entries)) ||
 762                 (le64_to_cpu(node->keys[index]) != keys[level]));
 763 }
 764
 765 static int insert(struct dm_btree_info *info, dm_block_t root,
 766                   uint64_t *keys, void *value, dm_block_t *new_root,
 767                   int *inserted)
 768                   __dm_written_to_disk(value)
 769 {
 770         int r;
 771         unsigned level, index = -1, last_level = info->levels - 1;
 772         dm_block_t block = root;
 773         struct shadow_spine spine;
 774         struct btree_node *n;
 775         struct dm_btree_value_type le64_type;
 776
 777         init_le64_type(info->tm, &le64_type);
 778         init_shadow_spine(&spine, info);
 779
 780         for (level = 0; level < (info->levels - 1); level++) {
 781                 r = btree_insert_raw(&spine, block, &le64_type, keys[level], &index);
 782                 if (r < 0)
 783                         goto bad;
 784
 785                 n = dm_block_data(shadow_current(&spine));
 786
 787                 if (need_insert(n, keys, level, index)) {
 788                         dm_block_t new_tree;
 789                         __le64 new_le;
 790
 791                         r = dm_btree_empty(info, &new_tree);
 792                         if (r < 0)
 793                                 goto bad;
 794
 795                         new_le = cpu_to_le64(new_tree);
 796                         __dm_bless_for_disk(&new_le);
 797
 798                         r = insert_at(sizeof(uint64_t), n, index,
 799                                       keys[level], &new_le);
 800                         if (r)
 801                                 goto bad;
 802                 }
 803
 804                 if (level < last_level)
 805                         block = value64(n, index);
 806         }
 807
 808         r = btree_insert_raw(&spine, block, &info->value_type,
 809                              keys[level], &index);
 810         if (r < 0)
 811                 goto bad;
 812
 813         n = dm_block_data(shadow_current(&spine));
 814
 815         if (need_insert(n, keys, level, index)) {
 816                 if (inserted)
 817                         *inserted = 1;
 818
 819                 r = insert_at(info->value_type.size, n, index,
 820                               keys[level], value);
 821                 if (r)
 822                         goto bad_unblessed;
 823         } else {
 824                 if (inserted)
 825                         *inserted = 0;
 826
 827                 if (info->value_type.dec &&
 828                     (!info->value_type.equal ||
 829                      !info->value_type.equal(
 830                              info->value_type.context,
 831                              value_ptr(n, index),
 832                              value))) {
 833                         info->value_type.dec(info->value_type.context,
 834                                              value_ptr(n, index));
 835                 }
 836                 memcpy_disk(value_ptr(n, index),
 837                             value, info->value_type.size);
 838         }
 839
 840         *new_root = shadow_root(&spine);
 841         exit_shadow_spine(&spine);
 842
 843         return 0;
 844
 845 bad:
 846         __dm_unbless_for_disk(value);
 847 bad_unblessed:
 848         exit_shadow_spine(&spine);
 849         return r;
 850 }
 851
 852 int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
 853                     uint64_t *keys, void *value, dm_block_t *new_root)
 854                     __dm_written_to_disk(value)
 855 {
 856         return insert(info, root, keys, value, new_root, NULL);
 857 }
 858 EXPORT_SYMBOL_GPL(dm_btree_insert);
 859
 860 int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
 861                            uint64_t *keys, void *value, dm_block_t *new_root,
 862                            int *inserted)
 863                            __dm_written_to_disk(value)
 864 {
 865         return insert(info, root, keys, value, new_root, inserted);
 866 }
 867 EXPORT_SYMBOL_GPL(dm_btree_insert_notify);
 868
 869 /*----------------------------------------------------------------*/
 870
 871 static int find_key(struct ro_spine *s, dm_block_t block, bool find_highest,
 872                     uint64_t *result_key, dm_block_t *next_block)
 873 {
 874         int i, r;
 875         uint32_t flags;
 876
 877         do {
 878                 r = ro_step(s, block);
 879                 if (r < 0)
 880                         return r;
 881
 882                 flags = le32_to_cpu(ro_node(s)->header.flags);
 883                 i = le32_to_cpu(ro_node(s)->header.nr_entries);
 884                 if (!i)
 885                         return -ENODATA;
 886                 else
 887                         i--;
 888
 889                 if (find_highest)
 890                         *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 891                 else
 892                         *result_key = le64_to_cpu(ro_node(s)->keys[0]);
 893
 894                 if (next_block || flags & INTERNAL_NODE) {
 895                         if (find_highest)
 896                                 block = value64(ro_node(s), i);
 897                         else
 898                                 block = value64(ro_node(s), 0);
 899                 }
 900
 901         } while (flags & INTERNAL_NODE);
 902
 903         if (next_block)
 904                 *next_block = block;
 905         return 0;
 906 }
 907
 908 static int dm_btree_find_key(struct dm_btree_info *info, dm_block_t root,
 909                              bool find_highest, uint64_t *result_keys)
 910 {
 911         int r = 0, count = 0, level;
 912         struct ro_spine spine;
 913
 914         init_ro_spine(&spine, info);
 915         for (level = 0; level < info->levels; level++) {
 916                 r = find_key(&spine, root, find_highest, result_keys + level,
 917                              level == info->levels - 1 ? NULL : &root);
 918                 if (r == -ENODATA) {
 919                         r = 0;
 920                         break;
 921
 922                 } else if (r)
 923                         break;
 924
 925                 count++;
 926         }
 927         exit_ro_spine(&spine);
 928
 929         return r ? r : count;
 930 }
 931
 932 int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
 933                               uint64_t *result_keys)
 934 {
 935         return dm_btree_find_key(info, root, true, result_keys);
 936 }
 937 EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);
 938
 939 int dm_btree_find_lowest_key(struct dm_btree_info *info, dm_block_t root,
 940                              uint64_t *result_keys)
 941 {
 942         return dm_btree_find_key(info, root, false, result_keys);
 943 }
 944 EXPORT_SYMBOL_GPL(dm_btree_find_lowest_key);
 945
 946 /*----------------------------------------------------------------*/
 947
 948 /*
 949  * FIXME: We shouldn't use a recursive algorithm when we have limited stack
 950  * space.  Also this only works for single level trees.
 951  */
 952 static int walk_node(struct dm_btree_info *info, dm_block_t block,
 953                      int (*fn)(void *context, uint64_t *keys, void *leaf),
 954                      void *context)
 955 {
 956         int r;
 957         unsigned i, nr;
 958         struct dm_block *node;
 959         struct btree_node *n;
 960         uint64_t keys;
 961
 962         r = bn_read_lock(info, block, &node);
 963         if (r)
 964                 return r;
 965
 966         n = dm_block_data(node);
 967
 968         nr = le32_to_cpu(n->header.nr_entries);
 969         for (i = 0; i < nr; i++) {
 970                 if (le32_to_cpu(n->header.flags) & INTERNAL_NODE) {
 971                         r = walk_node(info, value64(n, i), fn, context);
 972                         if (r)
 973                                 goto out;
 974                 } else {
 975                         keys = le64_to_cpu(*key_ptr(n, i));
 976                         r = fn(context, &keys, value_ptr(n, i));
 977                         if (r)
 978                                 goto out;
 979                 }
 980         }
 981
 982 out:
 983         dm_tm_unlock(info->tm, node);
 984         return r;
 985 }
 986
 987 int dm_btree_walk(struct dm_btree_info *info, dm_block_t root,
 988                   int (*fn)(void *context, uint64_t *keys, void *leaf),
 989                   void *context)
 990 {
 991         BUG_ON(info->levels > 1);
 992         return walk_node(info, root, fn, context);
 993 }
 994 EXPORT_SYMBOL_GPL(dm_btree_walk);
 995
 996 /*----------------------------------------------------------------*/
 997
 998 static void prefetch_values(struct dm_btree_cursor *c)
 999 {
1000         unsigned i, nr;
1001         __le64 value_le;
1002         struct cursor_node *n = c->nodes + c->depth - 1;
1003         struct btree_node *bn = dm_block_data(n->b);
1004         struct dm_block_manager *bm = dm_tm_get_bm(c->info->tm);
1005
1006         BUG_ON(c->info->value_type.size != sizeof(value_le));
1007
1008         nr = le32_to_cpu(bn->header.nr_entries);
1009         for (i = 0; i < nr; i++) {
1010                 memcpy(&value_le, value_ptr(bn, i), sizeof(value_le));
1011                 dm_bm_prefetch(bm, le64_to_cpu(value_le));
1012         }
1013 }
1014
1015 static bool leaf_node(struct dm_btree_cursor *c)
1016 {
1017         struct cursor_node *n = c->nodes + c->depth - 1;
1018         struct btree_node *bn = dm_block_data(n->b);
1019
1020         return le32_to_cpu(bn->header.flags) & LEAF_NODE;
1021 }
1022
1023 static int push_node(struct dm_btree_cursor *c, dm_block_t b)
1024 {
1025         int r;
1026         struct cursor_node *n = c->nodes + c->depth;
1027
1028         if (c->depth >= DM_BTREE_CURSOR_MAX_DEPTH - 1) {
1029                 DMERR("couldn't push cursor node, stack depth too high");
1030                 return -EINVAL;
1031         }
1032
1033         r = bn_read_lock(c->info, b, &n->b);
1034         if (r)
1035                 return r;
1036
1037         n->index = 0;
1038         c->depth++;
1039
1040         if (c->prefetch_leaves || !leaf_node(c))
1041                 prefetch_values(c);
1042
1043         return 0;
1044 }
1045
1046 static void pop_node(struct dm_btree_cursor *c)
1047 {
1048         c->depth--;
1049         unlock_block(c->info, c->nodes[c->depth].b);
1050 }
1051
1052 static int inc_or_backtrack(struct dm_btree_cursor *c)
1053 {
1054         struct cursor_node *n;
1055         struct btree_node *bn;
1056
1057         for (;;) {
1058                 if (!c->depth)
1059                         return -ENODATA;
1060
1061                 n = c->nodes + c->depth - 1;
1062                 bn = dm_block_data(n->b);
1063
1064                 n->index++;
1065                 if (n->index < le32_to_cpu(bn->header.nr_entries))
1066                         break;
1067
1068                 pop_node(c);
1069         }
1070
1071         return 0;
1072 }
1073
1074 static int find_leaf(struct dm_btree_cursor *c)
1075 {
1076         int r = 0;
1077         struct cursor_node *n;
1078         struct btree_node *bn;
1079         __le64 value_le;
1080
1081         for (;;) {
1082                 n = c->nodes + c->depth - 1;
1083                 bn = dm_block_data(n->b);
1084
1085                 if (le32_to_cpu(bn->header.flags) & LEAF_NODE)
1086                         break;
1087
1088                 memcpy(&value_le, value_ptr(bn, n->index), sizeof(value_le));
1089                 r = push_node(c, le64_to_cpu(value_le));
1090                 if (r) {
1091                         DMERR("push_node failed");
1092                         break;
1093                 }
1094         }
1095
1096         if (!r && (le32_to_cpu(bn->header.nr_entries) == 0))
1097                 return -ENODATA;
1098
1099         return r;
1100 }
1101
1102 int dm_btree_cursor_begin(struct dm_btree_info *info, dm_block_t root,
1103                           bool prefetch_leaves, struct dm_btree_cursor *c)
1104 {
1105         int r;
1106
1107         c->info = info;
1108         c->root = root;
1109         c->depth = 0;
1110         c->prefetch_leaves = prefetch_leaves;
1111
1112         r = push_node(c, root);
1113         if (r)
1114                 return r;
1115
1116         return find_leaf(c);
1117 }
1118 EXPORT_SYMBOL_GPL(dm_btree_cursor_begin);
1119
1120 void dm_btree_cursor_end(struct dm_btree_cursor *c)
1121 {
1122         while (c->depth)
1123                 pop_node(c);
1124 }
1125 EXPORT_SYMBOL_GPL(dm_btree_cursor_end);
1126
1127 int dm_btree_cursor_next(struct dm_btree_cursor *c)
1128 {
1129         int r = inc_or_backtrack(c);
1130         if (!r) {
1131                 r = find_leaf(c);
1132                 if (r)
1133                         DMERR("find_leaf failed");
1134         }
1135
1136         return r;
1137 }
1138 EXPORT_SYMBOL_GPL(dm_btree_cursor_next);
1139
1140 int dm_btree_cursor_skip(struct dm_btree_cursor *c, uint32_t count)
1141 {
1142         int r = 0;
1143
1144         while (count-- && !r)
1145                 r = dm_btree_cursor_next(c);
1146
1147         return r;
1148 }
1149 EXPORT_SYMBOL_GPL(dm_btree_cursor_skip);
1150
1151 int dm_btree_cursor_get_value(struct dm_btree_cursor *c, uint64_t *key, void *value_le)
1152 {
1153         if (c->depth) {
1154                 struct cursor_node *n = c->nodes + c->depth - 1;
1155                 struct btree_node *bn = dm_block_data(n->b);
1156
1157                 if (le32_to_cpu(bn->header.flags) & INTERNAL_NODE)
1158                         return -EINVAL;
1159
1160                 *key = le64_to_cpu(*key_ptr(bn, n->index));
1161                 memcpy(value_le, value_ptr(bn, n->index), c->info->value_type.size);
1162                 return 0;
1163
1164         } else
1165                 return -ENODATA;
1166 }
1167 EXPORT_SYMBOL_GPL(dm_btree_cursor_get_value);