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