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         memcpy(v, value_ptr(ro_node(s), i), value_size);
 370
 371         return 0;
 372 }
 373
 374 int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
 375                     uint64_t *keys, void *value_le)
 376 {
 377         unsigned level, last_level = info->levels - 1;
 378         int r = -ENODATA;
 379         uint64_t rkey;
 380         __le64 internal_value_le;
 381         struct ro_spine spine;
 382
 383         init_ro_spine(&spine, info);
 384         for (level = 0; level < info->levels; level++) {
 385                 size_t size;
 386                 void *value_p;
 387
 388                 if (level == last_level) {
 389                         value_p = value_le;
 390                         size = info->value_type.size;
 391
 392                 } else {
 393                         value_p = &internal_value_le;
 394                         size = sizeof(uint64_t);
 395                 }
 396
 397                 r = btree_lookup_raw(&spine, root, keys[level],
 398                                      lower_bound, &rkey,
 399                                      value_p, size);
 400
 401                 if (!r) {
 402                         if (rkey != keys[level]) {
 403                                 exit_ro_spine(&spine);
 404                                 return -ENODATA;
 405                         }
 406                 } else {
 407                         exit_ro_spine(&spine);
 408                         return r;
 409                 }
 410
 411                 root = le64_to_cpu(internal_value_le);
 412         }
 413         exit_ro_spine(&spine);
 414
 415         return r;
 416 }
 417 EXPORT_SYMBOL_GPL(dm_btree_lookup);
 418
 419 static int dm_btree_lookup_next_single(struct dm_btree_info *info, dm_block_t root,
 420                                        uint64_t key, uint64_t *rkey, void *value_le)
 421 {
 422         int r, i;
 423         uint32_t flags, nr_entries;
 424         struct dm_block *node;
 425         struct btree_node *n;
 426
 427         r = bn_read_lock(info, root, &node);
 428         if (r)
 429                 return r;
 430
 431         n = dm_block_data(node);
 432         flags = le32_to_cpu(n->header.flags);
 433         nr_entries = le32_to_cpu(n->header.nr_entries);
 434
 435         if (flags & INTERNAL_NODE) {
 436                 i = lower_bound(n, key);
 437                 if (i < 0) {
 438                         /*
 439                          * avoid early -ENODATA return when all entries are
 440                          * higher than the search @key.
 441                          */
 442                         i = 0;
 443                 }
 444                 if (i >= nr_entries) {
 445                         r = -ENODATA;
 446                         goto out;
 447                 }
 448
 449                 r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
 450                 if (r == -ENODATA && i < (nr_entries - 1)) {
 451                         i++;
 452                         r = dm_btree_lookup_next_single(info, value64(n, i), key, rkey, value_le);
 453                 }
 454
 455         } else {
 456                 i = upper_bound(n, key);
 457                 if (i < 0 || i >= nr_entries) {
 458                         r = -ENODATA;
 459                         goto out;
 460                 }
 461
 462                 *rkey = le64_to_cpu(n->keys[i]);
 463                 memcpy(value_le, value_ptr(n, i), info->value_type.size);
 464         }
 465 out:
 466         dm_tm_unlock(info->tm, node);
 467         return r;
 468 }
 469
 470 int dm_btree_lookup_next(struct dm_btree_info *info, dm_block_t root,
 471                          uint64_t *keys, uint64_t *rkey, void *value_le)
 472 {
 473         unsigned level;
 474         int r = -ENODATA;
 475         __le64 internal_value_le;
 476         struct ro_spine spine;
 477
 478         init_ro_spine(&spine, info);
 479         for (level = 0; level < info->levels - 1u; level++) {
 480                 r = btree_lookup_raw(&spine, root, keys[level],
 481                                      lower_bound, rkey,
 482                                      &internal_value_le, sizeof(uint64_t));
 483                 if (r)
 484                         goto out;
 485
 486                 if (*rkey != keys[level]) {
 487                         r = -ENODATA;
 488                         goto out;
 489                 }
 490
 491                 root = le64_to_cpu(internal_value_le);
 492         }
 493
 494         r = dm_btree_lookup_next_single(info, root, keys[level], rkey, value_le);
 495 out:
 496         exit_ro_spine(&spine);
 497         return r;
 498 }
 499
 500 EXPORT_SYMBOL_GPL(dm_btree_lookup_next);
 501
 502 /*
 503  * Splits a node by creating a sibling node and shifting half the nodes
 504  * contents across.  Assumes there is a parent node, and it has room for
 505  * another child.
 506  *
 507  * Before:
 508  *        +--------+
 509  *        | Parent |
 510  *        +--------+
 511  *           |
 512  *           v
 513  *      +----------+
 514  *      | A ++++++ |
 515  *      +----------+
 516  *
 517  *
 518  * After:
 519  *              +--------+
 520  *              | Parent |
 521  *              +--------+
 522  *                |     |
 523  *                v     +------+
 524  *          +---------+        |
 525  *          | A* +++  |        v
 526  *          +---------+   +-------+
 527  *                        | B +++ |
 528  *                        +-------+
 529  *
 530  * Where A* is a shadow of A.
 531  */
 532 static int btree_split_sibling(struct shadow_spine *s, unsigned parent_index,
 533                                uint64_t key)
 534 {
 535         int r;
 536         size_t size;
 537         unsigned nr_left, nr_right;
 538         struct dm_block *left, *right, *parent;
 539         struct btree_node *ln, *rn, *pn;
 540         __le64 location;
 541
 542         left = shadow_current(s);
 543
 544         r = new_block(s->info, &right);
 545         if (r < 0)
 546                 return r;
 547
 548         ln = dm_block_data(left);
 549         rn = dm_block_data(right);
 550
 551         nr_left = le32_to_cpu(ln->header.nr_entries) / 2;
 552         nr_right = le32_to_cpu(ln->header.nr_entries) - nr_left;
 553
 554         ln->header.nr_entries = cpu_to_le32(nr_left);
 555
 556         rn->header.flags = ln->header.flags;
 557         rn->header.nr_entries = cpu_to_le32(nr_right);
 558         rn->header.max_entries = ln->header.max_entries;
 559         rn->header.value_size = ln->header.value_size;
 560         memcpy(rn->keys, ln->keys + nr_left, nr_right * sizeof(rn->keys[0]));
 561
 562         size = le32_to_cpu(ln->header.flags) & INTERNAL_NODE ?
 563                 sizeof(uint64_t) : s->info->value_type.size;
 564         memcpy(value_ptr(rn, 0), value_ptr(ln, nr_left),
 565                size * nr_right);
 566
 567         /*
 568          * Patch up the parent
 569          */
 570         parent = shadow_parent(s);
 571
 572         pn = dm_block_data(parent);
 573         location = cpu_to_le64(dm_block_location(left));
 574         __dm_bless_for_disk(&location);
 575         memcpy_disk(value_ptr(pn, parent_index),
 576                     &location, sizeof(__le64));
 577
 578         location = cpu_to_le64(dm_block_location(right));
 579         __dm_bless_for_disk(&location);
 580
 581         r = insert_at(sizeof(__le64), pn, parent_index + 1,
 582                       le64_to_cpu(rn->keys[0]), &location);
 583         if (r) {
 584                 unlock_block(s->info, right);
 585                 return r;
 586         }
 587
 588         if (key < le64_to_cpu(rn->keys[0])) {
 589                 unlock_block(s->info, right);
 590                 s->nodes[1] = left;
 591         } else {
 592                 unlock_block(s->info, left);
 593                 s->nodes[1] = right;
 594         }
 595
 596         return 0;
 597 }
 598
 599 /*
 600  * Splits a node by creating two new children beneath the given node.
 601  *
 602  * Before:
 603  *        +----------+
 604  *        | A ++++++ |
 605  *        +----------+
 606  *
 607  *
 608  * After:
 609  *      +------------+
 610  *      | A (shadow) |
 611  *      +------------+
 612  *          |   |
 613  *   +------+   +----+
 614  *   |               |
 615  *   v               v
 616  * +-------+     +-------+
 617  * | B +++ |     | C +++ |
 618  * +-------+     +-------+
 619  */
 620 static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
 621 {
 622         int r;
 623         size_t size;
 624         unsigned nr_left, nr_right;
 625         struct dm_block *left, *right, *new_parent;
 626         struct btree_node *pn, *ln, *rn;
 627         __le64 val;
 628
 629         new_parent = shadow_current(s);
 630
 631         r = new_block(s->info, &left);
 632         if (r < 0)
 633                 return r;
 634
 635         r = new_block(s->info, &right);
 636         if (r < 0) {
 637                 unlock_block(s->info, left);
 638                 return r;
 639         }
 640
 641         pn = dm_block_data(new_parent);
 642         ln = dm_block_data(left);
 643         rn = dm_block_data(right);
 644
 645         nr_left = le32_to_cpu(pn->header.nr_entries) / 2;
 646         nr_right = le32_to_cpu(pn->header.nr_entries) - nr_left;
 647
 648         ln->header.flags = pn->header.flags;
 649         ln->header.nr_entries = cpu_to_le32(nr_left);
 650         ln->header.max_entries = pn->header.max_entries;
 651         ln->header.value_size = pn->header.value_size;
 652
 653         rn->header.flags = pn->header.flags;
 654         rn->header.nr_entries = cpu_to_le32(nr_right);
 655         rn->header.max_entries = pn->header.max_entries;
 656         rn->header.value_size = pn->header.value_size;
 657
 658         memcpy(ln->keys, pn->keys, nr_left * sizeof(pn->keys[0]));
 659         memcpy(rn->keys, pn->keys + nr_left, nr_right * sizeof(pn->keys[0]));
 660
 661         size = le32_to_cpu(pn->header.flags) & INTERNAL_NODE ?
 662                 sizeof(__le64) : s->info->value_type.size;
 663         memcpy(value_ptr(ln, 0), value_ptr(pn, 0), nr_left * size);
 664         memcpy(value_ptr(rn, 0), value_ptr(pn, nr_left),
 665                nr_right * size);
 666
 667         /* new_parent should just point to l and r now */
 668         pn->header.flags = cpu_to_le32(INTERNAL_NODE);
 669         pn->header.nr_entries = cpu_to_le32(2);
 670         pn->header.max_entries = cpu_to_le32(
 671                 calc_max_entries(sizeof(__le64),
 672                                  dm_bm_block_size(
 673                                          dm_tm_get_bm(s->info->tm))));
 674         pn->header.value_size = cpu_to_le32(sizeof(__le64));
 675
 676         val = cpu_to_le64(dm_block_location(left));
 677         __dm_bless_for_disk(&val);
 678         pn->keys[0] = ln->keys[0];
 679         memcpy_disk(value_ptr(pn, 0), &val, sizeof(__le64));
 680
 681         val = cpu_to_le64(dm_block_location(right));
 682         __dm_bless_for_disk(&val);
 683         pn->keys[1] = rn->keys[0];
 684         memcpy_disk(value_ptr(pn, 1), &val, sizeof(__le64));
 685
 686         /*
 687          * rejig the spine.  This is ugly, since it knows too
 688          * much about the spine
 689          */
 690         if (s->nodes[0] != new_parent) {
 691                 unlock_block(s->info, s->nodes[0]);
 692                 s->nodes[0] = new_parent;
 693         }
 694         if (key < le64_to_cpu(rn->keys[0])) {
 695                 unlock_block(s->info, right);
 696                 s->nodes[1] = left;
 697         } else {
 698                 unlock_block(s->info, left);
 699                 s->nodes[1] = right;
 700         }
 701         s->count = 2;
 702
 703         return 0;
 704 }
 705
 706 static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
 707                             struct dm_btree_value_type *vt,
 708                             uint64_t key, unsigned *index)
 709 {
 710         int r, i = *index, top = 1;
 711         struct btree_node *node;
 712
 713         for (;;) {
 714                 r = shadow_step(s, root, vt);
 715                 if (r < 0)
 716                         return r;
 717
 718                 node = dm_block_data(shadow_current(s));
 719
 720                 /*
 721                  * We have to patch up the parent node, ugly, but I don't
 722                  * see a way to do this automatically as part of the spine
 723                  * op.
 724                  */
 725                 if (shadow_has_parent(s) && i >= 0) { /* FIXME: second clause unness. */
 726                         __le64 location = cpu_to_le64(dm_block_location(shadow_current(s)));
 727
 728                         __dm_bless_for_disk(&location);
 729                         memcpy_disk(value_ptr(dm_block_data(shadow_parent(s)), i),
 730                                     &location, sizeof(__le64));
 731                 }
 732
 733                 node = dm_block_data(shadow_current(s));
 734
 735                 if (node->header.nr_entries == node->header.max_entries) {
 736                         if (top)
 737                                 r = btree_split_beneath(s, key);
 738                         else
 739                                 r = btree_split_sibling(s, i, key);
 740
 741                         if (r < 0)
 742                                 return r;
 743                 }
 744
 745                 node = dm_block_data(shadow_current(s));
 746
 747                 i = lower_bound(node, key);
 748
 749                 if (le32_to_cpu(node->header.flags) & LEAF_NODE)
 750                         break;
 751
 752                 if (i < 0) {
 753                         /* change the bounds on the lowest key */
 754                         node->keys[0] = cpu_to_le64(key);
 755                         i = 0;
 756                 }
 757
 758                 root = value64(node, i);
 759                 top = 0;
 760         }
 761
 762         if (i < 0 || le64_to_cpu(node->keys[i]) != key)
 763                 i++;
 764
 765         *index = i;
 766         return 0;
 767 }
 768
 769 static bool need_insert(struct btree_node *node, uint64_t *keys,
 770                         unsigned level, unsigned index)
 771 {
 772         return ((index >= le32_to_cpu(node->header.nr_entries)) ||
 773                 (le64_to_cpu(node->keys[index]) != keys[level]));
 774 }
 775
 776 static int insert(struct dm_btree_info *info, dm_block_t root,
 777                   uint64_t *keys, void *value, dm_block_t *new_root,
 778                   int *inserted)
 779                   __dm_written_to_disk(value)
 780 {
 781         int r;
 782         unsigned level, index = -1, last_level = info->levels - 1;
 783         dm_block_t block = root;
 784         struct shadow_spine spine;
 785         struct btree_node *n;
 786         struct dm_btree_value_type le64_type;
 787
 788         init_le64_type(info->tm, &le64_type);
 789         init_shadow_spine(&spine, info);
 790
 791         for (level = 0; level < (info->levels - 1); level++) {
 792                 r = btree_insert_raw(&spine, block, &le64_type, keys[level], &index);
 793                 if (r < 0)
 794                         goto bad;
 795
 796                 n = dm_block_data(shadow_current(&spine));
 797
 798                 if (need_insert(n, keys, level, index)) {
 799                         dm_block_t new_tree;
 800                         __le64 new_le;
 801
 802                         r = dm_btree_empty(info, &new_tree);
 803                         if (r < 0)
 804                                 goto bad;
 805
 806                         new_le = cpu_to_le64(new_tree);
 807                         __dm_bless_for_disk(&new_le);
 808
 809                         r = insert_at(sizeof(uint64_t), n, index,
 810                                       keys[level], &new_le);
 811                         if (r)
 812                                 goto bad;
 813                 }
 814
 815                 if (level < last_level)
 816                         block = value64(n, index);
 817         }
 818
 819         r = btree_insert_raw(&spine, block, &info->value_type,
 820                              keys[level], &index);
 821         if (r < 0)
 822                 goto bad;
 823
 824         n = dm_block_data(shadow_current(&spine));
 825
 826         if (need_insert(n, keys, level, index)) {
 827                 if (inserted)
 828                         *inserted = 1;
 829
 830                 r = insert_at(info->value_type.size, n, index,
 831                               keys[level], value);
 832                 if (r)
 833                         goto bad_unblessed;
 834         } else {
 835                 if (inserted)
 836                         *inserted = 0;
 837
 838                 if (info->value_type.dec &&
 839                     (!info->value_type.equal ||
 840                      !info->value_type.equal(
 841                              info->value_type.context,
 842                              value_ptr(n, index),
 843                              value))) {
 844                         info->value_type.dec(info->value_type.context,
 845                                              value_ptr(n, index));
 846                 }
 847                 memcpy_disk(value_ptr(n, index),
 848                             value, info->value_type.size);
 849         }
 850
 851         *new_root = shadow_root(&spine);
 852         exit_shadow_spine(&spine);
 853
 854         return 0;
 855
 856 bad:
 857         __dm_unbless_for_disk(value);
 858 bad_unblessed:
 859         exit_shadow_spine(&spine);
 860         return r;
 861 }
 862
 863 int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
 864                     uint64_t *keys, void *value, dm_block_t *new_root)
 865                     __dm_written_to_disk(value)
 866 {
 867         return insert(info, root, keys, value, new_root, NULL);
 868 }
 869 EXPORT_SYMBOL_GPL(dm_btree_insert);
 870
 871 int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
 872                            uint64_t *keys, void *value, dm_block_t *new_root,
 873                            int *inserted)
 874                            __dm_written_to_disk(value)
 875 {
 876         return insert(info, root, keys, value, new_root, inserted);
 877 }
 878 EXPORT_SYMBOL_GPL(dm_btree_insert_notify);
 879
 880 /*----------------------------------------------------------------*/
 881
 882 static int find_key(struct ro_spine *s, dm_block_t block, bool find_highest,
 883                     uint64_t *result_key, dm_block_t *next_block)
 884 {
 885         int i, r;
 886         uint32_t flags;
 887
 888         do {
 889                 r = ro_step(s, block);
 890                 if (r < 0)
 891                         return r;
 892
 893                 flags = le32_to_cpu(ro_node(s)->header.flags);
 894                 i = le32_to_cpu(ro_node(s)->header.nr_entries);
 895                 if (!i)
 896                         return -ENODATA;
 897                 else
 898                         i--;
 899
 900                 if (find_highest)
 901                         *result_key = le64_to_cpu(ro_node(s)->keys[i]);
 902                 else
 903                         *result_key = le64_to_cpu(ro_node(s)->keys[0]);
 904
 905                 if (next_block || flags & INTERNAL_NODE) {
 906                         if (find_highest)
 907                                 block = value64(ro_node(s), i);
 908                         else
 909                                 block = value64(ro_node(s), 0);
 910                 }
 911
 912         } while (flags & INTERNAL_NODE);
 913
 914         if (next_block)
 915                 *next_block = block;
 916         return 0;
 917 }
 918
 919 static int dm_btree_find_key(struct dm_btree_info *info, dm_block_t root,
 920                              bool find_highest, uint64_t *result_keys)
 921 {
 922         int r = 0, count = 0, level;
 923         struct ro_spine spine;
 924
 925         init_ro_spine(&spine, info);
 926         for (level = 0; level < info->levels; level++) {
 927                 r = find_key(&spine, root, find_highest, result_keys + level,
 928                              level == info->levels - 1 ? NULL : &root);
 929                 if (r == -ENODATA) {
 930                         r = 0;
 931                         break;
 932
 933                 } else if (r)
 934                         break;
 935
 936                 count++;
 937         }
 938         exit_ro_spine(&spine);
 939
 940         return r ? r : count;
 941 }
 942
 943 int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
 944                               uint64_t *result_keys)
 945 {
 946         return dm_btree_find_key(info, root, true, result_keys);
 947 }
 948 EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);
 949
 950 int dm_btree_find_lowest_key(struct dm_btree_info *info, dm_block_t root,
 951                              uint64_t *result_keys)
 952 {
 953         return dm_btree_find_key(info, root, false, result_keys);
 954 }
 955 EXPORT_SYMBOL_GPL(dm_btree_find_lowest_key);
 956
 957 /*----------------------------------------------------------------*/
 958
 959 /*
 960  * FIXME: We shouldn't use a recursive algorithm when we have limited stack
 961  * space.  Also this only works for single level trees.
 962  */
 963 static int walk_node(struct dm_btree_info *info, dm_block_t block,
 964                      int (*fn)(void *context, uint64_t *keys, void *leaf),
 965                      void *context)
 966 {
 967         int r;
 968         unsigned i, nr;
 969         struct dm_block *node;
 970         struct btree_node *n;
 971         uint64_t keys;
 972
 973         r = bn_read_lock(info, block, &node);
 974         if (r)
 975                 return r;
 976
 977         n = dm_block_data(node);
 978
 979         nr = le32_to_cpu(n->header.nr_entries);
 980         for (i = 0; i < nr; i++) {
 981                 if (le32_to_cpu(n->header.flags) & INTERNAL_NODE) {
 982                         r = walk_node(info, value64(n, i), fn, context);
 983                         if (r)
 984                                 goto out;
 985                 } else {
 986                         keys = le64_to_cpu(*key_ptr(n, i));
 987                         r = fn(context, &keys, value_ptr(n, i));
 988                         if (r)
 989                                 goto out;
 990                 }
 991         }
 992
 993 out:
 994         dm_tm_unlock(info->tm, node);
 995         return r;
 996 }
 997
 998 int dm_btree_walk(struct dm_btree_info *info, dm_block_t root,
 999                   int (*fn)(void *context, uint64_t *keys, void *leaf),
1000                   void *context)
1001 {
1002         BUG_ON(info->levels > 1);
1003         return walk_node(info, root, fn, context);
1004 }
1005 EXPORT_SYMBOL_GPL(dm_btree_walk);
1006
1007 /*----------------------------------------------------------------*/
1008
1009 static void prefetch_values(struct dm_btree_cursor *c)
1010 {
1011         unsigned i, nr;
1012         __le64 value_le;
1013         struct cursor_node *n = c->nodes + c->depth - 1;
1014         struct btree_node *bn = dm_block_data(n->b);
1015         struct dm_block_manager *bm = dm_tm_get_bm(c->info->tm);
1016
1017         BUG_ON(c->info->value_type.size != sizeof(value_le));
1018
1019         nr = le32_to_cpu(bn->header.nr_entries);
1020         for (i = 0; i < nr; i++) {
1021                 memcpy(&value_le, value_ptr(bn, i), sizeof(value_le));
1022                 dm_bm_prefetch(bm, le64_to_cpu(value_le));
1023         }
1024 }
1025
1026 static bool leaf_node(struct dm_btree_cursor *c)
1027 {
1028         struct cursor_node *n = c->nodes + c->depth - 1;
1029         struct btree_node *bn = dm_block_data(n->b);
1030
1031         return le32_to_cpu(bn->header.flags) & LEAF_NODE;
1032 }
1033
1034 static int push_node(struct dm_btree_cursor *c, dm_block_t b)
1035 {
1036         int r;
1037         struct cursor_node *n = c->nodes + c->depth;
1038
1039         if (c->depth >= DM_BTREE_CURSOR_MAX_DEPTH - 1) {
1040                 DMERR("couldn't push cursor node, stack depth too high");
1041                 return -EINVAL;
1042         }
1043
1044         r = bn_read_lock(c->info, b, &n->b);
1045         if (r)
1046                 return r;
1047
1048         n->index = 0;
1049         c->depth++;
1050
1051         if (c->prefetch_leaves || !leaf_node(c))
1052                 prefetch_values(c);
1053
1054         return 0;
1055 }
1056
1057 static void pop_node(struct dm_btree_cursor *c)
1058 {
1059         c->depth--;
1060         unlock_block(c->info, c->nodes[c->depth].b);
1061 }
1062
1063 static int inc_or_backtrack(struct dm_btree_cursor *c)
1064 {
1065         struct cursor_node *n;
1066         struct btree_node *bn;
1067
1068         for (;;) {
1069                 if (!c->depth)
1070                         return -ENODATA;
1071
1072                 n = c->nodes + c->depth - 1;
1073                 bn = dm_block_data(n->b);
1074
1075                 n->index++;
1076                 if (n->index < le32_to_cpu(bn->header.nr_entries))
1077                         break;
1078
1079                 pop_node(c);
1080         }
1081
1082         return 0;
1083 }
1084
1085 static int find_leaf(struct dm_btree_cursor *c)
1086 {
1087         int r = 0;
1088         struct cursor_node *n;
1089         struct btree_node *bn;
1090         __le64 value_le;
1091
1092         for (;;) {
1093                 n = c->nodes + c->depth - 1;
1094                 bn = dm_block_data(n->b);
1095
1096                 if (le32_to_cpu(bn->header.flags) & LEAF_NODE)
1097                         break;
1098
1099                 memcpy(&value_le, value_ptr(bn, n->index), sizeof(value_le));
1100                 r = push_node(c, le64_to_cpu(value_le));
1101                 if (r) {
1102                         DMERR("push_node failed");
1103                         break;
1104                 }
1105         }
1106
1107         if (!r && (le32_to_cpu(bn->header.nr_entries) == 0))
1108                 return -ENODATA;
1109
1110         return r;
1111 }
1112
1113 int dm_btree_cursor_begin(struct dm_btree_info *info, dm_block_t root,
1114                           bool prefetch_leaves, struct dm_btree_cursor *c)
1115 {
1116         int r;
1117
1118         c->info = info;
1119         c->root = root;
1120         c->depth = 0;
1121         c->prefetch_leaves = prefetch_leaves;
1122
1123         r = push_node(c, root);
1124         if (r)
1125                 return r;
1126
1127         return find_leaf(c);
1128 }
1129 EXPORT_SYMBOL_GPL(dm_btree_cursor_begin);
1130
1131 void dm_btree_cursor_end(struct dm_btree_cursor *c)
1132 {
1133         while (c->depth)
1134                 pop_node(c);
1135 }
1136 EXPORT_SYMBOL_GPL(dm_btree_cursor_end);
1137
1138 int dm_btree_cursor_next(struct dm_btree_cursor *c)
1139 {
1140         int r = inc_or_backtrack(c);
1141         if (!r) {
1142                 r = find_leaf(c);
1143                 if (r)
1144                         DMERR("find_leaf failed");
1145         }
1146
1147         return r;
1148 }
1149 EXPORT_SYMBOL_GPL(dm_btree_cursor_next);
1150
1151 int dm_btree_cursor_skip(struct dm_btree_cursor *c, uint32_t count)
1152 {
1153         int r = 0;
1154
1155         while (count-- && !r)
1156                 r = dm_btree_cursor_next(c);
1157
1158         return r;
1159 }
1160 EXPORT_SYMBOL_GPL(dm_btree_cursor_skip);
1161
1162 int dm_btree_cursor_get_value(struct dm_btree_cursor *c, uint64_t *key, void *value_le)
1163 {
1164         if (c->depth) {
1165                 struct cursor_node *n = c->nodes + c->depth - 1;
1166                 struct btree_node *bn = dm_block_data(n->b);
1167
1168                 if (le32_to_cpu(bn->header.flags) & INTERNAL_NODE)
1169                         return -EINVAL;
1170
1171                 *key = le64_to_cpu(*key_ptr(bn, n->index));
1172                 memcpy(value_le, value_ptr(bn, n->index), c->info->value_type.size);
1173                 return 0;
1174
1175         } else
1176                 return -ENODATA;
1177 }
1178 EXPORT_SYMBOL_GPL(dm_btree_cursor_get_value);