drivers/md/bcache/bset.c

   1 /*
   2  * Code for working with individual keys, and sorted sets of keys with in a
   3  * btree node
   4  *
   5  * Copyright 2012 Google, Inc.
   6  */
   7
   8 #include "bcache.h"
   9 #include "btree.h"
  10 #include "debug.h"
  11
  12 #include <linux/random.h>
  13 #include <linux/prefetch.h>
  14
  15 /* Keylists */
  16
  17 int __bch_keylist_realloc(struct keylist *l, unsigned u64s)
  18 {
  19         size_t oldsize = bch_keylist_nkeys(l);
  20         size_t newsize = oldsize + u64s;
  21         uint64_t *old_keys = l->keys_p == l->inline_keys ? NULL : l->keys_p;
  22         uint64_t *new_keys;
  23
  24         newsize = roundup_pow_of_two(newsize);
  25
  26         if (newsize <= KEYLIST_INLINE ||
  27             roundup_pow_of_two(oldsize) == newsize)
  28                 return 0;
  29
  30         new_keys = krealloc(old_keys, sizeof(uint64_t) * newsize, GFP_NOIO);
  31
  32         if (!new_keys)
  33                 return -ENOMEM;
  34
  35         if (!old_keys)
  36                 memcpy(new_keys, l->inline_keys, sizeof(uint64_t) * oldsize);
  37
  38         l->keys_p = new_keys;
  39         l->top_p = new_keys + oldsize;
  40
  41         return 0;
  42 }
  43
  44 struct bkey *bch_keylist_pop(struct keylist *l)
  45 {
  46         struct bkey *k = l->keys;
  47
  48         if (k == l->top)
  49                 return NULL;
  50
  51         while (bkey_next(k) != l->top)
  52                 k = bkey_next(k);
  53
  54         return l->top = k;
  55 }
  56
  57 void bch_keylist_pop_front(struct keylist *l)
  58 {
  59         l->top_p -= bkey_u64s(l->keys);
  60
  61         memmove(l->keys,
  62                 bkey_next(l->keys),
  63                 bch_keylist_bytes(l));
  64 }
  65
  66 /* Key/pointer manipulation */
  67
  68 void bch_bkey_copy_single_ptr(struct bkey *dest, const struct bkey *src,
  69                               unsigned i)
  70 {
  71         BUG_ON(i > KEY_PTRS(src));
  72
  73         /* Only copy the header, key, and one pointer. */
  74         memcpy(dest, src, 2 * sizeof(uint64_t));
  75         dest->ptr[0] = src->ptr[i];
  76         SET_KEY_PTRS(dest, 1);
  77         /* We didn't copy the checksum so clear that bit. */
  78         SET_KEY_CSUM(dest, 0);
  79 }
  80
  81 bool __bch_cut_front(const struct bkey *where, struct bkey *k)
  82 {
  83         unsigned i, len = 0;
  84
  85         if (bkey_cmp(where, &START_KEY(k)) <= 0)
  86                 return false;
  87
  88         if (bkey_cmp(where, k) < 0)
  89                 len = KEY_OFFSET(k) - KEY_OFFSET(where);
  90         else
  91                 bkey_copy_key(k, where);
  92
  93         for (i = 0; i < KEY_PTRS(k); i++)
  94                 SET_PTR_OFFSET(k, i, PTR_OFFSET(k, i) + KEY_SIZE(k) - len);
  95
  96         BUG_ON(len > KEY_SIZE(k));
  97         SET_KEY_SIZE(k, len);
  98         return true;
  99 }
 100
 101 bool __bch_cut_back(const struct bkey *where, struct bkey *k)
 102 {
 103         unsigned len = 0;
 104
 105         if (bkey_cmp(where, k) >= 0)
 106                 return false;
 107
 108         BUG_ON(KEY_INODE(where) != KEY_INODE(k));
 109
 110         if (bkey_cmp(where, &START_KEY(k)) > 0)
 111                 len = KEY_OFFSET(where) - KEY_START(k);
 112
 113         bkey_copy_key(k, where);
 114
 115         BUG_ON(len > KEY_SIZE(k));
 116         SET_KEY_SIZE(k, len);
 117         return true;
 118 }
 119
 120 /* Auxiliary search trees */
 121
 122 /* 32 bits total: */
 123 #define BKEY_MID_BITS           3
 124 #define BKEY_EXPONENT_BITS      7
 125 #define BKEY_MANTISSA_BITS      (32 - BKEY_MID_BITS - BKEY_EXPONENT_BITS)
 126 #define BKEY_MANTISSA_MASK      ((1 << BKEY_MANTISSA_BITS) - 1)
 127
 128 struct bkey_float {
 129         unsigned        exponent:BKEY_EXPONENT_BITS;
 130         unsigned        m:BKEY_MID_BITS;
 131         unsigned        mantissa:BKEY_MANTISSA_BITS;
 132 } __packed;
 133
 134 /*
 135  * BSET_CACHELINE was originally intended to match the hardware cacheline size -
 136  * it used to be 64, but I realized the lookup code would touch slightly less
 137  * memory if it was 128.
 138  *
 139  * It definites the number of bytes (in struct bset) per struct bkey_float in
 140  * the auxiliar search tree - when we're done searching the bset_float tree we
 141  * have this many bytes left that we do a linear search over.
 142  *
 143  * Since (after level 5) every level of the bset_tree is on a new cacheline,
 144  * we're touching one fewer cacheline in the bset tree in exchange for one more
 145  * cacheline in the linear search - but the linear search might stop before it
 146  * gets to the second cacheline.
 147  */
 148
 149 #define BSET_CACHELINE          128
 150
 151 /* Space required for the btree node keys */
 152 static inline size_t btree_keys_bytes(struct btree_keys *b)
 153 {
 154         return PAGE_SIZE << b->page_order;
 155 }
 156
 157 static inline size_t btree_keys_cachelines(struct btree_keys *b)
 158 {
 159         return btree_keys_bytes(b) / BSET_CACHELINE;
 160 }
 161
 162 /* Space required for the auxiliary search trees */
 163 static inline size_t bset_tree_bytes(struct btree_keys *b)
 164 {
 165         return btree_keys_cachelines(b) * sizeof(struct bkey_float);
 166 }
 167
 168 /* Space required for the prev pointers */
 169 static inline size_t bset_prev_bytes(struct btree_keys *b)
 170 {
 171         return btree_keys_cachelines(b) * sizeof(uint8_t);
 172 }
 173
 174 /* Memory allocation */
 175
 176 void bch_btree_keys_free(struct btree_keys *b)
 177 {
 178         struct bset_tree *t = b->set;
 179
 180         if (bset_prev_bytes(b) < PAGE_SIZE)
 181                 kfree(t->prev);
 182         else
 183                 free_pages((unsigned long) t->prev,
 184                            get_order(bset_prev_bytes(b)));
 185
 186         if (bset_tree_bytes(b) < PAGE_SIZE)
 187                 kfree(t->tree);
 188         else
 189                 free_pages((unsigned long) t->tree,
 190                            get_order(bset_tree_bytes(b)));
 191
 192         free_pages((unsigned long) t->data, b->page_order);
 193
 194         t->prev = NULL;
 195         t->tree = NULL;
 196         t->data = NULL;
 197 }
 198 EXPORT_SYMBOL(bch_btree_keys_free);
 199
 200 int bch_btree_keys_alloc(struct btree_keys *b, unsigned page_order, gfp_t gfp)
 201 {
 202         struct bset_tree *t = b->set;
 203
 204         BUG_ON(t->data);
 205
 206         b->page_order = page_order;
 207
 208         t->data = (void *) __get_free_pages(gfp, b->page_order);
 209         if (!t->data)
 210                 goto err;
 211
 212         t->tree = bset_tree_bytes(b) < PAGE_SIZE
 213                 ? kmalloc(bset_tree_bytes(b), gfp)
 214                 : (void *) __get_free_pages(gfp, get_order(bset_tree_bytes(b)));
 215         if (!t->tree)
 216                 goto err;
 217
 218         t->prev = bset_prev_bytes(b) < PAGE_SIZE
 219                 ? kmalloc(bset_prev_bytes(b), gfp)
 220                 : (void *) __get_free_pages(gfp, get_order(bset_prev_bytes(b)));
 221         if (!t->prev)
 222                 goto err;
 223
 224         return 0;
 225 err:
 226         bch_btree_keys_free(b);
 227         return -ENOMEM;
 228 }
 229 EXPORT_SYMBOL(bch_btree_keys_alloc);
 230
 231 void bch_btree_keys_init(struct btree_keys *b, const struct btree_keys_ops *ops,
 232                          bool *expensive_debug_checks)
 233 {
 234         unsigned i;
 235
 236         b->ops = ops;
 237         b->expensive_debug_checks = expensive_debug_checks;
 238         b->nsets = 0;
 239         b->last_set_unwritten = 0;
 240
 241         /* XXX: shouldn't be needed */
 242         for (i = 0; i < MAX_BSETS; i++)
 243                 b->set[i].size = 0;
 244         /*
 245          * Second loop starts at 1 because b->keys[0]->data is the memory we
 246          * allocated
 247          */
 248         for (i = 1; i < MAX_BSETS; i++)
 249                 b->set[i].data = NULL;
 250 }
 251 EXPORT_SYMBOL(bch_btree_keys_init);
 252
 253 /* Binary tree stuff for auxiliary search trees */
 254
 255 static unsigned inorder_next(unsigned j, unsigned size)
 256 {
 257         if (j * 2 + 1 < size) {
 258                 j = j * 2 + 1;
 259
 260                 while (j * 2 < size)
 261                         j *= 2;
 262         } else
 263                 j >>= ffz(j) + 1;
 264
 265         return j;
 266 }
 267
 268 static unsigned inorder_prev(unsigned j, unsigned size)
 269 {
 270         if (j * 2 < size) {
 271                 j = j * 2;
 272
 273                 while (j * 2 + 1 < size)
 274                         j = j * 2 + 1;
 275         } else
 276                 j >>= ffs(j);
 277
 278         return j;
 279 }
 280
 281 /* I have no idea why this code works... and I'm the one who wrote it
 282  *
 283  * However, I do know what it does:
 284  * Given a binary tree constructed in an array (i.e. how you normally implement
 285  * a heap), it converts a node in the tree - referenced by array index - to the
 286  * index it would have if you did an inorder traversal.
 287  *
 288  * Also tested for every j, size up to size somewhere around 6 million.
 289  *
 290  * The binary tree starts at array index 1, not 0
 291  * extra is a function of size:
 292  *   extra = (size - rounddown_pow_of_two(size - 1)) << 1;
 293  */
 294 static unsigned __to_inorder(unsigned j, unsigned size, unsigned extra)
 295 {
 296         unsigned b = fls(j);
 297         unsigned shift = fls(size - 1) - b;
 298
 299         j  ^= 1U << (b - 1);
 300         j <<= 1;
 301         j  |= 1;
 302         j <<= shift;
 303
 304         if (j > extra)
 305                 j -= (j - extra) >> 1;
 306
 307         return j;
 308 }
 309
 310 static unsigned to_inorder(unsigned j, struct bset_tree *t)
 311 {
 312         return __to_inorder(j, t->size, t->extra);
 313 }
 314
 315 static unsigned __inorder_to_tree(unsigned j, unsigned size, unsigned extra)
 316 {
 317         unsigned shift;
 318
 319         if (j > extra)
 320                 j += j - extra;
 321
 322         shift = ffs(j);
 323
 324         j >>= shift;
 325         j  |= roundup_pow_of_two(size) >> shift;
 326
 327         return j;
 328 }
 329
 330 static unsigned inorder_to_tree(unsigned j, struct bset_tree *t)
 331 {
 332         return __inorder_to_tree(j, t->size, t->extra);
 333 }
 334
 335 #if 0
 336 void inorder_test(void)
 337 {
 338         unsigned long done = 0;
 339         ktime_t start = ktime_get();
 340
 341         for (unsigned size = 2;
 342              size < 65536000;
 343              size++) {
 344                 unsigned extra = (size - rounddown_pow_of_two(size - 1)) << 1;
 345                 unsigned i = 1, j = rounddown_pow_of_two(size - 1);
 346
 347                 if (!(size % 4096))
 348                         printk(KERN_NOTICE "loop %u, %llu per us\n", size,
 349                                done / ktime_us_delta(ktime_get(), start));
 350
 351                 while (1) {
 352                         if (__inorder_to_tree(i, size, extra) != j)
 353                                 panic("size %10u j %10u i %10u", size, j, i);
 354
 355                         if (__to_inorder(j, size, extra) != i)
 356                                 panic("size %10u j %10u i %10u", size, j, i);
 357
 358                         if (j == rounddown_pow_of_two(size) - 1)
 359                                 break;
 360
 361                         BUG_ON(inorder_prev(inorder_next(j, size), size) != j);
 362
 363                         j = inorder_next(j, size);
 364                         i++;
 365                 }
 366
 367                 done += size - 1;
 368         }
 369 }
 370 #endif
 371
 372 /*
 373  * Cacheline/offset <-> bkey pointer arithmetic:
 374  *
 375  * t->tree is a binary search tree in an array; each node corresponds to a key
 376  * in one cacheline in t->set (BSET_CACHELINE bytes).
 377  *
 378  * This means we don't have to store the full index of the key that a node in
 379  * the binary tree points to; to_inorder() gives us the cacheline, and then
 380  * bkey_float->m gives us the offset within that cacheline, in units of 8 bytes.
 381  *
 382  * cacheline_to_bkey() and friends abstract out all the pointer arithmetic to
 383  * make this work.
 384  *
 385  * To construct the bfloat for an arbitrary key we need to know what the key
 386  * immediately preceding it is: we have to check if the two keys differ in the
 387  * bits we're going to store in bkey_float->mantissa. t->prev[j] stores the size
 388  * of the previous key so we can walk backwards to it from t->tree[j]'s key.
 389  */
 390
 391 static struct bkey *cacheline_to_bkey(struct bset_tree *t, unsigned cacheline,
 392                                       unsigned offset)
 393 {
 394         return ((void *) t->data) + cacheline * BSET_CACHELINE + offset * 8;
 395 }
 396
 397 static unsigned bkey_to_cacheline(struct bset_tree *t, struct bkey *k)
 398 {
 399         return ((void *) k - (void *) t->data) / BSET_CACHELINE;
 400 }
 401
 402 static unsigned bkey_to_cacheline_offset(struct bkey *k)
 403 {
 404         return ((size_t) k & (BSET_CACHELINE - 1)) / sizeof(uint64_t);
 405 }
 406
 407 static struct bkey *tree_to_bkey(struct bset_tree *t, unsigned j)
 408 {
 409         return cacheline_to_bkey(t, to_inorder(j, t), t->tree[j].m);
 410 }
 411
 412 static struct bkey *tree_to_prev_bkey(struct bset_tree *t, unsigned j)
 413 {
 414         return (void *) (((uint64_t *) tree_to_bkey(t, j)) - t->prev[j]);
 415 }
 416
 417 /*
 418  * For the write set - the one we're currently inserting keys into - we don't
 419  * maintain a full search tree, we just keep a simple lookup table in t->prev.
 420  */
 421 static struct bkey *table_to_bkey(struct bset_tree *t, unsigned cacheline)
 422 {
 423         return cacheline_to_bkey(t, cacheline, t->prev[cacheline]);
 424 }
 425
 426 static inline uint64_t shrd128(uint64_t high, uint64_t low, uint8_t shift)
 427 {
 428         low >>= shift;
 429         low  |= (high << 1) << (63U - shift);
 430         return low;
 431 }
 432
 433 static inline unsigned bfloat_mantissa(const struct bkey *k,
 434                                        struct bkey_float *f)
 435 {
 436         const uint64_t *p = &k->low - (f->exponent >> 6);
 437         return shrd128(p[-1], p[0], f->exponent & 63) & BKEY_MANTISSA_MASK;
 438 }
 439
 440 static void make_bfloat(struct bset_tree *t, unsigned j)
 441 {
 442         struct bkey_float *f = &t->tree[j];
 443         struct bkey *m = tree_to_bkey(t, j);
 444         struct bkey *p = tree_to_prev_bkey(t, j);
 445
 446         struct bkey *l = is_power_of_2(j)
 447                 ? t->data->start
 448                 : tree_to_prev_bkey(t, j >> ffs(j));
 449
 450         struct bkey *r = is_power_of_2(j + 1)
 451                 ? bset_bkey_idx(t->data, t->data->keys - bkey_u64s(&t->end))
 452                 : tree_to_bkey(t, j >> (ffz(j) + 1));
 453
 454         BUG_ON(m < l || m > r);
 455         BUG_ON(bkey_next(p) != m);
 456
 457         if (KEY_INODE(l) != KEY_INODE(r))
 458                 f->exponent = fls64(KEY_INODE(r) ^ KEY_INODE(l)) + 64;
 459         else
 460                 f->exponent = fls64(r->low ^ l->low);
 461
 462         f->exponent = max_t(int, f->exponent - BKEY_MANTISSA_BITS, 0);
 463
 464         /*
 465          * Setting f->exponent = 127 flags this node as failed, and causes the
 466          * lookup code to fall back to comparing against the original key.
 467          */
 468
 469         if (bfloat_mantissa(m, f) != bfloat_mantissa(p, f))
 470                 f->mantissa = bfloat_mantissa(m, f) - 1;
 471         else
 472                 f->exponent = 127;
 473 }
 474
 475 static void bset_alloc_tree(struct btree_keys *b, struct bset_tree *t)
 476 {
 477         if (t != b->set) {
 478                 unsigned j = roundup(t[-1].size,
 479                                      64 / sizeof(struct bkey_float));
 480
 481                 t->tree = t[-1].tree + j;
 482                 t->prev = t[-1].prev + j;
 483         }
 484
 485         while (t < b->set + MAX_BSETS)
 486                 t++->size = 0;
 487 }
 488
 489 static void bch_bset_build_unwritten_tree(struct btree_keys *b)
 490 {
 491         struct bset_tree *t = bset_tree_last(b);
 492
 493         BUG_ON(b->last_set_unwritten);
 494         b->last_set_unwritten = 1;
 495
 496         bset_alloc_tree(b, t);
 497
 498         if (t->tree != b->set->tree + btree_keys_cachelines(b)) {
 499                 t->prev[0] = bkey_to_cacheline_offset(t->data->start);
 500                 t->size = 1;
 501         }
 502 }
 503
 504 void bch_bset_init_next(struct btree_keys *b, struct bset *i, uint64_t magic)
 505 {
 506         if (i != b->set->data) {
 507                 b->set[++b->nsets].data = i;
 508                 i->seq = b->set->data->seq;
 509         } else
 510                 get_random_bytes(&i->seq, sizeof(uint64_t));
 511
 512         i->magic        = magic;
 513         i->version      = 0;
 514         i->keys         = 0;
 515
 516         bch_bset_build_unwritten_tree(b);
 517 }
 518 EXPORT_SYMBOL(bch_bset_init_next);
 519
 520 void bch_bset_build_written_tree(struct btree_keys *b)
 521 {
 522         struct bset_tree *t = bset_tree_last(b);
 523         struct bkey *k = t->data->start;
 524         unsigned j, cacheline = 1;
 525
 526         b->last_set_unwritten = 0;
 527
 528         bset_alloc_tree(b, t);
 529
 530         t->size = min_t(unsigned,
 531                         bkey_to_cacheline(t, bset_bkey_last(t->data)),
 532                         b->set->tree + btree_keys_cachelines(b) - t->tree);
 533
 534         if (t->size < 2) {
 535                 t->size = 0;
 536                 return;
 537         }
 538
 539         t->extra = (t->size - rounddown_pow_of_two(t->size - 1)) << 1;
 540
 541         /* First we figure out where the first key in each cacheline is */
 542         for (j = inorder_next(0, t->size);
 543              j;
 544              j = inorder_next(j, t->size)) {
 545                 while (bkey_to_cacheline(t, k) != cacheline)
 546                         k = bkey_next(k);
 547
 548                 t->prev[j] = bkey_u64s(k);
 549                 k = bkey_next(k);
 550                 cacheline++;
 551                 t->tree[j].m = bkey_to_cacheline_offset(k);
 552         }
 553
 554         while (bkey_next(k) != bset_bkey_last(t->data))
 555                 k = bkey_next(k);
 556
 557         t->end = *k;
 558
 559         /* Then we build the tree */
 560         for (j = inorder_next(0, t->size);
 561              j;
 562              j = inorder_next(j, t->size))
 563                 make_bfloat(t, j);
 564 }
 565 EXPORT_SYMBOL(bch_bset_build_written_tree);
 566
 567 void bch_bset_fix_invalidated_key(struct btree_keys *b, struct bkey *k)
 568 {
 569         struct bset_tree *t;
 570         unsigned inorder, j = 1;
 571
 572         for (t = b->set; t <= bset_tree_last(b); t++)
 573                 if (k < bset_bkey_last(t->data))
 574                         goto found_set;
 575
 576         BUG();
 577 found_set:
 578         if (!t->size || !bset_written(b, t))
 579                 return;
 580
 581         inorder = bkey_to_cacheline(t, k);
 582
 583         if (k == t->data->start)
 584                 goto fix_left;
 585
 586         if (bkey_next(k) == bset_bkey_last(t->data)) {
 587                 t->end = *k;
 588                 goto fix_right;
 589         }
 590
 591         j = inorder_to_tree(inorder, t);
 592
 593         if (j &&
 594             j < t->size &&
 595             k == tree_to_bkey(t, j))
 596 fix_left:       do {
 597                         make_bfloat(t, j);
 598                         j = j * 2;
 599                 } while (j < t->size);
 600
 601         j = inorder_to_tree(inorder + 1, t);
 602
 603         if (j &&
 604             j < t->size &&
 605             k == tree_to_prev_bkey(t, j))
 606 fix_right:      do {
 607                         make_bfloat(t, j);
 608                         j = j * 2 + 1;
 609                 } while (j < t->size);
 610 }
 611 EXPORT_SYMBOL(bch_bset_fix_invalidated_key);
 612
 613 static void bch_bset_fix_lookup_table(struct btree_keys *b,
 614                                       struct bset_tree *t,
 615                                       struct bkey *k)
 616 {
 617         unsigned shift = bkey_u64s(k);
 618         unsigned j = bkey_to_cacheline(t, k);
 619
 620         /* We're getting called from btree_split() or btree_gc, just bail out */
 621         if (!t->size)
 622                 return;
 623
 624         /* k is the key we just inserted; we need to find the entry in the
 625          * lookup table for the first key that is strictly greater than k:
 626          * it's either k's cacheline or the next one
 627          */
 628         if (j < t->size &&
 629             table_to_bkey(t, j) <= k)
 630                 j++;
 631
 632         /* Adjust all the lookup table entries, and find a new key for any that
 633          * have gotten too big
 634          */
 635         for (; j < t->size; j++) {
 636                 t->prev[j] += shift;
 637
 638                 if (t->prev[j] > 7) {
 639                         k = table_to_bkey(t, j - 1);
 640
 641                         while (k < cacheline_to_bkey(t, j, 0))
 642                                 k = bkey_next(k);
 643
 644                         t->prev[j] = bkey_to_cacheline_offset(k);
 645                 }
 646         }
 647
 648         if (t->size == b->set->tree + btree_keys_cachelines(b) - t->tree)
 649                 return;
 650
 651         /* Possibly add a new entry to the end of the lookup table */
 652
 653         for (k = table_to_bkey(t, t->size - 1);
 654              k != bset_bkey_last(t->data);
 655              k = bkey_next(k))
 656                 if (t->size == bkey_to_cacheline(t, k)) {
 657                         t->prev[t->size] = bkey_to_cacheline_offset(k);
 658                         t->size++;
 659                 }
 660 }
 661
 662 void bch_bset_insert(struct btree_keys *b, struct bkey *where,
 663                      struct bkey *insert)
 664 {
 665         struct bset_tree *t = bset_tree_last(b);
 666
 667         BUG_ON(!b->last_set_unwritten);
 668         BUG_ON(bset_byte_offset(b, t->data) +
 669                __set_bytes(t->data, t->data->keys + bkey_u64s(insert)) >
 670                PAGE_SIZE << b->page_order);
 671
 672         memmove((uint64_t *) where + bkey_u64s(insert),
 673                 where,
 674                 (void *) bset_bkey_last(t->data) - (void *) where);
 675
 676         t->data->keys += bkey_u64s(insert);
 677         bkey_copy(where, insert);
 678         bch_bset_fix_lookup_table(b, t, where);
 679 }
 680 EXPORT_SYMBOL(bch_bset_insert);
 681
 682 struct bset_search_iter {
 683         struct bkey *l, *r;
 684 };
 685
 686 static struct bset_search_iter bset_search_write_set(struct bset_tree *t,
 687                                                      const struct bkey *search)
 688 {
 689         unsigned li = 0, ri = t->size;
 690
 691         while (li + 1 != ri) {
 692                 unsigned m = (li + ri) >> 1;
 693
 694                 if (bkey_cmp(table_to_bkey(t, m), search) > 0)
 695                         ri = m;
 696                 else
 697                         li = m;
 698         }
 699
 700         return (struct bset_search_iter) {
 701                 table_to_bkey(t, li),
 702                 ri < t->size ? table_to_bkey(t, ri) : bset_bkey_last(t->data)
 703         };
 704 }
 705
 706 static struct bset_search_iter bset_search_tree(struct bset_tree *t,
 707                                                 const struct bkey *search)
 708 {
 709         struct bkey *l, *r;
 710         struct bkey_float *f;
 711         unsigned inorder, j, n = 1;
 712
 713         do {
 714                 unsigned p = n << 4;
 715                 p &= ((int) (p - t->size)) >> 31;
 716
 717                 prefetch(&t->tree[p]);
 718
 719                 j = n;
 720                 f = &t->tree[j];
 721
 722                 /*
 723                  * n = (f->mantissa > bfloat_mantissa())
 724                  *      ? j * 2
 725                  *      : j * 2 + 1;
 726                  *
 727                  * We need to subtract 1 from f->mantissa for the sign bit trick
 728                  * to work  - that's done in make_bfloat()
 729                  */
 730                 if (likely(f->exponent != 127))
 731                         n = j * 2 + (((unsigned)
 732                                       (f->mantissa -
 733                                        bfloat_mantissa(search, f))) >> 31);
 734                 else
 735                         n = (bkey_cmp(tree_to_bkey(t, j), search) > 0)
 736                                 ? j * 2
 737                                 : j * 2 + 1;
 738         } while (n < t->size);
 739
 740         inorder = to_inorder(j, t);
 741
 742         /*
 743          * n would have been the node we recursed to - the low bit tells us if
 744          * we recursed left or recursed right.
 745          */
 746         if (n & 1) {
 747                 l = cacheline_to_bkey(t, inorder, f->m);
 748
 749                 if (++inorder != t->size) {
 750                         f = &t->tree[inorder_next(j, t->size)];
 751                         r = cacheline_to_bkey(t, inorder, f->m);
 752                 } else
 753                         r = bset_bkey_last(t->data);
 754         } else {
 755                 r = cacheline_to_bkey(t, inorder, f->m);
 756
 757                 if (--inorder) {
 758                         f = &t->tree[inorder_prev(j, t->size)];
 759                         l = cacheline_to_bkey(t, inorder, f->m);
 760                 } else
 761                         l = t->data->start;
 762         }
 763
 764         return (struct bset_search_iter) {l, r};
 765 }
 766
 767 struct bkey *__bch_bset_search(struct btree *b, struct bset_tree *t,
 768                                const struct bkey *search)
 769 {
 770         struct bset_search_iter i;
 771
 772         /*
 773          * First, we search for a cacheline, then lastly we do a linear search
 774          * within that cacheline.
 775          *
 776          * To search for the cacheline, there's three different possibilities:
 777          *  * The set is too small to have a search tree, so we just do a linear
 778          *    search over the whole set.
 779          *  * The set is the one we're currently inserting into; keeping a full
 780          *    auxiliary search tree up to date would be too expensive, so we
 781          *    use a much simpler lookup table to do a binary search -
 782          *    bset_search_write_set().
 783          *  * Or we use the auxiliary search tree we constructed earlier -
 784          *    bset_search_tree()
 785          */
 786
 787         if (unlikely(!t->size)) {
 788                 i.l = t->data->start;
 789                 i.r = bset_bkey_last(t->data);
 790         } else if (bset_written(&b->keys, t)) {
 791                 /*
 792                  * Each node in the auxiliary search tree covers a certain range
 793                  * of bits, and keys above and below the set it covers might
 794                  * differ outside those bits - so we have to special case the
 795                  * start and end - handle that here:
 796                  */
 797
 798                 if (unlikely(bkey_cmp(search, &t->end) >= 0))
 799                         return bset_bkey_last(t->data);
 800
 801                 if (unlikely(bkey_cmp(search, t->data->start) < 0))
 802                         return t->data->start;
 803
 804                 i = bset_search_tree(t, search);
 805         } else {
 806                 BUG_ON(!b->keys.nsets &&
 807                        t->size < bkey_to_cacheline(t, bset_bkey_last(t->data)));
 808
 809                 i = bset_search_write_set(t, search);
 810         }
 811
 812         if (expensive_debug_checks(b->c)) {
 813                 BUG_ON(bset_written(&b->keys, t) &&
 814                        i.l != t->data->start &&
 815                        bkey_cmp(tree_to_prev_bkey(t,
 816                           inorder_to_tree(bkey_to_cacheline(t, i.l), t)),
 817                                 search) > 0);
 818
 819                 BUG_ON(i.r != bset_bkey_last(t->data) &&
 820                        bkey_cmp(i.r, search) <= 0);
 821         }
 822
 823         while (likely(i.l != i.r) &&
 824                bkey_cmp(i.l, search) <= 0)
 825                 i.l = bkey_next(i.l);
 826
 827         return i.l;
 828 }
 829 EXPORT_SYMBOL(__bch_bset_search);
 830
 831 /* Btree iterator */
 832
 833 typedef bool (btree_iter_cmp_fn)(struct btree_iter_set,
 834                                  struct btree_iter_set);
 835
 836 static inline bool btree_iter_cmp(struct btree_iter_set l,
 837                                   struct btree_iter_set r)
 838 {
 839         return bkey_cmp(l.k, r.k) > 0;
 840 }
 841
 842 static inline bool btree_iter_end(struct btree_iter *iter)
 843 {
 844         return !iter->used;
 845 }
 846
 847 void bch_btree_iter_push(struct btree_iter *iter, struct bkey *k,
 848                          struct bkey *end)
 849 {
 850         if (k != end)
 851                 BUG_ON(!heap_add(iter,
 852                                  ((struct btree_iter_set) { k, end }),
 853                                  btree_iter_cmp));
 854 }
 855
 856 static struct bkey *__bch_btree_iter_init(struct btree *b,
 857                                           struct btree_iter *iter,
 858                                           struct bkey *search,
 859                                           struct bset_tree *start)
 860 {
 861         struct bkey *ret = NULL;
 862         iter->size = ARRAY_SIZE(iter->data);
 863         iter->used = 0;
 864
 865 #ifdef CONFIG_BCACHE_DEBUG
 866         iter->b = b;
 867 #endif
 868
 869         for (; start <= bset_tree_last(&b->keys); start++) {
 870                 ret = bch_bset_search(b, start, search);
 871                 bch_btree_iter_push(iter, ret, bset_bkey_last(start->data));
 872         }
 873
 874         return ret;
 875 }
 876
 877 struct bkey *bch_btree_iter_init(struct btree *b,
 878                                  struct btree_iter *iter,
 879                                  struct bkey *search)
 880 {
 881         return __bch_btree_iter_init(b, iter, search, b->keys.set);
 882 }
 883 EXPORT_SYMBOL(bch_btree_iter_init);
 884
 885 static inline struct bkey *__bch_btree_iter_next(struct btree_iter *iter,
 886                                                  btree_iter_cmp_fn *cmp)
 887 {
 888         struct btree_iter_set unused;
 889         struct bkey *ret = NULL;
 890
 891         if (!btree_iter_end(iter)) {
 892                 bch_btree_iter_next_check(iter);
 893
 894                 ret = iter->data->k;
 895                 iter->data->k = bkey_next(iter->data->k);
 896
 897                 if (iter->data->k > iter->data->end) {
 898                         WARN_ONCE(1, "bset was corrupt!\n");
 899                         iter->data->k = iter->data->end;
 900                 }
 901
 902                 if (iter->data->k == iter->data->end)
 903                         heap_pop(iter, unused, cmp);
 904                 else
 905                         heap_sift(iter, 0, cmp);
 906         }
 907
 908         return ret;
 909 }
 910
 911 struct bkey *bch_btree_iter_next(struct btree_iter *iter)
 912 {
 913         return __bch_btree_iter_next(iter, btree_iter_cmp);
 914
 915 }
 916 EXPORT_SYMBOL(bch_btree_iter_next);
 917
 918 struct bkey *bch_btree_iter_next_filter(struct btree_iter *iter,
 919                                         struct btree_keys *b, ptr_filter_fn fn)
 920 {
 921         struct bkey *ret;
 922
 923         do {
 924                 ret = bch_btree_iter_next(iter);
 925         } while (ret && fn(b, ret));
 926
 927         return ret;
 928 }
 929
 930 /* Mergesort */
 931
 932 void bch_bset_sort_state_free(struct bset_sort_state *state)
 933 {
 934         if (state->pool)
 935                 mempool_destroy(state->pool);
 936 }
 937
 938 int bch_bset_sort_state_init(struct bset_sort_state *state, unsigned page_order)
 939 {
 940         spin_lock_init(&state->time.lock);
 941
 942         state->page_order = page_order;
 943         state->crit_factor = int_sqrt(1 << page_order);
 944
 945         state->pool = mempool_create_page_pool(1, page_order);
 946         if (!state->pool)
 947                 return -ENOMEM;
 948
 949         return 0;
 950 }
 951 EXPORT_SYMBOL(bch_bset_sort_state_init);
 952
 953 static void btree_mergesort(struct btree_keys *b, struct bset *out,
 954                             struct btree_iter *iter,
 955                             bool fixup, bool remove_stale)
 956 {
 957         int i;
 958         struct bkey *k, *last = NULL;
 959         BKEY_PADDED(k) tmp;
 960         bool (*bad)(struct btree_keys *, const struct bkey *) = remove_stale
 961                 ? bch_ptr_bad
 962                 : bch_ptr_invalid;
 963
 964         /* Heapify the iterator, using our comparison function */
 965         for (i = iter->used / 2 - 1; i >= 0; --i)
 966                 heap_sift(iter, i, b->ops->sort_cmp);
 967
 968         while (!btree_iter_end(iter)) {
 969                 if (b->ops->sort_fixup && fixup)
 970                         k = b->ops->sort_fixup(iter, &tmp.k);
 971                 else
 972                         k = NULL;
 973
 974                 if (!k)
 975                         k = __bch_btree_iter_next(iter, b->ops->sort_cmp);
 976
 977                 if (bad(b, k))
 978                         continue;
 979
 980                 if (!last) {
 981                         last = out->start;
 982                         bkey_copy(last, k);
 983                 } else if (!bch_bkey_try_merge(b, last, k)) {
 984                         last = bkey_next(last);
 985                         bkey_copy(last, k);
 986                 }
 987         }
 988
 989         out->keys = last ? (uint64_t *) bkey_next(last) - out->d : 0;
 990
 991         pr_debug("sorted %i keys", out->keys);
 992 }
 993
 994 static void __btree_sort(struct btree_keys *b, struct btree_iter *iter,
 995                          unsigned start, unsigned order, bool fixup,
 996                          struct bset_sort_state *state)
 997 {
 998         uint64_t start_time;
 999         bool used_mempool = false;
1000         struct bset *out = (void *) __get_free_pages(__GFP_NOWARN|GFP_NOIO,
1001                                                      order);
1002         if (!out) {
1003                 BUG_ON(order > state->page_order);
1004
1005                 out = page_address(mempool_alloc(state->pool, GFP_NOIO));
1006                 used_mempool = true;
1007                 order = state->page_order;
1008         }
1009
1010         start_time = local_clock();
1011
1012         btree_mergesort(b, out, iter, fixup, false);
1013         b->nsets = start;
1014
1015         if (!start && order == b->page_order) {
1016                 /*
1017                  * Our temporary buffer is the same size as the btree node's
1018                  * buffer, we can just swap buffers instead of doing a big
1019                  * memcpy()
1020                  */
1021
1022                 out->magic      = b->set->data->magic;
1023                 out->seq        = b->set->data->seq;
1024                 out->version    = b->set->data->version;
1025                 swap(out, b->set->data);
1026         } else {
1027                 b->set[start].data->keys = out->keys;
1028                 memcpy(b->set[start].data->start, out->start,
1029                        (void *) bset_bkey_last(out) - (void *) out->start);
1030         }
1031
1032         if (used_mempool)
1033                 mempool_free(virt_to_page(out), state->pool);
1034         else
1035                 free_pages((unsigned long) out, order);
1036
1037         bch_bset_build_written_tree(b);
1038
1039         if (!start)
1040                 bch_time_stats_update(&state->time, start_time);
1041 }
1042
1043 void bch_btree_sort_partial(struct btree *b, unsigned start,
1044                             struct bset_sort_state *state)
1045 {
1046         size_t order = b->keys.page_order, keys = 0;
1047         struct btree_iter iter;
1048         int oldsize = bch_count_data(b);
1049
1050         __bch_btree_iter_init(b, &iter, NULL, &b->keys.set[start]);
1051
1052         if (start) {
1053                 unsigned i;
1054
1055                 for (i = start; i <= b->keys.nsets; i++)
1056                         keys += b->keys.set[i].data->keys;
1057
1058                 order = roundup_pow_of_two(__set_bytes(b->keys.set->data,
1059                                                        keys)) / PAGE_SIZE;
1060                 if (order)
1061                         order = ilog2(order);
1062         }
1063
1064         __btree_sort(&b->keys, &iter, start, order, false, state);
1065
1066         EBUG_ON(b->written && oldsize >= 0 && bch_count_data(b) != oldsize);
1067 }
1068 EXPORT_SYMBOL(bch_btree_sort_partial);
1069
1070 void bch_btree_sort_and_fix_extents(struct btree_keys *b,
1071                                     struct btree_iter *iter,
1072                                     struct bset_sort_state *state)
1073 {
1074         __btree_sort(b, iter, 0, b->page_order, true, state);
1075 }
1076
1077 void bch_btree_sort_into(struct btree *b, struct btree *new,
1078                          struct bset_sort_state *state)
1079 {
1080         uint64_t start_time = local_clock();
1081
1082         struct btree_iter iter;
1083         bch_btree_iter_init(b, &iter, NULL);
1084
1085         btree_mergesort(&b->keys, new->keys.set->data, &iter, false, true);
1086
1087         bch_time_stats_update(&state->time, start_time);
1088
1089         new->keys.set->size = 0; // XXX: why?
1090 }
1091
1092 #define SORT_CRIT       (4096 / sizeof(uint64_t))
1093
1094 void bch_btree_sort_lazy(struct btree *b, struct bset_sort_state *state)
1095 {
1096         unsigned crit = SORT_CRIT;
1097         int i;
1098
1099         b->keys.last_set_unwritten = 0;
1100
1101         /* Don't sort if nothing to do */
1102         if (!b->keys.nsets)
1103                 goto out;
1104
1105         for (i = b->keys.nsets - 1; i >= 0; --i) {
1106                 crit *= state->crit_factor;
1107
1108                 if (b->keys.set[i].data->keys < crit) {
1109                         bch_btree_sort_partial(b, i, state);
1110                         return;
1111                 }
1112         }
1113
1114         /* Sort if we'd overflow */
1115         if (b->keys.nsets + 1 == MAX_BSETS) {
1116                 bch_btree_sort(b, state);
1117                 return;
1118         }
1119
1120 out:
1121         bch_bset_build_written_tree(&b->keys);
1122 }
1123 EXPORT_SYMBOL(bch_btree_sort_lazy);
1124
1125 /* Sysfs stuff */
1126
1127 struct bset_stats {
1128         struct btree_op op;
1129         size_t nodes;
1130         size_t sets_written, sets_unwritten;
1131         size_t bytes_written, bytes_unwritten;
1132         size_t floats, failed;
1133 };
1134
1135 static int btree_bset_stats(struct btree_op *op, struct btree *b)
1136 {
1137         struct bset_stats *stats = container_of(op, struct bset_stats, op);
1138         unsigned i;
1139
1140         stats->nodes++;
1141
1142         for (i = 0; i <= b->keys.nsets; i++) {
1143                 struct bset_tree *t = &b->keys.set[i];
1144                 size_t bytes = t->data->keys * sizeof(uint64_t);
1145                 size_t j;
1146
1147                 if (bset_written(&b->keys, t)) {
1148                         stats->sets_written++;
1149                         stats->bytes_written += bytes;
1150
1151                         stats->floats += t->size - 1;
1152
1153                         for (j = 1; j < t->size; j++)
1154                                 if (t->tree[j].exponent == 127)
1155                                         stats->failed++;
1156                 } else {
1157                         stats->sets_unwritten++;
1158                         stats->bytes_unwritten += bytes;
1159                 }
1160         }
1161
1162         return MAP_CONTINUE;
1163 }
1164
1165 int bch_bset_print_stats(struct cache_set *c, char *buf)
1166 {
1167         struct bset_stats t;
1168         int ret;
1169
1170         memset(&t, 0, sizeof(struct bset_stats));
1171         bch_btree_op_init(&t.op, -1);
1172
1173         ret = bch_btree_map_nodes(&t.op, c, &ZERO_KEY, btree_bset_stats);
1174         if (ret < 0)
1175                 return ret;
1176
1177         return snprintf(buf, PAGE_SIZE,
1178                         "btree nodes:           %zu\n"
1179                         "written sets:          %zu\n"
1180                         "unwritten sets:                %zu\n"
1181                         "written key bytes:     %zu\n"
1182                         "unwritten key bytes:   %zu\n"
1183                         "floats:                        %zu\n"
1184                         "failed:                        %zu\n",
1185                         t.nodes,
1186                         t.sets_written, t.sets_unwritten,
1187                         t.bytes_written, t.bytes_unwritten,
1188                         t.floats, t.failed);
1189 }