git.sesse.net Git - bcachefs-tools-debian/blob - libbcachefs/bset.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Code for working with individual keys, and sorted sets of keys with in a
   4  * btree node
   5  *
   6  * Copyright 2012 Google, Inc.
   7  */
   8
   9 #include "bcachefs.h"
  10 #include "btree_cache.h"
  11 #include "bset.h"
  12 #include "eytzinger.h"
  13 #include "util.h"
  14
  15 #include <asm/unaligned.h>
  16 #include <linux/console.h>
  17 #include <linux/random.h>
  18 #include <linux/prefetch.h>
  19
  20 /* hack.. */
  21 #include "alloc_types.h"
  22 #include <trace/events/bcachefs.h>
  23
  24 static inline void __bch2_btree_node_iter_advance(struct btree_node_iter *,
  25                                                   struct btree *);
  26
  27 static inline unsigned __btree_node_iter_used(struct btree_node_iter *iter)
  28 {
  29         unsigned n = ARRAY_SIZE(iter->data);
  30
  31         while (n && __btree_node_iter_set_end(iter, n - 1))
  32                 --n;
  33
  34         return n;
  35 }
  36
  37 struct bset_tree *bch2_bkey_to_bset(struct btree *b, struct bkey_packed *k)
  38 {
  39         unsigned offset = __btree_node_key_to_offset(b, k);
  40         struct bset_tree *t;
  41
  42         for_each_bset(b, t)
  43                 if (offset <= t->end_offset) {
  44                         EBUG_ON(offset < btree_bkey_first_offset(t));
  45                         return t;
  46                 }
  47
  48         BUG();
  49 }
  50
  51 /*
  52  * There are never duplicate live keys in the btree - but including keys that
  53  * have been flagged as deleted (and will be cleaned up later) we _will_ see
  54  * duplicates.
  55  *
  56  * Thus the sort order is: usual key comparison first, but for keys that compare
  57  * equal the deleted key(s) come first, and the (at most one) live version comes
  58  * last.
  59  *
  60  * The main reason for this is insertion: to handle overwrites, we first iterate
  61  * over keys that compare equal to our insert key, and then insert immediately
  62  * prior to the first key greater than the key we're inserting - our insert
  63  * position will be after all keys that compare equal to our insert key, which
  64  * by the time we actually do the insert will all be deleted.
  65  */
  66
  67 void bch2_dump_bset(struct bch_fs *c, struct btree *b,
  68                     struct bset *i, unsigned set)
  69 {
  70         struct bkey_packed *_k, *_n;
  71         struct bkey uk, n;
  72         struct bkey_s_c k;
  73         char buf[200];
  74
  75         if (!i->u64s)
  76                 return;
  77
  78         for (_k = i->start;
  79              _k < vstruct_last(i);
  80              _k = _n) {
  81                 _n = bkey_next(_k);
  82
  83                 k = bkey_disassemble(b, _k, &uk);
  84                 if (c)
  85                         bch2_bkey_val_to_text(&PBUF(buf), c, k);
  86                 else
  87                         bch2_bkey_to_text(&PBUF(buf), k.k);
  88                 printk(KERN_ERR "block %u key %5zu: %s\n", set,
  89                        _k->_data - i->_data, buf);
  90
  91                 if (_n == vstruct_last(i))
  92                         continue;
  93
  94                 n = bkey_unpack_key(b, _n);
  95
  96                 if (bpos_cmp(n.p, k.k->p) < 0) {
  97                         printk(KERN_ERR "Key skipped backwards\n");
  98                         continue;
  99                 }
 100
 101                 if (!bkey_deleted(k.k) &&
 102                     !bpos_cmp(n.p, k.k->p))
 103                         printk(KERN_ERR "Duplicate keys\n");
 104         }
 105 }
 106
 107 void bch2_dump_btree_node(struct bch_fs *c, struct btree *b)
 108 {
 109         struct bset_tree *t;
 110
 111         console_lock();
 112         for_each_bset(b, t)
 113                 bch2_dump_bset(c, b, bset(b, t), t - b->set);
 114         console_unlock();
 115 }
 116
 117 void bch2_dump_btree_node_iter(struct btree *b,
 118                               struct btree_node_iter *iter)
 119 {
 120         struct btree_node_iter_set *set;
 121
 122         printk(KERN_ERR "btree node iter with %u/%u sets:\n",
 123                __btree_node_iter_used(iter), b->nsets);
 124
 125         btree_node_iter_for_each(iter, set) {
 126                 struct bkey_packed *k = __btree_node_offset_to_key(b, set->k);
 127                 struct bset_tree *t = bch2_bkey_to_bset(b, k);
 128                 struct bkey uk = bkey_unpack_key(b, k);
 129                 char buf[100];
 130
 131                 bch2_bkey_to_text(&PBUF(buf), &uk);
 132                 printk(KERN_ERR "set %zu key %u: %s\n",
 133                        t - b->set, set->k, buf);
 134         }
 135 }
 136
 137 #ifdef CONFIG_BCACHEFS_DEBUG
 138
 139 void __bch2_verify_btree_nr_keys(struct btree *b)
 140 {
 141         struct bset_tree *t;
 142         struct bkey_packed *k;
 143         struct btree_nr_keys nr = { 0 };
 144
 145         for_each_bset(b, t)
 146                 bset_tree_for_each_key(b, t, k)
 147                         if (!bkey_deleted(k))
 148                                 btree_keys_account_key_add(&nr, t - b->set, k);
 149
 150         BUG_ON(memcmp(&nr, &b->nr, sizeof(nr)));
 151 }
 152
 153 static void bch2_btree_node_iter_next_check(struct btree_node_iter *_iter,
 154                                             struct btree *b)
 155 {
 156         struct btree_node_iter iter = *_iter;
 157         const struct bkey_packed *k, *n;
 158
 159         k = bch2_btree_node_iter_peek_all(&iter, b);
 160         __bch2_btree_node_iter_advance(&iter, b);
 161         n = bch2_btree_node_iter_peek_all(&iter, b);
 162
 163         bkey_unpack_key(b, k);
 164
 165         if (n &&
 166             bkey_iter_cmp(b, k, n) > 0) {
 167                 struct btree_node_iter_set *set;
 168                 struct bkey ku = bkey_unpack_key(b, k);
 169                 struct bkey nu = bkey_unpack_key(b, n);
 170                 char buf1[80], buf2[80];
 171
 172                 bch2_dump_btree_node(NULL, b);
 173                 bch2_bkey_to_text(&PBUF(buf1), &ku);
 174                 bch2_bkey_to_text(&PBUF(buf2), &nu);
 175                 printk(KERN_ERR "out of order/overlapping:\n%s\n%s\n",
 176                        buf1, buf2);
 177                 printk(KERN_ERR "iter was:");
 178
 179                 btree_node_iter_for_each(_iter, set) {
 180                         struct bkey_packed *k = __btree_node_offset_to_key(b, set->k);
 181                         struct bset_tree *t = bch2_bkey_to_bset(b, k);
 182                         printk(" [%zi %zi]", t - b->set,
 183                                k->_data - bset(b, t)->_data);
 184                 }
 185                 panic("\n");
 186         }
 187 }
 188
 189 void bch2_btree_node_iter_verify(struct btree_node_iter *iter,
 190                                  struct btree *b)
 191 {
 192         struct btree_node_iter_set *set, *s2;
 193         struct bkey_packed *k, *p;
 194         struct bset_tree *t;
 195
 196         if (bch2_btree_node_iter_end(iter))
 197                 return;
 198
 199         /* Verify no duplicates: */
 200         btree_node_iter_for_each(iter, set) {
 201                 BUG_ON(set->k > set->end);
 202                 btree_node_iter_for_each(iter, s2)
 203                         BUG_ON(set != s2 && set->end == s2->end);
 204         }
 205
 206         /* Verify that set->end is correct: */
 207         btree_node_iter_for_each(iter, set) {
 208                 for_each_bset(b, t)
 209                         if (set->end == t->end_offset)
 210                                 goto found;
 211                 BUG();
 212 found:
 213                 BUG_ON(set->k < btree_bkey_first_offset(t) ||
 214                        set->k >= t->end_offset);
 215         }
 216
 217         /* Verify iterator is sorted: */
 218         btree_node_iter_for_each(iter, set)
 219                 BUG_ON(set != iter->data &&
 220                        btree_node_iter_cmp(b, set[-1], set[0]) > 0);
 221
 222         k = bch2_btree_node_iter_peek_all(iter, b);
 223
 224         for_each_bset(b, t) {
 225                 if (iter->data[0].end == t->end_offset)
 226                         continue;
 227
 228                 p = bch2_bkey_prev_all(b, t,
 229                         bch2_btree_node_iter_bset_pos(iter, b, t));
 230
 231                 BUG_ON(p && bkey_iter_cmp(b, k, p) < 0);
 232         }
 233 }
 234
 235 void bch2_verify_insert_pos(struct btree *b, struct bkey_packed *where,
 236                             struct bkey_packed *insert, unsigned clobber_u64s)
 237 {
 238         struct bset_tree *t = bch2_bkey_to_bset(b, where);
 239         struct bkey_packed *prev = bch2_bkey_prev_all(b, t, where);
 240         struct bkey_packed *next = (void *) (where->_data + clobber_u64s);
 241 #if 0
 242         BUG_ON(prev &&
 243                bkey_iter_cmp(b, prev, insert) > 0);
 244 #else
 245         if (prev &&
 246             bkey_iter_cmp(b, prev, insert) > 0) {
 247                 struct bkey k1 = bkey_unpack_key(b, prev);
 248                 struct bkey k2 = bkey_unpack_key(b, insert);
 249                 char buf1[100];
 250                 char buf2[100];
 251
 252                 bch2_dump_btree_node(NULL, b);
 253                 bch2_bkey_to_text(&PBUF(buf1), &k1);
 254                 bch2_bkey_to_text(&PBUF(buf2), &k2);
 255
 256                 panic("prev > insert:\n"
 257                       "prev    key %s\n"
 258                       "insert  key %s\n",
 259                       buf1, buf2);
 260         }
 261 #endif
 262 #if 0
 263         BUG_ON(next != btree_bkey_last(b, t) &&
 264                bkey_iter_cmp(b, insert, next) > 0);
 265 #else
 266         if (next != btree_bkey_last(b, t) &&
 267             bkey_iter_cmp(b, insert, next) > 0) {
 268                 struct bkey k1 = bkey_unpack_key(b, insert);
 269                 struct bkey k2 = bkey_unpack_key(b, next);
 270                 char buf1[100];
 271                 char buf2[100];
 272
 273                 bch2_dump_btree_node(NULL, b);
 274                 bch2_bkey_to_text(&PBUF(buf1), &k1);
 275                 bch2_bkey_to_text(&PBUF(buf2), &k2);
 276
 277                 panic("insert > next:\n"
 278                       "insert  key %s\n"
 279                       "next    key %s\n",
 280                       buf1, buf2);
 281         }
 282 #endif
 283 }
 284
 285 #else
 286
 287 static inline void bch2_btree_node_iter_next_check(struct btree_node_iter *iter,
 288                                                    struct btree *b) {}
 289
 290 #endif
 291
 292 /* Auxiliary search trees */
 293
 294 #define BFLOAT_FAILED_UNPACKED  U8_MAX
 295 #define BFLOAT_FAILED           U8_MAX
 296
 297 struct bkey_float {
 298         u8              exponent;
 299         u8              key_offset;
 300         u16             mantissa;
 301 };
 302 #define BKEY_MANTISSA_BITS      16
 303
 304 static unsigned bkey_float_byte_offset(unsigned idx)
 305 {
 306         return idx * sizeof(struct bkey_float);
 307 }
 308
 309 struct ro_aux_tree {
 310         struct bkey_float       f[0];
 311 };
 312
 313 struct rw_aux_tree {
 314         u16             offset;
 315         struct bpos     k;
 316 };
 317
 318 static unsigned bset_aux_tree_buf_end(const struct bset_tree *t)
 319 {
 320         BUG_ON(t->aux_data_offset == U16_MAX);
 321
 322         switch (bset_aux_tree_type(t)) {
 323         case BSET_NO_AUX_TREE:
 324                 return t->aux_data_offset;
 325         case BSET_RO_AUX_TREE:
 326                 return t->aux_data_offset +
 327                         DIV_ROUND_UP(t->size * sizeof(struct bkey_float) +
 328                                      t->size * sizeof(u8), 8);
 329         case BSET_RW_AUX_TREE:
 330                 return t->aux_data_offset +
 331                         DIV_ROUND_UP(sizeof(struct rw_aux_tree) * t->size, 8);
 332         default:
 333                 BUG();
 334         }
 335 }
 336
 337 static unsigned bset_aux_tree_buf_start(const struct btree *b,
 338                                         const struct bset_tree *t)
 339 {
 340         return t == b->set
 341                 ? DIV_ROUND_UP(b->unpack_fn_len, 8)
 342                 : bset_aux_tree_buf_end(t - 1);
 343 }
 344
 345 static void *__aux_tree_base(const struct btree *b,
 346                              const struct bset_tree *t)
 347 {
 348         return b->aux_data + t->aux_data_offset * 8;
 349 }
 350
 351 static struct ro_aux_tree *ro_aux_tree_base(const struct btree *b,
 352                                             const struct bset_tree *t)
 353 {
 354         EBUG_ON(bset_aux_tree_type(t) != BSET_RO_AUX_TREE);
 355
 356         return __aux_tree_base(b, t);
 357 }
 358
 359 static u8 *ro_aux_tree_prev(const struct btree *b,
 360                             const struct bset_tree *t)
 361 {
 362         EBUG_ON(bset_aux_tree_type(t) != BSET_RO_AUX_TREE);
 363
 364         return __aux_tree_base(b, t) + bkey_float_byte_offset(t->size);
 365 }
 366
 367 static struct bkey_float *bkey_float(const struct btree *b,
 368                                      const struct bset_tree *t,
 369                                      unsigned idx)
 370 {
 371         return ro_aux_tree_base(b, t)->f + idx;
 372 }
 373
 374 static void bset_aux_tree_verify(const struct btree *b)
 375 {
 376 #ifdef CONFIG_BCACHEFS_DEBUG
 377         const struct bset_tree *t;
 378
 379         for_each_bset(b, t) {
 380                 if (t->aux_data_offset == U16_MAX)
 381                         continue;
 382
 383                 BUG_ON(t != b->set &&
 384                        t[-1].aux_data_offset == U16_MAX);
 385
 386                 BUG_ON(t->aux_data_offset < bset_aux_tree_buf_start(b, t));
 387                 BUG_ON(t->aux_data_offset > btree_aux_data_u64s(b));
 388                 BUG_ON(bset_aux_tree_buf_end(t) > btree_aux_data_u64s(b));
 389         }
 390 #endif
 391 }
 392
 393 void bch2_btree_keys_init(struct btree *b)
 394 {
 395         unsigned i;
 396
 397         b->nsets                = 0;
 398         memset(&b->nr, 0, sizeof(b->nr));
 399
 400         for (i = 0; i < MAX_BSETS; i++)
 401                 b->set[i].data_offset = U16_MAX;
 402
 403         bch2_bset_set_no_aux_tree(b, b->set);
 404 }
 405
 406 /* Binary tree stuff for auxiliary search trees */
 407
 408 /*
 409  * Cacheline/offset <-> bkey pointer arithmetic:
 410  *
 411  * t->tree is a binary search tree in an array; each node corresponds to a key
 412  * in one cacheline in t->set (BSET_CACHELINE bytes).
 413  *
 414  * This means we don't have to store the full index of the key that a node in
 415  * the binary tree points to; eytzinger1_to_inorder() gives us the cacheline, and
 416  * then bkey_float->m gives us the offset within that cacheline, in units of 8
 417  * bytes.
 418  *
 419  * cacheline_to_bkey() and friends abstract out all the pointer arithmetic to
 420  * make this work.
 421  *
 422  * To construct the bfloat for an arbitrary key we need to know what the key
 423  * immediately preceding it is: we have to check if the two keys differ in the
 424  * bits we're going to store in bkey_float->mantissa. t->prev[j] stores the size
 425  * of the previous key so we can walk backwards to it from t->tree[j]'s key.
 426  */
 427
 428 static inline void *bset_cacheline(const struct btree *b,
 429                                    const struct bset_tree *t,
 430                                    unsigned cacheline)
 431 {
 432         return (void *) round_down((unsigned long) btree_bkey_first(b, t),
 433                                    L1_CACHE_BYTES) +
 434                 cacheline * BSET_CACHELINE;
 435 }
 436
 437 static struct bkey_packed *cacheline_to_bkey(const struct btree *b,
 438                                              const struct bset_tree *t,
 439                                              unsigned cacheline,
 440                                              unsigned offset)
 441 {
 442         return bset_cacheline(b, t, cacheline) + offset * 8;
 443 }
 444
 445 static unsigned bkey_to_cacheline(const struct btree *b,
 446                                   const struct bset_tree *t,
 447                                   const struct bkey_packed *k)
 448 {
 449         return ((void *) k - bset_cacheline(b, t, 0)) / BSET_CACHELINE;
 450 }
 451
 452 static ssize_t __bkey_to_cacheline_offset(const struct btree *b,
 453                                           const struct bset_tree *t,
 454                                           unsigned cacheline,
 455                                           const struct bkey_packed *k)
 456 {
 457         return (u64 *) k - (u64 *) bset_cacheline(b, t, cacheline);
 458 }
 459
 460 static unsigned bkey_to_cacheline_offset(const struct btree *b,
 461                                          const struct bset_tree *t,
 462                                          unsigned cacheline,
 463                                          const struct bkey_packed *k)
 464 {
 465         size_t m = __bkey_to_cacheline_offset(b, t, cacheline, k);
 466
 467         EBUG_ON(m > U8_MAX);
 468         return m;
 469 }
 470
 471 static inline struct bkey_packed *tree_to_bkey(const struct btree *b,
 472                                                const struct bset_tree *t,
 473                                                unsigned j)
 474 {
 475         return cacheline_to_bkey(b, t,
 476                         __eytzinger1_to_inorder(j, t->size - 1, t->extra),
 477                         bkey_float(b, t, j)->key_offset);
 478 }
 479
 480 static struct bkey_packed *tree_to_prev_bkey(const struct btree *b,
 481                                              const struct bset_tree *t,
 482                                              unsigned j)
 483 {
 484         unsigned prev_u64s = ro_aux_tree_prev(b, t)[j];
 485
 486         return (void *) (tree_to_bkey(b, t, j)->_data - prev_u64s);
 487 }
 488
 489 static struct rw_aux_tree *rw_aux_tree(const struct btree *b,
 490                                        const struct bset_tree *t)
 491 {
 492         EBUG_ON(bset_aux_tree_type(t) != BSET_RW_AUX_TREE);
 493
 494         return __aux_tree_base(b, t);
 495 }
 496
 497 /*
 498  * For the write set - the one we're currently inserting keys into - we don't
 499  * maintain a full search tree, we just keep a simple lookup table in t->prev.
 500  */
 501 static struct bkey_packed *rw_aux_to_bkey(const struct btree *b,
 502                                           struct bset_tree *t,
 503                                           unsigned j)
 504 {
 505         return __btree_node_offset_to_key(b, rw_aux_tree(b, t)[j].offset);
 506 }
 507
 508 static void rw_aux_tree_set(const struct btree *b, struct bset_tree *t,
 509                             unsigned j, struct bkey_packed *k)
 510 {
 511         EBUG_ON(k >= btree_bkey_last(b, t));
 512
 513         rw_aux_tree(b, t)[j] = (struct rw_aux_tree) {
 514                 .offset = __btree_node_key_to_offset(b, k),
 515                 .k      = bkey_unpack_pos(b, k),
 516         };
 517 }
 518
 519 static void bch2_bset_verify_rw_aux_tree(struct btree *b,
 520                                         struct bset_tree *t)
 521 {
 522         struct bkey_packed *k = btree_bkey_first(b, t);
 523         unsigned j = 0;
 524
 525         if (!bch2_expensive_debug_checks)
 526                 return;
 527
 528         BUG_ON(bset_has_ro_aux_tree(t));
 529
 530         if (!bset_has_rw_aux_tree(t))
 531                 return;
 532
 533         BUG_ON(t->size < 1);
 534         BUG_ON(rw_aux_to_bkey(b, t, j) != k);
 535
 536         goto start;
 537         while (1) {
 538                 if (rw_aux_to_bkey(b, t, j) == k) {
 539                         BUG_ON(bpos_cmp(rw_aux_tree(b, t)[j].k,
 540                                         bkey_unpack_pos(b, k)));
 541 start:
 542                         if (++j == t->size)
 543                                 break;
 544
 545                         BUG_ON(rw_aux_tree(b, t)[j].offset <=
 546                                rw_aux_tree(b, t)[j - 1].offset);
 547                 }
 548
 549                 k = bkey_next(k);
 550                 BUG_ON(k >= btree_bkey_last(b, t));
 551         }
 552 }
 553
 554 /* returns idx of first entry >= offset: */
 555 static unsigned rw_aux_tree_bsearch(struct btree *b,
 556                                     struct bset_tree *t,
 557                                     unsigned offset)
 558 {
 559         unsigned bset_offs = offset - btree_bkey_first_offset(t);
 560         unsigned bset_u64s = t->end_offset - btree_bkey_first_offset(t);
 561         unsigned idx = bset_u64s ? bset_offs * t->size / bset_u64s : 0;
 562
 563         EBUG_ON(bset_aux_tree_type(t) != BSET_RW_AUX_TREE);
 564         EBUG_ON(!t->size);
 565         EBUG_ON(idx > t->size);
 566
 567         while (idx < t->size &&
 568                rw_aux_tree(b, t)[idx].offset < offset)
 569                 idx++;
 570
 571         while (idx &&
 572                rw_aux_tree(b, t)[idx - 1].offset >= offset)
 573                 idx--;
 574
 575         EBUG_ON(idx < t->size &&
 576                 rw_aux_tree(b, t)[idx].offset < offset);
 577         EBUG_ON(idx && rw_aux_tree(b, t)[idx - 1].offset >= offset);
 578         EBUG_ON(idx + 1 < t->size &&
 579                 rw_aux_tree(b, t)[idx].offset ==
 580                 rw_aux_tree(b, t)[idx + 1].offset);
 581
 582         return idx;
 583 }
 584
 585 static inline unsigned bkey_mantissa(const struct bkey_packed *k,
 586                                      const struct bkey_float *f,
 587                                      unsigned idx)
 588 {
 589         u64 v;
 590
 591         EBUG_ON(!bkey_packed(k));
 592
 593         v = get_unaligned((u64 *) (((u8 *) k->_data) + (f->exponent >> 3)));
 594
 595         /*
 596          * In little endian, we're shifting off low bits (and then the bits we
 597          * want are at the low end), in big endian we're shifting off high bits
 598          * (and then the bits we want are at the high end, so we shift them
 599          * back down):
 600          */
 601 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 602         v >>= f->exponent & 7;
 603 #else
 604         v >>= 64 - (f->exponent & 7) - BKEY_MANTISSA_BITS;
 605 #endif
 606         return (u16) v;
 607 }
 608
 609 __always_inline
 610 static inline void make_bfloat(struct btree *b, struct bset_tree *t,
 611                                unsigned j,
 612                                struct bkey_packed *min_key,
 613                                struct bkey_packed *max_key)
 614 {
 615         struct bkey_float *f = bkey_float(b, t, j);
 616         struct bkey_packed *m = tree_to_bkey(b, t, j);
 617         struct bkey_packed *l = is_power_of_2(j)
 618                 ? min_key
 619                 : tree_to_prev_bkey(b, t, j >> ffs(j));
 620         struct bkey_packed *r = is_power_of_2(j + 1)
 621                 ? max_key
 622                 : tree_to_bkey(b, t, j >> (ffz(j) + 1));
 623         unsigned mantissa;
 624         int shift, exponent, high_bit;
 625
 626         /*
 627          * for failed bfloats, the lookup code falls back to comparing against
 628          * the original key.
 629          */
 630
 631         if (!bkey_packed(l) || !bkey_packed(r) || !bkey_packed(m) ||
 632             !b->nr_key_bits) {
 633                 f->exponent = BFLOAT_FAILED_UNPACKED;
 634                 return;
 635         }
 636
 637         /*
 638          * The greatest differing bit of l and r is the first bit we must
 639          * include in the bfloat mantissa we're creating in order to do
 640          * comparisons - that bit always becomes the high bit of
 641          * bfloat->mantissa, and thus the exponent we're calculating here is
 642          * the position of what will become the low bit in bfloat->mantissa:
 643          *
 644          * Note that this may be negative - we may be running off the low end
 645          * of the key: we handle this later:
 646          */
 647         high_bit = max(bch2_bkey_greatest_differing_bit(b, l, r),
 648                        min_t(unsigned, BKEY_MANTISSA_BITS, b->nr_key_bits) - 1);
 649         exponent = high_bit - (BKEY_MANTISSA_BITS - 1);
 650
 651         /*
 652          * Then we calculate the actual shift value, from the start of the key
 653          * (k->_data), to get the key bits starting at exponent:
 654          */
 655 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 656         shift = (int) (b->format.key_u64s * 64 - b->nr_key_bits) + exponent;
 657
 658         EBUG_ON(shift + BKEY_MANTISSA_BITS > b->format.key_u64s * 64);
 659 #else
 660         shift = high_bit_offset +
 661                 b->nr_key_bits -
 662                 exponent -
 663                 BKEY_MANTISSA_BITS;
 664
 665         EBUG_ON(shift < KEY_PACKED_BITS_START);
 666 #endif
 667         EBUG_ON(shift < 0 || shift >= BFLOAT_FAILED);
 668
 669         f->exponent = shift;
 670         mantissa = bkey_mantissa(m, f, j);
 671
 672         /*
 673          * If we've got garbage bits, set them to all 1s - it's legal for the
 674          * bfloat to compare larger than the original key, but not smaller:
 675          */
 676         if (exponent < 0)
 677                 mantissa |= ~(~0U << -exponent);
 678
 679         f->mantissa = mantissa;
 680 }
 681
 682 /* bytes remaining - only valid for last bset: */
 683 static unsigned __bset_tree_capacity(const struct btree *b, const struct bset_tree *t)
 684 {
 685         bset_aux_tree_verify(b);
 686
 687         return btree_aux_data_bytes(b) - t->aux_data_offset * sizeof(u64);
 688 }
 689
 690 static unsigned bset_ro_tree_capacity(const struct btree *b, const struct bset_tree *t)
 691 {
 692         return __bset_tree_capacity(b, t) /
 693                 (sizeof(struct bkey_float) + sizeof(u8));
 694 }
 695
 696 static unsigned bset_rw_tree_capacity(const struct btree *b, const struct bset_tree *t)
 697 {
 698         return __bset_tree_capacity(b, t) / sizeof(struct rw_aux_tree);
 699 }
 700
 701 static noinline void __build_rw_aux_tree(struct btree *b, struct bset_tree *t)
 702 {
 703         struct bkey_packed *k;
 704
 705         t->size = 1;
 706         t->extra = BSET_RW_AUX_TREE_VAL;
 707         rw_aux_tree(b, t)[0].offset =
 708                 __btree_node_key_to_offset(b, btree_bkey_first(b, t));
 709
 710         bset_tree_for_each_key(b, t, k) {
 711                 if (t->size == bset_rw_tree_capacity(b, t))
 712                         break;
 713
 714                 if ((void *) k - (void *) rw_aux_to_bkey(b, t, t->size - 1) >
 715                     L1_CACHE_BYTES)
 716                         rw_aux_tree_set(b, t, t->size++, k);
 717         }
 718 }
 719
 720 static noinline void __build_ro_aux_tree(struct btree *b, struct bset_tree *t)
 721 {
 722         struct bkey_packed *prev = NULL, *k = btree_bkey_first(b, t);
 723         struct bkey_i min_key, max_key;
 724         unsigned j, cacheline = 1;
 725
 726         t->size = min(bkey_to_cacheline(b, t, btree_bkey_last(b, t)),
 727                       bset_ro_tree_capacity(b, t));
 728 retry:
 729         if (t->size < 2) {
 730                 t->size = 0;
 731                 t->extra = BSET_NO_AUX_TREE_VAL;
 732                 return;
 733         }
 734
 735         t->extra = (t->size - rounddown_pow_of_two(t->size - 1)) << 1;
 736
 737         /* First we figure out where the first key in each cacheline is */
 738         eytzinger1_for_each(j, t->size - 1) {
 739                 while (bkey_to_cacheline(b, t, k) < cacheline)
 740                         prev = k, k = bkey_next(k);
 741
 742                 if (k >= btree_bkey_last(b, t)) {
 743                         /* XXX: this path sucks */
 744                         t->size--;
 745                         goto retry;
 746                 }
 747
 748                 ro_aux_tree_prev(b, t)[j] = prev->u64s;
 749                 bkey_float(b, t, j)->key_offset =
 750                         bkey_to_cacheline_offset(b, t, cacheline++, k);
 751
 752                 EBUG_ON(tree_to_prev_bkey(b, t, j) != prev);
 753                 EBUG_ON(tree_to_bkey(b, t, j) != k);
 754         }
 755
 756         while (k != btree_bkey_last(b, t))
 757                 prev = k, k = bkey_next(k);
 758
 759         if (!bkey_pack_pos(bkey_to_packed(&min_key), b->data->min_key, b)) {
 760                 bkey_init(&min_key.k);
 761                 min_key.k.p = b->data->min_key;
 762         }
 763
 764         if (!bkey_pack_pos(bkey_to_packed(&max_key), b->data->max_key, b)) {
 765                 bkey_init(&max_key.k);
 766                 max_key.k.p = b->data->max_key;
 767         }
 768
 769         /* Then we build the tree */
 770         eytzinger1_for_each(j, t->size - 1)
 771                 make_bfloat(b, t, j,
 772                             bkey_to_packed(&min_key),
 773                             bkey_to_packed(&max_key));
 774 }
 775
 776 static void bset_alloc_tree(struct btree *b, struct bset_tree *t)
 777 {
 778         struct bset_tree *i;
 779
 780         for (i = b->set; i != t; i++)
 781                 BUG_ON(bset_has_rw_aux_tree(i));
 782
 783         bch2_bset_set_no_aux_tree(b, t);
 784
 785         /* round up to next cacheline: */
 786         t->aux_data_offset = round_up(bset_aux_tree_buf_start(b, t),
 787                                       SMP_CACHE_BYTES / sizeof(u64));
 788
 789         bset_aux_tree_verify(b);
 790 }
 791
 792 void bch2_bset_build_aux_tree(struct btree *b, struct bset_tree *t,
 793                              bool writeable)
 794 {
 795         if (writeable
 796             ? bset_has_rw_aux_tree(t)
 797             : bset_has_ro_aux_tree(t))
 798                 return;
 799
 800         bset_alloc_tree(b, t);
 801
 802         if (!__bset_tree_capacity(b, t))
 803                 return;
 804
 805         if (writeable)
 806                 __build_rw_aux_tree(b, t);
 807         else
 808                 __build_ro_aux_tree(b, t);
 809
 810         bset_aux_tree_verify(b);
 811 }
 812
 813 void bch2_bset_init_first(struct btree *b, struct bset *i)
 814 {
 815         struct bset_tree *t;
 816
 817         BUG_ON(b->nsets);
 818
 819         memset(i, 0, sizeof(*i));
 820         get_random_bytes(&i->seq, sizeof(i->seq));
 821         SET_BSET_BIG_ENDIAN(i, CPU_BIG_ENDIAN);
 822
 823         t = &b->set[b->nsets++];
 824         set_btree_bset(b, t, i);
 825 }
 826
 827 void bch2_bset_init_next(struct bch_fs *c, struct btree *b,
 828                          struct btree_node_entry *bne)
 829 {
 830         struct bset *i = &bne->keys;
 831         struct bset_tree *t;
 832
 833         BUG_ON(bset_byte_offset(b, bne) >= btree_bytes(c));
 834         BUG_ON((void *) bne < (void *) btree_bkey_last(b, bset_tree_last(b)));
 835         BUG_ON(b->nsets >= MAX_BSETS);
 836
 837         memset(i, 0, sizeof(*i));
 838         i->seq = btree_bset_first(b)->seq;
 839         SET_BSET_BIG_ENDIAN(i, CPU_BIG_ENDIAN);
 840
 841         t = &b->set[b->nsets++];
 842         set_btree_bset(b, t, i);
 843 }
 844
 845 /*
 846  * find _some_ key in the same bset as @k that precedes @k - not necessarily the
 847  * immediate predecessor:
 848  */
 849 static struct bkey_packed *__bkey_prev(struct btree *b, struct bset_tree *t,
 850                                        struct bkey_packed *k)
 851 {
 852         struct bkey_packed *p;
 853         unsigned offset;
 854         int j;
 855
 856         EBUG_ON(k < btree_bkey_first(b, t) ||
 857                 k > btree_bkey_last(b, t));
 858
 859         if (k == btree_bkey_first(b, t))
 860                 return NULL;
 861
 862         switch (bset_aux_tree_type(t)) {
 863         case BSET_NO_AUX_TREE:
 864                 p = btree_bkey_first(b, t);
 865                 break;
 866         case BSET_RO_AUX_TREE:
 867                 j = min_t(unsigned, t->size - 1, bkey_to_cacheline(b, t, k));
 868
 869                 do {
 870                         p = j ? tree_to_bkey(b, t,
 871                                         __inorder_to_eytzinger1(j--,
 872                                                         t->size - 1, t->extra))
 873                               : btree_bkey_first(b, t);
 874                 } while (p >= k);
 875                 break;
 876         case BSET_RW_AUX_TREE:
 877                 offset = __btree_node_key_to_offset(b, k);
 878                 j = rw_aux_tree_bsearch(b, t, offset);
 879                 p = j ? rw_aux_to_bkey(b, t, j - 1)
 880                       : btree_bkey_first(b, t);
 881                 break;
 882         }
 883
 884         return p;
 885 }
 886
 887 struct bkey_packed *bch2_bkey_prev_filter(struct btree *b,
 888                                           struct bset_tree *t,
 889                                           struct bkey_packed *k,
 890                                           unsigned min_key_type)
 891 {
 892         struct bkey_packed *p, *i, *ret = NULL, *orig_k = k;
 893
 894         while ((p = __bkey_prev(b, t, k)) && !ret) {
 895                 for (i = p; i != k; i = bkey_next(i))
 896                         if (i->type >= min_key_type)
 897                                 ret = i;
 898
 899                 k = p;
 900         }
 901
 902         if (bch2_expensive_debug_checks) {
 903                 BUG_ON(ret >= orig_k);
 904
 905                 for (i = ret
 906                         ? bkey_next(ret)
 907                         : btree_bkey_first(b, t);
 908                      i != orig_k;
 909                      i = bkey_next(i))
 910                         BUG_ON(i->type >= min_key_type);
 911         }
 912
 913         return ret;
 914 }
 915
 916 /* Insert */
 917
 918 static void bch2_bset_fix_lookup_table(struct btree *b,
 919                                        struct bset_tree *t,
 920                                        struct bkey_packed *_where,
 921                                        unsigned clobber_u64s,
 922                                        unsigned new_u64s)
 923 {
 924         int shift = new_u64s - clobber_u64s;
 925         unsigned l, j, where = __btree_node_key_to_offset(b, _where);
 926
 927         EBUG_ON(bset_has_ro_aux_tree(t));
 928
 929         if (!bset_has_rw_aux_tree(t))
 930                 return;
 931
 932         /* returns first entry >= where */
 933         l = rw_aux_tree_bsearch(b, t, where);
 934
 935         if (!l) /* never delete first entry */
 936                 l++;
 937         else if (l < t->size &&
 938                  where < t->end_offset &&
 939                  rw_aux_tree(b, t)[l].offset == where)
 940                 rw_aux_tree_set(b, t, l++, _where);
 941
 942         /* l now > where */
 943
 944         for (j = l;
 945              j < t->size &&
 946              rw_aux_tree(b, t)[j].offset < where + clobber_u64s;
 947              j++)
 948                 ;
 949
 950         if (j < t->size &&
 951             rw_aux_tree(b, t)[j].offset + shift ==
 952             rw_aux_tree(b, t)[l - 1].offset)
 953                 j++;
 954
 955         memmove(&rw_aux_tree(b, t)[l],
 956                 &rw_aux_tree(b, t)[j],
 957                 (void *) &rw_aux_tree(b, t)[t->size] -
 958                 (void *) &rw_aux_tree(b, t)[j]);
 959         t->size -= j - l;
 960
 961         for (j = l; j < t->size; j++)
 962                rw_aux_tree(b, t)[j].offset += shift;
 963
 964         EBUG_ON(l < t->size &&
 965                 rw_aux_tree(b, t)[l].offset ==
 966                 rw_aux_tree(b, t)[l - 1].offset);
 967
 968         if (t->size < bset_rw_tree_capacity(b, t) &&
 969             (l < t->size
 970              ? rw_aux_tree(b, t)[l].offset
 971              : t->end_offset) -
 972             rw_aux_tree(b, t)[l - 1].offset >
 973             L1_CACHE_BYTES / sizeof(u64)) {
 974                 struct bkey_packed *start = rw_aux_to_bkey(b, t, l - 1);
 975                 struct bkey_packed *end = l < t->size
 976                         ? rw_aux_to_bkey(b, t, l)
 977                         : btree_bkey_last(b, t);
 978                 struct bkey_packed *k = start;
 979
 980                 while (1) {
 981                         k = bkey_next(k);
 982                         if (k == end)
 983                                 break;
 984
 985                         if ((void *) k - (void *) start >= L1_CACHE_BYTES) {
 986                                 memmove(&rw_aux_tree(b, t)[l + 1],
 987                                         &rw_aux_tree(b, t)[l],
 988                                         (void *) &rw_aux_tree(b, t)[t->size] -
 989                                         (void *) &rw_aux_tree(b, t)[l]);
 990                                 t->size++;
 991                                 rw_aux_tree_set(b, t, l, k);
 992                                 break;
 993                         }
 994                 }
 995         }
 996
 997         bch2_bset_verify_rw_aux_tree(b, t);
 998         bset_aux_tree_verify(b);
 999 }
1000
1001 void bch2_bset_insert(struct btree *b,
1002                       struct btree_node_iter *iter,
1003                       struct bkey_packed *where,
1004                       struct bkey_i *insert,
1005                       unsigned clobber_u64s)
1006 {
1007         struct bkey_format *f = &b->format;
1008         struct bset_tree *t = bset_tree_last(b);
1009         struct bkey_packed packed, *src = bkey_to_packed(insert);
1010
1011         bch2_bset_verify_rw_aux_tree(b, t);
1012         bch2_verify_insert_pos(b, where, bkey_to_packed(insert), clobber_u64s);
1013
1014         if (bch2_bkey_pack_key(&packed, &insert->k, f))
1015                 src = &packed;
1016
1017         if (!bkey_deleted(&insert->k))
1018                 btree_keys_account_key_add(&b->nr, t - b->set, src);
1019
1020         if (src->u64s != clobber_u64s) {
1021                 u64 *src_p = where->_data + clobber_u64s;
1022                 u64 *dst_p = where->_data + src->u64s;
1023
1024                 EBUG_ON((int) le16_to_cpu(bset(b, t)->u64s) <
1025                         (int) clobber_u64s - src->u64s);
1026
1027                 memmove_u64s(dst_p, src_p, btree_bkey_last(b, t)->_data - src_p);
1028                 le16_add_cpu(&bset(b, t)->u64s, src->u64s - clobber_u64s);
1029                 set_btree_bset_end(b, t);
1030         }
1031
1032         memcpy_u64s(where, src,
1033                     bkeyp_key_u64s(f, src));
1034         memcpy_u64s(bkeyp_val(f, where), &insert->v,
1035                     bkeyp_val_u64s(f, src));
1036
1037         if (src->u64s != clobber_u64s)
1038                 bch2_bset_fix_lookup_table(b, t, where, clobber_u64s, src->u64s);
1039
1040         bch2_verify_btree_nr_keys(b);
1041 }
1042
1043 void bch2_bset_delete(struct btree *b,
1044                       struct bkey_packed *where,
1045                       unsigned clobber_u64s)
1046 {
1047         struct bset_tree *t = bset_tree_last(b);
1048         u64 *src_p = where->_data + clobber_u64s;
1049         u64 *dst_p = where->_data;
1050
1051         bch2_bset_verify_rw_aux_tree(b, t);
1052
1053         EBUG_ON(le16_to_cpu(bset(b, t)->u64s) < clobber_u64s);
1054
1055         memmove_u64s_down(dst_p, src_p, btree_bkey_last(b, t)->_data - src_p);
1056         le16_add_cpu(&bset(b, t)->u64s, -clobber_u64s);
1057         set_btree_bset_end(b, t);
1058
1059         bch2_bset_fix_lookup_table(b, t, where, clobber_u64s, 0);
1060 }
1061
1062 /* Lookup */
1063
1064 __flatten
1065 static struct bkey_packed *bset_search_write_set(const struct btree *b,
1066                                 struct bset_tree *t,
1067                                 struct bpos *search)
1068 {
1069         unsigned l = 0, r = t->size;
1070
1071         while (l + 1 != r) {
1072                 unsigned m = (l + r) >> 1;
1073
1074                 if (bpos_cmp(rw_aux_tree(b, t)[m].k, *search) < 0)
1075                         l = m;
1076                 else
1077                         r = m;
1078         }
1079
1080         return rw_aux_to_bkey(b, t, l);
1081 }
1082
1083 static inline void prefetch_four_cachelines(void *p)
1084 {
1085 #ifdef CONFIG_X86_64
1086         asm("prefetcht0 (-127 + 64 * 0)(%0);"
1087             "prefetcht0 (-127 + 64 * 1)(%0);"
1088             "prefetcht0 (-127 + 64 * 2)(%0);"
1089             "prefetcht0 (-127 + 64 * 3)(%0);"
1090             :
1091             : "r" (p + 127));
1092 #else
1093         prefetch(p + L1_CACHE_BYTES * 0);
1094         prefetch(p + L1_CACHE_BYTES * 1);
1095         prefetch(p + L1_CACHE_BYTES * 2);
1096         prefetch(p + L1_CACHE_BYTES * 3);
1097 #endif
1098 }
1099
1100 static inline bool bkey_mantissa_bits_dropped(const struct btree *b,
1101                                               const struct bkey_float *f,
1102                                               unsigned idx)
1103 {
1104 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
1105         unsigned key_bits_start = b->format.key_u64s * 64 - b->nr_key_bits;
1106
1107         return f->exponent > key_bits_start;
1108 #else
1109         unsigned key_bits_end = high_bit_offset + b->nr_key_bits;
1110
1111         return f->exponent + BKEY_MANTISSA_BITS < key_bits_end;
1112 #endif
1113 }
1114
1115 __flatten
1116 static struct bkey_packed *bset_search_tree(const struct btree *b,
1117                                 const struct bset_tree *t,
1118                                 const struct bpos *search,
1119                                 const struct bkey_packed *packed_search)
1120 {
1121         struct ro_aux_tree *base = ro_aux_tree_base(b, t);
1122         struct bkey_float *f;
1123         struct bkey_packed *k;
1124         unsigned inorder, n = 1, l, r;
1125         int cmp;
1126
1127         do {
1128                 if (likely(n << 4 < t->size))
1129                         prefetch(&base->f[n << 4]);
1130
1131                 f = &base->f[n];
1132                 if (unlikely(f->exponent >= BFLOAT_FAILED))
1133                         goto slowpath;
1134
1135                 l = f->mantissa;
1136                 r = bkey_mantissa(packed_search, f, n);
1137
1138                 if (unlikely(l == r) && bkey_mantissa_bits_dropped(b, f, n))
1139                         goto slowpath;
1140
1141                 n = n * 2 + (l < r);
1142                 continue;
1143 slowpath:
1144                 k = tree_to_bkey(b, t, n);
1145                 cmp = bkey_cmp_p_or_unp(b, k, packed_search, search);
1146                 if (!cmp)
1147                         return k;
1148
1149                 n = n * 2 + (cmp < 0);
1150         } while (n < t->size);
1151
1152         inorder = __eytzinger1_to_inorder(n >> 1, t->size - 1, t->extra);
1153
1154         /*
1155          * n would have been the node we recursed to - the low bit tells us if
1156          * we recursed left or recursed right.
1157          */
1158         if (likely(!(n & 1))) {
1159                 --inorder;
1160                 if (unlikely(!inorder))
1161                         return btree_bkey_first(b, t);
1162
1163                 f = &base->f[eytzinger1_prev(n >> 1, t->size - 1)];
1164         }
1165
1166         return cacheline_to_bkey(b, t, inorder, f->key_offset);
1167 }
1168
1169 static __always_inline __flatten
1170 struct bkey_packed *__bch2_bset_search(struct btree *b,
1171                                 struct bset_tree *t,
1172                                 struct bpos *search,
1173                                 const struct bkey_packed *lossy_packed_search)
1174 {
1175
1176         /*
1177          * First, we search for a cacheline, then lastly we do a linear search
1178          * within that cacheline.
1179          *
1180          * To search for the cacheline, there's three different possibilities:
1181          *  * The set is too small to have a search tree, so we just do a linear
1182          *    search over the whole set.
1183          *  * The set is the one we're currently inserting into; keeping a full
1184          *    auxiliary search tree up to date would be too expensive, so we
1185          *    use a much simpler lookup table to do a binary search -
1186          *    bset_search_write_set().
1187          *  * Or we use the auxiliary search tree we constructed earlier -
1188          *    bset_search_tree()
1189          */
1190
1191         switch (bset_aux_tree_type(t)) {
1192         case BSET_NO_AUX_TREE:
1193                 return btree_bkey_first(b, t);
1194         case BSET_RW_AUX_TREE:
1195                 return bset_search_write_set(b, t, search);
1196         case BSET_RO_AUX_TREE:
1197                 return bset_search_tree(b, t, search, lossy_packed_search);
1198         default:
1199                 unreachable();
1200         }
1201 }
1202
1203 static __always_inline __flatten
1204 struct bkey_packed *bch2_bset_search_linear(struct btree *b,
1205                                 struct bset_tree *t,
1206                                 struct bpos *search,
1207                                 struct bkey_packed *packed_search,
1208                                 const struct bkey_packed *lossy_packed_search,
1209                                 struct bkey_packed *m)
1210 {
1211         if (lossy_packed_search)
1212                 while (m != btree_bkey_last(b, t) &&
1213                        bkey_iter_cmp_p_or_unp(b, m,
1214                                         lossy_packed_search, search) < 0)
1215                         m = bkey_next(m);
1216
1217         if (!packed_search)
1218                 while (m != btree_bkey_last(b, t) &&
1219                        bkey_iter_pos_cmp(b, m, search) < 0)
1220                         m = bkey_next(m);
1221
1222         if (bch2_expensive_debug_checks) {
1223                 struct bkey_packed *prev = bch2_bkey_prev_all(b, t, m);
1224
1225                 BUG_ON(prev &&
1226                        bkey_iter_cmp_p_or_unp(b, prev,
1227                                         packed_search, search) >= 0);
1228         }
1229
1230         return m;
1231 }
1232
1233 /* Btree node iterator */
1234
1235 static inline void __bch2_btree_node_iter_push(struct btree_node_iter *iter,
1236                               struct btree *b,
1237                               const struct bkey_packed *k,
1238                               const struct bkey_packed *end)
1239 {
1240         if (k != end) {
1241                 struct btree_node_iter_set *pos;
1242
1243                 btree_node_iter_for_each(iter, pos)
1244                         ;
1245
1246                 BUG_ON(pos >= iter->data + ARRAY_SIZE(iter->data));
1247                 *pos = (struct btree_node_iter_set) {
1248                         __btree_node_key_to_offset(b, k),
1249                         __btree_node_key_to_offset(b, end)
1250                 };
1251         }
1252 }
1253
1254 void bch2_btree_node_iter_push(struct btree_node_iter *iter,
1255                                struct btree *b,
1256                                const struct bkey_packed *k,
1257                                const struct bkey_packed *end)
1258 {
1259         __bch2_btree_node_iter_push(iter, b, k, end);
1260         bch2_btree_node_iter_sort(iter, b);
1261 }
1262
1263 noinline __flatten __attribute__((cold))
1264 static void btree_node_iter_init_pack_failed(struct btree_node_iter *iter,
1265                               struct btree *b, struct bpos *search)
1266 {
1267         struct bkey_packed *k;
1268
1269         trace_bkey_pack_pos_fail(search);
1270
1271         bch2_btree_node_iter_init_from_start(iter, b);
1272
1273         while ((k = bch2_btree_node_iter_peek(iter, b)) &&
1274                bkey_iter_pos_cmp(b, k, search) < 0)
1275                 bch2_btree_node_iter_advance(iter, b);
1276 }
1277
1278 /**
1279  * bch_btree_node_iter_init - initialize a btree node iterator, starting from a
1280  * given position
1281  *
1282  * Main entry point to the lookup code for individual btree nodes:
1283  *
1284  * NOTE:
1285  *
1286  * When you don't filter out deleted keys, btree nodes _do_ contain duplicate
1287  * keys. This doesn't matter for most code, but it does matter for lookups.
1288  *
1289  * Some adjacent keys with a string of equal keys:
1290  *      i j k k k k l m
1291  *
1292  * If you search for k, the lookup code isn't guaranteed to return you any
1293  * specific k. The lookup code is conceptually doing a binary search and
1294  * iterating backwards is very expensive so if the pivot happens to land at the
1295  * last k that's what you'll get.
1296  *
1297  * This works out ok, but it's something to be aware of:
1298  *
1299  *  - For non extents, we guarantee that the live key comes last - see
1300  *    btree_node_iter_cmp(), keys_out_of_order(). So the duplicates you don't
1301  *    see will only be deleted keys you don't care about.
1302  *
1303  *  - For extents, deleted keys sort last (see the comment at the top of this
1304  *    file). But when you're searching for extents, you actually want the first
1305  *    key strictly greater than your search key - an extent that compares equal
1306  *    to the search key is going to have 0 sectors after the search key.
1307  *
1308  *    But this does mean that we can't just search for
1309  *    bpos_successor(start_of_range) to get the first extent that overlaps with
1310  *    the range we want - if we're unlucky and there's an extent that ends
1311  *    exactly where we searched, then there could be a deleted key at the same
1312  *    position and we'd get that when we search instead of the preceding extent
1313  *    we needed.
1314  *
1315  *    So we've got to search for start_of_range, then after the lookup iterate
1316  *    past any extents that compare equal to the position we searched for.
1317  */
1318 __flatten
1319 void bch2_btree_node_iter_init(struct btree_node_iter *iter,
1320                                struct btree *b, struct bpos *search)
1321 {
1322         struct bkey_packed p, *packed_search = NULL;
1323         struct btree_node_iter_set *pos = iter->data;
1324         struct bkey_packed *k[MAX_BSETS];
1325         unsigned i;
1326
1327         EBUG_ON(bpos_cmp(*search, b->data->min_key) < 0);
1328         EBUG_ON(bpos_cmp(*search, b->data->max_key) > 0);
1329         bset_aux_tree_verify(b);
1330
1331         memset(iter, 0, sizeof(*iter));
1332
1333         switch (bch2_bkey_pack_pos_lossy(&p, *search, b)) {
1334         case BKEY_PACK_POS_EXACT:
1335                 packed_search = &p;
1336                 break;
1337         case BKEY_PACK_POS_SMALLER:
1338                 packed_search = NULL;
1339                 break;
1340         case BKEY_PACK_POS_FAIL:
1341                 btree_node_iter_init_pack_failed(iter, b, search);
1342                 return;
1343         }
1344
1345         for (i = 0; i < b->nsets; i++) {
1346                 k[i] = __bch2_bset_search(b, b->set + i, search, &p);
1347                 prefetch_four_cachelines(k[i]);
1348         }
1349
1350         for (i = 0; i < b->nsets; i++) {
1351                 struct bset_tree *t = b->set + i;
1352                 struct bkey_packed *end = btree_bkey_last(b, t);
1353
1354                 k[i] = bch2_bset_search_linear(b, t, search,
1355                                                packed_search, &p, k[i]);
1356                 if (k[i] != end)
1357                         *pos++ = (struct btree_node_iter_set) {
1358                                 __btree_node_key_to_offset(b, k[i]),
1359                                 __btree_node_key_to_offset(b, end)
1360                         };
1361         }
1362
1363         bch2_btree_node_iter_sort(iter, b);
1364 }
1365
1366 void bch2_btree_node_iter_init_from_start(struct btree_node_iter *iter,
1367                                           struct btree *b)
1368 {
1369         struct bset_tree *t;
1370
1371         memset(iter, 0, sizeof(*iter));
1372
1373         for_each_bset(b, t)
1374                 __bch2_btree_node_iter_push(iter, b,
1375                                            btree_bkey_first(b, t),
1376                                            btree_bkey_last(b, t));
1377         bch2_btree_node_iter_sort(iter, b);
1378 }
1379
1380 struct bkey_packed *bch2_btree_node_iter_bset_pos(struct btree_node_iter *iter,
1381                                                   struct btree *b,
1382                                                   struct bset_tree *t)
1383 {
1384         struct btree_node_iter_set *set;
1385
1386         btree_node_iter_for_each(iter, set)
1387                 if (set->end == t->end_offset)
1388                         return __btree_node_offset_to_key(b, set->k);
1389
1390         return btree_bkey_last(b, t);
1391 }
1392
1393 static inline bool btree_node_iter_sort_two(struct btree_node_iter *iter,
1394                                             struct btree *b,
1395                                             unsigned first)
1396 {
1397         bool ret;
1398
1399         if ((ret = (btree_node_iter_cmp(b,
1400                                         iter->data[first],
1401                                         iter->data[first + 1]) > 0)))
1402                 swap(iter->data[first], iter->data[first + 1]);
1403         return ret;
1404 }
1405
1406 void bch2_btree_node_iter_sort(struct btree_node_iter *iter,
1407                                struct btree *b)
1408 {
1409         /* unrolled bubble sort: */
1410
1411         if (!__btree_node_iter_set_end(iter, 2)) {
1412                 btree_node_iter_sort_two(iter, b, 0);
1413                 btree_node_iter_sort_two(iter, b, 1);
1414         }
1415
1416         if (!__btree_node_iter_set_end(iter, 1))
1417                 btree_node_iter_sort_two(iter, b, 0);
1418 }
1419
1420 void bch2_btree_node_iter_set_drop(struct btree_node_iter *iter,
1421                                    struct btree_node_iter_set *set)
1422 {
1423         struct btree_node_iter_set *last =
1424                 iter->data + ARRAY_SIZE(iter->data) - 1;
1425
1426         memmove(&set[0], &set[1], (void *) last - (void *) set);
1427         *last = (struct btree_node_iter_set) { 0, 0 };
1428 }
1429
1430 static inline void __bch2_btree_node_iter_advance(struct btree_node_iter *iter,
1431                                                   struct btree *b)
1432 {
1433         iter->data->k += __bch2_btree_node_iter_peek_all(iter, b)->u64s;
1434
1435         EBUG_ON(iter->data->k > iter->data->end);
1436
1437         if (unlikely(__btree_node_iter_set_end(iter, 0))) {
1438                 bch2_btree_node_iter_set_drop(iter, iter->data);
1439                 return;
1440         }
1441
1442         if (__btree_node_iter_set_end(iter, 1))
1443                 return;
1444
1445         if (!btree_node_iter_sort_two(iter, b, 0))
1446                 return;
1447
1448         if (__btree_node_iter_set_end(iter, 2))
1449                 return;
1450
1451         btree_node_iter_sort_two(iter, b, 1);
1452 }
1453
1454 void bch2_btree_node_iter_advance(struct btree_node_iter *iter,
1455                                   struct btree *b)
1456 {
1457         if (bch2_expensive_debug_checks) {
1458                 bch2_btree_node_iter_verify(iter, b);
1459                 bch2_btree_node_iter_next_check(iter, b);
1460         }
1461
1462         __bch2_btree_node_iter_advance(iter, b);
1463 }
1464
1465 /*
1466  * Expensive:
1467  */
1468 struct bkey_packed *bch2_btree_node_iter_prev_all(struct btree_node_iter *iter,
1469                                                   struct btree *b)
1470 {
1471         struct bkey_packed *k, *prev = NULL;
1472         struct btree_node_iter_set *set;
1473         struct bset_tree *t;
1474         unsigned end = 0;
1475
1476         if (bch2_expensive_debug_checks)
1477                 bch2_btree_node_iter_verify(iter, b);
1478
1479         for_each_bset(b, t) {
1480                 k = bch2_bkey_prev_all(b, t,
1481                         bch2_btree_node_iter_bset_pos(iter, b, t));
1482                 if (k &&
1483                     (!prev || bkey_iter_cmp(b, k, prev) > 0)) {
1484                         prev = k;
1485                         end = t->end_offset;
1486                 }
1487         }
1488
1489         if (!prev)
1490                 return NULL;
1491
1492         /*
1493          * We're manually memmoving instead of just calling sort() to ensure the
1494          * prev we picked ends up in slot 0 - sort won't necessarily put it
1495          * there because of duplicate deleted keys:
1496          */
1497         btree_node_iter_for_each(iter, set)
1498                 if (set->end == end)
1499                         goto found;
1500
1501         BUG_ON(set != &iter->data[__btree_node_iter_used(iter)]);
1502 found:
1503         BUG_ON(set >= iter->data + ARRAY_SIZE(iter->data));
1504
1505         memmove(&iter->data[1],
1506                 &iter->data[0],
1507                 (void *) set - (void *) &iter->data[0]);
1508
1509         iter->data[0].k = __btree_node_key_to_offset(b, prev);
1510         iter->data[0].end = end;
1511
1512         if (bch2_expensive_debug_checks)
1513                 bch2_btree_node_iter_verify(iter, b);
1514         return prev;
1515 }
1516
1517 struct bkey_packed *bch2_btree_node_iter_prev(struct btree_node_iter *iter,
1518                                               struct btree *b)
1519 {
1520         struct bkey_packed *prev;
1521
1522         do {
1523                 prev = bch2_btree_node_iter_prev_all(iter, b);
1524         } while (prev && bkey_deleted(prev));
1525
1526         return prev;
1527 }
1528
1529 struct bkey_s_c bch2_btree_node_iter_peek_unpack(struct btree_node_iter *iter,
1530                                                  struct btree *b,
1531                                                  struct bkey *u)
1532 {
1533         struct bkey_packed *k = bch2_btree_node_iter_peek(iter, b);
1534
1535         return k ? bkey_disassemble(b, k, u) : bkey_s_c_null;
1536 }
1537
1538 /* Mergesort */
1539
1540 void bch2_btree_keys_stats(struct btree *b, struct bset_stats *stats)
1541 {
1542         struct bset_tree *t;
1543
1544         for_each_bset(b, t) {
1545                 enum bset_aux_tree_type type = bset_aux_tree_type(t);
1546                 size_t j;
1547
1548                 stats->sets[type].nr++;
1549                 stats->sets[type].bytes += le16_to_cpu(bset(b, t)->u64s) *
1550                         sizeof(u64);
1551
1552                 if (bset_has_ro_aux_tree(t)) {
1553                         stats->floats += t->size - 1;
1554
1555                         for (j = 1; j < t->size; j++)
1556                                 stats->failed +=
1557                                         bkey_float(b, t, j)->exponent ==
1558                                         BFLOAT_FAILED;
1559                 }
1560         }
1561 }
1562
1563 void bch2_bfloat_to_text(struct printbuf *out, struct btree *b,
1564                          struct bkey_packed *k)
1565 {
1566         struct bset_tree *t = bch2_bkey_to_bset(b, k);
1567         struct bkey uk;
1568         unsigned j, inorder;
1569
1570         if (out->pos != out->end)
1571                 *out->pos = '\0';
1572
1573         if (!bset_has_ro_aux_tree(t))
1574                 return;
1575
1576         inorder = bkey_to_cacheline(b, t, k);
1577         if (!inorder || inorder >= t->size)
1578                 return;
1579
1580         j = __inorder_to_eytzinger1(inorder, t->size - 1, t->extra);
1581         if (k != tree_to_bkey(b, t, j))
1582                 return;
1583
1584         switch (bkey_float(b, t, j)->exponent) {
1585         case BFLOAT_FAILED:
1586                 uk = bkey_unpack_key(b, k);
1587                 pr_buf(out,
1588                        "    failed unpacked at depth %u\n"
1589                        "\t",
1590                        ilog2(j));
1591                 bch2_bpos_to_text(out, uk.p);
1592                 pr_buf(out, "\n");
1593                 break;
1594         }
1595 }