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         struct printbuf buf = PRINTBUF;
  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
  85                 printbuf_reset(&buf);
  86                 if (c)
  87                         bch2_bkey_val_to_text(&buf, c, k);
  88                 else
  89                         bch2_bkey_to_text(&buf, k.k);
  90                 printk(KERN_ERR "block %u key %5zu: %s\n", set,
  91                        _k->_data - i->_data, buf.buf);
  92
  93                 if (_n == vstruct_last(i))
  94                         continue;
  95
  96                 n = bkey_unpack_key(b, _n);
  97
  98                 if (bpos_lt(n.p, k.k->p)) {
  99                         printk(KERN_ERR "Key skipped backwards\n");
 100                         continue;
 101                 }
 102
 103                 if (!bkey_deleted(k.k) && bpos_eq(n.p, k.k->p))
 104                         printk(KERN_ERR "Duplicate keys\n");
 105         }
 106
 107         printbuf_exit(&buf);
 108 }
 109
 110 void bch2_dump_btree_node(struct bch_fs *c, struct btree *b)
 111 {
 112         struct bset_tree *t;
 113
 114         console_lock();
 115         for_each_bset(b, t)
 116                 bch2_dump_bset(c, b, bset(b, t), t - b->set);
 117         console_unlock();
 118 }
 119
 120 void bch2_dump_btree_node_iter(struct btree *b,
 121                               struct btree_node_iter *iter)
 122 {
 123         struct btree_node_iter_set *set;
 124         struct printbuf buf = PRINTBUF;
 125
 126         printk(KERN_ERR "btree node iter with %u/%u sets:\n",
 127                __btree_node_iter_used(iter), b->nsets);
 128
 129         btree_node_iter_for_each(iter, set) {
 130                 struct bkey_packed *k = __btree_node_offset_to_key(b, set->k);
 131                 struct bset_tree *t = bch2_bkey_to_bset(b, k);
 132                 struct bkey uk = bkey_unpack_key(b, k);
 133
 134                 printbuf_reset(&buf);
 135                 bch2_bkey_to_text(&buf, &uk);
 136                 printk(KERN_ERR "set %zu key %u: %s\n",
 137                        t - b->set, set->k, buf.buf);
 138         }
 139
 140         printbuf_exit(&buf);
 141 }
 142
 143 #ifdef CONFIG_BCACHEFS_DEBUG
 144
 145 void __bch2_verify_btree_nr_keys(struct btree *b)
 146 {
 147         struct bset_tree *t;
 148         struct bkey_packed *k;
 149         struct btree_nr_keys nr = { 0 };
 150
 151         for_each_bset(b, t)
 152                 bset_tree_for_each_key(b, t, k)
 153                         if (!bkey_deleted(k))
 154                                 btree_keys_account_key_add(&nr, t - b->set, k);
 155
 156         BUG_ON(memcmp(&nr, &b->nr, sizeof(nr)));
 157 }
 158
 159 static void bch2_btree_node_iter_next_check(struct btree_node_iter *_iter,
 160                                             struct btree *b)
 161 {
 162         struct btree_node_iter iter = *_iter;
 163         const struct bkey_packed *k, *n;
 164
 165         k = bch2_btree_node_iter_peek_all(&iter, b);
 166         __bch2_btree_node_iter_advance(&iter, b);
 167         n = bch2_btree_node_iter_peek_all(&iter, b);
 168
 169         bkey_unpack_key(b, k);
 170
 171         if (n &&
 172             bkey_iter_cmp(b, k, n) > 0) {
 173                 struct btree_node_iter_set *set;
 174                 struct bkey ku = bkey_unpack_key(b, k);
 175                 struct bkey nu = bkey_unpack_key(b, n);
 176                 struct printbuf buf1 = PRINTBUF;
 177                 struct printbuf buf2 = PRINTBUF;
 178
 179                 bch2_dump_btree_node(NULL, b);
 180                 bch2_bkey_to_text(&buf1, &ku);
 181                 bch2_bkey_to_text(&buf2, &nu);
 182                 printk(KERN_ERR "out of order/overlapping:\n%s\n%s\n",
 183                        buf1.buf, buf2.buf);
 184                 printk(KERN_ERR "iter was:");
 185
 186                 btree_node_iter_for_each(_iter, set) {
 187                         struct bkey_packed *k = __btree_node_offset_to_key(b, set->k);
 188                         struct bset_tree *t = bch2_bkey_to_bset(b, k);
 189                         printk(" [%zi %zi]", t - b->set,
 190                                k->_data - bset(b, t)->_data);
 191                 }
 192                 panic("\n");
 193         }
 194 }
 195
 196 void bch2_btree_node_iter_verify(struct btree_node_iter *iter,
 197                                  struct btree *b)
 198 {
 199         struct btree_node_iter_set *set, *s2;
 200         struct bkey_packed *k, *p;
 201         struct bset_tree *t;
 202
 203         if (bch2_btree_node_iter_end(iter))
 204                 return;
 205
 206         /* Verify no duplicates: */
 207         btree_node_iter_for_each(iter, set) {
 208                 BUG_ON(set->k > set->end);
 209                 btree_node_iter_for_each(iter, s2)
 210                         BUG_ON(set != s2 && set->end == s2->end);
 211         }
 212
 213         /* Verify that set->end is correct: */
 214         btree_node_iter_for_each(iter, set) {
 215                 for_each_bset(b, t)
 216                         if (set->end == t->end_offset)
 217                                 goto found;
 218                 BUG();
 219 found:
 220                 BUG_ON(set->k < btree_bkey_first_offset(t) ||
 221                        set->k >= t->end_offset);
 222         }
 223
 224         /* Verify iterator is sorted: */
 225         btree_node_iter_for_each(iter, set)
 226                 BUG_ON(set != iter->data &&
 227                        btree_node_iter_cmp(b, set[-1], set[0]) > 0);
 228
 229         k = bch2_btree_node_iter_peek_all(iter, b);
 230
 231         for_each_bset(b, t) {
 232                 if (iter->data[0].end == t->end_offset)
 233                         continue;
 234
 235                 p = bch2_bkey_prev_all(b, t,
 236                         bch2_btree_node_iter_bset_pos(iter, b, t));
 237
 238                 BUG_ON(p && bkey_iter_cmp(b, k, p) < 0);
 239         }
 240 }
 241
 242 void bch2_verify_insert_pos(struct btree *b, struct bkey_packed *where,
 243                             struct bkey_packed *insert, unsigned clobber_u64s)
 244 {
 245         struct bset_tree *t = bch2_bkey_to_bset(b, where);
 246         struct bkey_packed *prev = bch2_bkey_prev_all(b, t, where);
 247         struct bkey_packed *next = (void *) (where->_data + clobber_u64s);
 248         struct printbuf buf1 = PRINTBUF;
 249         struct printbuf buf2 = PRINTBUF;
 250 #if 0
 251         BUG_ON(prev &&
 252                bkey_iter_cmp(b, prev, insert) > 0);
 253 #else
 254         if (prev &&
 255             bkey_iter_cmp(b, prev, insert) > 0) {
 256                 struct bkey k1 = bkey_unpack_key(b, prev);
 257                 struct bkey k2 = bkey_unpack_key(b, insert);
 258
 259                 bch2_dump_btree_node(NULL, b);
 260                 bch2_bkey_to_text(&buf1, &k1);
 261                 bch2_bkey_to_text(&buf2, &k2);
 262
 263                 panic("prev > insert:\n"
 264                       "prev    key %s\n"
 265                       "insert  key %s\n",
 266                       buf1.buf, buf2.buf);
 267         }
 268 #endif
 269 #if 0
 270         BUG_ON(next != btree_bkey_last(b, t) &&
 271                bkey_iter_cmp(b, insert, next) > 0);
 272 #else
 273         if (next != btree_bkey_last(b, t) &&
 274             bkey_iter_cmp(b, insert, next) > 0) {
 275                 struct bkey k1 = bkey_unpack_key(b, insert);
 276                 struct bkey k2 = bkey_unpack_key(b, next);
 277
 278                 bch2_dump_btree_node(NULL, b);
 279                 bch2_bkey_to_text(&buf1, &k1);
 280                 bch2_bkey_to_text(&buf2, &k2);
 281
 282                 panic("insert > next:\n"
 283                       "insert  key %s\n"
 284                       "next    key %s\n",
 285                       buf1.buf, buf2.buf);
 286         }
 287 #endif
 288 }
 289
 290 #else
 291
 292 static inline void bch2_btree_node_iter_next_check(struct btree_node_iter *iter,
 293                                                    struct btree *b) {}
 294
 295 #endif
 296
 297 /* Auxiliary search trees */
 298
 299 #define BFLOAT_FAILED_UNPACKED  U8_MAX
 300 #define BFLOAT_FAILED           U8_MAX
 301
 302 struct bkey_float {
 303         u8              exponent;
 304         u8              key_offset;
 305         u16             mantissa;
 306 };
 307 #define BKEY_MANTISSA_BITS      16
 308
 309 static unsigned bkey_float_byte_offset(unsigned idx)
 310 {
 311         return idx * sizeof(struct bkey_float);
 312 }
 313
 314 struct ro_aux_tree {
 315         struct bkey_float       f[0];
 316 };
 317
 318 struct rw_aux_tree {
 319         u16             offset;
 320         struct bpos     k;
 321 };
 322
 323 static unsigned bset_aux_tree_buf_end(const struct bset_tree *t)
 324 {
 325         BUG_ON(t->aux_data_offset == U16_MAX);
 326
 327         switch (bset_aux_tree_type(t)) {
 328         case BSET_NO_AUX_TREE:
 329                 return t->aux_data_offset;
 330         case BSET_RO_AUX_TREE:
 331                 return t->aux_data_offset +
 332                         DIV_ROUND_UP(t->size * sizeof(struct bkey_float) +
 333                                      t->size * sizeof(u8), 8);
 334         case BSET_RW_AUX_TREE:
 335                 return t->aux_data_offset +
 336                         DIV_ROUND_UP(sizeof(struct rw_aux_tree) * t->size, 8);
 337         default:
 338                 BUG();
 339         }
 340 }
 341
 342 static unsigned bset_aux_tree_buf_start(const struct btree *b,
 343                                         const struct bset_tree *t)
 344 {
 345         return t == b->set
 346                 ? DIV_ROUND_UP(b->unpack_fn_len, 8)
 347                 : bset_aux_tree_buf_end(t - 1);
 348 }
 349
 350 static void *__aux_tree_base(const struct btree *b,
 351                              const struct bset_tree *t)
 352 {
 353         return b->aux_data + t->aux_data_offset * 8;
 354 }
 355
 356 static struct ro_aux_tree *ro_aux_tree_base(const struct btree *b,
 357                                             const struct bset_tree *t)
 358 {
 359         EBUG_ON(bset_aux_tree_type(t) != BSET_RO_AUX_TREE);
 360
 361         return __aux_tree_base(b, t);
 362 }
 363
 364 static u8 *ro_aux_tree_prev(const struct btree *b,
 365                             const struct bset_tree *t)
 366 {
 367         EBUG_ON(bset_aux_tree_type(t) != BSET_RO_AUX_TREE);
 368
 369         return __aux_tree_base(b, t) + bkey_float_byte_offset(t->size);
 370 }
 371
 372 static struct bkey_float *bkey_float(const struct btree *b,
 373                                      const struct bset_tree *t,
 374                                      unsigned idx)
 375 {
 376         return ro_aux_tree_base(b, t)->f + idx;
 377 }
 378
 379 static void bset_aux_tree_verify(const struct btree *b)
 380 {
 381 #ifdef CONFIG_BCACHEFS_DEBUG
 382         const struct bset_tree *t;
 383
 384         for_each_bset(b, t) {
 385                 if (t->aux_data_offset == U16_MAX)
 386                         continue;
 387
 388                 BUG_ON(t != b->set &&
 389                        t[-1].aux_data_offset == U16_MAX);
 390
 391                 BUG_ON(t->aux_data_offset < bset_aux_tree_buf_start(b, t));
 392                 BUG_ON(t->aux_data_offset > btree_aux_data_u64s(b));
 393                 BUG_ON(bset_aux_tree_buf_end(t) > btree_aux_data_u64s(b));
 394         }
 395 #endif
 396 }
 397
 398 void bch2_btree_keys_init(struct btree *b)
 399 {
 400         unsigned i;
 401
 402         b->nsets                = 0;
 403         memset(&b->nr, 0, sizeof(b->nr));
 404
 405         for (i = 0; i < MAX_BSETS; i++)
 406                 b->set[i].data_offset = U16_MAX;
 407
 408         bch2_bset_set_no_aux_tree(b, b->set);
 409 }
 410
 411 /* Binary tree stuff for auxiliary search trees */
 412
 413 /*
 414  * Cacheline/offset <-> bkey pointer arithmetic:
 415  *
 416  * t->tree is a binary search tree in an array; each node corresponds to a key
 417  * in one cacheline in t->set (BSET_CACHELINE bytes).
 418  *
 419  * This means we don't have to store the full index of the key that a node in
 420  * the binary tree points to; eytzinger1_to_inorder() gives us the cacheline, and
 421  * then bkey_float->m gives us the offset within that cacheline, in units of 8
 422  * bytes.
 423  *
 424  * cacheline_to_bkey() and friends abstract out all the pointer arithmetic to
 425  * make this work.
 426  *
 427  * To construct the bfloat for an arbitrary key we need to know what the key
 428  * immediately preceding it is: we have to check if the two keys differ in the
 429  * bits we're going to store in bkey_float->mantissa. t->prev[j] stores the size
 430  * of the previous key so we can walk backwards to it from t->tree[j]'s key.
 431  */
 432
 433 static inline void *bset_cacheline(const struct btree *b,
 434                                    const struct bset_tree *t,
 435                                    unsigned cacheline)
 436 {
 437         return (void *) round_down((unsigned long) btree_bkey_first(b, t),
 438                                    L1_CACHE_BYTES) +
 439                 cacheline * BSET_CACHELINE;
 440 }
 441
 442 static struct bkey_packed *cacheline_to_bkey(const struct btree *b,
 443                                              const struct bset_tree *t,
 444                                              unsigned cacheline,
 445                                              unsigned offset)
 446 {
 447         return bset_cacheline(b, t, cacheline) + offset * 8;
 448 }
 449
 450 static unsigned bkey_to_cacheline(const struct btree *b,
 451                                   const struct bset_tree *t,
 452                                   const struct bkey_packed *k)
 453 {
 454         return ((void *) k - bset_cacheline(b, t, 0)) / BSET_CACHELINE;
 455 }
 456
 457 static ssize_t __bkey_to_cacheline_offset(const struct btree *b,
 458                                           const struct bset_tree *t,
 459                                           unsigned cacheline,
 460                                           const struct bkey_packed *k)
 461 {
 462         return (u64 *) k - (u64 *) bset_cacheline(b, t, cacheline);
 463 }
 464
 465 static unsigned bkey_to_cacheline_offset(const struct btree *b,
 466                                          const struct bset_tree *t,
 467                                          unsigned cacheline,
 468                                          const struct bkey_packed *k)
 469 {
 470         size_t m = __bkey_to_cacheline_offset(b, t, cacheline, k);
 471
 472         EBUG_ON(m > U8_MAX);
 473         return m;
 474 }
 475
 476 static inline struct bkey_packed *tree_to_bkey(const struct btree *b,
 477                                                const struct bset_tree *t,
 478                                                unsigned j)
 479 {
 480         return cacheline_to_bkey(b, t,
 481                         __eytzinger1_to_inorder(j, t->size - 1, t->extra),
 482                         bkey_float(b, t, j)->key_offset);
 483 }
 484
 485 static struct bkey_packed *tree_to_prev_bkey(const struct btree *b,
 486                                              const struct bset_tree *t,
 487                                              unsigned j)
 488 {
 489         unsigned prev_u64s = ro_aux_tree_prev(b, t)[j];
 490
 491         return (void *) (tree_to_bkey(b, t, j)->_data - prev_u64s);
 492 }
 493
 494 static struct rw_aux_tree *rw_aux_tree(const struct btree *b,
 495                                        const struct bset_tree *t)
 496 {
 497         EBUG_ON(bset_aux_tree_type(t) != BSET_RW_AUX_TREE);
 498
 499         return __aux_tree_base(b, t);
 500 }
 501
 502 /*
 503  * For the write set - the one we're currently inserting keys into - we don't
 504  * maintain a full search tree, we just keep a simple lookup table in t->prev.
 505  */
 506 static struct bkey_packed *rw_aux_to_bkey(const struct btree *b,
 507                                           struct bset_tree *t,
 508                                           unsigned j)
 509 {
 510         return __btree_node_offset_to_key(b, rw_aux_tree(b, t)[j].offset);
 511 }
 512
 513 static void rw_aux_tree_set(const struct btree *b, struct bset_tree *t,
 514                             unsigned j, struct bkey_packed *k)
 515 {
 516         EBUG_ON(k >= btree_bkey_last(b, t));
 517
 518         rw_aux_tree(b, t)[j] = (struct rw_aux_tree) {
 519                 .offset = __btree_node_key_to_offset(b, k),
 520                 .k      = bkey_unpack_pos(b, k),
 521         };
 522 }
 523
 524 static void bch2_bset_verify_rw_aux_tree(struct btree *b,
 525                                         struct bset_tree *t)
 526 {
 527         struct bkey_packed *k = btree_bkey_first(b, t);
 528         unsigned j = 0;
 529
 530         if (!bch2_expensive_debug_checks)
 531                 return;
 532
 533         BUG_ON(bset_has_ro_aux_tree(t));
 534
 535         if (!bset_has_rw_aux_tree(t))
 536                 return;
 537
 538         BUG_ON(t->size < 1);
 539         BUG_ON(rw_aux_to_bkey(b, t, j) != k);
 540
 541         goto start;
 542         while (1) {
 543                 if (rw_aux_to_bkey(b, t, j) == k) {
 544                         BUG_ON(!bpos_eq(rw_aux_tree(b, t)[j].k,
 545                                         bkey_unpack_pos(b, k)));
 546 start:
 547                         if (++j == t->size)
 548                                 break;
 549
 550                         BUG_ON(rw_aux_tree(b, t)[j].offset <=
 551                                rw_aux_tree(b, t)[j - 1].offset);
 552                 }
 553
 554                 k = bkey_next(k);
 555                 BUG_ON(k >= btree_bkey_last(b, t));
 556         }
 557 }
 558
 559 /* returns idx of first entry >= offset: */
 560 static unsigned rw_aux_tree_bsearch(struct btree *b,
 561                                     struct bset_tree *t,
 562                                     unsigned offset)
 563 {
 564         unsigned bset_offs = offset - btree_bkey_first_offset(t);
 565         unsigned bset_u64s = t->end_offset - btree_bkey_first_offset(t);
 566         unsigned idx = bset_u64s ? bset_offs * t->size / bset_u64s : 0;
 567
 568         EBUG_ON(bset_aux_tree_type(t) != BSET_RW_AUX_TREE);
 569         EBUG_ON(!t->size);
 570         EBUG_ON(idx > t->size);
 571
 572         while (idx < t->size &&
 573                rw_aux_tree(b, t)[idx].offset < offset)
 574                 idx++;
 575
 576         while (idx &&
 577                rw_aux_tree(b, t)[idx - 1].offset >= offset)
 578                 idx--;
 579
 580         EBUG_ON(idx < t->size &&
 581                 rw_aux_tree(b, t)[idx].offset < offset);
 582         EBUG_ON(idx && rw_aux_tree(b, t)[idx - 1].offset >= offset);
 583         EBUG_ON(idx + 1 < t->size &&
 584                 rw_aux_tree(b, t)[idx].offset ==
 585                 rw_aux_tree(b, t)[idx + 1].offset);
 586
 587         return idx;
 588 }
 589
 590 static inline unsigned bkey_mantissa(const struct bkey_packed *k,
 591                                      const struct bkey_float *f,
 592                                      unsigned idx)
 593 {
 594         u64 v;
 595
 596         EBUG_ON(!bkey_packed(k));
 597
 598         v = get_unaligned((u64 *) (((u8 *) k->_data) + (f->exponent >> 3)));
 599
 600         /*
 601          * In little endian, we're shifting off low bits (and then the bits we
 602          * want are at the low end), in big endian we're shifting off high bits
 603          * (and then the bits we want are at the high end, so we shift them
 604          * back down):
 605          */
 606 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 607         v >>= f->exponent & 7;
 608 #else
 609         v >>= 64 - (f->exponent & 7) - BKEY_MANTISSA_BITS;
 610 #endif
 611         return (u16) v;
 612 }
 613
 614 __always_inline
 615 static inline void make_bfloat(struct btree *b, struct bset_tree *t,
 616                                unsigned j,
 617                                struct bkey_packed *min_key,
 618                                struct bkey_packed *max_key)
 619 {
 620         struct bkey_float *f = bkey_float(b, t, j);
 621         struct bkey_packed *m = tree_to_bkey(b, t, j);
 622         struct bkey_packed *l = is_power_of_2(j)
 623                 ? min_key
 624                 : tree_to_prev_bkey(b, t, j >> ffs(j));
 625         struct bkey_packed *r = is_power_of_2(j + 1)
 626                 ? max_key
 627                 : tree_to_bkey(b, t, j >> (ffz(j) + 1));
 628         unsigned mantissa;
 629         int shift, exponent, high_bit;
 630
 631         /*
 632          * for failed bfloats, the lookup code falls back to comparing against
 633          * the original key.
 634          */
 635
 636         if (!bkey_packed(l) || !bkey_packed(r) || !bkey_packed(m) ||
 637             !b->nr_key_bits) {
 638                 f->exponent = BFLOAT_FAILED_UNPACKED;
 639                 return;
 640         }
 641
 642         /*
 643          * The greatest differing bit of l and r is the first bit we must
 644          * include in the bfloat mantissa we're creating in order to do
 645          * comparisons - that bit always becomes the high bit of
 646          * bfloat->mantissa, and thus the exponent we're calculating here is
 647          * the position of what will become the low bit in bfloat->mantissa:
 648          *
 649          * Note that this may be negative - we may be running off the low end
 650          * of the key: we handle this later:
 651          */
 652         high_bit = max(bch2_bkey_greatest_differing_bit(b, l, r),
 653                        min_t(unsigned, BKEY_MANTISSA_BITS, b->nr_key_bits) - 1);
 654         exponent = high_bit - (BKEY_MANTISSA_BITS - 1);
 655
 656         /*
 657          * Then we calculate the actual shift value, from the start of the key
 658          * (k->_data), to get the key bits starting at exponent:
 659          */
 660 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 661         shift = (int) (b->format.key_u64s * 64 - b->nr_key_bits) + exponent;
 662
 663         EBUG_ON(shift + BKEY_MANTISSA_BITS > b->format.key_u64s * 64);
 664 #else
 665         shift = high_bit_offset +
 666                 b->nr_key_bits -
 667                 exponent -
 668                 BKEY_MANTISSA_BITS;
 669
 670         EBUG_ON(shift < KEY_PACKED_BITS_START);
 671 #endif
 672         EBUG_ON(shift < 0 || shift >= BFLOAT_FAILED);
 673
 674         f->exponent = shift;
 675         mantissa = bkey_mantissa(m, f, j);
 676
 677         /*
 678          * If we've got garbage bits, set them to all 1s - it's legal for the
 679          * bfloat to compare larger than the original key, but not smaller:
 680          */
 681         if (exponent < 0)
 682                 mantissa |= ~(~0U << -exponent);
 683
 684         f->mantissa = mantissa;
 685 }
 686
 687 /* bytes remaining - only valid for last bset: */
 688 static unsigned __bset_tree_capacity(const struct btree *b, const struct bset_tree *t)
 689 {
 690         bset_aux_tree_verify(b);
 691
 692         return btree_aux_data_bytes(b) - t->aux_data_offset * sizeof(u64);
 693 }
 694
 695 static unsigned bset_ro_tree_capacity(const struct btree *b, const struct bset_tree *t)
 696 {
 697         return __bset_tree_capacity(b, t) /
 698                 (sizeof(struct bkey_float) + sizeof(u8));
 699 }
 700
 701 static unsigned bset_rw_tree_capacity(const struct btree *b, const struct bset_tree *t)
 702 {
 703         return __bset_tree_capacity(b, t) / sizeof(struct rw_aux_tree);
 704 }
 705
 706 static noinline void __build_rw_aux_tree(struct btree *b, struct bset_tree *t)
 707 {
 708         struct bkey_packed *k;
 709
 710         t->size = 1;
 711         t->extra = BSET_RW_AUX_TREE_VAL;
 712         rw_aux_tree(b, t)[0].offset =
 713                 __btree_node_key_to_offset(b, btree_bkey_first(b, t));
 714
 715         bset_tree_for_each_key(b, t, k) {
 716                 if (t->size == bset_rw_tree_capacity(b, t))
 717                         break;
 718
 719                 if ((void *) k - (void *) rw_aux_to_bkey(b, t, t->size - 1) >
 720                     L1_CACHE_BYTES)
 721                         rw_aux_tree_set(b, t, t->size++, k);
 722         }
 723 }
 724
 725 static noinline void __build_ro_aux_tree(struct btree *b, struct bset_tree *t)
 726 {
 727         struct bkey_packed *prev = NULL, *k = btree_bkey_first(b, t);
 728         struct bkey_i min_key, max_key;
 729         unsigned j, cacheline = 1;
 730
 731         t->size = min(bkey_to_cacheline(b, t, btree_bkey_last(b, t)),
 732                       bset_ro_tree_capacity(b, t));
 733 retry:
 734         if (t->size < 2) {
 735                 t->size = 0;
 736                 t->extra = BSET_NO_AUX_TREE_VAL;
 737                 return;
 738         }
 739
 740         t->extra = (t->size - rounddown_pow_of_two(t->size - 1)) << 1;
 741
 742         /* First we figure out where the first key in each cacheline is */
 743         eytzinger1_for_each(j, t->size - 1) {
 744                 while (bkey_to_cacheline(b, t, k) < cacheline)
 745                         prev = k, k = bkey_next(k);
 746
 747                 if (k >= btree_bkey_last(b, t)) {
 748                         /* XXX: this path sucks */
 749                         t->size--;
 750                         goto retry;
 751                 }
 752
 753                 ro_aux_tree_prev(b, t)[j] = prev->u64s;
 754                 bkey_float(b, t, j)->key_offset =
 755                         bkey_to_cacheline_offset(b, t, cacheline++, k);
 756
 757                 EBUG_ON(tree_to_prev_bkey(b, t, j) != prev);
 758                 EBUG_ON(tree_to_bkey(b, t, j) != k);
 759         }
 760
 761         while (k != btree_bkey_last(b, t))
 762                 prev = k, k = bkey_next(k);
 763
 764         if (!bkey_pack_pos(bkey_to_packed(&min_key), b->data->min_key, b)) {
 765                 bkey_init(&min_key.k);
 766                 min_key.k.p = b->data->min_key;
 767         }
 768
 769         if (!bkey_pack_pos(bkey_to_packed(&max_key), b->data->max_key, b)) {
 770                 bkey_init(&max_key.k);
 771                 max_key.k.p = b->data->max_key;
 772         }
 773
 774         /* Then we build the tree */
 775         eytzinger1_for_each(j, t->size - 1)
 776                 make_bfloat(b, t, j,
 777                             bkey_to_packed(&min_key),
 778                             bkey_to_packed(&max_key));
 779 }
 780
 781 static void bset_alloc_tree(struct btree *b, struct bset_tree *t)
 782 {
 783         struct bset_tree *i;
 784
 785         for (i = b->set; i != t; i++)
 786                 BUG_ON(bset_has_rw_aux_tree(i));
 787
 788         bch2_bset_set_no_aux_tree(b, t);
 789
 790         /* round up to next cacheline: */
 791         t->aux_data_offset = round_up(bset_aux_tree_buf_start(b, t),
 792                                       SMP_CACHE_BYTES / sizeof(u64));
 793
 794         bset_aux_tree_verify(b);
 795 }
 796
 797 void bch2_bset_build_aux_tree(struct btree *b, struct bset_tree *t,
 798                              bool writeable)
 799 {
 800         if (writeable
 801             ? bset_has_rw_aux_tree(t)
 802             : bset_has_ro_aux_tree(t))
 803                 return;
 804
 805         bset_alloc_tree(b, t);
 806
 807         if (!__bset_tree_capacity(b, t))
 808                 return;
 809
 810         if (writeable)
 811                 __build_rw_aux_tree(b, t);
 812         else
 813                 __build_ro_aux_tree(b, t);
 814
 815         bset_aux_tree_verify(b);
 816 }
 817
 818 void bch2_bset_init_first(struct btree *b, struct bset *i)
 819 {
 820         struct bset_tree *t;
 821
 822         BUG_ON(b->nsets);
 823
 824         memset(i, 0, sizeof(*i));
 825         get_random_bytes(&i->seq, sizeof(i->seq));
 826         SET_BSET_BIG_ENDIAN(i, CPU_BIG_ENDIAN);
 827
 828         t = &b->set[b->nsets++];
 829         set_btree_bset(b, t, i);
 830 }
 831
 832 void bch2_bset_init_next(struct bch_fs *c, struct btree *b,
 833                          struct btree_node_entry *bne)
 834 {
 835         struct bset *i = &bne->keys;
 836         struct bset_tree *t;
 837
 838         BUG_ON(bset_byte_offset(b, bne) >= btree_bytes(c));
 839         BUG_ON((void *) bne < (void *) btree_bkey_last(b, bset_tree_last(b)));
 840         BUG_ON(b->nsets >= MAX_BSETS);
 841
 842         memset(i, 0, sizeof(*i));
 843         i->seq = btree_bset_first(b)->seq;
 844         SET_BSET_BIG_ENDIAN(i, CPU_BIG_ENDIAN);
 845
 846         t = &b->set[b->nsets++];
 847         set_btree_bset(b, t, i);
 848 }
 849
 850 /*
 851  * find _some_ key in the same bset as @k that precedes @k - not necessarily the
 852  * immediate predecessor:
 853  */
 854 static struct bkey_packed *__bkey_prev(struct btree *b, struct bset_tree *t,
 855                                        struct bkey_packed *k)
 856 {
 857         struct bkey_packed *p;
 858         unsigned offset;
 859         int j;
 860
 861         EBUG_ON(k < btree_bkey_first(b, t) ||
 862                 k > btree_bkey_last(b, t));
 863
 864         if (k == btree_bkey_first(b, t))
 865                 return NULL;
 866
 867         switch (bset_aux_tree_type(t)) {
 868         case BSET_NO_AUX_TREE:
 869                 p = btree_bkey_first(b, t);
 870                 break;
 871         case BSET_RO_AUX_TREE:
 872                 j = min_t(unsigned, t->size - 1, bkey_to_cacheline(b, t, k));
 873
 874                 do {
 875                         p = j ? tree_to_bkey(b, t,
 876                                         __inorder_to_eytzinger1(j--,
 877                                                         t->size - 1, t->extra))
 878                               : btree_bkey_first(b, t);
 879                 } while (p >= k);
 880                 break;
 881         case BSET_RW_AUX_TREE:
 882                 offset = __btree_node_key_to_offset(b, k);
 883                 j = rw_aux_tree_bsearch(b, t, offset);
 884                 p = j ? rw_aux_to_bkey(b, t, j - 1)
 885                       : btree_bkey_first(b, t);
 886                 break;
 887         }
 888
 889         return p;
 890 }
 891
 892 struct bkey_packed *bch2_bkey_prev_filter(struct btree *b,
 893                                           struct bset_tree *t,
 894                                           struct bkey_packed *k,
 895                                           unsigned min_key_type)
 896 {
 897         struct bkey_packed *p, *i, *ret = NULL, *orig_k = k;
 898
 899         while ((p = __bkey_prev(b, t, k)) && !ret) {
 900                 for (i = p; i != k; i = bkey_next(i))
 901                         if (i->type >= min_key_type)
 902                                 ret = i;
 903
 904                 k = p;
 905         }
 906
 907         if (bch2_expensive_debug_checks) {
 908                 BUG_ON(ret >= orig_k);
 909
 910                 for (i = ret
 911                         ? bkey_next(ret)
 912                         : btree_bkey_first(b, t);
 913                      i != orig_k;
 914                      i = bkey_next(i))
 915                         BUG_ON(i->type >= min_key_type);
 916         }
 917
 918         return ret;
 919 }
 920
 921 /* Insert */
 922
 923 static void bch2_bset_fix_lookup_table(struct btree *b,
 924                                        struct bset_tree *t,
 925                                        struct bkey_packed *_where,
 926                                        unsigned clobber_u64s,
 927                                        unsigned new_u64s)
 928 {
 929         int shift = new_u64s - clobber_u64s;
 930         unsigned l, j, where = __btree_node_key_to_offset(b, _where);
 931
 932         EBUG_ON(bset_has_ro_aux_tree(t));
 933
 934         if (!bset_has_rw_aux_tree(t))
 935                 return;
 936
 937         /* returns first entry >= where */
 938         l = rw_aux_tree_bsearch(b, t, where);
 939
 940         if (!l) /* never delete first entry */
 941                 l++;
 942         else if (l < t->size &&
 943                  where < t->end_offset &&
 944                  rw_aux_tree(b, t)[l].offset == where)
 945                 rw_aux_tree_set(b, t, l++, _where);
 946
 947         /* l now > where */
 948
 949         for (j = l;
 950              j < t->size &&
 951              rw_aux_tree(b, t)[j].offset < where + clobber_u64s;
 952              j++)
 953                 ;
 954
 955         if (j < t->size &&
 956             rw_aux_tree(b, t)[j].offset + shift ==
 957             rw_aux_tree(b, t)[l - 1].offset)
 958                 j++;
 959
 960         memmove(&rw_aux_tree(b, t)[l],
 961                 &rw_aux_tree(b, t)[j],
 962                 (void *) &rw_aux_tree(b, t)[t->size] -
 963                 (void *) &rw_aux_tree(b, t)[j]);
 964         t->size -= j - l;
 965
 966         for (j = l; j < t->size; j++)
 967                 rw_aux_tree(b, t)[j].offset += shift;
 968
 969         EBUG_ON(l < t->size &&
 970                 rw_aux_tree(b, t)[l].offset ==
 971                 rw_aux_tree(b, t)[l - 1].offset);
 972
 973         if (t->size < bset_rw_tree_capacity(b, t) &&
 974             (l < t->size
 975              ? rw_aux_tree(b, t)[l].offset
 976              : t->end_offset) -
 977             rw_aux_tree(b, t)[l - 1].offset >
 978             L1_CACHE_BYTES / sizeof(u64)) {
 979                 struct bkey_packed *start = rw_aux_to_bkey(b, t, l - 1);
 980                 struct bkey_packed *end = l < t->size
 981                         ? rw_aux_to_bkey(b, t, l)
 982                         : btree_bkey_last(b, t);
 983                 struct bkey_packed *k = start;
 984
 985                 while (1) {
 986                         k = bkey_next(k);
 987                         if (k == end)
 988                                 break;
 989
 990                         if ((void *) k - (void *) start >= L1_CACHE_BYTES) {
 991                                 memmove(&rw_aux_tree(b, t)[l + 1],
 992                                         &rw_aux_tree(b, t)[l],
 993                                         (void *) &rw_aux_tree(b, t)[t->size] -
 994                                         (void *) &rw_aux_tree(b, t)[l]);
 995                                 t->size++;
 996                                 rw_aux_tree_set(b, t, l, k);
 997                                 break;
 998                         }
 999                 }
1000         }
1001
1002         bch2_bset_verify_rw_aux_tree(b, t);
1003         bset_aux_tree_verify(b);
1004 }
1005
1006 void bch2_bset_insert(struct btree *b,
1007                       struct btree_node_iter *iter,
1008                       struct bkey_packed *where,
1009                       struct bkey_i *insert,
1010                       unsigned clobber_u64s)
1011 {
1012         struct bkey_format *f = &b->format;
1013         struct bset_tree *t = bset_tree_last(b);
1014         struct bkey_packed packed, *src = bkey_to_packed(insert);
1015
1016         bch2_bset_verify_rw_aux_tree(b, t);
1017         bch2_verify_insert_pos(b, where, bkey_to_packed(insert), clobber_u64s);
1018
1019         if (bch2_bkey_pack_key(&packed, &insert->k, f))
1020                 src = &packed;
1021
1022         if (!bkey_deleted(&insert->k))
1023                 btree_keys_account_key_add(&b->nr, t - b->set, src);
1024
1025         if (src->u64s != clobber_u64s) {
1026                 u64 *src_p = where->_data + clobber_u64s;
1027                 u64 *dst_p = where->_data + src->u64s;
1028
1029                 EBUG_ON((int) le16_to_cpu(bset(b, t)->u64s) <
1030                         (int) clobber_u64s - src->u64s);
1031
1032                 memmove_u64s(dst_p, src_p, btree_bkey_last(b, t)->_data - src_p);
1033                 le16_add_cpu(&bset(b, t)->u64s, src->u64s - clobber_u64s);
1034                 set_btree_bset_end(b, t);
1035         }
1036
1037         memcpy_u64s(where, src,
1038                     bkeyp_key_u64s(f, src));
1039         memcpy_u64s(bkeyp_val(f, where), &insert->v,
1040                     bkeyp_val_u64s(f, src));
1041
1042         if (src->u64s != clobber_u64s)
1043                 bch2_bset_fix_lookup_table(b, t, where, clobber_u64s, src->u64s);
1044
1045         bch2_verify_btree_nr_keys(b);
1046 }
1047
1048 void bch2_bset_delete(struct btree *b,
1049                       struct bkey_packed *where,
1050                       unsigned clobber_u64s)
1051 {
1052         struct bset_tree *t = bset_tree_last(b);
1053         u64 *src_p = where->_data + clobber_u64s;
1054         u64 *dst_p = where->_data;
1055
1056         bch2_bset_verify_rw_aux_tree(b, t);
1057
1058         EBUG_ON(le16_to_cpu(bset(b, t)->u64s) < clobber_u64s);
1059
1060         memmove_u64s_down(dst_p, src_p, btree_bkey_last(b, t)->_data - src_p);
1061         le16_add_cpu(&bset(b, t)->u64s, -clobber_u64s);
1062         set_btree_bset_end(b, t);
1063
1064         bch2_bset_fix_lookup_table(b, t, where, clobber_u64s, 0);
1065 }
1066
1067 /* Lookup */
1068
1069 __flatten
1070 static struct bkey_packed *bset_search_write_set(const struct btree *b,
1071                                 struct bset_tree *t,
1072                                 struct bpos *search)
1073 {
1074         unsigned l = 0, r = t->size;
1075
1076         while (l + 1 != r) {
1077                 unsigned m = (l + r) >> 1;
1078
1079                 if (bpos_lt(rw_aux_tree(b, t)[m].k, *search))
1080                         l = m;
1081                 else
1082                         r = m;
1083         }
1084
1085         return rw_aux_to_bkey(b, t, l);
1086 }
1087
1088 static inline void prefetch_four_cachelines(void *p)
1089 {
1090 #ifdef CONFIG_X86_64
1091         asm("prefetcht0 (-127 + 64 * 0)(%0);"
1092             "prefetcht0 (-127 + 64 * 1)(%0);"
1093             "prefetcht0 (-127 + 64 * 2)(%0);"
1094             "prefetcht0 (-127 + 64 * 3)(%0);"
1095             :
1096             : "r" (p + 127));
1097 #else
1098         prefetch(p + L1_CACHE_BYTES * 0);
1099         prefetch(p + L1_CACHE_BYTES * 1);
1100         prefetch(p + L1_CACHE_BYTES * 2);
1101         prefetch(p + L1_CACHE_BYTES * 3);
1102 #endif
1103 }
1104
1105 static inline bool bkey_mantissa_bits_dropped(const struct btree *b,
1106                                               const struct bkey_float *f,
1107                                               unsigned idx)
1108 {
1109 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
1110         unsigned key_bits_start = b->format.key_u64s * 64 - b->nr_key_bits;
1111
1112         return f->exponent > key_bits_start;
1113 #else
1114         unsigned key_bits_end = high_bit_offset + b->nr_key_bits;
1115
1116         return f->exponent + BKEY_MANTISSA_BITS < key_bits_end;
1117 #endif
1118 }
1119
1120 __flatten
1121 static struct bkey_packed *bset_search_tree(const struct btree *b,
1122                                 const struct bset_tree *t,
1123                                 const struct bpos *search,
1124                                 const struct bkey_packed *packed_search)
1125 {
1126         struct ro_aux_tree *base = ro_aux_tree_base(b, t);
1127         struct bkey_float *f;
1128         struct bkey_packed *k;
1129         unsigned inorder, n = 1, l, r;
1130         int cmp;
1131
1132         do {
1133                 if (likely(n << 4 < t->size))
1134                         prefetch(&base->f[n << 4]);
1135
1136                 f = &base->f[n];
1137                 if (unlikely(f->exponent >= BFLOAT_FAILED))
1138                         goto slowpath;
1139
1140                 l = f->mantissa;
1141                 r = bkey_mantissa(packed_search, f, n);
1142
1143                 if (unlikely(l == r) && bkey_mantissa_bits_dropped(b, f, n))
1144                         goto slowpath;
1145
1146                 n = n * 2 + (l < r);
1147                 continue;
1148 slowpath:
1149                 k = tree_to_bkey(b, t, n);
1150                 cmp = bkey_cmp_p_or_unp(b, k, packed_search, search);
1151                 if (!cmp)
1152                         return k;
1153
1154                 n = n * 2 + (cmp < 0);
1155         } while (n < t->size);
1156
1157         inorder = __eytzinger1_to_inorder(n >> 1, t->size - 1, t->extra);
1158
1159         /*
1160          * n would have been the node we recursed to - the low bit tells us if
1161          * we recursed left or recursed right.
1162          */
1163         if (likely(!(n & 1))) {
1164                 --inorder;
1165                 if (unlikely(!inorder))
1166                         return btree_bkey_first(b, t);
1167
1168                 f = &base->f[eytzinger1_prev(n >> 1, t->size - 1)];
1169         }
1170
1171         return cacheline_to_bkey(b, t, inorder, f->key_offset);
1172 }
1173
1174 static __always_inline __flatten
1175 struct bkey_packed *__bch2_bset_search(struct btree *b,
1176                                 struct bset_tree *t,
1177                                 struct bpos *search,
1178                                 const struct bkey_packed *lossy_packed_search)
1179 {
1180
1181         /*
1182          * First, we search for a cacheline, then lastly we do a linear search
1183          * within that cacheline.
1184          *
1185          * To search for the cacheline, there's three different possibilities:
1186          *  * The set is too small to have a search tree, so we just do a linear
1187          *    search over the whole set.
1188          *  * The set is the one we're currently inserting into; keeping a full
1189          *    auxiliary search tree up to date would be too expensive, so we
1190          *    use a much simpler lookup table to do a binary search -
1191          *    bset_search_write_set().
1192          *  * Or we use the auxiliary search tree we constructed earlier -
1193          *    bset_search_tree()
1194          */
1195
1196         switch (bset_aux_tree_type(t)) {
1197         case BSET_NO_AUX_TREE:
1198                 return btree_bkey_first(b, t);
1199         case BSET_RW_AUX_TREE:
1200                 return bset_search_write_set(b, t, search);
1201         case BSET_RO_AUX_TREE:
1202                 return bset_search_tree(b, t, search, lossy_packed_search);
1203         default:
1204                 unreachable();
1205         }
1206 }
1207
1208 static __always_inline __flatten
1209 struct bkey_packed *bch2_bset_search_linear(struct btree *b,
1210                                 struct bset_tree *t,
1211                                 struct bpos *search,
1212                                 struct bkey_packed *packed_search,
1213                                 const struct bkey_packed *lossy_packed_search,
1214                                 struct bkey_packed *m)
1215 {
1216         if (lossy_packed_search)
1217                 while (m != btree_bkey_last(b, t) &&
1218                        bkey_iter_cmp_p_or_unp(b, m,
1219                                         lossy_packed_search, search) < 0)
1220                         m = bkey_next(m);
1221
1222         if (!packed_search)
1223                 while (m != btree_bkey_last(b, t) &&
1224                        bkey_iter_pos_cmp(b, m, search) < 0)
1225                         m = bkey_next(m);
1226
1227         if (bch2_expensive_debug_checks) {
1228                 struct bkey_packed *prev = bch2_bkey_prev_all(b, t, m);
1229
1230                 BUG_ON(prev &&
1231                        bkey_iter_cmp_p_or_unp(b, prev,
1232                                         packed_search, search) >= 0);
1233         }
1234
1235         return m;
1236 }
1237
1238 /* Btree node iterator */
1239
1240 static inline void __bch2_btree_node_iter_push(struct btree_node_iter *iter,
1241                               struct btree *b,
1242                               const struct bkey_packed *k,
1243                               const struct bkey_packed *end)
1244 {
1245         if (k != end) {
1246                 struct btree_node_iter_set *pos;
1247
1248                 btree_node_iter_for_each(iter, pos)
1249                         ;
1250
1251                 BUG_ON(pos >= iter->data + ARRAY_SIZE(iter->data));
1252                 *pos = (struct btree_node_iter_set) {
1253                         __btree_node_key_to_offset(b, k),
1254                         __btree_node_key_to_offset(b, end)
1255                 };
1256         }
1257 }
1258
1259 void bch2_btree_node_iter_push(struct btree_node_iter *iter,
1260                                struct btree *b,
1261                                const struct bkey_packed *k,
1262                                const struct bkey_packed *end)
1263 {
1264         __bch2_btree_node_iter_push(iter, b, k, end);
1265         bch2_btree_node_iter_sort(iter, b);
1266 }
1267
1268 noinline __flatten __cold
1269 static void btree_node_iter_init_pack_failed(struct btree_node_iter *iter,
1270                               struct btree *b, struct bpos *search)
1271 {
1272         struct bkey_packed *k;
1273
1274         trace_bkey_pack_pos_fail(search);
1275
1276         bch2_btree_node_iter_init_from_start(iter, b);
1277
1278         while ((k = bch2_btree_node_iter_peek(iter, b)) &&
1279                bkey_iter_pos_cmp(b, k, search) < 0)
1280                 bch2_btree_node_iter_advance(iter, b);
1281 }
1282
1283 /**
1284  * bch_btree_node_iter_init - initialize a btree node iterator, starting from a
1285  * given position
1286  *
1287  * Main entry point to the lookup code for individual btree nodes:
1288  *
1289  * NOTE:
1290  *
1291  * When you don't filter out deleted keys, btree nodes _do_ contain duplicate
1292  * keys. This doesn't matter for most code, but it does matter for lookups.
1293  *
1294  * Some adjacent keys with a string of equal keys:
1295  *      i j k k k k l m
1296  *
1297  * If you search for k, the lookup code isn't guaranteed to return you any
1298  * specific k. The lookup code is conceptually doing a binary search and
1299  * iterating backwards is very expensive so if the pivot happens to land at the
1300  * last k that's what you'll get.
1301  *
1302  * This works out ok, but it's something to be aware of:
1303  *
1304  *  - For non extents, we guarantee that the live key comes last - see
1305  *    btree_node_iter_cmp(), keys_out_of_order(). So the duplicates you don't
1306  *    see will only be deleted keys you don't care about.
1307  *
1308  *  - For extents, deleted keys sort last (see the comment at the top of this
1309  *    file). But when you're searching for extents, you actually want the first
1310  *    key strictly greater than your search key - an extent that compares equal
1311  *    to the search key is going to have 0 sectors after the search key.
1312  *
1313  *    But this does mean that we can't just search for
1314  *    bpos_successor(start_of_range) to get the first extent that overlaps with
1315  *    the range we want - if we're unlucky and there's an extent that ends
1316  *    exactly where we searched, then there could be a deleted key at the same
1317  *    position and we'd get that when we search instead of the preceding extent
1318  *    we needed.
1319  *
1320  *    So we've got to search for start_of_range, then after the lookup iterate
1321  *    past any extents that compare equal to the position we searched for.
1322  */
1323 __flatten
1324 void bch2_btree_node_iter_init(struct btree_node_iter *iter,
1325                                struct btree *b, struct bpos *search)
1326 {
1327         struct bkey_packed p, *packed_search = NULL;
1328         struct btree_node_iter_set *pos = iter->data;
1329         struct bkey_packed *k[MAX_BSETS];
1330         unsigned i;
1331
1332         EBUG_ON(bpos_lt(*search, b->data->min_key));
1333         EBUG_ON(bpos_gt(*search, b->data->max_key));
1334         bset_aux_tree_verify(b);
1335
1336         memset(iter, 0, sizeof(*iter));
1337
1338         switch (bch2_bkey_pack_pos_lossy(&p, *search, b)) {
1339         case BKEY_PACK_POS_EXACT:
1340                 packed_search = &p;
1341                 break;
1342         case BKEY_PACK_POS_SMALLER:
1343                 packed_search = NULL;
1344                 break;
1345         case BKEY_PACK_POS_FAIL:
1346                 btree_node_iter_init_pack_failed(iter, b, search);
1347                 return;
1348         }
1349
1350         for (i = 0; i < b->nsets; i++) {
1351                 k[i] = __bch2_bset_search(b, b->set + i, search, &p);
1352                 prefetch_four_cachelines(k[i]);
1353         }
1354
1355         for (i = 0; i < b->nsets; i++) {
1356                 struct bset_tree *t = b->set + i;
1357                 struct bkey_packed *end = btree_bkey_last(b, t);
1358
1359                 k[i] = bch2_bset_search_linear(b, t, search,
1360                                                packed_search, &p, k[i]);
1361                 if (k[i] != end)
1362                         *pos++ = (struct btree_node_iter_set) {
1363                                 __btree_node_key_to_offset(b, k[i]),
1364                                 __btree_node_key_to_offset(b, end)
1365                         };
1366         }
1367
1368         bch2_btree_node_iter_sort(iter, b);
1369 }
1370
1371 void bch2_btree_node_iter_init_from_start(struct btree_node_iter *iter,
1372                                           struct btree *b)
1373 {
1374         struct bset_tree *t;
1375
1376         memset(iter, 0, sizeof(*iter));
1377
1378         for_each_bset(b, t)
1379                 __bch2_btree_node_iter_push(iter, b,
1380                                            btree_bkey_first(b, t),
1381                                            btree_bkey_last(b, t));
1382         bch2_btree_node_iter_sort(iter, b);
1383 }
1384
1385 struct bkey_packed *bch2_btree_node_iter_bset_pos(struct btree_node_iter *iter,
1386                                                   struct btree *b,
1387                                                   struct bset_tree *t)
1388 {
1389         struct btree_node_iter_set *set;
1390
1391         btree_node_iter_for_each(iter, set)
1392                 if (set->end == t->end_offset)
1393                         return __btree_node_offset_to_key(b, set->k);
1394
1395         return btree_bkey_last(b, t);
1396 }
1397
1398 static inline bool btree_node_iter_sort_two(struct btree_node_iter *iter,
1399                                             struct btree *b,
1400                                             unsigned first)
1401 {
1402         bool ret;
1403
1404         if ((ret = (btree_node_iter_cmp(b,
1405                                         iter->data[first],
1406                                         iter->data[first + 1]) > 0)))
1407                 swap(iter->data[first], iter->data[first + 1]);
1408         return ret;
1409 }
1410
1411 void bch2_btree_node_iter_sort(struct btree_node_iter *iter,
1412                                struct btree *b)
1413 {
1414         /* unrolled bubble sort: */
1415
1416         if (!__btree_node_iter_set_end(iter, 2)) {
1417                 btree_node_iter_sort_two(iter, b, 0);
1418                 btree_node_iter_sort_two(iter, b, 1);
1419         }
1420
1421         if (!__btree_node_iter_set_end(iter, 1))
1422                 btree_node_iter_sort_two(iter, b, 0);
1423 }
1424
1425 void bch2_btree_node_iter_set_drop(struct btree_node_iter *iter,
1426                                    struct btree_node_iter_set *set)
1427 {
1428         struct btree_node_iter_set *last =
1429                 iter->data + ARRAY_SIZE(iter->data) - 1;
1430
1431         memmove(&set[0], &set[1], (void *) last - (void *) set);
1432         *last = (struct btree_node_iter_set) { 0, 0 };
1433 }
1434
1435 static inline void __bch2_btree_node_iter_advance(struct btree_node_iter *iter,
1436                                                   struct btree *b)
1437 {
1438         iter->data->k += __bch2_btree_node_iter_peek_all(iter, b)->u64s;
1439
1440         EBUG_ON(iter->data->k > iter->data->end);
1441
1442         if (unlikely(__btree_node_iter_set_end(iter, 0))) {
1443                 /* avoid an expensive memmove call: */
1444                 iter->data[0] = iter->data[1];
1445                 iter->data[1] = iter->data[2];
1446                 iter->data[2] = (struct btree_node_iter_set) { 0, 0 };
1447                 return;
1448         }
1449
1450         if (__btree_node_iter_set_end(iter, 1))
1451                 return;
1452
1453         if (!btree_node_iter_sort_two(iter, b, 0))
1454                 return;
1455
1456         if (__btree_node_iter_set_end(iter, 2))
1457                 return;
1458
1459         btree_node_iter_sort_two(iter, b, 1);
1460 }
1461
1462 void bch2_btree_node_iter_advance(struct btree_node_iter *iter,
1463                                   struct btree *b)
1464 {
1465         if (bch2_expensive_debug_checks) {
1466                 bch2_btree_node_iter_verify(iter, b);
1467                 bch2_btree_node_iter_next_check(iter, b);
1468         }
1469
1470         __bch2_btree_node_iter_advance(iter, b);
1471 }
1472
1473 /*
1474  * Expensive:
1475  */
1476 struct bkey_packed *bch2_btree_node_iter_prev_all(struct btree_node_iter *iter,
1477                                                   struct btree *b)
1478 {
1479         struct bkey_packed *k, *prev = NULL;
1480         struct btree_node_iter_set *set;
1481         struct bset_tree *t;
1482         unsigned end = 0;
1483
1484         if (bch2_expensive_debug_checks)
1485                 bch2_btree_node_iter_verify(iter, b);
1486
1487         for_each_bset(b, t) {
1488                 k = bch2_bkey_prev_all(b, t,
1489                         bch2_btree_node_iter_bset_pos(iter, b, t));
1490                 if (k &&
1491                     (!prev || bkey_iter_cmp(b, k, prev) > 0)) {
1492                         prev = k;
1493                         end = t->end_offset;
1494                 }
1495         }
1496
1497         if (!prev)
1498                 return NULL;
1499
1500         /*
1501          * We're manually memmoving instead of just calling sort() to ensure the
1502          * prev we picked ends up in slot 0 - sort won't necessarily put it
1503          * there because of duplicate deleted keys:
1504          */
1505         btree_node_iter_for_each(iter, set)
1506                 if (set->end == end)
1507                         goto found;
1508
1509         BUG_ON(set != &iter->data[__btree_node_iter_used(iter)]);
1510 found:
1511         BUG_ON(set >= iter->data + ARRAY_SIZE(iter->data));
1512
1513         memmove(&iter->data[1],
1514                 &iter->data[0],
1515                 (void *) set - (void *) &iter->data[0]);
1516
1517         iter->data[0].k = __btree_node_key_to_offset(b, prev);
1518         iter->data[0].end = end;
1519
1520         if (bch2_expensive_debug_checks)
1521                 bch2_btree_node_iter_verify(iter, b);
1522         return prev;
1523 }
1524
1525 struct bkey_packed *bch2_btree_node_iter_prev(struct btree_node_iter *iter,
1526                                               struct btree *b)
1527 {
1528         struct bkey_packed *prev;
1529
1530         do {
1531                 prev = bch2_btree_node_iter_prev_all(iter, b);
1532         } while (prev && bkey_deleted(prev));
1533
1534         return prev;
1535 }
1536
1537 struct bkey_s_c bch2_btree_node_iter_peek_unpack(struct btree_node_iter *iter,
1538                                                  struct btree *b,
1539                                                  struct bkey *u)
1540 {
1541         struct bkey_packed *k = bch2_btree_node_iter_peek(iter, b);
1542
1543         return k ? bkey_disassemble(b, k, u) : bkey_s_c_null;
1544 }
1545
1546 /* Mergesort */
1547
1548 void bch2_btree_keys_stats(struct btree *b, struct bset_stats *stats)
1549 {
1550         struct bset_tree *t;
1551
1552         for_each_bset(b, t) {
1553                 enum bset_aux_tree_type type = bset_aux_tree_type(t);
1554                 size_t j;
1555
1556                 stats->sets[type].nr++;
1557                 stats->sets[type].bytes += le16_to_cpu(bset(b, t)->u64s) *
1558                         sizeof(u64);
1559
1560                 if (bset_has_ro_aux_tree(t)) {
1561                         stats->floats += t->size - 1;
1562
1563                         for (j = 1; j < t->size; j++)
1564                                 stats->failed +=
1565                                         bkey_float(b, t, j)->exponent ==
1566                                         BFLOAT_FAILED;
1567                 }
1568         }
1569 }
1570
1571 void bch2_bfloat_to_text(struct printbuf *out, struct btree *b,
1572                          struct bkey_packed *k)
1573 {
1574         struct bset_tree *t = bch2_bkey_to_bset(b, k);
1575         struct bkey uk;
1576         unsigned j, inorder;
1577
1578         if (!bset_has_ro_aux_tree(t))
1579                 return;
1580
1581         inorder = bkey_to_cacheline(b, t, k);
1582         if (!inorder || inorder >= t->size)
1583                 return;
1584
1585         j = __inorder_to_eytzinger1(inorder, t->size - 1, t->extra);
1586         if (k != tree_to_bkey(b, t, j))
1587                 return;
1588
1589         switch (bkey_float(b, t, j)->exponent) {
1590         case BFLOAT_FAILED:
1591                 uk = bkey_unpack_key(b, k);
1592                 prt_printf(out,
1593                        "    failed unpacked at depth %u\n"
1594                        "\t",
1595                        ilog2(j));
1596                 bch2_bpos_to_text(out, uk.p);
1597                 prt_printf(out, "\n");
1598                 break;
1599         }
1600 }