fs/bcachefs/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 "trace.h"
  14 #include "util.h"
  15
  16 #include <asm/unaligned.h>
  17 #include <linux/console.h>
  18 #include <linux/random.h>
  19 #include <linux/prefetch.h>
  20
  21 static inline void __bch2_btree_node_iter_advance(struct btree_node_iter *,
  22                                                   struct btree *);
  23
  24 static inline unsigned __btree_node_iter_used(struct btree_node_iter *iter)
  25 {
  26         unsigned n = ARRAY_SIZE(iter->data);
  27
  28         while (n && __btree_node_iter_set_end(iter, n - 1))
  29                 --n;
  30
  31         return n;
  32 }
  33
  34 struct bset_tree *bch2_bkey_to_bset(struct btree *b, struct bkey_packed *k)
  35 {
  36         return bch2_bkey_to_bset_inlined(b, k);
  37 }
  38
  39 /*
  40  * There are never duplicate live keys in the btree - but including keys that
  41  * have been flagged as deleted (and will be cleaned up later) we _will_ see
  42  * duplicates.
  43  *
  44  * Thus the sort order is: usual key comparison first, but for keys that compare
  45  * equal the deleted key(s) come first, and the (at most one) live version comes
  46  * last.
  47  *
  48  * The main reason for this is insertion: to handle overwrites, we first iterate
  49  * over keys that compare equal to our insert key, and then insert immediately
  50  * prior to the first key greater than the key we're inserting - our insert
  51  * position will be after all keys that compare equal to our insert key, which
  52  * by the time we actually do the insert will all be deleted.
  53  */
  54
  55 void bch2_dump_bset(struct bch_fs *c, struct btree *b,
  56                     struct bset *i, unsigned set)
  57 {
  58         struct bkey_packed *_k, *_n;
  59         struct bkey uk, n;
  60         struct bkey_s_c k;
  61         struct printbuf buf = PRINTBUF;
  62
  63         if (!i->u64s)
  64                 return;
  65
  66         for (_k = i->start;
  67              _k < vstruct_last(i);
  68              _k = _n) {
  69                 _n = bkey_p_next(_k);
  70
  71                 if (!_k->u64s) {
  72                         printk(KERN_ERR "block %u key %5zu - u64s 0? aieee!\n", set,
  73                                _k->_data - i->_data);
  74                         break;
  75                 }
  76
  77                 k = bkey_disassemble(b, _k, &uk);
  78
  79                 printbuf_reset(&buf);
  80                 if (c)
  81                         bch2_bkey_val_to_text(&buf, c, k);
  82                 else
  83                         bch2_bkey_to_text(&buf, k.k);
  84                 printk(KERN_ERR "block %u key %5zu: %s\n", set,
  85                        _k->_data - i->_data, buf.buf);
  86
  87                 if (_n == vstruct_last(i))
  88                         continue;
  89
  90                 n = bkey_unpack_key(b, _n);
  91
  92                 if (bpos_lt(n.p, k.k->p)) {
  93                         printk(KERN_ERR "Key skipped backwards\n");
  94                         continue;
  95                 }
  96
  97                 if (!bkey_deleted(k.k) && bpos_eq(n.p, k.k->p))
  98                         printk(KERN_ERR "Duplicate keys\n");
  99         }
 100
 101         printbuf_exit(&buf);
 102 }
 103
 104 void bch2_dump_btree_node(struct bch_fs *c, struct btree *b)
 105 {
 106         struct bset_tree *t;
 107
 108         console_lock();
 109         for_each_bset(b, t)
 110                 bch2_dump_bset(c, b, bset(b, t), t - b->set);
 111         console_unlock();
 112 }
 113
 114 void bch2_dump_btree_node_iter(struct btree *b,
 115                               struct btree_node_iter *iter)
 116 {
 117         struct btree_node_iter_set *set;
 118         struct printbuf buf = PRINTBUF;
 119
 120         printk(KERN_ERR "btree node iter with %u/%u sets:\n",
 121                __btree_node_iter_used(iter), b->nsets);
 122
 123         btree_node_iter_for_each(iter, set) {
 124                 struct bkey_packed *k = __btree_node_offset_to_key(b, set->k);
 125                 struct bset_tree *t = bch2_bkey_to_bset(b, k);
 126                 struct bkey uk = bkey_unpack_key(b, k);
 127
 128                 printbuf_reset(&buf);
 129                 bch2_bkey_to_text(&buf, &uk);
 130                 printk(KERN_ERR "set %zu key %u: %s\n",
 131                        t - b->set, set->k, buf.buf);
 132         }
 133
 134         printbuf_exit(&buf);
 135 }
 136
 137 struct btree_nr_keys bch2_btree_node_count_keys(struct btree *b)
 138 {
 139         struct bset_tree *t;
 140         struct bkey_packed *k;
 141         struct btree_nr_keys nr = {};
 142
 143         for_each_bset(b, t)
 144                 bset_tree_for_each_key(b, t, k)
 145                         if (!bkey_deleted(k))
 146                                 btree_keys_account_key_add(&nr, t - b->set, k);
 147         return nr;
 148 }
 149
 150 #ifdef CONFIG_BCACHEFS_DEBUG
 151
 152 void __bch2_verify_btree_nr_keys(struct btree *b)
 153 {
 154         struct btree_nr_keys nr = bch2_btree_node_count_keys(b);
 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 *k2 = __btree_node_offset_to_key(b, set->k);
 188                         struct bset_tree *t = bch2_bkey_to_bset(b, k2);
 189                         printk(" [%zi %zi]", t - b->set,
 190                                k2->_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 *) ((u64 *) 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         u8                      nothing[0];
 316         struct bkey_float       f[];
 317 };
 318
 319 struct rw_aux_tree {
 320         u16             offset;
 321         struct bpos     k;
 322 };
 323
 324 static unsigned bset_aux_tree_buf_end(const struct bset_tree *t)
 325 {
 326         BUG_ON(t->aux_data_offset == U16_MAX);
 327
 328         switch (bset_aux_tree_type(t)) {
 329         case BSET_NO_AUX_TREE:
 330                 return t->aux_data_offset;
 331         case BSET_RO_AUX_TREE:
 332                 return t->aux_data_offset +
 333                         DIV_ROUND_UP(t->size * sizeof(struct bkey_float) +
 334                                      t->size * sizeof(u8), 8);
 335         case BSET_RW_AUX_TREE:
 336                 return t->aux_data_offset +
 337                         DIV_ROUND_UP(sizeof(struct rw_aux_tree) * t->size, 8);
 338         default:
 339                 BUG();
 340         }
 341 }
 342
 343 static unsigned bset_aux_tree_buf_start(const struct btree *b,
 344                                         const struct bset_tree *t)
 345 {
 346         return t == b->set
 347                 ? DIV_ROUND_UP(b->unpack_fn_len, 8)
 348                 : bset_aux_tree_buf_end(t - 1);
 349 }
 350
 351 static void *__aux_tree_base(const struct btree *b,
 352                              const struct bset_tree *t)
 353 {
 354         return b->aux_data + t->aux_data_offset * 8;
 355 }
 356
 357 static struct ro_aux_tree *ro_aux_tree_base(const struct btree *b,
 358                                             const struct bset_tree *t)
 359 {
 360         EBUG_ON(bset_aux_tree_type(t) != BSET_RO_AUX_TREE);
 361
 362         return __aux_tree_base(b, t);
 363 }
 364
 365 static u8 *ro_aux_tree_prev(const struct btree *b,
 366                             const struct bset_tree *t)
 367 {
 368         EBUG_ON(bset_aux_tree_type(t) != BSET_RO_AUX_TREE);
 369
 370         return __aux_tree_base(b, t) + bkey_float_byte_offset(t->size);
 371 }
 372
 373 static struct bkey_float *bkey_float(const struct btree *b,
 374                                      const struct bset_tree *t,
 375                                      unsigned idx)
 376 {
 377         return ro_aux_tree_base(b, t)->f + idx;
 378 }
 379
 380 static void bset_aux_tree_verify(const struct btree *b)
 381 {
 382 #ifdef CONFIG_BCACHEFS_DEBUG
 383         const struct bset_tree *t;
 384
 385         for_each_bset(b, t) {
 386                 if (t->aux_data_offset == U16_MAX)
 387                         continue;
 388
 389                 BUG_ON(t != b->set &&
 390                        t[-1].aux_data_offset == U16_MAX);
 391
 392                 BUG_ON(t->aux_data_offset < bset_aux_tree_buf_start(b, t));
 393                 BUG_ON(t->aux_data_offset > btree_aux_data_u64s(b));
 394                 BUG_ON(bset_aux_tree_buf_end(t) > btree_aux_data_u64s(b));
 395         }
 396 #endif
 397 }
 398
 399 void bch2_btree_keys_init(struct btree *b)
 400 {
 401         unsigned i;
 402
 403         b->nsets                = 0;
 404         memset(&b->nr, 0, sizeof(b->nr));
 405
 406         for (i = 0; i < MAX_BSETS; i++)
 407                 b->set[i].data_offset = U16_MAX;
 408
 409         bch2_bset_set_no_aux_tree(b, b->set);
 410 }
 411
 412 /* Binary tree stuff for auxiliary search trees */
 413
 414 /*
 415  * Cacheline/offset <-> bkey pointer arithmetic:
 416  *
 417  * t->tree is a binary search tree in an array; each node corresponds to a key
 418  * in one cacheline in t->set (BSET_CACHELINE bytes).
 419  *
 420  * This means we don't have to store the full index of the key that a node in
 421  * the binary tree points to; eytzinger1_to_inorder() gives us the cacheline, and
 422  * then bkey_float->m gives us the offset within that cacheline, in units of 8
 423  * bytes.
 424  *
 425  * cacheline_to_bkey() and friends abstract out all the pointer arithmetic to
 426  * make this work.
 427  *
 428  * To construct the bfloat for an arbitrary key we need to know what the key
 429  * immediately preceding it is: we have to check if the two keys differ in the
 430  * bits we're going to store in bkey_float->mantissa. t->prev[j] stores the size
 431  * of the previous key so we can walk backwards to it from t->tree[j]'s key.
 432  */
 433
 434 static inline void *bset_cacheline(const struct btree *b,
 435                                    const struct bset_tree *t,
 436                                    unsigned cacheline)
 437 {
 438         return (void *) round_down((unsigned long) btree_bkey_first(b, t),
 439                                    L1_CACHE_BYTES) +
 440                 cacheline * BSET_CACHELINE;
 441 }
 442
 443 static struct bkey_packed *cacheline_to_bkey(const struct btree *b,
 444                                              const struct bset_tree *t,
 445                                              unsigned cacheline,
 446                                              unsigned offset)
 447 {
 448         return bset_cacheline(b, t, cacheline) + offset * 8;
 449 }
 450
 451 static unsigned bkey_to_cacheline(const struct btree *b,
 452                                   const struct bset_tree *t,
 453                                   const struct bkey_packed *k)
 454 {
 455         return ((void *) k - bset_cacheline(b, t, 0)) / BSET_CACHELINE;
 456 }
 457
 458 static ssize_t __bkey_to_cacheline_offset(const struct btree *b,
 459                                           const struct bset_tree *t,
 460                                           unsigned cacheline,
 461                                           const struct bkey_packed *k)
 462 {
 463         return (u64 *) k - (u64 *) bset_cacheline(b, t, cacheline);
 464 }
 465
 466 static unsigned bkey_to_cacheline_offset(const struct btree *b,
 467                                          const struct bset_tree *t,
 468                                          unsigned cacheline,
 469                                          const struct bkey_packed *k)
 470 {
 471         size_t m = __bkey_to_cacheline_offset(b, t, cacheline, k);
 472
 473         EBUG_ON(m > U8_MAX);
 474         return m;
 475 }
 476
 477 static inline struct bkey_packed *tree_to_bkey(const struct btree *b,
 478                                                const struct bset_tree *t,
 479                                                unsigned j)
 480 {
 481         return cacheline_to_bkey(b, t,
 482                         __eytzinger1_to_inorder(j, t->size - 1, t->extra),
 483                         bkey_float(b, t, j)->key_offset);
 484 }
 485
 486 static struct bkey_packed *tree_to_prev_bkey(const struct btree *b,
 487                                              const struct bset_tree *t,
 488                                              unsigned j)
 489 {
 490         unsigned prev_u64s = ro_aux_tree_prev(b, t)[j];
 491
 492         return (void *) ((u64 *) tree_to_bkey(b, t, j)->_data - prev_u64s);
 493 }
 494
 495 static struct rw_aux_tree *rw_aux_tree(const struct btree *b,
 496                                        const struct bset_tree *t)
 497 {
 498         EBUG_ON(bset_aux_tree_type(t) != BSET_RW_AUX_TREE);
 499
 500         return __aux_tree_base(b, t);
 501 }
 502
 503 /*
 504  * For the write set - the one we're currently inserting keys into - we don't
 505  * maintain a full search tree, we just keep a simple lookup table in t->prev.
 506  */
 507 static struct bkey_packed *rw_aux_to_bkey(const struct btree *b,
 508                                           struct bset_tree *t,
 509                                           unsigned j)
 510 {
 511         return __btree_node_offset_to_key(b, rw_aux_tree(b, t)[j].offset);
 512 }
 513
 514 static void rw_aux_tree_set(const struct btree *b, struct bset_tree *t,
 515                             unsigned j, struct bkey_packed *k)
 516 {
 517         EBUG_ON(k >= btree_bkey_last(b, t));
 518
 519         rw_aux_tree(b, t)[j] = (struct rw_aux_tree) {
 520                 .offset = __btree_node_key_to_offset(b, k),
 521                 .k      = bkey_unpack_pos(b, k),
 522         };
 523 }
 524
 525 static void bch2_bset_verify_rw_aux_tree(struct btree *b,
 526                                         struct bset_tree *t)
 527 {
 528         struct bkey_packed *k = btree_bkey_first(b, t);
 529         unsigned j = 0;
 530
 531         if (!bch2_expensive_debug_checks)
 532                 return;
 533
 534         BUG_ON(bset_has_ro_aux_tree(t));
 535
 536         if (!bset_has_rw_aux_tree(t))
 537                 return;
 538
 539         BUG_ON(t->size < 1);
 540         BUG_ON(rw_aux_to_bkey(b, t, j) != k);
 541
 542         goto start;
 543         while (1) {
 544                 if (rw_aux_to_bkey(b, t, j) == k) {
 545                         BUG_ON(!bpos_eq(rw_aux_tree(b, t)[j].k,
 546                                         bkey_unpack_pos(b, k)));
 547 start:
 548                         if (++j == t->size)
 549                                 break;
 550
 551                         BUG_ON(rw_aux_tree(b, t)[j].offset <=
 552                                rw_aux_tree(b, t)[j - 1].offset);
 553                 }
 554
 555                 k = bkey_p_next(k);
 556                 BUG_ON(k >= btree_bkey_last(b, t));
 557         }
 558 }
 559
 560 /* returns idx of first entry >= offset: */
 561 static unsigned rw_aux_tree_bsearch(struct btree *b,
 562                                     struct bset_tree *t,
 563                                     unsigned offset)
 564 {
 565         unsigned bset_offs = offset - btree_bkey_first_offset(t);
 566         unsigned bset_u64s = t->end_offset - btree_bkey_first_offset(t);
 567         unsigned idx = bset_u64s ? bset_offs * t->size / bset_u64s : 0;
 568
 569         EBUG_ON(bset_aux_tree_type(t) != BSET_RW_AUX_TREE);
 570         EBUG_ON(!t->size);
 571         EBUG_ON(idx > t->size);
 572
 573         while (idx < t->size &&
 574                rw_aux_tree(b, t)[idx].offset < offset)
 575                 idx++;
 576
 577         while (idx &&
 578                rw_aux_tree(b, t)[idx - 1].offset >= offset)
 579                 idx--;
 580
 581         EBUG_ON(idx < t->size &&
 582                 rw_aux_tree(b, t)[idx].offset < offset);
 583         EBUG_ON(idx && rw_aux_tree(b, t)[idx - 1].offset >= offset);
 584         EBUG_ON(idx + 1 < t->size &&
 585                 rw_aux_tree(b, t)[idx].offset ==
 586                 rw_aux_tree(b, t)[idx + 1].offset);
 587
 588         return idx;
 589 }
 590
 591 static inline unsigned bkey_mantissa(const struct bkey_packed *k,
 592                                      const struct bkey_float *f,
 593                                      unsigned idx)
 594 {
 595         u64 v;
 596
 597         EBUG_ON(!bkey_packed(k));
 598
 599         v = get_unaligned((u64 *) (((u8 *) k->_data) + (f->exponent >> 3)));
 600
 601         /*
 602          * In little endian, we're shifting off low bits (and then the bits we
 603          * want are at the low end), in big endian we're shifting off high bits
 604          * (and then the bits we want are at the high end, so we shift them
 605          * back down):
 606          */
 607 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 608         v >>= f->exponent & 7;
 609 #else
 610         v >>= 64 - (f->exponent & 7) - BKEY_MANTISSA_BITS;
 611 #endif
 612         return (u16) v;
 613 }
 614
 615 static __always_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 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_p_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_p_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 btree *b, struct btree_node_entry *bne)
 833 {
 834         struct bset *i = &bne->keys;
 835         struct bset_tree *t;
 836
 837         BUG_ON(bset_byte_offset(b, bne) >= btree_buf_bytes(b));
 838         BUG_ON((void *) bne < (void *) btree_bkey_last(b, bset_tree_last(b)));
 839         BUG_ON(b->nsets >= MAX_BSETS);
 840
 841         memset(i, 0, sizeof(*i));
 842         i->seq = btree_bset_first(b)->seq;
 843         SET_BSET_BIG_ENDIAN(i, CPU_BIG_ENDIAN);
 844
 845         t = &b->set[b->nsets++];
 846         set_btree_bset(b, t, i);
 847 }
 848
 849 /*
 850  * find _some_ key in the same bset as @k that precedes @k - not necessarily the
 851  * immediate predecessor:
 852  */
 853 static struct bkey_packed *__bkey_prev(struct btree *b, struct bset_tree *t,
 854                                        struct bkey_packed *k)
 855 {
 856         struct bkey_packed *p;
 857         unsigned offset;
 858         int j;
 859
 860         EBUG_ON(k < btree_bkey_first(b, t) ||
 861                 k > btree_bkey_last(b, t));
 862
 863         if (k == btree_bkey_first(b, t))
 864                 return NULL;
 865
 866         switch (bset_aux_tree_type(t)) {
 867         case BSET_NO_AUX_TREE:
 868                 p = btree_bkey_first(b, t);
 869                 break;
 870         case BSET_RO_AUX_TREE:
 871                 j = min_t(unsigned, t->size - 1, bkey_to_cacheline(b, t, k));
 872
 873                 do {
 874                         p = j ? tree_to_bkey(b, t,
 875                                         __inorder_to_eytzinger1(j--,
 876                                                         t->size - 1, t->extra))
 877                               : btree_bkey_first(b, t);
 878                 } while (p >= k);
 879                 break;
 880         case BSET_RW_AUX_TREE:
 881                 offset = __btree_node_key_to_offset(b, k);
 882                 j = rw_aux_tree_bsearch(b, t, offset);
 883                 p = j ? rw_aux_to_bkey(b, t, j - 1)
 884                       : btree_bkey_first(b, t);
 885                 break;
 886         }
 887
 888         return p;
 889 }
 890
 891 struct bkey_packed *bch2_bkey_prev_filter(struct btree *b,
 892                                           struct bset_tree *t,
 893                                           struct bkey_packed *k,
 894                                           unsigned min_key_type)
 895 {
 896         struct bkey_packed *p, *i, *ret = NULL, *orig_k = k;
 897
 898         while ((p = __bkey_prev(b, t, k)) && !ret) {
 899                 for (i = p; i != k; i = bkey_p_next(i))
 900                         if (i->type >= min_key_type)
 901                                 ret = i;
 902
 903                 k = p;
 904         }
 905
 906         if (bch2_expensive_debug_checks) {
 907                 BUG_ON(ret >= orig_k);
 908
 909                 for (i = ret
 910                         ? bkey_p_next(ret)
 911                         : btree_bkey_first(b, t);
 912                      i != orig_k;
 913                      i = bkey_p_next(i))
 914                         BUG_ON(i->type >= min_key_type);
 915         }
 916
 917         return ret;
 918 }
 919
 920 /* Insert */
 921
 922 static void bch2_bset_fix_lookup_table(struct btree *b,
 923                                        struct bset_tree *t,
 924                                        struct bkey_packed *_where,
 925                                        unsigned clobber_u64s,
 926                                        unsigned new_u64s)
 927 {
 928         int shift = new_u64s - clobber_u64s;
 929         unsigned l, j, where = __btree_node_key_to_offset(b, _where);
 930
 931         EBUG_ON(bset_has_ro_aux_tree(t));
 932
 933         if (!bset_has_rw_aux_tree(t))
 934                 return;
 935
 936         /* returns first entry >= where */
 937         l = rw_aux_tree_bsearch(b, t, where);
 938
 939         if (!l) /* never delete first entry */
 940                 l++;
 941         else if (l < t->size &&
 942                  where < t->end_offset &&
 943                  rw_aux_tree(b, t)[l].offset == where)
 944                 rw_aux_tree_set(b, t, l++, _where);
 945
 946         /* l now > where */
 947
 948         for (j = l;
 949              j < t->size &&
 950              rw_aux_tree(b, t)[j].offset < where + clobber_u64s;
 951              j++)
 952                 ;
 953
 954         if (j < t->size &&
 955             rw_aux_tree(b, t)[j].offset + shift ==
 956             rw_aux_tree(b, t)[l - 1].offset)
 957                 j++;
 958
 959         memmove(&rw_aux_tree(b, t)[l],
 960                 &rw_aux_tree(b, t)[j],
 961                 (void *) &rw_aux_tree(b, t)[t->size] -
 962                 (void *) &rw_aux_tree(b, t)[j]);
 963         t->size -= j - l;
 964
 965         for (j = l; j < t->size; j++)
 966                 rw_aux_tree(b, t)[j].offset += shift;
 967
 968         EBUG_ON(l < t->size &&
 969                 rw_aux_tree(b, t)[l].offset ==
 970                 rw_aux_tree(b, t)[l - 1].offset);
 971
 972         if (t->size < bset_rw_tree_capacity(b, t) &&
 973             (l < t->size
 974              ? rw_aux_tree(b, t)[l].offset
 975              : t->end_offset) -
 976             rw_aux_tree(b, t)[l - 1].offset >
 977             L1_CACHE_BYTES / sizeof(u64)) {
 978                 struct bkey_packed *start = rw_aux_to_bkey(b, t, l - 1);
 979                 struct bkey_packed *end = l < t->size
 980                         ? rw_aux_to_bkey(b, t, l)
 981                         : btree_bkey_last(b, t);
 982                 struct bkey_packed *k = start;
 983
 984                 while (1) {
 985                         k = bkey_p_next(k);
 986                         if (k == end)
 987                                 break;
 988
 989                         if ((void *) k - (void *) start >= L1_CACHE_BYTES) {
 990                                 memmove(&rw_aux_tree(b, t)[l + 1],
 991                                         &rw_aux_tree(b, t)[l],
 992                                         (void *) &rw_aux_tree(b, t)[t->size] -
 993                                         (void *) &rw_aux_tree(b, t)[l]);
 994                                 t->size++;
 995                                 rw_aux_tree_set(b, t, l, k);
 996                                 break;
 997                         }
 998                 }
 999         }
1000
1001         bch2_bset_verify_rw_aux_tree(b, t);
1002         bset_aux_tree_verify(b);
1003 }
1004
1005 void bch2_bset_insert(struct btree *b,
1006                       struct btree_node_iter *iter,
1007                       struct bkey_packed *where,
1008                       struct bkey_i *insert,
1009                       unsigned clobber_u64s)
1010 {
1011         struct bkey_format *f = &b->format;
1012         struct bset_tree *t = bset_tree_last(b);
1013         struct bkey_packed packed, *src = bkey_to_packed(insert);
1014
1015         bch2_bset_verify_rw_aux_tree(b, t);
1016         bch2_verify_insert_pos(b, where, bkey_to_packed(insert), clobber_u64s);
1017
1018         if (bch2_bkey_pack_key(&packed, &insert->k, f))
1019                 src = &packed;
1020
1021         if (!bkey_deleted(&insert->k))
1022                 btree_keys_account_key_add(&b->nr, t - b->set, src);
1023
1024         if (src->u64s != clobber_u64s) {
1025                 u64 *src_p = (u64 *) where->_data + clobber_u64s;
1026                 u64 *dst_p = (u64 *) where->_data + src->u64s;
1027
1028                 EBUG_ON((int) le16_to_cpu(bset(b, t)->u64s) <
1029                         (int) clobber_u64s - src->u64s);
1030
1031                 memmove_u64s(dst_p, src_p, btree_bkey_last(b, t)->_data - src_p);
1032                 le16_add_cpu(&bset(b, t)->u64s, src->u64s - clobber_u64s);
1033                 set_btree_bset_end(b, t);
1034         }
1035
1036         memcpy_u64s_small(where, src,
1037                     bkeyp_key_u64s(f, src));
1038         memcpy_u64s(bkeyp_val(f, where), &insert->v,
1039                     bkeyp_val_u64s(f, src));
1040
1041         if (src->u64s != clobber_u64s)
1042                 bch2_bset_fix_lookup_table(b, t, where, clobber_u64s, src->u64s);
1043
1044         bch2_verify_btree_nr_keys(b);
1045 }
1046
1047 void bch2_bset_delete(struct btree *b,
1048                       struct bkey_packed *where,
1049                       unsigned clobber_u64s)
1050 {
1051         struct bset_tree *t = bset_tree_last(b);
1052         u64 *src_p = (u64 *) where->_data + clobber_u64s;
1053         u64 *dst_p = where->_data;
1054
1055         bch2_bset_verify_rw_aux_tree(b, t);
1056
1057         EBUG_ON(le16_to_cpu(bset(b, t)->u64s) < clobber_u64s);
1058
1059         memmove_u64s_down(dst_p, src_p, btree_bkey_last(b, t)->_data - src_p);
1060         le16_add_cpu(&bset(b, t)->u64s, -clobber_u64s);
1061         set_btree_bset_end(b, t);
1062
1063         bch2_bset_fix_lookup_table(b, t, where, clobber_u64s, 0);
1064 }
1065
1066 /* Lookup */
1067
1068 __flatten
1069 static struct bkey_packed *bset_search_write_set(const struct btree *b,
1070                                 struct bset_tree *t,
1071                                 struct bpos *search)
1072 {
1073         unsigned l = 0, r = t->size;
1074
1075         while (l + 1 != r) {
1076                 unsigned m = (l + r) >> 1;
1077
1078                 if (bpos_lt(rw_aux_tree(b, t)[m].k, *search))
1079                         l = m;
1080                 else
1081                         r = m;
1082         }
1083
1084         return rw_aux_to_bkey(b, t, l);
1085 }
1086
1087 static inline void prefetch_four_cachelines(void *p)
1088 {
1089 #ifdef CONFIG_X86_64
1090         asm("prefetcht0 (-127 + 64 * 0)(%0);"
1091             "prefetcht0 (-127 + 64 * 1)(%0);"
1092             "prefetcht0 (-127 + 64 * 2)(%0);"
1093             "prefetcht0 (-127 + 64 * 3)(%0);"
1094             :
1095             : "r" (p + 127));
1096 #else
1097         prefetch(p + L1_CACHE_BYTES * 0);
1098         prefetch(p + L1_CACHE_BYTES * 1);
1099         prefetch(p + L1_CACHE_BYTES * 2);
1100         prefetch(p + L1_CACHE_BYTES * 3);
1101 #endif
1102 }
1103
1104 static inline bool bkey_mantissa_bits_dropped(const struct btree *b,
1105                                               const struct bkey_float *f,
1106                                               unsigned idx)
1107 {
1108 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
1109         unsigned key_bits_start = b->format.key_u64s * 64 - b->nr_key_bits;
1110
1111         return f->exponent > key_bits_start;
1112 #else
1113         unsigned key_bits_end = high_bit_offset + b->nr_key_bits;
1114
1115         return f->exponent + BKEY_MANTISSA_BITS < key_bits_end;
1116 #endif
1117 }
1118
1119 __flatten
1120 static struct bkey_packed *bset_search_tree(const struct btree *b,
1121                                 const struct bset_tree *t,
1122                                 const struct bpos *search,
1123                                 const struct bkey_packed *packed_search)
1124 {
1125         struct ro_aux_tree *base = ro_aux_tree_base(b, t);
1126         struct bkey_float *f;
1127         struct bkey_packed *k;
1128         unsigned inorder, n = 1, l, r;
1129         int cmp;
1130
1131         do {
1132                 if (likely(n << 4 < t->size))
1133                         prefetch(&base->f[n << 4]);
1134
1135                 f = &base->f[n];
1136                 if (unlikely(f->exponent >= BFLOAT_FAILED))
1137                         goto slowpath;
1138
1139                 l = f->mantissa;
1140                 r = bkey_mantissa(packed_search, f, n);
1141
1142                 if (unlikely(l == r) && bkey_mantissa_bits_dropped(b, f, n))
1143                         goto slowpath;
1144
1145                 n = n * 2 + (l < r);
1146                 continue;
1147 slowpath:
1148                 k = tree_to_bkey(b, t, n);
1149                 cmp = bkey_cmp_p_or_unp(b, k, packed_search, search);
1150                 if (!cmp)
1151                         return k;
1152
1153                 n = n * 2 + (cmp < 0);
1154         } while (n < t->size);
1155
1156         inorder = __eytzinger1_to_inorder(n >> 1, t->size - 1, t->extra);
1157
1158         /*
1159          * n would have been the node we recursed to - the low bit tells us if
1160          * we recursed left or recursed right.
1161          */
1162         if (likely(!(n & 1))) {
1163                 --inorder;
1164                 if (unlikely(!inorder))
1165                         return btree_bkey_first(b, t);
1166
1167                 f = &base->f[eytzinger1_prev(n >> 1, t->size - 1)];
1168         }
1169
1170         return cacheline_to_bkey(b, t, inorder, f->key_offset);
1171 }
1172
1173 static __always_inline __flatten
1174 struct bkey_packed *__bch2_bset_search(struct btree *b,
1175                                 struct bset_tree *t,
1176                                 struct bpos *search,
1177                                 const struct bkey_packed *lossy_packed_search)
1178 {
1179
1180         /*
1181          * First, we search for a cacheline, then lastly we do a linear search
1182          * within that cacheline.
1183          *
1184          * To search for the cacheline, there's three different possibilities:
1185          *  * The set is too small to have a search tree, so we just do a linear
1186          *    search over the whole set.
1187          *  * The set is the one we're currently inserting into; keeping a full
1188          *    auxiliary search tree up to date would be too expensive, so we
1189          *    use a much simpler lookup table to do a binary search -
1190          *    bset_search_write_set().
1191          *  * Or we use the auxiliary search tree we constructed earlier -
1192          *    bset_search_tree()
1193          */
1194
1195         switch (bset_aux_tree_type(t)) {
1196         case BSET_NO_AUX_TREE:
1197                 return btree_bkey_first(b, t);
1198         case BSET_RW_AUX_TREE:
1199                 return bset_search_write_set(b, t, search);
1200         case BSET_RO_AUX_TREE:
1201                 return bset_search_tree(b, t, search, lossy_packed_search);
1202         default:
1203                 BUG();
1204         }
1205 }
1206
1207 static __always_inline __flatten
1208 struct bkey_packed *bch2_bset_search_linear(struct btree *b,
1209                                 struct bset_tree *t,
1210                                 struct bpos *search,
1211                                 struct bkey_packed *packed_search,
1212                                 const struct bkey_packed *lossy_packed_search,
1213                                 struct bkey_packed *m)
1214 {
1215         if (lossy_packed_search)
1216                 while (m != btree_bkey_last(b, t) &&
1217                        bkey_iter_cmp_p_or_unp(b, m,
1218                                         lossy_packed_search, search) < 0)
1219                         m = bkey_p_next(m);
1220
1221         if (!packed_search)
1222                 while (m != btree_bkey_last(b, t) &&
1223                        bkey_iter_pos_cmp(b, m, search) < 0)
1224                         m = bkey_p_next(m);
1225
1226         if (bch2_expensive_debug_checks) {
1227                 struct bkey_packed *prev = bch2_bkey_prev_all(b, t, m);
1228
1229                 BUG_ON(prev &&
1230                        bkey_iter_cmp_p_or_unp(b, prev,
1231                                         packed_search, search) >= 0);
1232         }
1233
1234         return m;
1235 }
1236
1237 /* Btree node iterator */
1238
1239 static inline void __bch2_btree_node_iter_push(struct btree_node_iter *iter,
1240                               struct btree *b,
1241                               const struct bkey_packed *k,
1242                               const struct bkey_packed *end)
1243 {
1244         if (k != end) {
1245                 struct btree_node_iter_set *pos;
1246
1247                 btree_node_iter_for_each(iter, pos)
1248                         ;
1249
1250                 BUG_ON(pos >= iter->data + ARRAY_SIZE(iter->data));
1251                 *pos = (struct btree_node_iter_set) {
1252                         __btree_node_key_to_offset(b, k),
1253                         __btree_node_key_to_offset(b, end)
1254                 };
1255         }
1256 }
1257
1258 void bch2_btree_node_iter_push(struct btree_node_iter *iter,
1259                                struct btree *b,
1260                                const struct bkey_packed *k,
1261                                const struct bkey_packed *end)
1262 {
1263         __bch2_btree_node_iter_push(iter, b, k, end);
1264         bch2_btree_node_iter_sort(iter, b);
1265 }
1266
1267 noinline __flatten __cold
1268 static void btree_node_iter_init_pack_failed(struct btree_node_iter *iter,
1269                               struct btree *b, struct bpos *search)
1270 {
1271         struct bkey_packed *k;
1272
1273         trace_bkey_pack_pos_fail(search);
1274
1275         bch2_btree_node_iter_init_from_start(iter, b);
1276
1277         while ((k = bch2_btree_node_iter_peek(iter, b)) &&
1278                bkey_iter_pos_cmp(b, k, search) < 0)
1279                 bch2_btree_node_iter_advance(iter, b);
1280 }
1281
1282 /**
1283  * bch2_btree_node_iter_init - initialize a btree node iterator, starting from a
1284  * given position
1285  *
1286  * @iter:       iterator to initialize
1287  * @b:          btree node to search
1288  * @search:     search key
1289  *
1290  * Main entry point to the lookup code for individual btree nodes:
1291  *
1292  * NOTE:
1293  *
1294  * When you don't filter out deleted keys, btree nodes _do_ contain duplicate
1295  * keys. This doesn't matter for most code, but it does matter for lookups.
1296  *
1297  * Some adjacent keys with a string of equal keys:
1298  *      i j k k k k l m
1299  *
1300  * If you search for k, the lookup code isn't guaranteed to return you any
1301  * specific k. The lookup code is conceptually doing a binary search and
1302  * iterating backwards is very expensive so if the pivot happens to land at the
1303  * last k that's what you'll get.
1304  *
1305  * This works out ok, but it's something to be aware of:
1306  *
1307  *  - For non extents, we guarantee that the live key comes last - see
1308  *    btree_node_iter_cmp(), keys_out_of_order(). So the duplicates you don't
1309  *    see will only be deleted keys you don't care about.
1310  *
1311  *  - For extents, deleted keys sort last (see the comment at the top of this
1312  *    file). But when you're searching for extents, you actually want the first
1313  *    key strictly greater than your search key - an extent that compares equal
1314  *    to the search key is going to have 0 sectors after the search key.
1315  *
1316  *    But this does mean that we can't just search for
1317  *    bpos_successor(start_of_range) to get the first extent that overlaps with
1318  *    the range we want - if we're unlucky and there's an extent that ends
1319  *    exactly where we searched, then there could be a deleted key at the same
1320  *    position and we'd get that when we search instead of the preceding extent
1321  *    we needed.
1322  *
1323  *    So we've got to search for start_of_range, then after the lookup iterate
1324  *    past any extents that compare equal to the position we searched for.
1325  */
1326 __flatten
1327 void bch2_btree_node_iter_init(struct btree_node_iter *iter,
1328                                struct btree *b, struct bpos *search)
1329 {
1330         struct bkey_packed p, *packed_search = NULL;
1331         struct btree_node_iter_set *pos = iter->data;
1332         struct bkey_packed *k[MAX_BSETS];
1333         unsigned i;
1334
1335         EBUG_ON(bpos_lt(*search, b->data->min_key));
1336         EBUG_ON(bpos_gt(*search, b->data->max_key));
1337         bset_aux_tree_verify(b);
1338
1339         memset(iter, 0, sizeof(*iter));
1340
1341         switch (bch2_bkey_pack_pos_lossy(&p, *search, b)) {
1342         case BKEY_PACK_POS_EXACT:
1343                 packed_search = &p;
1344                 break;
1345         case BKEY_PACK_POS_SMALLER:
1346                 packed_search = NULL;
1347                 break;
1348         case BKEY_PACK_POS_FAIL:
1349                 btree_node_iter_init_pack_failed(iter, b, search);
1350                 return;
1351         }
1352
1353         for (i = 0; i < b->nsets; i++) {
1354                 k[i] = __bch2_bset_search(b, b->set + i, search, &p);
1355                 prefetch_four_cachelines(k[i]);
1356         }
1357
1358         for (i = 0; i < b->nsets; i++) {
1359                 struct bset_tree *t = b->set + i;
1360                 struct bkey_packed *end = btree_bkey_last(b, t);
1361
1362                 k[i] = bch2_bset_search_linear(b, t, search,
1363                                                packed_search, &p, k[i]);
1364                 if (k[i] != end)
1365                         *pos++ = (struct btree_node_iter_set) {
1366                                 __btree_node_key_to_offset(b, k[i]),
1367                                 __btree_node_key_to_offset(b, end)
1368                         };
1369         }
1370
1371         bch2_btree_node_iter_sort(iter, b);
1372 }
1373
1374 void bch2_btree_node_iter_init_from_start(struct btree_node_iter *iter,
1375                                           struct btree *b)
1376 {
1377         struct bset_tree *t;
1378
1379         memset(iter, 0, sizeof(*iter));
1380
1381         for_each_bset(b, t)
1382                 __bch2_btree_node_iter_push(iter, b,
1383                                            btree_bkey_first(b, t),
1384                                            btree_bkey_last(b, t));
1385         bch2_btree_node_iter_sort(iter, b);
1386 }
1387
1388 struct bkey_packed *bch2_btree_node_iter_bset_pos(struct btree_node_iter *iter,
1389                                                   struct btree *b,
1390                                                   struct bset_tree *t)
1391 {
1392         struct btree_node_iter_set *set;
1393
1394         btree_node_iter_for_each(iter, set)
1395                 if (set->end == t->end_offset)
1396                         return __btree_node_offset_to_key(b, set->k);
1397
1398         return btree_bkey_last(b, t);
1399 }
1400
1401 static inline bool btree_node_iter_sort_two(struct btree_node_iter *iter,
1402                                             struct btree *b,
1403                                             unsigned first)
1404 {
1405         bool ret;
1406
1407         if ((ret = (btree_node_iter_cmp(b,
1408                                         iter->data[first],
1409                                         iter->data[first + 1]) > 0)))
1410                 swap(iter->data[first], iter->data[first + 1]);
1411         return ret;
1412 }
1413
1414 void bch2_btree_node_iter_sort(struct btree_node_iter *iter,
1415                                struct btree *b)
1416 {
1417         /* unrolled bubble sort: */
1418
1419         if (!__btree_node_iter_set_end(iter, 2)) {
1420                 btree_node_iter_sort_two(iter, b, 0);
1421                 btree_node_iter_sort_two(iter, b, 1);
1422         }
1423
1424         if (!__btree_node_iter_set_end(iter, 1))
1425                 btree_node_iter_sort_two(iter, b, 0);
1426 }
1427
1428 void bch2_btree_node_iter_set_drop(struct btree_node_iter *iter,
1429                                    struct btree_node_iter_set *set)
1430 {
1431         struct btree_node_iter_set *last =
1432                 iter->data + ARRAY_SIZE(iter->data) - 1;
1433
1434         memmove(&set[0], &set[1], (void *) last - (void *) set);
1435         *last = (struct btree_node_iter_set) { 0, 0 };
1436 }
1437
1438 static inline void __bch2_btree_node_iter_advance(struct btree_node_iter *iter,
1439                                                   struct btree *b)
1440 {
1441         iter->data->k += __bch2_btree_node_iter_peek_all(iter, b)->u64s;
1442
1443         EBUG_ON(iter->data->k > iter->data->end);
1444
1445         if (unlikely(__btree_node_iter_set_end(iter, 0))) {
1446                 /* avoid an expensive memmove call: */
1447                 iter->data[0] = iter->data[1];
1448                 iter->data[1] = iter->data[2];
1449                 iter->data[2] = (struct btree_node_iter_set) { 0, 0 };
1450                 return;
1451         }
1452
1453         if (__btree_node_iter_set_end(iter, 1))
1454                 return;
1455
1456         if (!btree_node_iter_sort_two(iter, b, 0))
1457                 return;
1458
1459         if (__btree_node_iter_set_end(iter, 2))
1460                 return;
1461
1462         btree_node_iter_sort_two(iter, b, 1);
1463 }
1464
1465 void bch2_btree_node_iter_advance(struct btree_node_iter *iter,
1466                                   struct btree *b)
1467 {
1468         if (bch2_expensive_debug_checks) {
1469                 bch2_btree_node_iter_verify(iter, b);
1470                 bch2_btree_node_iter_next_check(iter, b);
1471         }
1472
1473         __bch2_btree_node_iter_advance(iter, b);
1474 }
1475
1476 /*
1477  * Expensive:
1478  */
1479 struct bkey_packed *bch2_btree_node_iter_prev_all(struct btree_node_iter *iter,
1480                                                   struct btree *b)
1481 {
1482         struct bkey_packed *k, *prev = NULL;
1483         struct btree_node_iter_set *set;
1484         struct bset_tree *t;
1485         unsigned end = 0;
1486
1487         if (bch2_expensive_debug_checks)
1488                 bch2_btree_node_iter_verify(iter, b);
1489
1490         for_each_bset(b, t) {
1491                 k = bch2_bkey_prev_all(b, t,
1492                         bch2_btree_node_iter_bset_pos(iter, b, t));
1493                 if (k &&
1494                     (!prev || bkey_iter_cmp(b, k, prev) > 0)) {
1495                         prev = k;
1496                         end = t->end_offset;
1497                 }
1498         }
1499
1500         if (!prev)
1501                 return NULL;
1502
1503         /*
1504          * We're manually memmoving instead of just calling sort() to ensure the
1505          * prev we picked ends up in slot 0 - sort won't necessarily put it
1506          * there because of duplicate deleted keys:
1507          */
1508         btree_node_iter_for_each(iter, set)
1509                 if (set->end == end)
1510                         goto found;
1511
1512         BUG_ON(set != &iter->data[__btree_node_iter_used(iter)]);
1513 found:
1514         BUG_ON(set >= iter->data + ARRAY_SIZE(iter->data));
1515
1516         memmove(&iter->data[1],
1517                 &iter->data[0],
1518                 (void *) set - (void *) &iter->data[0]);
1519
1520         iter->data[0].k = __btree_node_key_to_offset(b, prev);
1521         iter->data[0].end = end;
1522
1523         if (bch2_expensive_debug_checks)
1524                 bch2_btree_node_iter_verify(iter, b);
1525         return prev;
1526 }
1527
1528 struct bkey_packed *bch2_btree_node_iter_prev(struct btree_node_iter *iter,
1529                                               struct btree *b)
1530 {
1531         struct bkey_packed *prev;
1532
1533         do {
1534                 prev = bch2_btree_node_iter_prev_all(iter, b);
1535         } while (prev && bkey_deleted(prev));
1536
1537         return prev;
1538 }
1539
1540 struct bkey_s_c bch2_btree_node_iter_peek_unpack(struct btree_node_iter *iter,
1541                                                  struct btree *b,
1542                                                  struct bkey *u)
1543 {
1544         struct bkey_packed *k = bch2_btree_node_iter_peek(iter, b);
1545
1546         return k ? bkey_disassemble(b, k, u) : bkey_s_c_null;
1547 }
1548
1549 /* Mergesort */
1550
1551 void bch2_btree_keys_stats(const struct btree *b, struct bset_stats *stats)
1552 {
1553         const struct bset_tree *t;
1554
1555         for_each_bset(b, t) {
1556                 enum bset_aux_tree_type type = bset_aux_tree_type(t);
1557                 size_t j;
1558
1559                 stats->sets[type].nr++;
1560                 stats->sets[type].bytes += le16_to_cpu(bset(b, t)->u64s) *
1561                         sizeof(u64);
1562
1563                 if (bset_has_ro_aux_tree(t)) {
1564                         stats->floats += t->size - 1;
1565
1566                         for (j = 1; j < t->size; j++)
1567                                 stats->failed +=
1568                                         bkey_float(b, t, j)->exponent ==
1569                                         BFLOAT_FAILED;
1570                 }
1571         }
1572 }
1573
1574 void bch2_bfloat_to_text(struct printbuf *out, struct btree *b,
1575                          struct bkey_packed *k)
1576 {
1577         struct bset_tree *t = bch2_bkey_to_bset(b, k);
1578         struct bkey uk;
1579         unsigned j, inorder;
1580
1581         if (!bset_has_ro_aux_tree(t))
1582                 return;
1583
1584         inorder = bkey_to_cacheline(b, t, k);
1585         if (!inorder || inorder >= t->size)
1586                 return;
1587
1588         j = __inorder_to_eytzinger1(inorder, t->size - 1, t->extra);
1589         if (k != tree_to_bkey(b, t, j))
1590                 return;
1591
1592         switch (bkey_float(b, t, j)->exponent) {
1593         case BFLOAT_FAILED:
1594                 uk = bkey_unpack_key(b, k);
1595                 prt_printf(out,
1596                        "    failed unpacked at depth %u\n"
1597                        "\t",
1598                        ilog2(j));
1599                 bch2_bpos_to_text(out, uk.p);
1600                 prt_printf(out, "\n");
1601                 break;
1602         }
1603 }