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