git.sesse.net Git - bcachefs-tools-debian/blob - c_src/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 "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 #ifdef CONFIG_BCACHEFS_DEBUG
 138
 139 void __bch2_verify_btree_nr_keys(struct btree *b)
 140 {
 141         struct bset_tree *t;
 142         struct bkey_packed *k;
 143         struct btree_nr_keys nr = { 0 };
 144
 145         for_each_bset(b, t)
 146                 bset_tree_for_each_key(b, t, k)
 147                         if (!bkey_deleted(k))
 148                                 btree_keys_account_key_add(&nr, t - b->set, k);
 149
 150         BUG_ON(memcmp(&nr, &b->nr, sizeof(nr)));
 151 }
 152
 153 static void bch2_btree_node_iter_next_check(struct btree_node_iter *_iter,
 154                                             struct btree *b)
 155 {
 156         struct btree_node_iter iter = *_iter;
 157         const struct bkey_packed *k, *n;
 158
 159         k = bch2_btree_node_iter_peek_all(&iter, b);
 160         __bch2_btree_node_iter_advance(&iter, b);
 161         n = bch2_btree_node_iter_peek_all(&iter, b);
 162
 163         bkey_unpack_key(b, k);
 164
 165         if (n &&
 166             bkey_iter_cmp(b, k, n) > 0) {
 167                 struct btree_node_iter_set *set;
 168                 struct bkey ku = bkey_unpack_key(b, k);
 169                 struct bkey nu = bkey_unpack_key(b, n);
 170                 struct printbuf buf1 = PRINTBUF;
 171                 struct printbuf buf2 = PRINTBUF;
 172
 173                 bch2_dump_btree_node(NULL, b);
 174                 bch2_bkey_to_text(&buf1, &ku);
 175                 bch2_bkey_to_text(&buf2, &nu);
 176                 printk(KERN_ERR "out of order/overlapping:\n%s\n%s\n",
 177                        buf1.buf, buf2.buf);
 178                 printk(KERN_ERR "iter was:");
 179
 180                 btree_node_iter_for_each(_iter, set) {
 181                         struct bkey_packed *k2 = __btree_node_offset_to_key(b, set->k);
 182                         struct bset_tree *t = bch2_bkey_to_bset(b, k2);
 183                         printk(" [%zi %zi]", t - b->set,
 184                                k2->_data - bset(b, t)->_data);
 185                 }
 186                 panic("\n");
 187         }
 188 }
 189
 190 void bch2_btree_node_iter_verify(struct btree_node_iter *iter,
 191                                  struct btree *b)
 192 {
 193         struct btree_node_iter_set *set, *s2;
 194         struct bkey_packed *k, *p;
 195         struct bset_tree *t;
 196
 197         if (bch2_btree_node_iter_end(iter))
 198                 return;
 199
 200         /* Verify no duplicates: */
 201         btree_node_iter_for_each(iter, set) {
 202                 BUG_ON(set->k > set->end);
 203                 btree_node_iter_for_each(iter, s2)
 204                         BUG_ON(set != s2 && set->end == s2->end);
 205         }
 206
 207         /* Verify that set->end is correct: */
 208         btree_node_iter_for_each(iter, set) {
 209                 for_each_bset(b, t)
 210                         if (set->end == t->end_offset)
 211                                 goto found;
 212                 BUG();
 213 found:
 214                 BUG_ON(set->k < btree_bkey_first_offset(t) ||
 215                        set->k >= t->end_offset);
 216         }
 217
 218         /* Verify iterator is sorted: */
 219         btree_node_iter_for_each(iter, set)
 220                 BUG_ON(set != iter->data &&
 221                        btree_node_iter_cmp(b, set[-1], set[0]) > 0);
 222
 223         k = bch2_btree_node_iter_peek_all(iter, b);
 224
 225         for_each_bset(b, t) {
 226                 if (iter->data[0].end == t->end_offset)
 227                         continue;
 228
 229                 p = bch2_bkey_prev_all(b, t,
 230                         bch2_btree_node_iter_bset_pos(iter, b, t));
 231
 232                 BUG_ON(p && bkey_iter_cmp(b, k, p) < 0);
 233         }
 234 }
 235
 236 void bch2_verify_insert_pos(struct btree *b, struct bkey_packed *where,
 237                             struct bkey_packed *insert, unsigned clobber_u64s)
 238 {
 239         struct bset_tree *t = bch2_bkey_to_bset(b, where);
 240         struct bkey_packed *prev = bch2_bkey_prev_all(b, t, where);
 241         struct bkey_packed *next = (void *) ((u64 *) where->_data + clobber_u64s);
 242         struct printbuf buf1 = PRINTBUF;
 243         struct printbuf buf2 = PRINTBUF;
 244 #if 0
 245         BUG_ON(prev &&
 246                bkey_iter_cmp(b, prev, insert) > 0);
 247 #else
 248         if (prev &&
 249             bkey_iter_cmp(b, prev, insert) > 0) {
 250                 struct bkey k1 = bkey_unpack_key(b, prev);
 251                 struct bkey k2 = bkey_unpack_key(b, insert);
 252
 253                 bch2_dump_btree_node(NULL, b);
 254                 bch2_bkey_to_text(&buf1, &k1);
 255                 bch2_bkey_to_text(&buf2, &k2);
 256
 257                 panic("prev > insert:\n"
 258                       "prev    key %s\n"
 259                       "insert  key %s\n",
 260                       buf1.buf, buf2.buf);
 261         }
 262 #endif
 263 #if 0
 264         BUG_ON(next != btree_bkey_last(b, t) &&
 265                bkey_iter_cmp(b, insert, next) > 0);
 266 #else
 267         if (next != btree_bkey_last(b, t) &&
 268             bkey_iter_cmp(b, insert, next) > 0) {
 269                 struct bkey k1 = bkey_unpack_key(b, insert);
 270                 struct bkey k2 = bkey_unpack_key(b, next);
 271
 272                 bch2_dump_btree_node(NULL, b);
 273                 bch2_bkey_to_text(&buf1, &k1);
 274                 bch2_bkey_to_text(&buf2, &k2);
 275
 276                 panic("insert > next:\n"
 277                       "insert  key %s\n"
 278                       "next    key %s\n",
 279                       buf1.buf, buf2.buf);
 280         }
 281 #endif
 282 }
 283
 284 #else
 285
 286 static inline void bch2_btree_node_iter_next_check(struct btree_node_iter *iter,
 287                                                    struct btree *b) {}
 288
 289 #endif
 290
 291 /* Auxiliary search trees */
 292
 293 #define BFLOAT_FAILED_UNPACKED  U8_MAX
 294 #define BFLOAT_FAILED           U8_MAX
 295
 296 struct bkey_float {
 297         u8              exponent;
 298         u8              key_offset;
 299         u16             mantissa;
 300 };
 301 #define BKEY_MANTISSA_BITS      16
 302
 303 static unsigned bkey_float_byte_offset(unsigned idx)
 304 {
 305         return idx * sizeof(struct bkey_float);
 306 }
 307
 308 struct ro_aux_tree {
 309         u8                      nothing[0];
 310         struct bkey_float       f[];
 311 };
 312
 313 struct rw_aux_tree {
 314         u16             offset;
 315         struct bpos     k;
 316 };
 317
 318 static unsigned bset_aux_tree_buf_end(const struct bset_tree *t)
 319 {
 320         BUG_ON(t->aux_data_offset == U16_MAX);
 321
 322         switch (bset_aux_tree_type(t)) {
 323         case BSET_NO_AUX_TREE:
 324                 return t->aux_data_offset;
 325         case BSET_RO_AUX_TREE:
 326                 return t->aux_data_offset +
 327                         DIV_ROUND_UP(t->size * sizeof(struct bkey_float) +
 328                                      t->size * sizeof(u8), 8);
 329         case BSET_RW_AUX_TREE:
 330                 return t->aux_data_offset +
 331                         DIV_ROUND_UP(sizeof(struct rw_aux_tree) * t->size, 8);
 332         default:
 333                 BUG();
 334         }
 335 }
 336
 337 static unsigned bset_aux_tree_buf_start(const struct btree *b,
 338                                         const struct bset_tree *t)
 339 {
 340         return t == b->set
 341                 ? DIV_ROUND_UP(b->unpack_fn_len, 8)
 342                 : bset_aux_tree_buf_end(t - 1);
 343 }
 344
 345 static void *__aux_tree_base(const struct btree *b,
 346                              const struct bset_tree *t)
 347 {
 348         return b->aux_data + t->aux_data_offset * 8;
 349 }
 350
 351 static struct ro_aux_tree *ro_aux_tree_base(const struct btree *b,
 352                                             const struct bset_tree *t)
 353 {
 354         EBUG_ON(bset_aux_tree_type(t) != BSET_RO_AUX_TREE);
 355
 356         return __aux_tree_base(b, t);
 357 }
 358
 359 static u8 *ro_aux_tree_prev(const struct btree *b,
 360                             const struct bset_tree *t)
 361 {
 362         EBUG_ON(bset_aux_tree_type(t) != BSET_RO_AUX_TREE);
 363
 364         return __aux_tree_base(b, t) + bkey_float_byte_offset(t->size);
 365 }
 366
 367 static struct bkey_float *bkey_float(const struct btree *b,
 368                                      const struct bset_tree *t,
 369                                      unsigned idx)
 370 {
 371         return ro_aux_tree_base(b, t)->f + idx;
 372 }
 373
 374 static void bset_aux_tree_verify(const struct btree *b)
 375 {
 376 #ifdef CONFIG_BCACHEFS_DEBUG
 377         const struct bset_tree *t;
 378
 379         for_each_bset(b, t) {
 380                 if (t->aux_data_offset == U16_MAX)
 381                         continue;
 382
 383                 BUG_ON(t != b->set &&
 384                        t[-1].aux_data_offset == U16_MAX);
 385
 386                 BUG_ON(t->aux_data_offset < bset_aux_tree_buf_start(b, t));
 387                 BUG_ON(t->aux_data_offset > btree_aux_data_u64s(b));
 388                 BUG_ON(bset_aux_tree_buf_end(t) > btree_aux_data_u64s(b));
 389         }
 390 #endif
 391 }
 392
 393 void bch2_btree_keys_init(struct btree *b)
 394 {
 395         unsigned i;
 396
 397         b->nsets                = 0;
 398         memset(&b->nr, 0, sizeof(b->nr));
 399
 400         for (i = 0; i < MAX_BSETS; i++)
 401                 b->set[i].data_offset = U16_MAX;
 402
 403         bch2_bset_set_no_aux_tree(b, b->set);
 404 }
 405
 406 /* Binary tree stuff for auxiliary search trees */
 407
 408 /*
 409  * Cacheline/offset <-> bkey pointer arithmetic:
 410  *
 411  * t->tree is a binary search tree in an array; each node corresponds to a key
 412  * in one cacheline in t->set (BSET_CACHELINE bytes).
 413  *
 414  * This means we don't have to store the full index of the key that a node in
 415  * the binary tree points to; eytzinger1_to_inorder() gives us the cacheline, and
 416  * then bkey_float->m gives us the offset within that cacheline, in units of 8
 417  * bytes.
 418  *
 419  * cacheline_to_bkey() and friends abstract out all the pointer arithmetic to
 420  * make this work.
 421  *
 422  * To construct the bfloat for an arbitrary key we need to know what the key
 423  * immediately preceding it is: we have to check if the two keys differ in the
 424  * bits we're going to store in bkey_float->mantissa. t->prev[j] stores the size
 425  * of the previous key so we can walk backwards to it from t->tree[j]'s key.
 426  */
 427
 428 static inline void *bset_cacheline(const struct btree *b,
 429                                    const struct bset_tree *t,
 430                                    unsigned cacheline)
 431 {
 432         return (void *) round_down((unsigned long) btree_bkey_first(b, t),
 433                                    L1_CACHE_BYTES) +
 434                 cacheline * BSET_CACHELINE;
 435 }
 436
 437 static struct bkey_packed *cacheline_to_bkey(const struct btree *b,
 438                                              const struct bset_tree *t,
 439                                              unsigned cacheline,
 440                                              unsigned offset)
 441 {
 442         return bset_cacheline(b, t, cacheline) + offset * 8;
 443 }
 444
 445 static unsigned bkey_to_cacheline(const struct btree *b,
 446                                   const struct bset_tree *t,
 447                                   const struct bkey_packed *k)
 448 {
 449         return ((void *) k - bset_cacheline(b, t, 0)) / BSET_CACHELINE;
 450 }
 451
 452 static ssize_t __bkey_to_cacheline_offset(const struct btree *b,
 453                                           const struct bset_tree *t,
 454                                           unsigned cacheline,
 455                                           const struct bkey_packed *k)
 456 {
 457         return (u64 *) k - (u64 *) bset_cacheline(b, t, cacheline);
 458 }
 459
 460 static unsigned bkey_to_cacheline_offset(const struct btree *b,
 461                                          const struct bset_tree *t,
 462                                          unsigned cacheline,
 463                                          const struct bkey_packed *k)
 464 {
 465         size_t m = __bkey_to_cacheline_offset(b, t, cacheline, k);
 466
 467         EBUG_ON(m > U8_MAX);
 468         return m;
 469 }
 470
 471 static inline struct bkey_packed *tree_to_bkey(const struct btree *b,
 472                                                const struct bset_tree *t,
 473                                                unsigned j)
 474 {
 475         return cacheline_to_bkey(b, t,
 476                         __eytzinger1_to_inorder(j, t->size - 1, t->extra),
 477                         bkey_float(b, t, j)->key_offset);
 478 }
 479
 480 static struct bkey_packed *tree_to_prev_bkey(const struct btree *b,
 481                                              const struct bset_tree *t,
 482                                              unsigned j)
 483 {
 484         unsigned prev_u64s = ro_aux_tree_prev(b, t)[j];
 485
 486         return (void *) ((u64 *) tree_to_bkey(b, t, j)->_data - prev_u64s);
 487 }
 488
 489 static struct rw_aux_tree *rw_aux_tree(const struct btree *b,
 490                                        const struct bset_tree *t)
 491 {
 492         EBUG_ON(bset_aux_tree_type(t) != BSET_RW_AUX_TREE);
 493
 494         return __aux_tree_base(b, t);
 495 }
 496
 497 /*
 498  * For the write set - the one we're currently inserting keys into - we don't
 499  * maintain a full search tree, we just keep a simple lookup table in t->prev.
 500  */
 501 static struct bkey_packed *rw_aux_to_bkey(const struct btree *b,
 502                                           struct bset_tree *t,
 503                                           unsigned j)
 504 {
 505         return __btree_node_offset_to_key(b, rw_aux_tree(b, t)[j].offset);
 506 }
 507
 508 static void rw_aux_tree_set(const struct btree *b, struct bset_tree *t,
 509                             unsigned j, struct bkey_packed *k)
 510 {
 511         EBUG_ON(k >= btree_bkey_last(b, t));
 512
 513         rw_aux_tree(b, t)[j] = (struct rw_aux_tree) {
 514                 .offset = __btree_node_key_to_offset(b, k),
 515                 .k      = bkey_unpack_pos(b, k),
 516         };
 517 }
 518
 519 static void bch2_bset_verify_rw_aux_tree(struct btree *b,
 520                                         struct bset_tree *t)
 521 {
 522         struct bkey_packed *k = btree_bkey_first(b, t);
 523         unsigned j = 0;
 524
 525         if (!bch2_expensive_debug_checks)
 526                 return;
 527
 528         BUG_ON(bset_has_ro_aux_tree(t));
 529
 530         if (!bset_has_rw_aux_tree(t))
 531                 return;
 532
 533         BUG_ON(t->size < 1);
 534         BUG_ON(rw_aux_to_bkey(b, t, j) != k);
 535
 536         goto start;
 537         while (1) {
 538                 if (rw_aux_to_bkey(b, t, j) == k) {
 539                         BUG_ON(!bpos_eq(rw_aux_tree(b, t)[j].k,
 540                                         bkey_unpack_pos(b, k)));
 541 start:
 542                         if (++j == t->size)
 543                                 break;
 544
 545                         BUG_ON(rw_aux_tree(b, t)[j].offset <=
 546                                rw_aux_tree(b, t)[j - 1].offset);
 547                 }
 548
 549                 k = bkey_p_next(k);
 550                 BUG_ON(k >= btree_bkey_last(b, t));
 551         }
 552 }
 553
 554 /* returns idx of first entry >= offset: */
 555 static unsigned rw_aux_tree_bsearch(struct btree *b,
 556                                     struct bset_tree *t,
 557                                     unsigned offset)
 558 {
 559         unsigned bset_offs = offset - btree_bkey_first_offset(t);
 560         unsigned bset_u64s = t->end_offset - btree_bkey_first_offset(t);
 561         unsigned idx = bset_u64s ? bset_offs * t->size / bset_u64s : 0;
 562
 563         EBUG_ON(bset_aux_tree_type(t) != BSET_RW_AUX_TREE);
 564         EBUG_ON(!t->size);
 565         EBUG_ON(idx > t->size);
 566
 567         while (idx < t->size &&
 568                rw_aux_tree(b, t)[idx].offset < offset)
 569                 idx++;
 570
 571         while (idx &&
 572                rw_aux_tree(b, t)[idx - 1].offset >= offset)
 573                 idx--;
 574
 575         EBUG_ON(idx < t->size &&
 576                 rw_aux_tree(b, t)[idx].offset < offset);
 577         EBUG_ON(idx && rw_aux_tree(b, t)[idx - 1].offset >= offset);
 578         EBUG_ON(idx + 1 < t->size &&
 579                 rw_aux_tree(b, t)[idx].offset ==
 580                 rw_aux_tree(b, t)[idx + 1].offset);
 581
 582         return idx;
 583 }
 584
 585 static inline unsigned bkey_mantissa(const struct bkey_packed *k,
 586                                      const struct bkey_float *f,
 587                                      unsigned idx)
 588 {
 589         u64 v;
 590
 591         EBUG_ON(!bkey_packed(k));
 592
 593         v = get_unaligned((u64 *) (((u8 *) k->_data) + (f->exponent >> 3)));
 594
 595         /*
 596          * In little endian, we're shifting off low bits (and then the bits we
 597          * want are at the low end), in big endian we're shifting off high bits
 598          * (and then the bits we want are at the high end, so we shift them
 599          * back down):
 600          */
 601 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 602         v >>= f->exponent & 7;
 603 #else
 604         v >>= 64 - (f->exponent & 7) - BKEY_MANTISSA_BITS;
 605 #endif
 606         return (u16) v;
 607 }
 608
 609 static __always_inline void make_bfloat(struct btree *b, struct bset_tree *t,
 610                                         unsigned j,
 611                                         struct bkey_packed *min_key,
 612                                         struct bkey_packed *max_key)
 613 {
 614         struct bkey_float *f = bkey_float(b, t, j);
 615         struct bkey_packed *m = tree_to_bkey(b, t, j);
 616         struct bkey_packed *l = is_power_of_2(j)
 617                 ? min_key
 618                 : tree_to_prev_bkey(b, t, j >> ffs(j));
 619         struct bkey_packed *r = is_power_of_2(j + 1)
 620                 ? max_key
 621                 : tree_to_bkey(b, t, j >> (ffz(j) + 1));
 622         unsigned mantissa;
 623         int shift, exponent, high_bit;
 624
 625         /*
 626          * for failed bfloats, the lookup code falls back to comparing against
 627          * the original key.
 628          */
 629
 630         if (!bkey_packed(l) || !bkey_packed(r) || !bkey_packed(m) ||
 631             !b->nr_key_bits) {
 632                 f->exponent = BFLOAT_FAILED_UNPACKED;
 633                 return;
 634         }
 635
 636         /*
 637          * The greatest differing bit of l and r is the first bit we must
 638          * include in the bfloat mantissa we're creating in order to do
 639          * comparisons - that bit always becomes the high bit of
 640          * bfloat->mantissa, and thus the exponent we're calculating here is
 641          * the position of what will become the low bit in bfloat->mantissa:
 642          *
 643          * Note that this may be negative - we may be running off the low end
 644          * of the key: we handle this later:
 645          */
 646         high_bit = max(bch2_bkey_greatest_differing_bit(b, l, r),
 647                        min_t(unsigned, BKEY_MANTISSA_BITS, b->nr_key_bits) - 1);
 648         exponent = high_bit - (BKEY_MANTISSA_BITS - 1);
 649
 650         /*
 651          * Then we calculate the actual shift value, from the start of the key
 652          * (k->_data), to get the key bits starting at exponent:
 653          */
 654 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 655         shift = (int) (b->format.key_u64s * 64 - b->nr_key_bits) + exponent;
 656
 657         EBUG_ON(shift + BKEY_MANTISSA_BITS > b->format.key_u64s * 64);
 658 #else
 659         shift = high_bit_offset +
 660                 b->nr_key_bits -
 661                 exponent -
 662                 BKEY_MANTISSA_BITS;
 663
 664         EBUG_ON(shift < KEY_PACKED_BITS_START);
 665 #endif
 666         EBUG_ON(shift < 0 || shift >= BFLOAT_FAILED);
 667
 668         f->exponent = shift;
 669         mantissa = bkey_mantissa(m, f, j);
 670
 671         /*
 672          * If we've got garbage bits, set them to all 1s - it's legal for the
 673          * bfloat to compare larger than the original key, but not smaller:
 674          */
 675         if (exponent < 0)
 676                 mantissa |= ~(~0U << -exponent);
 677
 678         f->mantissa = mantissa;
 679 }
 680
 681 /* bytes remaining - only valid for last bset: */
 682 static unsigned __bset_tree_capacity(const struct btree *b, const struct bset_tree *t)
 683 {
 684         bset_aux_tree_verify(b);
 685
 686         return btree_aux_data_bytes(b) - t->aux_data_offset * sizeof(u64);
 687 }
 688
 689 static unsigned bset_ro_tree_capacity(const struct btree *b, const struct bset_tree *t)
 690 {
 691         return __bset_tree_capacity(b, t) /
 692                 (sizeof(struct bkey_float) + sizeof(u8));
 693 }
 694
 695 static unsigned bset_rw_tree_capacity(const struct btree *b, const struct bset_tree *t)
 696 {
 697         return __bset_tree_capacity(b, t) / sizeof(struct rw_aux_tree);
 698 }
 699
 700 static noinline void __build_rw_aux_tree(struct btree *b, struct bset_tree *t)
 701 {
 702         struct bkey_packed *k;
 703
 704         t->size = 1;
 705         t->extra = BSET_RW_AUX_TREE_VAL;
 706         rw_aux_tree(b, t)[0].offset =
 707                 __btree_node_key_to_offset(b, btree_bkey_first(b, t));
 708
 709         bset_tree_for_each_key(b, t, k) {
 710                 if (t->size == bset_rw_tree_capacity(b, t))
 711                         break;
 712
 713                 if ((void *) k - (void *) rw_aux_to_bkey(b, t, t->size - 1) >
 714                     L1_CACHE_BYTES)
 715                         rw_aux_tree_set(b, t, t->size++, k);
 716         }
 717 }
 718
 719 static noinline void __build_ro_aux_tree(struct btree *b, struct bset_tree *t)
 720 {
 721         struct bkey_packed *prev = NULL, *k = btree_bkey_first(b, t);
 722         struct bkey_i min_key, max_key;
 723         unsigned j, cacheline = 1;
 724
 725         t->size = min(bkey_to_cacheline(b, t, btree_bkey_last(b, t)),
 726                       bset_ro_tree_capacity(b, t));
 727 retry:
 728         if (t->size < 2) {
 729                 t->size = 0;
 730                 t->extra = BSET_NO_AUX_TREE_VAL;
 731                 return;
 732         }
 733
 734         t->extra = (t->size - rounddown_pow_of_two(t->size - 1)) << 1;
 735
 736         /* First we figure out where the first key in each cacheline is */
 737         eytzinger1_for_each(j, t->size - 1) {
 738                 while (bkey_to_cacheline(b, t, k) < cacheline)
 739                         prev = k, k = bkey_p_next(k);
 740
 741                 if (k >= btree_bkey_last(b, t)) {
 742                         /* XXX: this path sucks */
 743                         t->size--;
 744                         goto retry;
 745                 }
 746
 747                 ro_aux_tree_prev(b, t)[j] = prev->u64s;
 748                 bkey_float(b, t, j)->key_offset =
 749                         bkey_to_cacheline_offset(b, t, cacheline++, k);
 750
 751                 EBUG_ON(tree_to_prev_bkey(b, t, j) != prev);
 752                 EBUG_ON(tree_to_bkey(b, t, j) != k);
 753         }
 754
 755         while (k != btree_bkey_last(b, t))
 756                 prev = k, k = bkey_p_next(k);
 757
 758         if (!bkey_pack_pos(bkey_to_packed(&min_key), b->data->min_key, b)) {
 759                 bkey_init(&min_key.k);
 760                 min_key.k.p = b->data->min_key;
 761         }
 762
 763         if (!bkey_pack_pos(bkey_to_packed(&max_key), b->data->max_key, b)) {
 764                 bkey_init(&max_key.k);
 765                 max_key.k.p = b->data->max_key;
 766         }
 767
 768         /* Then we build the tree */
 769         eytzinger1_for_each(j, t->size - 1)
 770                 make_bfloat(b, t, j,
 771                             bkey_to_packed(&min_key),
 772                             bkey_to_packed(&max_key));
 773 }
 774
 775 static void bset_alloc_tree(struct btree *b, struct bset_tree *t)
 776 {
 777         struct bset_tree *i;
 778
 779         for (i = b->set; i != t; i++)
 780                 BUG_ON(bset_has_rw_aux_tree(i));
 781
 782         bch2_bset_set_no_aux_tree(b, t);
 783
 784         /* round up to next cacheline: */
 785         t->aux_data_offset = round_up(bset_aux_tree_buf_start(b, t),
 786                                       SMP_CACHE_BYTES / sizeof(u64));
 787
 788         bset_aux_tree_verify(b);
 789 }
 790
 791 void bch2_bset_build_aux_tree(struct btree *b, struct bset_tree *t,
 792                              bool writeable)
 793 {
 794         if (writeable
 795             ? bset_has_rw_aux_tree(t)
 796             : bset_has_ro_aux_tree(t))
 797                 return;
 798
 799         bset_alloc_tree(b, t);
 800
 801         if (!__bset_tree_capacity(b, t))
 802                 return;
 803
 804         if (writeable)
 805                 __build_rw_aux_tree(b, t);
 806         else
 807                 __build_ro_aux_tree(b, t);
 808
 809         bset_aux_tree_verify(b);
 810 }
 811
 812 void bch2_bset_init_first(struct btree *b, struct bset *i)
 813 {
 814         struct bset_tree *t;
 815
 816         BUG_ON(b->nsets);
 817
 818         memset(i, 0, sizeof(*i));
 819         get_random_bytes(&i->seq, sizeof(i->seq));
 820         SET_BSET_BIG_ENDIAN(i, CPU_BIG_ENDIAN);
 821
 822         t = &b->set[b->nsets++];
 823         set_btree_bset(b, t, i);
 824 }
 825
 826 void bch2_bset_init_next(struct bch_fs *c, struct btree *b,
 827                          struct btree_node_entry *bne)
 828 {
 829         struct bset *i = &bne->keys;
 830         struct bset_tree *t;
 831
 832         BUG_ON(bset_byte_offset(b, bne) >= btree_bytes(c));
 833         BUG_ON((void *) bne < (void *) btree_bkey_last(b, bset_tree_last(b)));
 834         BUG_ON(b->nsets >= MAX_BSETS);
 835
 836         memset(i, 0, sizeof(*i));
 837         i->seq = btree_bset_first(b)->seq;
 838         SET_BSET_BIG_ENDIAN(i, CPU_BIG_ENDIAN);
 839
 840         t = &b->set[b->nsets++];
 841         set_btree_bset(b, t, i);
 842 }
 843
 844 /*
 845  * find _some_ key in the same bset as @k that precedes @k - not necessarily the
 846  * immediate predecessor:
 847  */
 848 static struct bkey_packed *__bkey_prev(struct btree *b, struct bset_tree *t,
 849                                        struct bkey_packed *k)
 850 {
 851         struct bkey_packed *p;
 852         unsigned offset;
 853         int j;
 854
 855         EBUG_ON(k < btree_bkey_first(b, t) ||
 856                 k > btree_bkey_last(b, t));
 857
 858         if (k == btree_bkey_first(b, t))
 859                 return NULL;
 860
 861         switch (bset_aux_tree_type(t)) {
 862         case BSET_NO_AUX_TREE:
 863                 p = btree_bkey_first(b, t);
 864                 break;
 865         case BSET_RO_AUX_TREE:
 866                 j = min_t(unsigned, t->size - 1, bkey_to_cacheline(b, t, k));
 867
 868                 do {
 869                         p = j ? tree_to_bkey(b, t,
 870                                         __inorder_to_eytzinger1(j--,
 871                                                         t->size - 1, t->extra))
 872                               : btree_bkey_first(b, t);
 873                 } while (p >= k);
 874                 break;
 875         case BSET_RW_AUX_TREE:
 876                 offset = __btree_node_key_to_offset(b, k);
 877                 j = rw_aux_tree_bsearch(b, t, offset);
 878                 p = j ? rw_aux_to_bkey(b, t, j - 1)
 879                       : btree_bkey_first(b, t);
 880                 break;
 881         }
 882
 883         return p;
 884 }
 885
 886 struct bkey_packed *bch2_bkey_prev_filter(struct btree *b,
 887                                           struct bset_tree *t,
 888                                           struct bkey_packed *k,
 889                                           unsigned min_key_type)
 890 {
 891         struct bkey_packed *p, *i, *ret = NULL, *orig_k = k;
 892
 893         while ((p = __bkey_prev(b, t, k)) && !ret) {
 894                 for (i = p; i != k; i = bkey_p_next(i))
 895                         if (i->type >= min_key_type)
 896                                 ret = i;
 897
 898                 k = p;
 899         }
 900
 901         if (bch2_expensive_debug_checks) {
 902                 BUG_ON(ret >= orig_k);
 903
 904                 for (i = ret
 905                         ? bkey_p_next(ret)
 906                         : btree_bkey_first(b, t);
 907                      i != orig_k;
 908                      i = bkey_p_next(i))
 909                         BUG_ON(i->type >= min_key_type);
 910         }
 911
 912         return ret;
 913 }
 914
 915 /* Insert */
 916
 917 static void bch2_bset_fix_lookup_table(struct btree *b,
 918                                        struct bset_tree *t,
 919                                        struct bkey_packed *_where,
 920                                        unsigned clobber_u64s,
 921                                        unsigned new_u64s)
 922 {
 923         int shift = new_u64s - clobber_u64s;
 924         unsigned l, j, where = __btree_node_key_to_offset(b, _where);
 925
 926         EBUG_ON(bset_has_ro_aux_tree(t));
 927
 928         if (!bset_has_rw_aux_tree(t))
 929                 return;
 930
 931         /* returns first entry >= where */
 932         l = rw_aux_tree_bsearch(b, t, where);
 933
 934         if (!l) /* never delete first entry */
 935                 l++;
 936         else if (l < t->size &&
 937                  where < t->end_offset &&
 938                  rw_aux_tree(b, t)[l].offset == where)
 939                 rw_aux_tree_set(b, t, l++, _where);
 940
 941         /* l now > where */
 942
 943         for (j = l;
 944              j < t->size &&
 945              rw_aux_tree(b, t)[j].offset < where + clobber_u64s;
 946              j++)
 947                 ;
 948
 949         if (j < t->size &&
 950             rw_aux_tree(b, t)[j].offset + shift ==
 951             rw_aux_tree(b, t)[l - 1].offset)
 952                 j++;
 953
 954         memmove(&rw_aux_tree(b, t)[l],
 955                 &rw_aux_tree(b, t)[j],
 956                 (void *) &rw_aux_tree(b, t)[t->size] -
 957                 (void *) &rw_aux_tree(b, t)[j]);
 958         t->size -= j - l;
 959
 960         for (j = l; j < t->size; j++)
 961                 rw_aux_tree(b, t)[j].offset += shift;
 962
 963         EBUG_ON(l < t->size &&
 964                 rw_aux_tree(b, t)[l].offset ==
 965                 rw_aux_tree(b, t)[l - 1].offset);
 966
 967         if (t->size < bset_rw_tree_capacity(b, t) &&
 968             (l < t->size
 969              ? rw_aux_tree(b, t)[l].offset
 970              : t->end_offset) -
 971             rw_aux_tree(b, t)[l - 1].offset >
 972             L1_CACHE_BYTES / sizeof(u64)) {
 973                 struct bkey_packed *start = rw_aux_to_bkey(b, t, l - 1);
 974                 struct bkey_packed *end = l < t->size
 975                         ? rw_aux_to_bkey(b, t, l)
 976                         : btree_bkey_last(b, t);
 977                 struct bkey_packed *k = start;
 978
 979                 while (1) {
 980                         k = bkey_p_next(k);
 981                         if (k == end)
 982                                 break;
 983
 984                         if ((void *) k - (void *) start >= L1_CACHE_BYTES) {
 985                                 memmove(&rw_aux_tree(b, t)[l + 1],
 986                                         &rw_aux_tree(b, t)[l],
 987                                         (void *) &rw_aux_tree(b, t)[t->size] -
 988                                         (void *) &rw_aux_tree(b, t)[l]);
 989                                 t->size++;
 990                                 rw_aux_tree_set(b, t, l, k);
 991                                 break;
 992                         }
 993                 }
 994         }
 995
 996         bch2_bset_verify_rw_aux_tree(b, t);
 997         bset_aux_tree_verify(b);
 998 }
 999
1000 void bch2_bset_insert(struct btree *b,
1001                       struct btree_node_iter *iter,
1002                       struct bkey_packed *where,
1003                       struct bkey_i *insert,
1004                       unsigned clobber_u64s)
1005 {
1006         struct bkey_format *f = &b->format;
1007         struct bset_tree *t = bset_tree_last(b);
1008         struct bkey_packed packed, *src = bkey_to_packed(insert);
1009
1010         bch2_bset_verify_rw_aux_tree(b, t);
1011         bch2_verify_insert_pos(b, where, bkey_to_packed(insert), clobber_u64s);
1012
1013         if (bch2_bkey_pack_key(&packed, &insert->k, f))
1014                 src = &packed;
1015
1016         if (!bkey_deleted(&insert->k))
1017                 btree_keys_account_key_add(&b->nr, t - b->set, src);
1018
1019         if (src->u64s != clobber_u64s) {
1020                 u64 *src_p = (u64 *) where->_data + clobber_u64s;
1021                 u64 *dst_p = (u64 *) where->_data + src->u64s;
1022
1023                 EBUG_ON((int) le16_to_cpu(bset(b, t)->u64s) <
1024                         (int) clobber_u64s - src->u64s);
1025
1026                 memmove_u64s(dst_p, src_p, btree_bkey_last(b, t)->_data - src_p);
1027                 le16_add_cpu(&bset(b, t)->u64s, src->u64s - clobber_u64s);
1028                 set_btree_bset_end(b, t);
1029         }
1030
1031         memcpy_u64s_small(where, src,
1032                     bkeyp_key_u64s(f, src));
1033         memcpy_u64s(bkeyp_val(f, where), &insert->v,
1034                     bkeyp_val_u64s(f, src));
1035
1036         if (src->u64s != clobber_u64s)
1037                 bch2_bset_fix_lookup_table(b, t, where, clobber_u64s, src->u64s);
1038
1039         bch2_verify_btree_nr_keys(b);
1040 }
1041
1042 void bch2_bset_delete(struct btree *b,
1043                       struct bkey_packed *where,
1044                       unsigned clobber_u64s)
1045 {
1046         struct bset_tree *t = bset_tree_last(b);
1047         u64 *src_p = (u64 *) where->_data + clobber_u64s;
1048         u64 *dst_p = where->_data;
1049
1050         bch2_bset_verify_rw_aux_tree(b, t);
1051
1052         EBUG_ON(le16_to_cpu(bset(b, t)->u64s) < clobber_u64s);
1053
1054         memmove_u64s_down(dst_p, src_p, btree_bkey_last(b, t)->_data - src_p);
1055         le16_add_cpu(&bset(b, t)->u64s, -clobber_u64s);
1056         set_btree_bset_end(b, t);
1057
1058         bch2_bset_fix_lookup_table(b, t, where, clobber_u64s, 0);
1059 }
1060
1061 /* Lookup */
1062
1063 __flatten
1064 static struct bkey_packed *bset_search_write_set(const struct btree *b,
1065                                 struct bset_tree *t,
1066                                 struct bpos *search)
1067 {
1068         unsigned l = 0, r = t->size;
1069
1070         while (l + 1 != r) {
1071                 unsigned m = (l + r) >> 1;
1072
1073                 if (bpos_lt(rw_aux_tree(b, t)[m].k, *search))
1074                         l = m;
1075                 else
1076                         r = m;
1077         }
1078
1079         return rw_aux_to_bkey(b, t, l);
1080 }
1081
1082 static inline void prefetch_four_cachelines(void *p)
1083 {
1084 #ifdef CONFIG_X86_64
1085         asm("prefetcht0 (-127 + 64 * 0)(%0);"
1086             "prefetcht0 (-127 + 64 * 1)(%0);"
1087             "prefetcht0 (-127 + 64 * 2)(%0);"
1088             "prefetcht0 (-127 + 64 * 3)(%0);"
1089             :
1090             : "r" (p + 127));
1091 #else
1092         prefetch(p + L1_CACHE_BYTES * 0);
1093         prefetch(p + L1_CACHE_BYTES * 1);
1094         prefetch(p + L1_CACHE_BYTES * 2);
1095         prefetch(p + L1_CACHE_BYTES * 3);
1096 #endif
1097 }
1098
1099 static inline bool bkey_mantissa_bits_dropped(const struct btree *b,
1100                                               const struct bkey_float *f,
1101                                               unsigned idx)
1102 {
1103 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
1104         unsigned key_bits_start = b->format.key_u64s * 64 - b->nr_key_bits;
1105
1106         return f->exponent > key_bits_start;
1107 #else
1108         unsigned key_bits_end = high_bit_offset + b->nr_key_bits;
1109
1110         return f->exponent + BKEY_MANTISSA_BITS < key_bits_end;
1111 #endif
1112 }
1113
1114 __flatten
1115 static struct bkey_packed *bset_search_tree(const struct btree *b,
1116                                 const struct bset_tree *t,
1117                                 const struct bpos *search,
1118                                 const struct bkey_packed *packed_search)
1119 {
1120         struct ro_aux_tree *base = ro_aux_tree_base(b, t);
1121         struct bkey_float *f;
1122         struct bkey_packed *k;
1123         unsigned inorder, n = 1, l, r;
1124         int cmp;
1125
1126         do {
1127                 if (likely(n << 4 < t->size))
1128                         prefetch(&base->f[n << 4]);
1129
1130                 f = &base->f[n];
1131                 if (unlikely(f->exponent >= BFLOAT_FAILED))
1132                         goto slowpath;
1133
1134                 l = f->mantissa;
1135                 r = bkey_mantissa(packed_search, f, n);
1136
1137                 if (unlikely(l == r) && bkey_mantissa_bits_dropped(b, f, n))
1138                         goto slowpath;
1139
1140                 n = n * 2 + (l < r);
1141                 continue;
1142 slowpath:
1143                 k = tree_to_bkey(b, t, n);
1144                 cmp = bkey_cmp_p_or_unp(b, k, packed_search, search);
1145                 if (!cmp)
1146                         return k;
1147
1148                 n = n * 2 + (cmp < 0);
1149         } while (n < t->size);
1150
1151         inorder = __eytzinger1_to_inorder(n >> 1, t->size - 1, t->extra);
1152
1153         /*
1154          * n would have been the node we recursed to - the low bit tells us if
1155          * we recursed left or recursed right.
1156          */
1157         if (likely(!(n & 1))) {
1158                 --inorder;
1159                 if (unlikely(!inorder))
1160                         return btree_bkey_first(b, t);
1161
1162                 f = &base->f[eytzinger1_prev(n >> 1, t->size - 1)];
1163         }
1164
1165         return cacheline_to_bkey(b, t, inorder, f->key_offset);
1166 }
1167
1168 static __always_inline __flatten
1169 struct bkey_packed *__bch2_bset_search(struct btree *b,
1170                                 struct bset_tree *t,
1171                                 struct bpos *search,
1172                                 const struct bkey_packed *lossy_packed_search)
1173 {
1174
1175         /*
1176          * First, we search for a cacheline, then lastly we do a linear search
1177          * within that cacheline.
1178          *
1179          * To search for the cacheline, there's three different possibilities:
1180          *  * The set is too small to have a search tree, so we just do a linear
1181          *    search over the whole set.
1182          *  * The set is the one we're currently inserting into; keeping a full
1183          *    auxiliary search tree up to date would be too expensive, so we
1184          *    use a much simpler lookup table to do a binary search -
1185          *    bset_search_write_set().
1186          *  * Or we use the auxiliary search tree we constructed earlier -
1187          *    bset_search_tree()
1188          */
1189
1190         switch (bset_aux_tree_type(t)) {
1191         case BSET_NO_AUX_TREE:
1192                 return btree_bkey_first(b, t);
1193         case BSET_RW_AUX_TREE:
1194                 return bset_search_write_set(b, t, search);
1195         case BSET_RO_AUX_TREE:
1196                 return bset_search_tree(b, t, search, lossy_packed_search);
1197         default:
1198                 BUG();
1199         }
1200 }
1201
1202 static __always_inline __flatten
1203 struct bkey_packed *bch2_bset_search_linear(struct btree *b,
1204                                 struct bset_tree *t,
1205                                 struct bpos *search,
1206                                 struct bkey_packed *packed_search,
1207                                 const struct bkey_packed *lossy_packed_search,
1208                                 struct bkey_packed *m)
1209 {
1210         if (lossy_packed_search)
1211                 while (m != btree_bkey_last(b, t) &&
1212                        bkey_iter_cmp_p_or_unp(b, m,
1213                                         lossy_packed_search, search) < 0)
1214                         m = bkey_p_next(m);
1215
1216         if (!packed_search)
1217                 while (m != btree_bkey_last(b, t) &&
1218                        bkey_iter_pos_cmp(b, m, search) < 0)
1219                         m = bkey_p_next(m);
1220
1221         if (bch2_expensive_debug_checks) {
1222                 struct bkey_packed *prev = bch2_bkey_prev_all(b, t, m);
1223
1224                 BUG_ON(prev &&
1225                        bkey_iter_cmp_p_or_unp(b, prev,
1226                                         packed_search, search) >= 0);
1227         }
1228
1229         return m;
1230 }
1231
1232 /* Btree node iterator */
1233
1234 static inline void __bch2_btree_node_iter_push(struct btree_node_iter *iter,
1235                               struct btree *b,
1236                               const struct bkey_packed *k,
1237                               const struct bkey_packed *end)
1238 {
1239         if (k != end) {
1240                 struct btree_node_iter_set *pos;
1241
1242                 btree_node_iter_for_each(iter, pos)
1243                         ;
1244
1245                 BUG_ON(pos >= iter->data + ARRAY_SIZE(iter->data));
1246                 *pos = (struct btree_node_iter_set) {
1247                         __btree_node_key_to_offset(b, k),
1248                         __btree_node_key_to_offset(b, end)
1249                 };
1250         }
1251 }
1252
1253 void bch2_btree_node_iter_push(struct btree_node_iter *iter,
1254                                struct btree *b,
1255                                const struct bkey_packed *k,
1256                                const struct bkey_packed *end)
1257 {
1258         __bch2_btree_node_iter_push(iter, b, k, end);
1259         bch2_btree_node_iter_sort(iter, b);
1260 }
1261
1262 noinline __flatten __cold
1263 static void btree_node_iter_init_pack_failed(struct btree_node_iter *iter,
1264                               struct btree *b, struct bpos *search)
1265 {
1266         struct bkey_packed *k;
1267
1268         trace_bkey_pack_pos_fail(search);
1269
1270         bch2_btree_node_iter_init_from_start(iter, b);
1271
1272         while ((k = bch2_btree_node_iter_peek(iter, b)) &&
1273                bkey_iter_pos_cmp(b, k, search) < 0)
1274                 bch2_btree_node_iter_advance(iter, b);
1275 }
1276
1277 /**
1278  * bch2_btree_node_iter_init - initialize a btree node iterator, starting from a
1279  * given position
1280  *
1281  * @iter:       iterator to initialize
1282  * @b:          btree node to search
1283  * @search:     search key
1284  *
1285  * Main entry point to the lookup code for individual btree nodes:
1286  *
1287  * NOTE:
1288  *
1289  * When you don't filter out deleted keys, btree nodes _do_ contain duplicate
1290  * keys. This doesn't matter for most code, but it does matter for lookups.
1291  *
1292  * Some adjacent keys with a string of equal keys:
1293  *      i j k k k k l m
1294  *
1295  * If you search for k, the lookup code isn't guaranteed to return you any
1296  * specific k. The lookup code is conceptually doing a binary search and
1297  * iterating backwards is very expensive so if the pivot happens to land at the
1298  * last k that's what you'll get.
1299  *
1300  * This works out ok, but it's something to be aware of:
1301  *
1302  *  - For non extents, we guarantee that the live key comes last - see
1303  *    btree_node_iter_cmp(), keys_out_of_order(). So the duplicates you don't
1304  *    see will only be deleted keys you don't care about.
1305  *
1306  *  - For extents, deleted keys sort last (see the comment at the top of this
1307  *    file). But when you're searching for extents, you actually want the first
1308  *    key strictly greater than your search key - an extent that compares equal
1309  *    to the search key is going to have 0 sectors after the search key.
1310  *
1311  *    But this does mean that we can't just search for
1312  *    bpos_successor(start_of_range) to get the first extent that overlaps with
1313  *    the range we want - if we're unlucky and there's an extent that ends
1314  *    exactly where we searched, then there could be a deleted key at the same
1315  *    position and we'd get that when we search instead of the preceding extent
1316  *    we needed.
1317  *
1318  *    So we've got to search for start_of_range, then after the lookup iterate
1319  *    past any extents that compare equal to the position we searched for.
1320  */
1321 __flatten
1322 void bch2_btree_node_iter_init(struct btree_node_iter *iter,
1323                                struct btree *b, struct bpos *search)
1324 {
1325         struct bkey_packed p, *packed_search = NULL;
1326         struct btree_node_iter_set *pos = iter->data;
1327         struct bkey_packed *k[MAX_BSETS];
1328         unsigned i;
1329
1330         EBUG_ON(bpos_lt(*search, b->data->min_key));
1331         EBUG_ON(bpos_gt(*search, b->data->max_key));
1332         bset_aux_tree_verify(b);
1333
1334         memset(iter, 0, sizeof(*iter));
1335
1336         switch (bch2_bkey_pack_pos_lossy(&p, *search, b)) {
1337         case BKEY_PACK_POS_EXACT:
1338                 packed_search = &p;
1339                 break;
1340         case BKEY_PACK_POS_SMALLER:
1341                 packed_search = NULL;
1342                 break;
1343         case BKEY_PACK_POS_FAIL:
1344                 btree_node_iter_init_pack_failed(iter, b, search);
1345                 return;
1346         }
1347
1348         for (i = 0; i < b->nsets; i++) {
1349                 k[i] = __bch2_bset_search(b, b->set + i, search, &p);
1350                 prefetch_four_cachelines(k[i]);
1351         }
1352
1353         for (i = 0; i < b->nsets; i++) {
1354                 struct bset_tree *t = b->set + i;
1355                 struct bkey_packed *end = btree_bkey_last(b, t);
1356
1357                 k[i] = bch2_bset_search_linear(b, t, search,
1358                                                packed_search, &p, k[i]);
1359                 if (k[i] != end)
1360                         *pos++ = (struct btree_node_iter_set) {
1361                                 __btree_node_key_to_offset(b, k[i]),
1362                                 __btree_node_key_to_offset(b, end)
1363                         };
1364         }
1365
1366         bch2_btree_node_iter_sort(iter, b);
1367 }
1368
1369 void bch2_btree_node_iter_init_from_start(struct btree_node_iter *iter,
1370                                           struct btree *b)
1371 {
1372         struct bset_tree *t;
1373
1374         memset(iter, 0, sizeof(*iter));
1375
1376         for_each_bset(b, t)
1377                 __bch2_btree_node_iter_push(iter, b,
1378                                            btree_bkey_first(b, t),
1379                                            btree_bkey_last(b, t));
1380         bch2_btree_node_iter_sort(iter, b);
1381 }
1382
1383 struct bkey_packed *bch2_btree_node_iter_bset_pos(struct btree_node_iter *iter,
1384                                                   struct btree *b,
1385                                                   struct bset_tree *t)
1386 {
1387         struct btree_node_iter_set *set;
1388
1389         btree_node_iter_for_each(iter, set)
1390                 if (set->end == t->end_offset)
1391                         return __btree_node_offset_to_key(b, set->k);
1392
1393         return btree_bkey_last(b, t);
1394 }
1395
1396 static inline bool btree_node_iter_sort_two(struct btree_node_iter *iter,
1397                                             struct btree *b,
1398                                             unsigned first)
1399 {
1400         bool ret;
1401
1402         if ((ret = (btree_node_iter_cmp(b,
1403                                         iter->data[first],
1404                                         iter->data[first + 1]) > 0)))
1405                 swap(iter->data[first], iter->data[first + 1]);
1406         return ret;
1407 }
1408
1409 void bch2_btree_node_iter_sort(struct btree_node_iter *iter,
1410                                struct btree *b)
1411 {
1412         /* unrolled bubble sort: */
1413
1414         if (!__btree_node_iter_set_end(iter, 2)) {
1415                 btree_node_iter_sort_two(iter, b, 0);
1416                 btree_node_iter_sort_two(iter, b, 1);
1417         }
1418
1419         if (!__btree_node_iter_set_end(iter, 1))
1420                 btree_node_iter_sort_two(iter, b, 0);
1421 }
1422
1423 void bch2_btree_node_iter_set_drop(struct btree_node_iter *iter,
1424                                    struct btree_node_iter_set *set)
1425 {
1426         struct btree_node_iter_set *last =
1427                 iter->data + ARRAY_SIZE(iter->data) - 1;
1428
1429         memmove(&set[0], &set[1], (void *) last - (void *) set);
1430         *last = (struct btree_node_iter_set) { 0, 0 };
1431 }
1432
1433 static inline void __bch2_btree_node_iter_advance(struct btree_node_iter *iter,
1434                                                   struct btree *b)
1435 {
1436         iter->data->k += __bch2_btree_node_iter_peek_all(iter, b)->u64s;
1437
1438         EBUG_ON(iter->data->k > iter->data->end);
1439
1440         if (unlikely(__btree_node_iter_set_end(iter, 0))) {
1441                 /* avoid an expensive memmove call: */
1442                 iter->data[0] = iter->data[1];
1443                 iter->data[1] = iter->data[2];
1444                 iter->data[2] = (struct btree_node_iter_set) { 0, 0 };
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(const struct btree *b, struct bset_stats *stats)
1547 {
1548         const 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                 prt_printf(out,
1591                        "    failed unpacked at depth %u\n"
1592                        "\t",
1593                        ilog2(j));
1594                 bch2_bpos_to_text(out, uk.p);
1595                 prt_printf(out, "\n");
1596                 break;
1597         }
1598 }