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

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "bcachefs.h"
   4 #include "bkey_methods.h"
   5 #include "bkey_buf.h"
   6 #include "btree_cache.h"
   7 #include "btree_iter.h"
   8 #include "btree_key_cache.h"
   9 #include "btree_locking.h"
  10 #include "btree_update.h"
  11 #include "debug.h"
  12 #include "error.h"
  13 #include "extents.h"
  14 #include "journal.h"
  15 #include "recovery.h"
  16 #include "replicas.h"
  17 #include "subvolume.h"
  18
  19 #include <linux/random.h>
  20 #include <linux/prefetch.h>
  21 #include <trace/events/bcachefs.h>
  22
  23 static inline void btree_path_list_remove(struct btree_trans *, struct btree_path *);
  24 static inline void btree_path_list_add(struct btree_trans *, struct btree_path *,
  25                                        struct btree_path *);
  26
  27 static inline unsigned long btree_iter_ip_allocated(struct btree_iter *iter)
  28 {
  29 #ifdef TRACK_PATH_ALLOCATED
  30         return iter->ip_allocated;
  31 #else
  32         return 0;
  33 #endif
  34 }
  35
  36 static struct btree_path *btree_path_alloc(struct btree_trans *, struct btree_path *);
  37
  38 /*
  39  * Unlocks before scheduling
  40  * Note: does not revalidate iterator
  41  */
  42 static inline int bch2_trans_cond_resched(struct btree_trans *trans)
  43 {
  44         if (need_resched() || race_fault()) {
  45                 bch2_trans_unlock(trans);
  46                 schedule();
  47                 return bch2_trans_relock(trans);
  48         } else {
  49                 return 0;
  50         }
  51 }
  52
  53 static inline int __btree_path_cmp(const struct btree_path *l,
  54                                    enum btree_id        r_btree_id,
  55                                    bool                 r_cached,
  56                                    struct bpos          r_pos,
  57                                    unsigned             r_level)
  58 {
  59         /*
  60          * Must match lock ordering as defined by __bch2_btree_node_lock:
  61          */
  62         return   cmp_int(l->btree_id,   r_btree_id) ?:
  63                  cmp_int((int) l->cached,       (int) r_cached) ?:
  64                  bpos_cmp(l->pos,       r_pos) ?:
  65                 -cmp_int(l->level,      r_level);
  66 }
  67
  68 static inline int btree_path_cmp(const struct btree_path *l,
  69                                  const struct btree_path *r)
  70 {
  71         return __btree_path_cmp(l, r->btree_id, r->cached, r->pos, r->level);
  72 }
  73
  74 static inline struct bpos bkey_successor(struct btree_iter *iter, struct bpos p)
  75 {
  76         /* Are we iterating over keys in all snapshots? */
  77         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  78                 p = bpos_successor(p);
  79         } else {
  80                 p = bpos_nosnap_successor(p);
  81                 p.snapshot = iter->snapshot;
  82         }
  83
  84         return p;
  85 }
  86
  87 static inline struct bpos bkey_predecessor(struct btree_iter *iter, struct bpos p)
  88 {
  89         /* Are we iterating over keys in all snapshots? */
  90         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  91                 p = bpos_predecessor(p);
  92         } else {
  93                 p = bpos_nosnap_predecessor(p);
  94                 p.snapshot = iter->snapshot;
  95         }
  96
  97         return p;
  98 }
  99
 100 static inline struct bpos btree_iter_search_key(struct btree_iter *iter)
 101 {
 102         struct bpos pos = iter->pos;
 103
 104         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
 105             !bkey_eq(pos, POS_MAX))
 106                 pos = bkey_successor(iter, pos);
 107         return pos;
 108 }
 109
 110 static inline bool btree_path_pos_before_node(struct btree_path *path,
 111                                               struct btree *b)
 112 {
 113         return bpos_lt(path->pos, b->data->min_key);
 114 }
 115
 116 static inline bool btree_path_pos_after_node(struct btree_path *path,
 117                                              struct btree *b)
 118 {
 119         return bpos_gt(path->pos, b->key.k.p);
 120 }
 121
 122 static inline bool btree_path_pos_in_node(struct btree_path *path,
 123                                           struct btree *b)
 124 {
 125         return path->btree_id == b->c.btree_id &&
 126                 !btree_path_pos_before_node(path, b) &&
 127                 !btree_path_pos_after_node(path, b);
 128 }
 129
 130 /* Btree iterator: */
 131
 132 #ifdef CONFIG_BCACHEFS_DEBUG
 133
 134 static void bch2_btree_path_verify_cached(struct btree_trans *trans,
 135                                           struct btree_path *path)
 136 {
 137         struct bkey_cached *ck;
 138         bool locked = btree_node_locked(path, 0);
 139
 140         if (!bch2_btree_node_relock(trans, path, 0))
 141                 return;
 142
 143         ck = (void *) path->l[0].b;
 144         BUG_ON(ck->key.btree_id != path->btree_id ||
 145                !bkey_eq(ck->key.pos, path->pos));
 146
 147         if (!locked)
 148                 btree_node_unlock(trans, path, 0);
 149 }
 150
 151 static void bch2_btree_path_verify_level(struct btree_trans *trans,
 152                                 struct btree_path *path, unsigned level)
 153 {
 154         struct btree_path_level *l;
 155         struct btree_node_iter tmp;
 156         bool locked;
 157         struct bkey_packed *p, *k;
 158         struct printbuf buf1 = PRINTBUF;
 159         struct printbuf buf2 = PRINTBUF;
 160         struct printbuf buf3 = PRINTBUF;
 161         const char *msg;
 162
 163         if (!bch2_debug_check_iterators)
 164                 return;
 165
 166         l       = &path->l[level];
 167         tmp     = l->iter;
 168         locked  = btree_node_locked(path, level);
 169
 170         if (path->cached) {
 171                 if (!level)
 172                         bch2_btree_path_verify_cached(trans, path);
 173                 return;
 174         }
 175
 176         if (!btree_path_node(path, level))
 177                 return;
 178
 179         if (!bch2_btree_node_relock_notrace(trans, path, level))
 180                 return;
 181
 182         BUG_ON(!btree_path_pos_in_node(path, l->b));
 183
 184         bch2_btree_node_iter_verify(&l->iter, l->b);
 185
 186         /*
 187          * For interior nodes, the iterator will have skipped past deleted keys:
 188          */
 189         p = level
 190                 ? bch2_btree_node_iter_prev(&tmp, l->b)
 191                 : bch2_btree_node_iter_prev_all(&tmp, l->b);
 192         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
 193
 194         if (p && bkey_iter_pos_cmp(l->b, p, &path->pos) >= 0) {
 195                 msg = "before";
 196                 goto err;
 197         }
 198
 199         if (k && bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
 200                 msg = "after";
 201                 goto err;
 202         }
 203
 204         if (!locked)
 205                 btree_node_unlock(trans, path, level);
 206         return;
 207 err:
 208         bch2_bpos_to_text(&buf1, path->pos);
 209
 210         if (p) {
 211                 struct bkey uk = bkey_unpack_key(l->b, p);
 212
 213                 bch2_bkey_to_text(&buf2, &uk);
 214         } else {
 215                 prt_printf(&buf2, "(none)");
 216         }
 217
 218         if (k) {
 219                 struct bkey uk = bkey_unpack_key(l->b, k);
 220
 221                 bch2_bkey_to_text(&buf3, &uk);
 222         } else {
 223                 prt_printf(&buf3, "(none)");
 224         }
 225
 226         panic("path should be %s key at level %u:\n"
 227               "path pos %s\n"
 228               "prev key %s\n"
 229               "cur  key %s\n",
 230               msg, level, buf1.buf, buf2.buf, buf3.buf);
 231 }
 232
 233 static void bch2_btree_path_verify(struct btree_trans *trans,
 234                                    struct btree_path *path)
 235 {
 236         struct bch_fs *c = trans->c;
 237         unsigned i;
 238
 239         EBUG_ON(path->btree_id >= BTREE_ID_NR);
 240
 241         for (i = 0; i < (!path->cached ? BTREE_MAX_DEPTH : 1); i++) {
 242                 if (!path->l[i].b) {
 243                         BUG_ON(!path->cached &&
 244                                c->btree_roots[path->btree_id].b->c.level > i);
 245                         break;
 246                 }
 247
 248                 bch2_btree_path_verify_level(trans, path, i);
 249         }
 250
 251         bch2_btree_path_verify_locks(path);
 252 }
 253
 254 void bch2_trans_verify_paths(struct btree_trans *trans)
 255 {
 256         struct btree_path *path;
 257
 258         trans_for_each_path(trans, path)
 259                 bch2_btree_path_verify(trans, path);
 260 }
 261
 262 static void bch2_btree_iter_verify(struct btree_iter *iter)
 263 {
 264         struct btree_trans *trans = iter->trans;
 265
 266         BUG_ON(iter->btree_id >= BTREE_ID_NR);
 267
 268         BUG_ON(!!(iter->flags & BTREE_ITER_CACHED) != iter->path->cached);
 269
 270         BUG_ON((iter->flags & BTREE_ITER_IS_EXTENTS) &&
 271                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS));
 272
 273         BUG_ON(!(iter->flags & __BTREE_ITER_ALL_SNAPSHOTS) &&
 274                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 275                !btree_type_has_snapshots(iter->btree_id));
 276
 277         if (iter->update_path)
 278                 bch2_btree_path_verify(trans, iter->update_path);
 279         bch2_btree_path_verify(trans, iter->path);
 280 }
 281
 282 static void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter)
 283 {
 284         BUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
 285                !iter->pos.snapshot);
 286
 287         BUG_ON(!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 288                iter->pos.snapshot != iter->snapshot);
 289
 290         BUG_ON(bkey_lt(iter->pos, bkey_start_pos(&iter->k)) ||
 291                bkey_gt(iter->pos, iter->k.p));
 292 }
 293
 294 static int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k)
 295 {
 296         struct btree_trans *trans = iter->trans;
 297         struct btree_iter copy;
 298         struct bkey_s_c prev;
 299         int ret = 0;
 300
 301         if (!bch2_debug_check_iterators)
 302                 return 0;
 303
 304         if (!(iter->flags & BTREE_ITER_FILTER_SNAPSHOTS))
 305                 return 0;
 306
 307         if (bkey_err(k) || !k.k)
 308                 return 0;
 309
 310         BUG_ON(!bch2_snapshot_is_ancestor(trans->c,
 311                                           iter->snapshot,
 312                                           k.k->p.snapshot));
 313
 314         bch2_trans_iter_init(trans, &copy, iter->btree_id, iter->pos,
 315                              BTREE_ITER_NOPRESERVE|
 316                              BTREE_ITER_ALL_SNAPSHOTS);
 317         prev = bch2_btree_iter_prev(&copy);
 318         if (!prev.k)
 319                 goto out;
 320
 321         ret = bkey_err(prev);
 322         if (ret)
 323                 goto out;
 324
 325         if (bkey_eq(prev.k->p, k.k->p) &&
 326             bch2_snapshot_is_ancestor(trans->c, iter->snapshot,
 327                                       prev.k->p.snapshot) > 0) {
 328                 struct printbuf buf1 = PRINTBUF, buf2 = PRINTBUF;
 329
 330                 bch2_bkey_to_text(&buf1, k.k);
 331                 bch2_bkey_to_text(&buf2, prev.k);
 332
 333                 panic("iter snap %u\n"
 334                       "k    %s\n"
 335                       "prev %s\n",
 336                       iter->snapshot,
 337                       buf1.buf, buf2.buf);
 338         }
 339 out:
 340         bch2_trans_iter_exit(trans, &copy);
 341         return ret;
 342 }
 343
 344 void bch2_assert_pos_locked(struct btree_trans *trans, enum btree_id id,
 345                             struct bpos pos, bool key_cache)
 346 {
 347         struct btree_path *path;
 348         unsigned idx;
 349         struct printbuf buf = PRINTBUF;
 350
 351         btree_trans_sort_paths(trans);
 352
 353         trans_for_each_path_inorder(trans, path, idx) {
 354                 int cmp = cmp_int(path->btree_id, id) ?:
 355                         cmp_int(path->cached, key_cache);
 356
 357                 if (cmp > 0)
 358                         break;
 359                 if (cmp < 0)
 360                         continue;
 361
 362                 if (!btree_node_locked(path, 0) ||
 363                     !path->should_be_locked)
 364                         continue;
 365
 366                 if (!key_cache) {
 367                         if (bkey_ge(pos, path->l[0].b->data->min_key) &&
 368                             bkey_le(pos, path->l[0].b->key.k.p))
 369                                 return;
 370                 } else {
 371                         if (bkey_eq(pos, path->pos))
 372                                 return;
 373                 }
 374         }
 375
 376         bch2_dump_trans_paths_updates(trans);
 377         bch2_bpos_to_text(&buf, pos);
 378
 379         panic("not locked: %s %s%s\n",
 380               bch2_btree_ids[id], buf.buf,
 381               key_cache ? " cached" : "");
 382 }
 383
 384 #else
 385
 386 static inline void bch2_btree_path_verify_level(struct btree_trans *trans,
 387                                                 struct btree_path *path, unsigned l) {}
 388 static inline void bch2_btree_path_verify(struct btree_trans *trans,
 389                                           struct btree_path *path) {}
 390 static inline void bch2_btree_iter_verify(struct btree_iter *iter) {}
 391 static inline void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter) {}
 392 static inline int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k) { return 0; }
 393
 394 #endif
 395
 396 /* Btree path: fixups after btree updates */
 397
 398 static void btree_node_iter_set_set_pos(struct btree_node_iter *iter,
 399                                         struct btree *b,
 400                                         struct bset_tree *t,
 401                                         struct bkey_packed *k)
 402 {
 403         struct btree_node_iter_set *set;
 404
 405         btree_node_iter_for_each(iter, set)
 406                 if (set->end == t->end_offset) {
 407                         set->k = __btree_node_key_to_offset(b, k);
 408                         bch2_btree_node_iter_sort(iter, b);
 409                         return;
 410                 }
 411
 412         bch2_btree_node_iter_push(iter, b, k, btree_bkey_last(b, t));
 413 }
 414
 415 static void __bch2_btree_path_fix_key_modified(struct btree_path *path,
 416                                                struct btree *b,
 417                                                struct bkey_packed *where)
 418 {
 419         struct btree_path_level *l = &path->l[b->c.level];
 420
 421         if (where != bch2_btree_node_iter_peek_all(&l->iter, l->b))
 422                 return;
 423
 424         if (bkey_iter_pos_cmp(l->b, where, &path->pos) < 0)
 425                 bch2_btree_node_iter_advance(&l->iter, l->b);
 426 }
 427
 428 void bch2_btree_path_fix_key_modified(struct btree_trans *trans,
 429                                       struct btree *b,
 430                                       struct bkey_packed *where)
 431 {
 432         struct btree_path *path;
 433
 434         trans_for_each_path_with_node(trans, b, path) {
 435                 __bch2_btree_path_fix_key_modified(path, b, where);
 436                 bch2_btree_path_verify_level(trans, path, b->c.level);
 437         }
 438 }
 439
 440 static void __bch2_btree_node_iter_fix(struct btree_path *path,
 441                                        struct btree *b,
 442                                        struct btree_node_iter *node_iter,
 443                                        struct bset_tree *t,
 444                                        struct bkey_packed *where,
 445                                        unsigned clobber_u64s,
 446                                        unsigned new_u64s)
 447 {
 448         const struct bkey_packed *end = btree_bkey_last(b, t);
 449         struct btree_node_iter_set *set;
 450         unsigned offset = __btree_node_key_to_offset(b, where);
 451         int shift = new_u64s - clobber_u64s;
 452         unsigned old_end = t->end_offset - shift;
 453         unsigned orig_iter_pos = node_iter->data[0].k;
 454         bool iter_current_key_modified =
 455                 orig_iter_pos >= offset &&
 456                 orig_iter_pos <= offset + clobber_u64s;
 457
 458         btree_node_iter_for_each(node_iter, set)
 459                 if (set->end == old_end)
 460                         goto found;
 461
 462         /* didn't find the bset in the iterator - might have to readd it: */
 463         if (new_u64s &&
 464             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 465                 bch2_btree_node_iter_push(node_iter, b, where, end);
 466                 goto fixup_done;
 467         } else {
 468                 /* Iterator is after key that changed */
 469                 return;
 470         }
 471 found:
 472         set->end = t->end_offset;
 473
 474         /* Iterator hasn't gotten to the key that changed yet: */
 475         if (set->k < offset)
 476                 return;
 477
 478         if (new_u64s &&
 479             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 480                 set->k = offset;
 481         } else if (set->k < offset + clobber_u64s) {
 482                 set->k = offset + new_u64s;
 483                 if (set->k == set->end)
 484                         bch2_btree_node_iter_set_drop(node_iter, set);
 485         } else {
 486                 /* Iterator is after key that changed */
 487                 set->k = (int) set->k + shift;
 488                 return;
 489         }
 490
 491         bch2_btree_node_iter_sort(node_iter, b);
 492 fixup_done:
 493         if (node_iter->data[0].k != orig_iter_pos)
 494                 iter_current_key_modified = true;
 495
 496         /*
 497          * When a new key is added, and the node iterator now points to that
 498          * key, the iterator might have skipped past deleted keys that should
 499          * come after the key the iterator now points to. We have to rewind to
 500          * before those deleted keys - otherwise
 501          * bch2_btree_node_iter_prev_all() breaks:
 502          */
 503         if (!bch2_btree_node_iter_end(node_iter) &&
 504             iter_current_key_modified &&
 505             b->c.level) {
 506                 struct bset_tree *t;
 507                 struct bkey_packed *k, *k2, *p;
 508
 509                 k = bch2_btree_node_iter_peek_all(node_iter, b);
 510
 511                 for_each_bset(b, t) {
 512                         bool set_pos = false;
 513
 514                         if (node_iter->data[0].end == t->end_offset)
 515                                 continue;
 516
 517                         k2 = bch2_btree_node_iter_bset_pos(node_iter, b, t);
 518
 519                         while ((p = bch2_bkey_prev_all(b, t, k2)) &&
 520                                bkey_iter_cmp(b, k, p) < 0) {
 521                                 k2 = p;
 522                                 set_pos = true;
 523                         }
 524
 525                         if (set_pos)
 526                                 btree_node_iter_set_set_pos(node_iter,
 527                                                             b, t, k2);
 528                 }
 529         }
 530 }
 531
 532 void bch2_btree_node_iter_fix(struct btree_trans *trans,
 533                               struct btree_path *path,
 534                               struct btree *b,
 535                               struct btree_node_iter *node_iter,
 536                               struct bkey_packed *where,
 537                               unsigned clobber_u64s,
 538                               unsigned new_u64s)
 539 {
 540         struct bset_tree *t = bch2_bkey_to_bset_inlined(b, where);
 541         struct btree_path *linked;
 542
 543         if (node_iter != &path->l[b->c.level].iter) {
 544                 __bch2_btree_node_iter_fix(path, b, node_iter, t,
 545                                            where, clobber_u64s, new_u64s);
 546
 547                 if (bch2_debug_check_iterators)
 548                         bch2_btree_node_iter_verify(node_iter, b);
 549         }
 550
 551         trans_for_each_path_with_node(trans, b, linked) {
 552                 __bch2_btree_node_iter_fix(linked, b,
 553                                            &linked->l[b->c.level].iter, t,
 554                                            where, clobber_u64s, new_u64s);
 555                 bch2_btree_path_verify_level(trans, linked, b->c.level);
 556         }
 557 }
 558
 559 /* Btree path level: pointer to a particular btree node and node iter */
 560
 561 static inline struct bkey_s_c __btree_iter_unpack(struct bch_fs *c,
 562                                                   struct btree_path_level *l,
 563                                                   struct bkey *u,
 564                                                   struct bkey_packed *k)
 565 {
 566         if (unlikely(!k)) {
 567                 /*
 568                  * signal to bch2_btree_iter_peek_slot() that we're currently at
 569                  * a hole
 570                  */
 571                 u->type = KEY_TYPE_deleted;
 572                 return bkey_s_c_null;
 573         }
 574
 575         return bkey_disassemble(l->b, k, u);
 576 }
 577
 578 static inline struct bkey_s_c btree_path_level_peek_all(struct bch_fs *c,
 579                                                         struct btree_path_level *l,
 580                                                         struct bkey *u)
 581 {
 582         return __btree_iter_unpack(c, l, u,
 583                         bch2_btree_node_iter_peek_all(&l->iter, l->b));
 584 }
 585
 586 static inline struct bkey_s_c btree_path_level_peek(struct btree_trans *trans,
 587                                                     struct btree_path *path,
 588                                                     struct btree_path_level *l,
 589                                                     struct bkey *u)
 590 {
 591         struct bkey_s_c k = __btree_iter_unpack(trans->c, l, u,
 592                         bch2_btree_node_iter_peek(&l->iter, l->b));
 593
 594         path->pos = k.k ? k.k->p : l->b->key.k.p;
 595         trans->paths_sorted = false;
 596         bch2_btree_path_verify_level(trans, path, l - path->l);
 597         return k;
 598 }
 599
 600 static inline struct bkey_s_c btree_path_level_prev(struct btree_trans *trans,
 601                                                     struct btree_path *path,
 602                                                     struct btree_path_level *l,
 603                                                     struct bkey *u)
 604 {
 605         struct bkey_s_c k = __btree_iter_unpack(trans->c, l, u,
 606                         bch2_btree_node_iter_prev(&l->iter, l->b));
 607
 608         path->pos = k.k ? k.k->p : l->b->data->min_key;
 609         trans->paths_sorted = false;
 610         bch2_btree_path_verify_level(trans, path, l - path->l);
 611         return k;
 612 }
 613
 614 static inline bool btree_path_advance_to_pos(struct btree_path *path,
 615                                              struct btree_path_level *l,
 616                                              int max_advance)
 617 {
 618         struct bkey_packed *k;
 619         int nr_advanced = 0;
 620
 621         while ((k = bch2_btree_node_iter_peek_all(&l->iter, l->b)) &&
 622                bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
 623                 if (max_advance > 0 && nr_advanced >= max_advance)
 624                         return false;
 625
 626                 bch2_btree_node_iter_advance(&l->iter, l->b);
 627                 nr_advanced++;
 628         }
 629
 630         return true;
 631 }
 632
 633 static inline void __btree_path_level_init(struct btree_path *path,
 634                                            unsigned level)
 635 {
 636         struct btree_path_level *l = &path->l[level];
 637
 638         bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
 639
 640         /*
 641          * Iterators to interior nodes should always be pointed at the first non
 642          * whiteout:
 643          */
 644         if (level)
 645                 bch2_btree_node_iter_peek(&l->iter, l->b);
 646 }
 647
 648 void bch2_btree_path_level_init(struct btree_trans *trans,
 649                                 struct btree_path *path,
 650                                 struct btree *b)
 651 {
 652         BUG_ON(path->cached);
 653
 654         EBUG_ON(!btree_path_pos_in_node(path, b));
 655         EBUG_ON(b->c.lock.state.seq & 1);
 656
 657         path->l[b->c.level].lock_seq = b->c.lock.state.seq;
 658         path->l[b->c.level].b = b;
 659         __btree_path_level_init(path, b->c.level);
 660 }
 661
 662 /* Btree path: fixups after btree node updates: */
 663
 664 static void bch2_trans_revalidate_updates_in_node(struct btree_trans *trans, struct btree *b)
 665 {
 666         struct bch_fs *c = trans->c;
 667         struct btree_insert_entry *i;
 668
 669         trans_for_each_update(trans, i)
 670                 if (!i->cached &&
 671                     i->level    == b->c.level &&
 672                     i->btree_id == b->c.btree_id &&
 673                     bpos_cmp(i->k->k.p, b->data->min_key) >= 0 &&
 674                     bpos_cmp(i->k->k.p, b->data->max_key) <= 0) {
 675                         i->old_v = bch2_btree_path_peek_slot(i->path, &i->old_k).v;
 676
 677                         if (unlikely(trans->journal_replay_not_finished)) {
 678                                 struct bkey_i *j_k =
 679                                         bch2_journal_keys_peek_slot(c, i->btree_id, i->level,
 680                                                                     i->k->k.p);
 681
 682                                 if (j_k) {
 683                                         i->old_k = j_k->k;
 684                                         i->old_v = &j_k->v;
 685                                 }
 686                         }
 687                 }
 688 }
 689
 690 /*
 691  * A btree node is being replaced - update the iterator to point to the new
 692  * node:
 693  */
 694 void bch2_trans_node_add(struct btree_trans *trans, struct btree *b)
 695 {
 696         struct btree_path *path;
 697
 698         trans_for_each_path(trans, path)
 699                 if (path->uptodate == BTREE_ITER_UPTODATE &&
 700                     !path->cached &&
 701                     btree_path_pos_in_node(path, b)) {
 702                         enum btree_node_locked_type t =
 703                                 btree_lock_want(path, b->c.level);
 704
 705                         if (t != BTREE_NODE_UNLOCKED) {
 706                                 btree_node_unlock(trans, path, b->c.level);
 707                                 six_lock_increment(&b->c.lock, t);
 708                                 mark_btree_node_locked(trans, path, b->c.level, t);
 709                         }
 710
 711                         bch2_btree_path_level_init(trans, path, b);
 712                 }
 713
 714         bch2_trans_revalidate_updates_in_node(trans, b);
 715 }
 716
 717 /*
 718  * A btree node has been modified in such a way as to invalidate iterators - fix
 719  * them:
 720  */
 721 void bch2_trans_node_reinit_iter(struct btree_trans *trans, struct btree *b)
 722 {
 723         struct btree_path *path;
 724
 725         trans_for_each_path_with_node(trans, b, path)
 726                 __btree_path_level_init(path, b->c.level);
 727
 728         bch2_trans_revalidate_updates_in_node(trans, b);
 729 }
 730
 731 /* Btree path: traverse, set_pos: */
 732
 733 static inline int btree_path_lock_root(struct btree_trans *trans,
 734                                        struct btree_path *path,
 735                                        unsigned depth_want,
 736                                        unsigned long trace_ip)
 737 {
 738         struct bch_fs *c = trans->c;
 739         struct btree *b, **rootp = &c->btree_roots[path->btree_id].b;
 740         enum six_lock_type lock_type;
 741         unsigned i;
 742         int ret;
 743
 744         EBUG_ON(path->nodes_locked);
 745
 746         while (1) {
 747                 b = READ_ONCE(*rootp);
 748                 path->level = READ_ONCE(b->c.level);
 749
 750                 if (unlikely(path->level < depth_want)) {
 751                         /*
 752                          * the root is at a lower depth than the depth we want:
 753                          * got to the end of the btree, or we're walking nodes
 754                          * greater than some depth and there are no nodes >=
 755                          * that depth
 756                          */
 757                         path->level = depth_want;
 758                         for (i = path->level; i < BTREE_MAX_DEPTH; i++)
 759                                 path->l[i].b = NULL;
 760                         return 1;
 761                 }
 762
 763                 lock_type = __btree_lock_want(path, path->level);
 764                 ret = btree_node_lock(trans, path, &b->c,
 765                                       path->level, lock_type, trace_ip);
 766                 if (unlikely(ret)) {
 767                         if (bch2_err_matches(ret, BCH_ERR_lock_fail_root_changed))
 768                                 continue;
 769                         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 770                                 return ret;
 771                         BUG();
 772                 }
 773
 774                 if (likely(b == READ_ONCE(*rootp) &&
 775                            b->c.level == path->level &&
 776                            !race_fault())) {
 777                         for (i = 0; i < path->level; i++)
 778                                 path->l[i].b = ERR_PTR(-BCH_ERR_no_btree_node_lock_root);
 779                         path->l[path->level].b = b;
 780                         for (i = path->level + 1; i < BTREE_MAX_DEPTH; i++)
 781                                 path->l[i].b = NULL;
 782
 783                         mark_btree_node_locked(trans, path, path->level, lock_type);
 784                         bch2_btree_path_level_init(trans, path, b);
 785                         return 0;
 786                 }
 787
 788                 six_unlock_type(&b->c.lock, lock_type);
 789         }
 790 }
 791
 792 noinline
 793 static int btree_path_prefetch(struct btree_trans *trans, struct btree_path *path)
 794 {
 795         struct bch_fs *c = trans->c;
 796         struct btree_path_level *l = path_l(path);
 797         struct btree_node_iter node_iter = l->iter;
 798         struct bkey_packed *k;
 799         struct bkey_buf tmp;
 800         unsigned nr = test_bit(BCH_FS_STARTED, &c->flags)
 801                 ? (path->level > 1 ? 0 :  2)
 802                 : (path->level > 1 ? 1 : 16);
 803         bool was_locked = btree_node_locked(path, path->level);
 804         int ret = 0;
 805
 806         bch2_bkey_buf_init(&tmp);
 807
 808         while (nr-- && !ret) {
 809                 if (!bch2_btree_node_relock(trans, path, path->level))
 810                         break;
 811
 812                 bch2_btree_node_iter_advance(&node_iter, l->b);
 813                 k = bch2_btree_node_iter_peek(&node_iter, l->b);
 814                 if (!k)
 815                         break;
 816
 817                 bch2_bkey_buf_unpack(&tmp, c, l->b, k);
 818                 ret = bch2_btree_node_prefetch(trans, path, tmp.k, path->btree_id,
 819                                                path->level - 1);
 820         }
 821
 822         if (!was_locked)
 823                 btree_node_unlock(trans, path, path->level);
 824
 825         bch2_bkey_buf_exit(&tmp, c);
 826         return ret;
 827 }
 828
 829 static int btree_path_prefetch_j(struct btree_trans *trans, struct btree_path *path,
 830                                  struct btree_and_journal_iter *jiter)
 831 {
 832         struct bch_fs *c = trans->c;
 833         struct bkey_s_c k;
 834         struct bkey_buf tmp;
 835         unsigned nr = test_bit(BCH_FS_STARTED, &c->flags)
 836                 ? (path->level > 1 ? 0 :  2)
 837                 : (path->level > 1 ? 1 : 16);
 838         bool was_locked = btree_node_locked(path, path->level);
 839         int ret = 0;
 840
 841         bch2_bkey_buf_init(&tmp);
 842
 843         while (nr-- && !ret) {
 844                 if (!bch2_btree_node_relock(trans, path, path->level))
 845                         break;
 846
 847                 bch2_btree_and_journal_iter_advance(jiter);
 848                 k = bch2_btree_and_journal_iter_peek(jiter);
 849                 if (!k.k)
 850                         break;
 851
 852                 bch2_bkey_buf_reassemble(&tmp, c, k);
 853                 ret = bch2_btree_node_prefetch(trans, path, tmp.k, path->btree_id,
 854                                                path->level - 1);
 855         }
 856
 857         if (!was_locked)
 858                 btree_node_unlock(trans, path, path->level);
 859
 860         bch2_bkey_buf_exit(&tmp, c);
 861         return ret;
 862 }
 863
 864 static noinline void btree_node_mem_ptr_set(struct btree_trans *trans,
 865                                             struct btree_path *path,
 866                                             unsigned plevel, struct btree *b)
 867 {
 868         struct btree_path_level *l = &path->l[plevel];
 869         bool locked = btree_node_locked(path, plevel);
 870         struct bkey_packed *k;
 871         struct bch_btree_ptr_v2 *bp;
 872
 873         if (!bch2_btree_node_relock(trans, path, plevel))
 874                 return;
 875
 876         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
 877         BUG_ON(k->type != KEY_TYPE_btree_ptr_v2);
 878
 879         bp = (void *) bkeyp_val(&l->b->format, k);
 880         bp->mem_ptr = (unsigned long)b;
 881
 882         if (!locked)
 883                 btree_node_unlock(trans, path, plevel);
 884 }
 885
 886 static noinline int btree_node_iter_and_journal_peek(struct btree_trans *trans,
 887                                                      struct btree_path *path,
 888                                                      unsigned flags,
 889                                                      struct bkey_buf *out)
 890 {
 891         struct bch_fs *c = trans->c;
 892         struct btree_path_level *l = path_l(path);
 893         struct btree_and_journal_iter jiter;
 894         struct bkey_s_c k;
 895         int ret = 0;
 896
 897         __bch2_btree_and_journal_iter_init_node_iter(&jiter, c, l->b, l->iter, path->pos);
 898
 899         k = bch2_btree_and_journal_iter_peek(&jiter);
 900
 901         bch2_bkey_buf_reassemble(out, c, k);
 902
 903         if (flags & BTREE_ITER_PREFETCH)
 904                 ret = btree_path_prefetch_j(trans, path, &jiter);
 905
 906         bch2_btree_and_journal_iter_exit(&jiter);
 907         return ret;
 908 }
 909
 910 static __always_inline int btree_path_down(struct btree_trans *trans,
 911                                            struct btree_path *path,
 912                                            unsigned flags,
 913                                            unsigned long trace_ip)
 914 {
 915         struct bch_fs *c = trans->c;
 916         struct btree_path_level *l = path_l(path);
 917         struct btree *b;
 918         unsigned level = path->level - 1;
 919         enum six_lock_type lock_type = __btree_lock_want(path, level);
 920         struct bkey_buf tmp;
 921         int ret;
 922
 923         EBUG_ON(!btree_node_locked(path, path->level));
 924
 925         bch2_bkey_buf_init(&tmp);
 926
 927         if (unlikely(trans->journal_replay_not_finished)) {
 928                 ret = btree_node_iter_and_journal_peek(trans, path, flags, &tmp);
 929                 if (ret)
 930                         goto err;
 931         } else {
 932                 bch2_bkey_buf_unpack(&tmp, c, l->b,
 933                                  bch2_btree_node_iter_peek(&l->iter, l->b));
 934
 935                 if (flags & BTREE_ITER_PREFETCH) {
 936                         ret = btree_path_prefetch(trans, path);
 937                         if (ret)
 938                                 goto err;
 939                 }
 940         }
 941
 942         b = bch2_btree_node_get(trans, path, tmp.k, level, lock_type, trace_ip);
 943         ret = PTR_ERR_OR_ZERO(b);
 944         if (unlikely(ret))
 945                 goto err;
 946
 947         if (likely(!trans->journal_replay_not_finished &&
 948                    tmp.k->k.type == KEY_TYPE_btree_ptr_v2) &&
 949             unlikely(b != btree_node_mem_ptr(tmp.k)))
 950                 btree_node_mem_ptr_set(trans, path, level + 1, b);
 951
 952         if (btree_node_read_locked(path, level + 1))
 953                 btree_node_unlock(trans, path, level + 1);
 954
 955         mark_btree_node_locked(trans, path, level, lock_type);
 956         path->level = level;
 957         bch2_btree_path_level_init(trans, path, b);
 958
 959         bch2_btree_path_verify_locks(path);
 960 err:
 961         bch2_bkey_buf_exit(&tmp, c);
 962         return ret;
 963 }
 964
 965
 966 static int bch2_btree_path_traverse_all(struct btree_trans *trans)
 967 {
 968         struct bch_fs *c = trans->c;
 969         struct btree_path *path;
 970         unsigned long trace_ip = _RET_IP_;
 971         int i, ret = 0;
 972
 973         if (trans->in_traverse_all)
 974                 return -BCH_ERR_transaction_restart_in_traverse_all;
 975
 976         trans->in_traverse_all = true;
 977 retry_all:
 978         trans->restarted = 0;
 979         trans->last_restarted_ip = 0;
 980
 981         trans_for_each_path(trans, path)
 982                 path->should_be_locked = false;
 983
 984         btree_trans_sort_paths(trans);
 985
 986         bch2_trans_unlock(trans);
 987         cond_resched();
 988
 989         if (unlikely(trans->memory_allocation_failure)) {
 990                 struct closure cl;
 991
 992                 closure_init_stack(&cl);
 993
 994                 do {
 995                         ret = bch2_btree_cache_cannibalize_lock(c, &cl);
 996                         closure_sync(&cl);
 997                 } while (ret);
 998         }
 999
1000         /* Now, redo traversals in correct order: */
1001         i = 0;
1002         while (i < trans->nr_sorted) {
1003                 path = trans->paths + trans->sorted[i];
1004
1005                 /*
1006                  * Traversing a path can cause another path to be added at about
1007                  * the same position:
1008                  */
1009                 if (path->uptodate) {
1010                         __btree_path_get(path, false);
1011                         ret = bch2_btree_path_traverse_one(trans, path, 0, _THIS_IP_);
1012                         __btree_path_put(path, false);
1013
1014                         if (bch2_err_matches(ret, BCH_ERR_transaction_restart) ||
1015                             bch2_err_matches(ret, ENOMEM))
1016                                 goto retry_all;
1017                         if (ret)
1018                                 goto err;
1019                 } else {
1020                         i++;
1021                 }
1022         }
1023
1024         /*
1025          * We used to assert that all paths had been traversed here
1026          * (path->uptodate < BTREE_ITER_NEED_TRAVERSE); however, since
1027          * path->Should_be_locked is not set yet, we we might have unlocked and
1028          * then failed to relock a path - that's fine.
1029          */
1030 err:
1031         bch2_btree_cache_cannibalize_unlock(c);
1032
1033         trans->in_traverse_all = false;
1034
1035         trace_and_count(c, trans_traverse_all, trans, trace_ip);
1036         return ret;
1037 }
1038
1039 static inline bool btree_path_check_pos_in_node(struct btree_path *path,
1040                                                 unsigned l, int check_pos)
1041 {
1042         if (check_pos < 0 && btree_path_pos_before_node(path, path->l[l].b))
1043                 return false;
1044         if (check_pos > 0 && btree_path_pos_after_node(path, path->l[l].b))
1045                 return false;
1046         return true;
1047 }
1048
1049 static inline bool btree_path_good_node(struct btree_trans *trans,
1050                                         struct btree_path *path,
1051                                         unsigned l, int check_pos)
1052 {
1053         return is_btree_node(path, l) &&
1054                 bch2_btree_node_relock(trans, path, l) &&
1055                 btree_path_check_pos_in_node(path, l, check_pos);
1056 }
1057
1058 static void btree_path_set_level_down(struct btree_trans *trans,
1059                                       struct btree_path *path,
1060                                       unsigned new_level)
1061 {
1062         unsigned l;
1063
1064         path->level = new_level;
1065
1066         for (l = path->level + 1; l < BTREE_MAX_DEPTH; l++)
1067                 if (btree_lock_want(path, l) == BTREE_NODE_UNLOCKED)
1068                         btree_node_unlock(trans, path, l);
1069
1070         btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1071         bch2_btree_path_verify(trans, path);
1072 }
1073
1074 static noinline unsigned __btree_path_up_until_good_node(struct btree_trans *trans,
1075                                                          struct btree_path *path,
1076                                                          int check_pos)
1077 {
1078         unsigned i, l = path->level;
1079 again:
1080         while (btree_path_node(path, l) &&
1081                !btree_path_good_node(trans, path, l, check_pos))
1082                 __btree_path_set_level_up(trans, path, l++);
1083
1084         /* If we need intent locks, take them too: */
1085         for (i = l + 1;
1086              i < path->locks_want && btree_path_node(path, i);
1087              i++)
1088                 if (!bch2_btree_node_relock(trans, path, i)) {
1089                         while (l <= i)
1090                                 __btree_path_set_level_up(trans, path, l++);
1091                         goto again;
1092                 }
1093
1094         return l;
1095 }
1096
1097 static inline unsigned btree_path_up_until_good_node(struct btree_trans *trans,
1098                                                      struct btree_path *path,
1099                                                      int check_pos)
1100 {
1101         return likely(btree_node_locked(path, path->level) &&
1102                       btree_path_check_pos_in_node(path, path->level, check_pos))
1103                 ? path->level
1104                 : __btree_path_up_until_good_node(trans, path, check_pos);
1105 }
1106
1107 /*
1108  * This is the main state machine for walking down the btree - walks down to a
1109  * specified depth
1110  *
1111  * Returns 0 on success, -EIO on error (error reading in a btree node).
1112  *
1113  * On error, caller (peek_node()/peek_key()) must return NULL; the error is
1114  * stashed in the iterator and returned from bch2_trans_exit().
1115  */
1116 int bch2_btree_path_traverse_one(struct btree_trans *trans,
1117                                  struct btree_path *path,
1118                                  unsigned flags,
1119                                  unsigned long trace_ip)
1120 {
1121         unsigned depth_want = path->level;
1122         int ret = -((int) trans->restarted);
1123
1124         if (unlikely(ret))
1125                 goto out;
1126
1127         /*
1128          * Ensure we obey path->should_be_locked: if it's set, we can't unlock
1129          * and re-traverse the path without a transaction restart:
1130          */
1131         if (path->should_be_locked) {
1132                 ret = bch2_btree_path_relock(trans, path, trace_ip);
1133                 goto out;
1134         }
1135
1136         if (path->cached) {
1137                 ret = bch2_btree_path_traverse_cached(trans, path, flags);
1138                 goto out;
1139         }
1140
1141         if (unlikely(path->level >= BTREE_MAX_DEPTH))
1142                 goto out;
1143
1144         path->level = btree_path_up_until_good_node(trans, path, 0);
1145
1146         EBUG_ON(btree_path_node(path, path->level) &&
1147                 !btree_node_locked(path, path->level));
1148
1149         /*
1150          * Note: path->nodes[path->level] may be temporarily NULL here - that
1151          * would indicate to other code that we got to the end of the btree,
1152          * here it indicates that relocking the root failed - it's critical that
1153          * btree_path_lock_root() comes next and that it can't fail
1154          */
1155         while (path->level > depth_want) {
1156                 ret = btree_path_node(path, path->level)
1157                         ? btree_path_down(trans, path, flags, trace_ip)
1158                         : btree_path_lock_root(trans, path, depth_want, trace_ip);
1159                 if (unlikely(ret)) {
1160                         if (ret == 1) {
1161                                 /*
1162                                  * No nodes at this level - got to the end of
1163                                  * the btree:
1164                                  */
1165                                 ret = 0;
1166                                 goto out;
1167                         }
1168
1169                         __bch2_btree_path_unlock(trans, path);
1170                         path->level = depth_want;
1171                         path->l[path->level].b = ERR_PTR(ret);
1172                         goto out;
1173                 }
1174         }
1175
1176         path->uptodate = BTREE_ITER_UPTODATE;
1177 out:
1178         if (bch2_err_matches(ret, BCH_ERR_transaction_restart) != !!trans->restarted)
1179                 panic("ret %s (%i) trans->restarted %s (%i)\n",
1180                       bch2_err_str(ret), ret,
1181                       bch2_err_str(trans->restarted), trans->restarted);
1182         bch2_btree_path_verify(trans, path);
1183         return ret;
1184 }
1185
1186 static inline void btree_path_copy(struct btree_trans *trans, struct btree_path *dst,
1187                             struct btree_path *src)
1188 {
1189         unsigned i, offset = offsetof(struct btree_path, pos);
1190
1191         memcpy((void *) dst + offset,
1192                (void *) src + offset,
1193                sizeof(struct btree_path) - offset);
1194
1195         for (i = 0; i < BTREE_MAX_DEPTH; i++) {
1196                 unsigned t = btree_node_locked_type(dst, i);
1197
1198                 if (t != BTREE_NODE_UNLOCKED)
1199                         six_lock_increment(&dst->l[i].b->c.lock, t);
1200         }
1201 }
1202
1203 static struct btree_path *btree_path_clone(struct btree_trans *trans, struct btree_path *src,
1204                                            bool intent)
1205 {
1206         struct btree_path *new = btree_path_alloc(trans, src);
1207
1208         btree_path_copy(trans, new, src);
1209         __btree_path_get(new, intent);
1210         return new;
1211 }
1212
1213 __flatten
1214 struct btree_path *__bch2_btree_path_make_mut(struct btree_trans *trans,
1215                          struct btree_path *path, bool intent,
1216                          unsigned long ip)
1217 {
1218         __btree_path_put(path, intent);
1219         path = btree_path_clone(trans, path, intent);
1220         path->preserve = false;
1221         return path;
1222 }
1223
1224 struct btree_path * __must_check
1225 __bch2_btree_path_set_pos(struct btree_trans *trans,
1226                    struct btree_path *path, struct bpos new_pos,
1227                    bool intent, unsigned long ip, int cmp)
1228 {
1229         unsigned level = path->level;
1230
1231         bch2_trans_verify_not_in_restart(trans);
1232         EBUG_ON(!path->ref);
1233
1234         path = bch2_btree_path_make_mut(trans, path, intent, ip);
1235
1236         path->pos               = new_pos;
1237         trans->paths_sorted     = false;
1238
1239         if (unlikely(path->cached)) {
1240                 btree_node_unlock(trans, path, 0);
1241                 path->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_up);
1242                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1243                 goto out;
1244         }
1245
1246         level = btree_path_up_until_good_node(trans, path, cmp);
1247
1248         if (btree_path_node(path, level)) {
1249                 struct btree_path_level *l = &path->l[level];
1250
1251                 BUG_ON(!btree_node_locked(path, level));
1252                 /*
1253                  * We might have to skip over many keys, or just a few: try
1254                  * advancing the node iterator, and if we have to skip over too
1255                  * many keys just reinit it (or if we're rewinding, since that
1256                  * is expensive).
1257                  */
1258                 if (cmp < 0 ||
1259                     !btree_path_advance_to_pos(path, l, 8))
1260                         bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
1261
1262                 /*
1263                  * Iterators to interior nodes should always be pointed at the first non
1264                  * whiteout:
1265                  */
1266                 if (unlikely(level))
1267                         bch2_btree_node_iter_peek(&l->iter, l->b);
1268         }
1269
1270         if (unlikely(level != path->level)) {
1271                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1272                 __bch2_btree_path_unlock(trans, path);
1273         }
1274 out:
1275         bch2_btree_path_verify(trans, path);
1276         return path;
1277 }
1278
1279 /* Btree path: main interface: */
1280
1281 static struct btree_path *have_path_at_pos(struct btree_trans *trans, struct btree_path *path)
1282 {
1283         struct btree_path *sib;
1284
1285         sib = prev_btree_path(trans, path);
1286         if (sib && !btree_path_cmp(sib, path))
1287                 return sib;
1288
1289         sib = next_btree_path(trans, path);
1290         if (sib && !btree_path_cmp(sib, path))
1291                 return sib;
1292
1293         return NULL;
1294 }
1295
1296 static struct btree_path *have_node_at_pos(struct btree_trans *trans, struct btree_path *path)
1297 {
1298         struct btree_path *sib;
1299
1300         sib = prev_btree_path(trans, path);
1301         if (sib && sib->level == path->level && path_l(sib)->b == path_l(path)->b)
1302                 return sib;
1303
1304         sib = next_btree_path(trans, path);
1305         if (sib && sib->level == path->level && path_l(sib)->b == path_l(path)->b)
1306                 return sib;
1307
1308         return NULL;
1309 }
1310
1311 static inline void __bch2_path_free(struct btree_trans *trans, struct btree_path *path)
1312 {
1313         __bch2_btree_path_unlock(trans, path);
1314         btree_path_list_remove(trans, path);
1315         trans->paths_allocated &= ~(1ULL << path->idx);
1316 }
1317
1318 void bch2_path_put(struct btree_trans *trans, struct btree_path *path, bool intent)
1319 {
1320         struct btree_path *dup;
1321
1322         EBUG_ON(trans->paths + path->idx != path);
1323         EBUG_ON(!path->ref);
1324
1325         if (!__btree_path_put(path, intent))
1326                 return;
1327
1328         dup = path->preserve
1329                 ? have_path_at_pos(trans, path)
1330                 : have_node_at_pos(trans, path);
1331
1332         if (!dup && !(!path->preserve && !is_btree_node(path, path->level)))
1333                 return;
1334
1335         if (path->should_be_locked &&
1336             !trans->restarted &&
1337             (!dup || !bch2_btree_path_relock_norestart(trans, dup, _THIS_IP_)))
1338                 return;
1339
1340         if (dup) {
1341                 dup->preserve           |= path->preserve;
1342                 dup->should_be_locked   |= path->should_be_locked;
1343         }
1344
1345         __bch2_path_free(trans, path);
1346 }
1347
1348 static void bch2_path_put_nokeep(struct btree_trans *trans, struct btree_path *path,
1349                                  bool intent)
1350 {
1351         EBUG_ON(trans->paths + path->idx != path);
1352         EBUG_ON(!path->ref);
1353
1354         if (!__btree_path_put(path, intent))
1355                 return;
1356
1357         __bch2_path_free(trans, path);
1358 }
1359
1360 void bch2_trans_restart_error(struct btree_trans *trans, u32 restart_count)
1361 {
1362         panic("trans->restart_count %u, should be %u, last restarted by %pS\n",
1363               trans->restart_count, restart_count,
1364               (void *) trans->last_begin_ip);
1365 }
1366
1367 void bch2_trans_in_restart_error(struct btree_trans *trans)
1368 {
1369         panic("in transaction restart: %s, last restarted by %pS\n",
1370               bch2_err_str(trans->restarted),
1371               (void *) trans->last_restarted_ip);
1372 }
1373
1374 noinline __cold
1375 void bch2_trans_updates_to_text(struct printbuf *buf, struct btree_trans *trans)
1376 {
1377         struct btree_insert_entry *i;
1378         struct btree_write_buffered_key *wb;
1379
1380         prt_printf(buf, "transaction updates for %s journal seq %llu",
1381                trans->fn, trans->journal_res.seq);
1382         prt_newline(buf);
1383         printbuf_indent_add(buf, 2);
1384
1385         trans_for_each_update(trans, i) {
1386                 struct bkey_s_c old = { &i->old_k, i->old_v };
1387
1388                 prt_printf(buf, "update: btree=%s cached=%u %pS",
1389                        bch2_btree_ids[i->btree_id],
1390                        i->cached,
1391                        (void *) i->ip_allocated);
1392                 prt_newline(buf);
1393
1394                 prt_printf(buf, "  old ");
1395                 bch2_bkey_val_to_text(buf, trans->c, old);
1396                 prt_newline(buf);
1397
1398                 prt_printf(buf, "  new ");
1399                 bch2_bkey_val_to_text(buf, trans->c, bkey_i_to_s_c(i->k));
1400                 prt_newline(buf);
1401         }
1402
1403         trans_for_each_wb_update(trans, wb) {
1404                 prt_printf(buf, "update: btree=%s wb=1 %pS",
1405                        bch2_btree_ids[wb->btree],
1406                        (void *) i->ip_allocated);
1407                 prt_newline(buf);
1408
1409                 prt_printf(buf, "  new ");
1410                 bch2_bkey_val_to_text(buf, trans->c, bkey_i_to_s_c(&wb->k));
1411                 prt_newline(buf);
1412         }
1413
1414         printbuf_indent_sub(buf, 2);
1415 }
1416
1417 noinline __cold
1418 void bch2_dump_trans_updates(struct btree_trans *trans)
1419 {
1420         struct printbuf buf = PRINTBUF;
1421
1422         bch2_trans_updates_to_text(&buf, trans);
1423         bch2_print_string_as_lines(KERN_ERR, buf.buf);
1424         printbuf_exit(&buf);
1425 }
1426
1427 noinline __cold
1428 void bch2_btree_path_to_text(struct printbuf *out, struct btree_path *path)
1429 {
1430         prt_printf(out, "path: idx %2u ref %u:%u %c %c btree=%s l=%u pos ",
1431                    path->idx, path->ref, path->intent_ref,
1432                    path->preserve ? 'P' : ' ',
1433                    path->should_be_locked ? 'S' : ' ',
1434                    bch2_btree_ids[path->btree_id],
1435                    path->level);
1436         bch2_bpos_to_text(out, path->pos);
1437
1438         prt_printf(out, " locks %u", path->nodes_locked);
1439 #ifdef TRACK_PATH_ALLOCATED
1440         prt_printf(out, " %pS", (void *) path->ip_allocated);
1441 #endif
1442         prt_newline(out);
1443 }
1444
1445 noinline __cold
1446 void __bch2_trans_paths_to_text(struct printbuf *out, struct btree_trans *trans,
1447                                 bool nosort)
1448 {
1449         struct btree_path *path;
1450         unsigned idx;
1451
1452         if (!nosort)
1453                 btree_trans_sort_paths(trans);
1454
1455         trans_for_each_path_inorder(trans, path, idx)
1456                 bch2_btree_path_to_text(out, path);
1457 }
1458
1459 noinline __cold
1460 void bch2_trans_paths_to_text(struct printbuf *out, struct btree_trans *trans)
1461 {
1462         __bch2_trans_paths_to_text(out, trans, false);
1463 }
1464
1465 noinline __cold
1466 void __bch2_dump_trans_paths_updates(struct btree_trans *trans, bool nosort)
1467 {
1468         struct printbuf buf = PRINTBUF;
1469
1470         __bch2_trans_paths_to_text(&buf, trans, nosort);
1471         bch2_trans_updates_to_text(&buf, trans);
1472
1473         bch2_print_string_as_lines(KERN_ERR, buf.buf);
1474         printbuf_exit(&buf);
1475 }
1476
1477 noinline __cold
1478 void bch2_dump_trans_paths_updates(struct btree_trans *trans)
1479 {
1480         __bch2_dump_trans_paths_updates(trans, false);
1481 }
1482
1483 noinline __cold
1484 static void bch2_trans_update_max_paths(struct btree_trans *trans)
1485 {
1486         struct btree_transaction_stats *s = btree_trans_stats(trans);
1487         struct printbuf buf = PRINTBUF;
1488
1489         if (!s)
1490                 return;
1491
1492         bch2_trans_paths_to_text(&buf, trans);
1493
1494         if (!buf.allocation_failure) {
1495                 mutex_lock(&s->lock);
1496                 if (s->nr_max_paths < hweight64(trans->paths_allocated)) {
1497                         s->nr_max_paths = trans->nr_max_paths =
1498                                 hweight64(trans->paths_allocated);
1499                         swap(s->max_paths_text, buf.buf);
1500                 }
1501                 mutex_unlock(&s->lock);
1502         }
1503
1504         printbuf_exit(&buf);
1505
1506         trans->nr_max_paths = hweight64(trans->paths_allocated);
1507 }
1508
1509 static noinline void btree_path_overflow(struct btree_trans *trans)
1510 {
1511         bch2_dump_trans_paths_updates(trans);
1512         panic("trans path oveflow\n");
1513 }
1514
1515 static inline struct btree_path *btree_path_alloc(struct btree_trans *trans,
1516                                                   struct btree_path *pos)
1517 {
1518         struct btree_path *path;
1519         unsigned idx;
1520
1521         if (unlikely(trans->paths_allocated ==
1522                      ~((~0ULL << 1) << (BTREE_ITER_MAX - 1))))
1523                 btree_path_overflow(trans);
1524
1525         idx = __ffs64(~trans->paths_allocated);
1526
1527         /*
1528          * Do this before marking the new path as allocated, since it won't be
1529          * initialized yet:
1530          */
1531         if (unlikely(idx > trans->nr_max_paths))
1532                 bch2_trans_update_max_paths(trans);
1533
1534         trans->paths_allocated |= 1ULL << idx;
1535
1536         path = &trans->paths[idx];
1537         path->idx               = idx;
1538         path->ref               = 0;
1539         path->intent_ref        = 0;
1540         path->nodes_locked      = 0;
1541
1542         btree_path_list_add(trans, pos, path);
1543         trans->paths_sorted = false;
1544         return path;
1545 }
1546
1547 struct btree_path *bch2_path_get(struct btree_trans *trans,
1548                                  enum btree_id btree_id, struct bpos pos,
1549                                  unsigned locks_want, unsigned level,
1550                                  unsigned flags, unsigned long ip)
1551 {
1552         struct btree_path *path, *path_pos = NULL;
1553         bool cached = flags & BTREE_ITER_CACHED;
1554         bool intent = flags & BTREE_ITER_INTENT;
1555         int i;
1556
1557         bch2_trans_verify_not_in_restart(trans);
1558         bch2_trans_verify_locks(trans);
1559
1560         btree_trans_sort_paths(trans);
1561
1562         trans_for_each_path_inorder(trans, path, i) {
1563                 if (__btree_path_cmp(path,
1564                                      btree_id,
1565                                      cached,
1566                                      pos,
1567                                      level) > 0)
1568                         break;
1569
1570                 path_pos = path;
1571         }
1572
1573         if (path_pos &&
1574             path_pos->cached    == cached &&
1575             path_pos->btree_id  == btree_id &&
1576             path_pos->level     == level) {
1577                 __btree_path_get(path_pos, intent);
1578                 path = bch2_btree_path_set_pos(trans, path_pos, pos, intent, ip);
1579         } else {
1580                 path = btree_path_alloc(trans, path_pos);
1581                 path_pos = NULL;
1582
1583                 __btree_path_get(path, intent);
1584                 path->pos                       = pos;
1585                 path->btree_id                  = btree_id;
1586                 path->cached                    = cached;
1587                 path->uptodate                  = BTREE_ITER_NEED_TRAVERSE;
1588                 path->should_be_locked          = false;
1589                 path->level                     = level;
1590                 path->locks_want                = locks_want;
1591                 path->nodes_locked              = 0;
1592                 for (i = 0; i < ARRAY_SIZE(path->l); i++)
1593                         path->l[i].b            = ERR_PTR(-BCH_ERR_no_btree_node_init);
1594 #ifdef TRACK_PATH_ALLOCATED
1595                 path->ip_allocated              = ip;
1596 #endif
1597                 trans->paths_sorted             = false;
1598         }
1599
1600         if (!(flags & BTREE_ITER_NOPRESERVE))
1601                 path->preserve = true;
1602
1603         if (path->intent_ref)
1604                 locks_want = max(locks_want, level + 1);
1605
1606         /*
1607          * If the path has locks_want greater than requested, we don't downgrade
1608          * it here - on transaction restart because btree node split needs to
1609          * upgrade locks, we might be putting/getting the iterator again.
1610          * Downgrading iterators only happens via bch2_trans_downgrade(), after
1611          * a successful transaction commit.
1612          */
1613
1614         locks_want = min(locks_want, BTREE_MAX_DEPTH);
1615         if (locks_want > path->locks_want)
1616                 bch2_btree_path_upgrade_noupgrade_sibs(trans, path, locks_want);
1617
1618         return path;
1619 }
1620
1621 struct bkey_s_c bch2_btree_path_peek_slot(struct btree_path *path, struct bkey *u)
1622 {
1623
1624         struct btree_path_level *l = path_l(path);
1625         struct bkey_packed *_k;
1626         struct bkey_s_c k;
1627
1628         if (unlikely(!l->b))
1629                 return bkey_s_c_null;
1630
1631         EBUG_ON(path->uptodate != BTREE_ITER_UPTODATE);
1632         EBUG_ON(!btree_node_locked(path, path->level));
1633
1634         if (!path->cached) {
1635                 _k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
1636                 k = _k ? bkey_disassemble(l->b, _k, u) : bkey_s_c_null;
1637
1638                 EBUG_ON(k.k && bkey_deleted(k.k) && bpos_eq(k.k->p, path->pos));
1639
1640                 if (!k.k || !bpos_eq(path->pos, k.k->p))
1641                         goto hole;
1642         } else {
1643                 struct bkey_cached *ck = (void *) path->l[0].b;
1644
1645                 EBUG_ON(ck &&
1646                         (path->btree_id != ck->key.btree_id ||
1647                          !bkey_eq(path->pos, ck->key.pos)));
1648                 if (!ck || !ck->valid)
1649                         return bkey_s_c_null;
1650
1651                 *u = ck->k->k;
1652                 k = bkey_i_to_s_c(ck->k);
1653         }
1654
1655         return k;
1656 hole:
1657         bkey_init(u);
1658         u->p = path->pos;
1659         return (struct bkey_s_c) { u, NULL };
1660 }
1661
1662 /* Btree iterators: */
1663
1664 int __must_check
1665 __bch2_btree_iter_traverse(struct btree_iter *iter)
1666 {
1667         return bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
1668 }
1669
1670 int __must_check
1671 bch2_btree_iter_traverse(struct btree_iter *iter)
1672 {
1673         int ret;
1674
1675         iter->path = bch2_btree_path_set_pos(iter->trans, iter->path,
1676                                         btree_iter_search_key(iter),
1677                                         iter->flags & BTREE_ITER_INTENT,
1678                                         btree_iter_ip_allocated(iter));
1679
1680         ret = bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
1681         if (ret)
1682                 return ret;
1683
1684         btree_path_set_should_be_locked(iter->path);
1685         return 0;
1686 }
1687
1688 /* Iterate across nodes (leaf and interior nodes) */
1689
1690 struct btree *bch2_btree_iter_peek_node(struct btree_iter *iter)
1691 {
1692         struct btree_trans *trans = iter->trans;
1693         struct btree *b = NULL;
1694         int ret;
1695
1696         EBUG_ON(iter->path->cached);
1697         bch2_btree_iter_verify(iter);
1698
1699         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
1700         if (ret)
1701                 goto err;
1702
1703         b = btree_path_node(iter->path, iter->path->level);
1704         if (!b)
1705                 goto out;
1706
1707         BUG_ON(bpos_lt(b->key.k.p, iter->pos));
1708
1709         bkey_init(&iter->k);
1710         iter->k.p = iter->pos = b->key.k.p;
1711
1712         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
1713                                         iter->flags & BTREE_ITER_INTENT,
1714                                         btree_iter_ip_allocated(iter));
1715         btree_path_set_should_be_locked(iter->path);
1716 out:
1717         bch2_btree_iter_verify_entry_exit(iter);
1718         bch2_btree_iter_verify(iter);
1719
1720         return b;
1721 err:
1722         b = ERR_PTR(ret);
1723         goto out;
1724 }
1725
1726 struct btree *bch2_btree_iter_peek_node_and_restart(struct btree_iter *iter)
1727 {
1728         struct btree *b;
1729
1730         while (b = bch2_btree_iter_peek_node(iter),
1731                bch2_err_matches(PTR_ERR_OR_ZERO(b), BCH_ERR_transaction_restart))
1732                 bch2_trans_begin(iter->trans);
1733
1734         return b;
1735 }
1736
1737 struct btree *bch2_btree_iter_next_node(struct btree_iter *iter)
1738 {
1739         struct btree_trans *trans = iter->trans;
1740         struct btree_path *path = iter->path;
1741         struct btree *b = NULL;
1742         int ret;
1743
1744         bch2_trans_verify_not_in_restart(trans);
1745         EBUG_ON(iter->path->cached);
1746         bch2_btree_iter_verify(iter);
1747
1748         /* already at end? */
1749         if (!btree_path_node(path, path->level))
1750                 return NULL;
1751
1752         /* got to end? */
1753         if (!btree_path_node(path, path->level + 1)) {
1754                 btree_path_set_level_up(trans, path);
1755                 return NULL;
1756         }
1757
1758         if (!bch2_btree_node_relock(trans, path, path->level + 1)) {
1759                 __bch2_btree_path_unlock(trans, path);
1760                 path->l[path->level].b          = ERR_PTR(-BCH_ERR_no_btree_node_relock);
1761                 path->l[path->level + 1].b      = ERR_PTR(-BCH_ERR_no_btree_node_relock);
1762                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1763                 trace_and_count(trans->c, trans_restart_relock_next_node, trans, _THIS_IP_, path);
1764                 ret = btree_trans_restart(trans, BCH_ERR_transaction_restart_relock);
1765                 goto err;
1766         }
1767
1768         b = btree_path_node(path, path->level + 1);
1769
1770         if (bpos_eq(iter->pos, b->key.k.p)) {
1771                 __btree_path_set_level_up(trans, path, path->level++);
1772         } else {
1773                 /*
1774                  * Haven't gotten to the end of the parent node: go back down to
1775                  * the next child node
1776                  */
1777                 path = iter->path =
1778                         bch2_btree_path_set_pos(trans, path, bpos_successor(iter->pos),
1779                                            iter->flags & BTREE_ITER_INTENT,
1780                                            btree_iter_ip_allocated(iter));
1781
1782                 btree_path_set_level_down(trans, path, iter->min_depth);
1783
1784                 ret = bch2_btree_path_traverse(trans, path, iter->flags);
1785                 if (ret)
1786                         goto err;
1787
1788                 b = path->l[path->level].b;
1789         }
1790
1791         bkey_init(&iter->k);
1792         iter->k.p = iter->pos = b->key.k.p;
1793
1794         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
1795                                         iter->flags & BTREE_ITER_INTENT,
1796                                         btree_iter_ip_allocated(iter));
1797         btree_path_set_should_be_locked(iter->path);
1798         BUG_ON(iter->path->uptodate);
1799 out:
1800         bch2_btree_iter_verify_entry_exit(iter);
1801         bch2_btree_iter_verify(iter);
1802
1803         return b;
1804 err:
1805         b = ERR_PTR(ret);
1806         goto out;
1807 }
1808
1809 /* Iterate across keys (in leaf nodes only) */
1810
1811 inline bool bch2_btree_iter_advance(struct btree_iter *iter)
1812 {
1813         if (likely(!(iter->flags & BTREE_ITER_ALL_LEVELS))) {
1814                 struct bpos pos = iter->k.p;
1815                 bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
1816                              ? bpos_eq(pos, SPOS_MAX)
1817                              : bkey_eq(pos, SPOS_MAX));
1818
1819                 if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
1820                         pos = bkey_successor(iter, pos);
1821                 bch2_btree_iter_set_pos(iter, pos);
1822                 return ret;
1823         } else {
1824                 if (!btree_path_node(iter->path, iter->path->level))
1825                         return true;
1826
1827                 iter->advanced = true;
1828                 return false;
1829         }
1830 }
1831
1832 inline bool bch2_btree_iter_rewind(struct btree_iter *iter)
1833 {
1834         struct bpos pos = bkey_start_pos(&iter->k);
1835         bool ret = !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS
1836                      ? bpos_eq(pos, POS_MIN)
1837                      : bkey_eq(pos, POS_MIN));
1838
1839         if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
1840                 pos = bkey_predecessor(iter, pos);
1841         bch2_btree_iter_set_pos(iter, pos);
1842         return ret;
1843 }
1844
1845 static noinline
1846 struct bkey_i *__bch2_btree_trans_peek_updates(struct btree_iter *iter)
1847 {
1848         struct btree_insert_entry *i;
1849         struct bkey_i *ret = NULL;
1850
1851         trans_for_each_update(iter->trans, i) {
1852                 if (i->btree_id < iter->btree_id)
1853                         continue;
1854                 if (i->btree_id > iter->btree_id)
1855                         break;
1856                 if (bpos_lt(i->k->k.p, iter->path->pos))
1857                         continue;
1858                 if (i->key_cache_already_flushed)
1859                         continue;
1860                 if (!ret || bpos_lt(i->k->k.p, ret->k.p))
1861                         ret = i->k;
1862         }
1863
1864         return ret;
1865 }
1866
1867 static inline struct bkey_i *btree_trans_peek_updates(struct btree_iter *iter)
1868 {
1869         return iter->flags & BTREE_ITER_WITH_UPDATES
1870                 ? __bch2_btree_trans_peek_updates(iter)
1871                 : NULL;
1872 }
1873
1874 struct bkey_i *bch2_btree_journal_peek(struct btree_trans *trans,
1875                                        struct btree_iter *iter,
1876                                        struct bpos end_pos)
1877 {
1878         struct bkey_i *k;
1879
1880         if (bpos_lt(iter->path->pos, iter->journal_pos))
1881                 iter->journal_idx = 0;
1882
1883         k = bch2_journal_keys_peek_upto(trans->c, iter->btree_id,
1884                                         iter->path->level,
1885                                         iter->path->pos,
1886                                         end_pos,
1887                                         &iter->journal_idx);
1888
1889         iter->journal_pos = k ? k->k.p : end_pos;
1890         return k;
1891 }
1892
1893 static noinline
1894 struct bkey_s_c btree_trans_peek_slot_journal(struct btree_trans *trans,
1895                                               struct btree_iter *iter)
1896 {
1897         struct bkey_i *k = bch2_btree_journal_peek(trans, iter, iter->path->pos);
1898
1899         if (k) {
1900                 iter->k = k->k;
1901                 return bkey_i_to_s_c(k);
1902         } else {
1903                 return bkey_s_c_null;
1904         }
1905 }
1906
1907 static noinline
1908 struct bkey_s_c btree_trans_peek_journal(struct btree_trans *trans,
1909                                          struct btree_iter *iter,
1910                                          struct bkey_s_c k)
1911 {
1912         struct bkey_i *next_journal =
1913                 bch2_btree_journal_peek(trans, iter,
1914                                 k.k ? k.k->p : path_l(iter->path)->b->key.k.p);
1915
1916         if (next_journal) {
1917                 iter->k = next_journal->k;
1918                 k = bkey_i_to_s_c(next_journal);
1919         }
1920
1921         return k;
1922 }
1923
1924 /*
1925  * Checks btree key cache for key at iter->pos and returns it if present, or
1926  * bkey_s_c_null:
1927  */
1928 static noinline
1929 struct bkey_s_c btree_trans_peek_key_cache(struct btree_iter *iter, struct bpos pos)
1930 {
1931         struct btree_trans *trans = iter->trans;
1932         struct bch_fs *c = trans->c;
1933         struct bkey u;
1934         struct bkey_s_c k;
1935         int ret;
1936
1937         if ((iter->flags & BTREE_ITER_KEY_CACHE_FILL) &&
1938             bpos_eq(iter->pos, pos))
1939                 return bkey_s_c_null;
1940
1941         if (!bch2_btree_key_cache_find(c, iter->btree_id, pos))
1942                 return bkey_s_c_null;
1943
1944         if (!iter->key_cache_path)
1945                 iter->key_cache_path = bch2_path_get(trans, iter->btree_id, pos,
1946                                                      iter->flags & BTREE_ITER_INTENT, 0,
1947                                                      iter->flags|BTREE_ITER_CACHED|
1948                                                      BTREE_ITER_CACHED_NOFILL,
1949                                                      _THIS_IP_);
1950
1951         iter->key_cache_path = bch2_btree_path_set_pos(trans, iter->key_cache_path, pos,
1952                                         iter->flags & BTREE_ITER_INTENT,
1953                                         btree_iter_ip_allocated(iter));
1954
1955         ret =   bch2_btree_path_traverse(trans, iter->key_cache_path,
1956                                          iter->flags|BTREE_ITER_CACHED) ?:
1957                 bch2_btree_path_relock(trans, iter->path, _THIS_IP_);
1958         if (unlikely(ret))
1959                 return bkey_s_c_err(ret);
1960
1961         btree_path_set_should_be_locked(iter->key_cache_path);
1962
1963         k = bch2_btree_path_peek_slot(iter->key_cache_path, &u);
1964         if (k.k && !bkey_err(k)) {
1965                 iter->k = u;
1966                 k.k = &iter->k;
1967         }
1968         return k;
1969 }
1970
1971 static struct bkey_s_c __bch2_btree_iter_peek(struct btree_iter *iter, struct bpos search_key)
1972 {
1973         struct btree_trans *trans = iter->trans;
1974         struct bkey_i *next_update;
1975         struct bkey_s_c k, k2;
1976         int ret;
1977
1978         EBUG_ON(iter->path->cached);
1979         bch2_btree_iter_verify(iter);
1980
1981         while (1) {
1982                 struct btree_path_level *l;
1983
1984                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
1985                                         iter->flags & BTREE_ITER_INTENT,
1986                                         btree_iter_ip_allocated(iter));
1987
1988                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
1989                 if (unlikely(ret)) {
1990                         /* ensure that iter->k is consistent with iter->pos: */
1991                         bch2_btree_iter_set_pos(iter, iter->pos);
1992                         k = bkey_s_c_err(ret);
1993                         goto out;
1994                 }
1995
1996                 l = path_l(iter->path);
1997
1998                 if (unlikely(!l->b)) {
1999                         /* No btree nodes at requested level: */
2000                         bch2_btree_iter_set_pos(iter, SPOS_MAX);
2001                         k = bkey_s_c_null;
2002                         goto out;
2003                 }
2004
2005                 btree_path_set_should_be_locked(iter->path);
2006
2007                 k = btree_path_level_peek_all(trans->c, l, &iter->k);
2008
2009                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
2010                     k.k &&
2011                     (k2 = btree_trans_peek_key_cache(iter, k.k->p)).k) {
2012                         k = k2;
2013                         ret = bkey_err(k);
2014                         if (ret) {
2015                                 bch2_btree_iter_set_pos(iter, iter->pos);
2016                                 goto out;
2017                         }
2018                 }
2019
2020                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL))
2021                         k = btree_trans_peek_journal(trans, iter, k);
2022
2023                 next_update = btree_trans_peek_updates(iter);
2024
2025                 if (next_update &&
2026                     bpos_le(next_update->k.p,
2027                             k.k ? k.k->p : l->b->key.k.p)) {
2028                         iter->k = next_update->k;
2029                         k = bkey_i_to_s_c(next_update);
2030                 }
2031
2032                 if (k.k && bkey_deleted(k.k)) {
2033                         /*
2034                          * If we've got a whiteout, and it's after the search
2035                          * key, advance the search key to the whiteout instead
2036                          * of just after the whiteout - it might be a btree
2037                          * whiteout, with a real key at the same position, since
2038                          * in the btree deleted keys sort before non deleted.
2039                          */
2040                         search_key = !bpos_eq(search_key, k.k->p)
2041                                 ? k.k->p
2042                                 : bpos_successor(k.k->p);
2043                         continue;
2044                 }
2045
2046                 if (likely(k.k)) {
2047                         break;
2048                 } else if (likely(!bpos_eq(l->b->key.k.p, SPOS_MAX))) {
2049                         /* Advance to next leaf node: */
2050                         search_key = bpos_successor(l->b->key.k.p);
2051                 } else {
2052                         /* End of btree: */
2053                         bch2_btree_iter_set_pos(iter, SPOS_MAX);
2054                         k = bkey_s_c_null;
2055                         goto out;
2056                 }
2057         }
2058 out:
2059         bch2_btree_iter_verify(iter);
2060
2061         return k;
2062 }
2063
2064 /**
2065  * bch2_btree_iter_peek: returns first key greater than or equal to iterator's
2066  * current position
2067  */
2068 struct bkey_s_c bch2_btree_iter_peek_upto(struct btree_iter *iter, struct bpos end)
2069 {
2070         struct btree_trans *trans = iter->trans;
2071         struct bpos search_key = btree_iter_search_key(iter);
2072         struct bkey_s_c k;
2073         struct bpos iter_pos;
2074         int ret;
2075
2076         EBUG_ON(iter->flags & BTREE_ITER_ALL_LEVELS);
2077         EBUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) && bkey_eq(end, POS_MAX));
2078
2079         if (iter->update_path) {
2080                 bch2_path_put_nokeep(trans, iter->update_path,
2081                                      iter->flags & BTREE_ITER_INTENT);
2082                 iter->update_path = NULL;
2083         }
2084
2085         bch2_btree_iter_verify_entry_exit(iter);
2086
2087         while (1) {
2088                 k = __bch2_btree_iter_peek(iter, search_key);
2089                 if (unlikely(!k.k))
2090                         goto end;
2091                 if (unlikely(bkey_err(k)))
2092                         goto out_no_locked;
2093
2094                 /*
2095                  * iter->pos should be mononotically increasing, and always be
2096                  * equal to the key we just returned - except extents can
2097                  * straddle iter->pos:
2098                  */
2099                 if (!(iter->flags & BTREE_ITER_IS_EXTENTS))
2100                         iter_pos = k.k->p;
2101                 else
2102                         iter_pos = bkey_max(iter->pos, bkey_start_pos(k.k));
2103
2104                 if (unlikely(!(iter->flags & BTREE_ITER_IS_EXTENTS)
2105                              ? bkey_gt(iter_pos, end)
2106                              : bkey_ge(iter_pos, end)))
2107                         goto end;
2108
2109                 if (iter->update_path &&
2110                     !bkey_eq(iter->update_path->pos, k.k->p)) {
2111                         bch2_path_put_nokeep(trans, iter->update_path,
2112                                              iter->flags & BTREE_ITER_INTENT);
2113                         iter->update_path = NULL;
2114                 }
2115
2116                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2117                     (iter->flags & BTREE_ITER_INTENT) &&
2118                     !(iter->flags & BTREE_ITER_IS_EXTENTS) &&
2119                     !iter->update_path) {
2120                         struct bpos pos = k.k->p;
2121
2122                         if (pos.snapshot < iter->snapshot) {
2123                                 search_key = bpos_successor(k.k->p);
2124                                 continue;
2125                         }
2126
2127                         pos.snapshot = iter->snapshot;
2128
2129                         /*
2130                          * advance, same as on exit for iter->path, but only up
2131                          * to snapshot
2132                          */
2133                         __btree_path_get(iter->path, iter->flags & BTREE_ITER_INTENT);
2134                         iter->update_path = iter->path;
2135
2136                         iter->update_path = bch2_btree_path_set_pos(trans,
2137                                                 iter->update_path, pos,
2138                                                 iter->flags & BTREE_ITER_INTENT,
2139                                                 _THIS_IP_);
2140                         ret = bch2_btree_path_traverse(trans, iter->update_path, iter->flags);
2141                         if (unlikely(ret)) {
2142                                 k = bkey_s_c_err(ret);
2143                                 goto out_no_locked;
2144                         }
2145                 }
2146
2147                 /*
2148                  * We can never have a key in a leaf node at POS_MAX, so
2149                  * we don't have to check these successor() calls:
2150                  */
2151                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2152                     !bch2_snapshot_is_ancestor(trans->c,
2153                                                iter->snapshot,
2154                                                k.k->p.snapshot)) {
2155                         search_key = bpos_successor(k.k->p);
2156                         continue;
2157                 }
2158
2159                 if (bkey_whiteout(k.k) &&
2160                     !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS)) {
2161                         search_key = bkey_successor(iter, k.k->p);
2162                         continue;
2163                 }
2164
2165                 break;
2166         }
2167
2168         iter->pos = iter_pos;
2169
2170         iter->path = bch2_btree_path_set_pos(trans, iter->path, k.k->p,
2171                                 iter->flags & BTREE_ITER_INTENT,
2172                                 btree_iter_ip_allocated(iter));
2173
2174         btree_path_set_should_be_locked(iter->path);
2175 out_no_locked:
2176         if (iter->update_path) {
2177                 ret = bch2_btree_path_relock(trans, iter->update_path, _THIS_IP_);
2178                 if (unlikely(ret))
2179                         k = bkey_s_c_err(ret);
2180                 else
2181                         btree_path_set_should_be_locked(iter->update_path);
2182         }
2183
2184         if (!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS))
2185                 iter->pos.snapshot = iter->snapshot;
2186
2187         ret = bch2_btree_iter_verify_ret(iter, k);
2188         if (unlikely(ret)) {
2189                 bch2_btree_iter_set_pos(iter, iter->pos);
2190                 k = bkey_s_c_err(ret);
2191         }
2192
2193         bch2_btree_iter_verify_entry_exit(iter);
2194
2195         return k;
2196 end:
2197         bch2_btree_iter_set_pos(iter, end);
2198         k = bkey_s_c_null;
2199         goto out_no_locked;
2200 }
2201
2202 /**
2203  * bch2_btree_iter_peek_all_levels: returns the first key greater than or equal
2204  * to iterator's current position, returning keys from every level of the btree.
2205  * For keys at different levels of the btree that compare equal, the key from
2206  * the lower level (leaf) is returned first.
2207  */
2208 struct bkey_s_c bch2_btree_iter_peek_all_levels(struct btree_iter *iter)
2209 {
2210         struct btree_trans *trans = iter->trans;
2211         struct bkey_s_c k;
2212         int ret;
2213
2214         EBUG_ON(iter->path->cached);
2215         bch2_btree_iter_verify(iter);
2216         BUG_ON(iter->path->level < iter->min_depth);
2217         BUG_ON(!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS));
2218         EBUG_ON(!(iter->flags & BTREE_ITER_ALL_LEVELS));
2219
2220         while (1) {
2221                 iter->path = bch2_btree_path_set_pos(trans, iter->path, iter->pos,
2222                                         iter->flags & BTREE_ITER_INTENT,
2223                                         btree_iter_ip_allocated(iter));
2224
2225                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2226                 if (unlikely(ret)) {
2227                         /* ensure that iter->k is consistent with iter->pos: */
2228                         bch2_btree_iter_set_pos(iter, iter->pos);
2229                         k = bkey_s_c_err(ret);
2230                         goto out_no_locked;
2231                 }
2232
2233                 /* Already at end? */
2234                 if (!btree_path_node(iter->path, iter->path->level)) {
2235                         k = bkey_s_c_null;
2236                         goto out_no_locked;
2237                 }
2238
2239                 k = btree_path_level_peek_all(trans->c,
2240                                 &iter->path->l[iter->path->level], &iter->k);
2241
2242                 /* Check if we should go up to the parent node: */
2243                 if (!k.k ||
2244                     (iter->advanced &&
2245                      bpos_eq(path_l(iter->path)->b->key.k.p, iter->pos))) {
2246                         iter->pos = path_l(iter->path)->b->key.k.p;
2247                         btree_path_set_level_up(trans, iter->path);
2248                         iter->advanced = false;
2249                         continue;
2250                 }
2251
2252                 /*
2253                  * Check if we should go back down to a leaf:
2254                  * If we're not in a leaf node, we only return the current key
2255                  * if it exactly matches iter->pos - otherwise we first have to
2256                  * go back to the leaf:
2257                  */
2258                 if (iter->path->level != iter->min_depth &&
2259                     (iter->advanced ||
2260                      !k.k ||
2261                      !bpos_eq(iter->pos, k.k->p))) {
2262                         btree_path_set_level_down(trans, iter->path, iter->min_depth);
2263                         iter->pos = bpos_successor(iter->pos);
2264                         iter->advanced = false;
2265                         continue;
2266                 }
2267
2268                 /* Check if we should go to the next key: */
2269                 if (iter->path->level == iter->min_depth &&
2270                     iter->advanced &&
2271                     k.k &&
2272                     bpos_eq(iter->pos, k.k->p)) {
2273                         iter->pos = bpos_successor(iter->pos);
2274                         iter->advanced = false;
2275                         continue;
2276                 }
2277
2278                 if (iter->advanced &&
2279                     iter->path->level == iter->min_depth &&
2280                     !bpos_eq(k.k->p, iter->pos))
2281                         iter->advanced = false;
2282
2283                 BUG_ON(iter->advanced);
2284                 BUG_ON(!k.k);
2285                 break;
2286         }
2287
2288         iter->pos = k.k->p;
2289         btree_path_set_should_be_locked(iter->path);
2290 out_no_locked:
2291         bch2_btree_iter_verify(iter);
2292
2293         return k;
2294 }
2295
2296 /**
2297  * bch2_btree_iter_next: returns first key greater than iterator's current
2298  * position
2299  */
2300 struct bkey_s_c bch2_btree_iter_next(struct btree_iter *iter)
2301 {
2302         if (!bch2_btree_iter_advance(iter))
2303                 return bkey_s_c_null;
2304
2305         return bch2_btree_iter_peek(iter);
2306 }
2307
2308 /**
2309  * bch2_btree_iter_peek_prev: returns first key less than or equal to
2310  * iterator's current position
2311  */
2312 struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_iter *iter)
2313 {
2314         struct btree_trans *trans = iter->trans;
2315         struct bpos search_key = iter->pos;
2316         struct btree_path *saved_path = NULL;
2317         struct bkey_s_c k;
2318         struct bkey saved_k;
2319         const struct bch_val *saved_v;
2320         int ret;
2321
2322         EBUG_ON(iter->path->cached || iter->path->level);
2323         EBUG_ON(iter->flags & BTREE_ITER_WITH_UPDATES);
2324
2325         if (iter->flags & BTREE_ITER_WITH_JOURNAL)
2326                 return bkey_s_c_err(-EIO);
2327
2328         bch2_btree_iter_verify(iter);
2329         bch2_btree_iter_verify_entry_exit(iter);
2330
2331         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2332                 search_key.snapshot = U32_MAX;
2333
2334         while (1) {
2335                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2336                                                 iter->flags & BTREE_ITER_INTENT,
2337                                                 btree_iter_ip_allocated(iter));
2338
2339                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2340                 if (unlikely(ret)) {
2341                         /* ensure that iter->k is consistent with iter->pos: */
2342                         bch2_btree_iter_set_pos(iter, iter->pos);
2343                         k = bkey_s_c_err(ret);
2344                         goto out_no_locked;
2345                 }
2346
2347                 k = btree_path_level_peek(trans, iter->path,
2348                                           &iter->path->l[0], &iter->k);
2349                 if (!k.k ||
2350                     ((iter->flags & BTREE_ITER_IS_EXTENTS)
2351                      ? bpos_ge(bkey_start_pos(k.k), search_key)
2352                      : bpos_gt(k.k->p, search_key)))
2353                         k = btree_path_level_prev(trans, iter->path,
2354                                                   &iter->path->l[0], &iter->k);
2355
2356                 if (likely(k.k)) {
2357                         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) {
2358                                 if (k.k->p.snapshot == iter->snapshot)
2359                                         goto got_key;
2360
2361                                 /*
2362                                  * If we have a saved candidate, and we're no
2363                                  * longer at the same _key_ (not pos), return
2364                                  * that candidate
2365                                  */
2366                                 if (saved_path && !bkey_eq(k.k->p, saved_k.p)) {
2367                                         bch2_path_put_nokeep(trans, iter->path,
2368                                                       iter->flags & BTREE_ITER_INTENT);
2369                                         iter->path = saved_path;
2370                                         saved_path = NULL;
2371                                         iter->k = saved_k;
2372                                         k.v     = saved_v;
2373                                         goto got_key;
2374                                 }
2375
2376                                 if (bch2_snapshot_is_ancestor(iter->trans->c,
2377                                                               iter->snapshot,
2378                                                               k.k->p.snapshot)) {
2379                                         if (saved_path)
2380                                                 bch2_path_put_nokeep(trans, saved_path,
2381                                                       iter->flags & BTREE_ITER_INTENT);
2382                                         saved_path = btree_path_clone(trans, iter->path,
2383                                                                 iter->flags & BTREE_ITER_INTENT);
2384                                         saved_k = *k.k;
2385                                         saved_v = k.v;
2386                                 }
2387
2388                                 search_key = bpos_predecessor(k.k->p);
2389                                 continue;
2390                         }
2391 got_key:
2392                         if (bkey_whiteout(k.k) &&
2393                             !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS)) {
2394                                 search_key = bkey_predecessor(iter, k.k->p);
2395                                 if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2396                                         search_key.snapshot = U32_MAX;
2397                                 continue;
2398                         }
2399
2400                         break;
2401                 } else if (likely(!bpos_eq(iter->path->l[0].b->data->min_key, POS_MIN))) {
2402                         /* Advance to previous leaf node: */
2403                         search_key = bpos_predecessor(iter->path->l[0].b->data->min_key);
2404                 } else {
2405                         /* Start of btree: */
2406                         bch2_btree_iter_set_pos(iter, POS_MIN);
2407                         k = bkey_s_c_null;
2408                         goto out_no_locked;
2409                 }
2410         }
2411
2412         EBUG_ON(bkey_gt(bkey_start_pos(k.k), iter->pos));
2413
2414         /* Extents can straddle iter->pos: */
2415         if (bkey_lt(k.k->p, iter->pos))
2416                 iter->pos = k.k->p;
2417
2418         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2419                 iter->pos.snapshot = iter->snapshot;
2420
2421         btree_path_set_should_be_locked(iter->path);
2422 out_no_locked:
2423         if (saved_path)
2424                 bch2_path_put_nokeep(trans, saved_path, iter->flags & BTREE_ITER_INTENT);
2425
2426         bch2_btree_iter_verify_entry_exit(iter);
2427         bch2_btree_iter_verify(iter);
2428
2429         return k;
2430 }
2431
2432 /**
2433  * bch2_btree_iter_prev: returns first key less than iterator's current
2434  * position
2435  */
2436 struct bkey_s_c bch2_btree_iter_prev(struct btree_iter *iter)
2437 {
2438         if (!bch2_btree_iter_rewind(iter))
2439                 return bkey_s_c_null;
2440
2441         return bch2_btree_iter_peek_prev(iter);
2442 }
2443
2444 struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_iter *iter)
2445 {
2446         struct btree_trans *trans = iter->trans;
2447         struct bpos search_key;
2448         struct bkey_s_c k;
2449         int ret;
2450
2451         bch2_btree_iter_verify(iter);
2452         bch2_btree_iter_verify_entry_exit(iter);
2453         EBUG_ON(iter->flags & BTREE_ITER_ALL_LEVELS);
2454         EBUG_ON(iter->path->level && (iter->flags & BTREE_ITER_WITH_KEY_CACHE));
2455
2456         /* extents can't span inode numbers: */
2457         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
2458             unlikely(iter->pos.offset == KEY_OFFSET_MAX)) {
2459                 if (iter->pos.inode == KEY_INODE_MAX)
2460                         return bkey_s_c_null;
2461
2462                 bch2_btree_iter_set_pos(iter, bpos_nosnap_successor(iter->pos));
2463         }
2464
2465         search_key = btree_iter_search_key(iter);
2466         iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2467                                         iter->flags & BTREE_ITER_INTENT,
2468                                         btree_iter_ip_allocated(iter));
2469
2470         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2471         if (unlikely(ret)) {
2472                 k = bkey_s_c_err(ret);
2473                 goto out_no_locked;
2474         }
2475
2476         if ((iter->flags & BTREE_ITER_CACHED) ||
2477             !(iter->flags & (BTREE_ITER_IS_EXTENTS|BTREE_ITER_FILTER_SNAPSHOTS))) {
2478                 struct bkey_i *next_update;
2479
2480                 if ((next_update = btree_trans_peek_updates(iter)) &&
2481                     bpos_eq(next_update->k.p, iter->pos)) {
2482                         iter->k = next_update->k;
2483                         k = bkey_i_to_s_c(next_update);
2484                         goto out;
2485                 }
2486
2487                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL) &&
2488                     (k = btree_trans_peek_slot_journal(trans, iter)).k)
2489                         goto out;
2490
2491                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
2492                     (k = btree_trans_peek_key_cache(iter, iter->pos)).k) {
2493                         if (!bkey_err(k))
2494                                 iter->k = *k.k;
2495                         /* We're not returning a key from iter->path: */
2496                         goto out_no_locked;
2497                 }
2498
2499                 k = bch2_btree_path_peek_slot(iter->path, &iter->k);
2500                 if (unlikely(!k.k))
2501                         goto out_no_locked;
2502         } else {
2503                 struct bpos next;
2504                 struct bpos end = iter->pos;
2505
2506                 if (iter->flags & BTREE_ITER_IS_EXTENTS)
2507                         end.offset = U64_MAX;
2508
2509                 EBUG_ON(iter->path->level);
2510
2511                 if (iter->flags & BTREE_ITER_INTENT) {
2512                         struct btree_iter iter2;
2513
2514                         bch2_trans_copy_iter(&iter2, iter);
2515                         k = bch2_btree_iter_peek_upto(&iter2, end);
2516
2517                         if (k.k && !bkey_err(k)) {
2518                                 iter->k = iter2.k;
2519                                 k.k = &iter->k;
2520                         }
2521                         bch2_trans_iter_exit(trans, &iter2);
2522                 } else {
2523                         struct bpos pos = iter->pos;
2524
2525                         k = bch2_btree_iter_peek_upto(iter, end);
2526                         if (unlikely(bkey_err(k)))
2527                                 bch2_btree_iter_set_pos(iter, pos);
2528                         else
2529                                 iter->pos = pos;
2530                 }
2531
2532                 if (unlikely(bkey_err(k)))
2533                         goto out_no_locked;
2534
2535                 next = k.k ? bkey_start_pos(k.k) : POS_MAX;
2536
2537                 if (bkey_lt(iter->pos, next)) {
2538                         bkey_init(&iter->k);
2539                         iter->k.p = iter->pos;
2540
2541                         if (iter->flags & BTREE_ITER_IS_EXTENTS) {
2542                                 bch2_key_resize(&iter->k,
2543                                                 min_t(u64, KEY_SIZE_MAX,
2544                                                       (next.inode == iter->pos.inode
2545                                                        ? next.offset
2546                                                        : KEY_OFFSET_MAX) -
2547                                                       iter->pos.offset));
2548                                 EBUG_ON(!iter->k.size);
2549                         }
2550
2551                         k = (struct bkey_s_c) { &iter->k, NULL };
2552                 }
2553         }
2554 out:
2555         btree_path_set_should_be_locked(iter->path);
2556 out_no_locked:
2557         bch2_btree_iter_verify_entry_exit(iter);
2558         bch2_btree_iter_verify(iter);
2559         ret = bch2_btree_iter_verify_ret(iter, k);
2560         if (unlikely(ret))
2561                 return bkey_s_c_err(ret);
2562
2563         return k;
2564 }
2565
2566 struct bkey_s_c bch2_btree_iter_next_slot(struct btree_iter *iter)
2567 {
2568         if (!bch2_btree_iter_advance(iter))
2569                 return bkey_s_c_null;
2570
2571         return bch2_btree_iter_peek_slot(iter);
2572 }
2573
2574 struct bkey_s_c bch2_btree_iter_prev_slot(struct btree_iter *iter)
2575 {
2576         if (!bch2_btree_iter_rewind(iter))
2577                 return bkey_s_c_null;
2578
2579         return bch2_btree_iter_peek_slot(iter);
2580 }
2581
2582 struct bkey_s_c bch2_btree_iter_peek_and_restart_outlined(struct btree_iter *iter)
2583 {
2584         struct bkey_s_c k;
2585
2586         while (btree_trans_too_many_iters(iter->trans) ||
2587                (k = bch2_btree_iter_peek_type(iter, iter->flags),
2588                 bch2_err_matches(bkey_err(k), BCH_ERR_transaction_restart)))
2589                 bch2_trans_begin(iter->trans);
2590
2591         return k;
2592 }
2593
2594 /* new transactional stuff: */
2595
2596 #ifdef CONFIG_BCACHEFS_DEBUG
2597 static void btree_trans_verify_sorted_refs(struct btree_trans *trans)
2598 {
2599         struct btree_path *path;
2600         unsigned i;
2601
2602         BUG_ON(trans->nr_sorted != hweight64(trans->paths_allocated));
2603
2604         trans_for_each_path(trans, path) {
2605                 BUG_ON(path->sorted_idx >= trans->nr_sorted);
2606                 BUG_ON(trans->sorted[path->sorted_idx] != path->idx);
2607         }
2608
2609         for (i = 0; i < trans->nr_sorted; i++) {
2610                 unsigned idx = trans->sorted[i];
2611
2612                 EBUG_ON(!(trans->paths_allocated & (1ULL << idx)));
2613                 BUG_ON(trans->paths[idx].sorted_idx != i);
2614         }
2615 }
2616
2617 static void btree_trans_verify_sorted(struct btree_trans *trans)
2618 {
2619         struct btree_path *path, *prev = NULL;
2620         unsigned i;
2621
2622         if (!bch2_debug_check_iterators)
2623                 return;
2624
2625         trans_for_each_path_inorder(trans, path, i) {
2626                 if (prev && btree_path_cmp(prev, path) > 0) {
2627                         __bch2_dump_trans_paths_updates(trans, true);
2628                         panic("trans paths out of order!\n");
2629                 }
2630                 prev = path;
2631         }
2632 }
2633 #else
2634 static inline void btree_trans_verify_sorted_refs(struct btree_trans *trans) {}
2635 static inline void btree_trans_verify_sorted(struct btree_trans *trans) {}
2636 #endif
2637
2638 void __bch2_btree_trans_sort_paths(struct btree_trans *trans)
2639 {
2640         int i, l = 0, r = trans->nr_sorted, inc = 1;
2641         bool swapped;
2642
2643         btree_trans_verify_sorted_refs(trans);
2644
2645         if (trans->paths_sorted)
2646                 goto out;
2647
2648         /*
2649          * Cocktail shaker sort: this is efficient because iterators will be
2650          * mostly sorted.
2651          */
2652         do {
2653                 swapped = false;
2654
2655                 for (i = inc > 0 ? l : r - 2;
2656                      i + 1 < r && i >= l;
2657                      i += inc) {
2658                         if (btree_path_cmp(trans->paths + trans->sorted[i],
2659                                            trans->paths + trans->sorted[i + 1]) > 0) {
2660                                 swap(trans->sorted[i], trans->sorted[i + 1]);
2661                                 trans->paths[trans->sorted[i]].sorted_idx = i;
2662                                 trans->paths[trans->sorted[i + 1]].sorted_idx = i + 1;
2663                                 swapped = true;
2664                         }
2665                 }
2666
2667                 if (inc > 0)
2668                         --r;
2669                 else
2670                         l++;
2671                 inc = -inc;
2672         } while (swapped);
2673
2674         trans->paths_sorted = true;
2675 out:
2676         btree_trans_verify_sorted(trans);
2677 }
2678
2679 static inline void btree_path_list_remove(struct btree_trans *trans,
2680                                           struct btree_path *path)
2681 {
2682         unsigned i;
2683
2684         EBUG_ON(path->sorted_idx >= trans->nr_sorted);
2685 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
2686         trans->nr_sorted--;
2687         memmove_u64s_down_small(trans->sorted + path->sorted_idx,
2688                                 trans->sorted + path->sorted_idx + 1,
2689                                 DIV_ROUND_UP(trans->nr_sorted - path->sorted_idx, 8));
2690 #else
2691         array_remove_item(trans->sorted, trans->nr_sorted, path->sorted_idx);
2692 #endif
2693         for (i = path->sorted_idx; i < trans->nr_sorted; i++)
2694                 trans->paths[trans->sorted[i]].sorted_idx = i;
2695
2696         path->sorted_idx = U8_MAX;
2697 }
2698
2699 static inline void btree_path_list_add(struct btree_trans *trans,
2700                                        struct btree_path *pos,
2701                                        struct btree_path *path)
2702 {
2703         unsigned i;
2704
2705         path->sorted_idx = pos ? pos->sorted_idx + 1 : trans->nr_sorted;
2706
2707 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
2708         memmove_u64s_up_small(trans->sorted + path->sorted_idx + 1,
2709                               trans->sorted + path->sorted_idx,
2710                               DIV_ROUND_UP(trans->nr_sorted - path->sorted_idx, 8));
2711         trans->nr_sorted++;
2712         trans->sorted[path->sorted_idx] = path->idx;
2713 #else
2714         array_insert_item(trans->sorted, trans->nr_sorted, path->sorted_idx, path->idx);
2715 #endif
2716
2717         for (i = path->sorted_idx; i < trans->nr_sorted; i++)
2718                 trans->paths[trans->sorted[i]].sorted_idx = i;
2719
2720         btree_trans_verify_sorted_refs(trans);
2721 }
2722
2723 void bch2_trans_iter_exit(struct btree_trans *trans, struct btree_iter *iter)
2724 {
2725         if (iter->update_path)
2726                 bch2_path_put_nokeep(trans, iter->update_path,
2727                               iter->flags & BTREE_ITER_INTENT);
2728         if (iter->path)
2729                 bch2_path_put(trans, iter->path,
2730                               iter->flags & BTREE_ITER_INTENT);
2731         if (iter->key_cache_path)
2732                 bch2_path_put(trans, iter->key_cache_path,
2733                               iter->flags & BTREE_ITER_INTENT);
2734         iter->path = NULL;
2735         iter->update_path = NULL;
2736         iter->key_cache_path = NULL;
2737 }
2738
2739 static inline void bch2_trans_iter_init_inlined(struct btree_trans *trans,
2740                           struct btree_iter *iter,
2741                           unsigned btree_id, struct bpos pos,
2742                           unsigned flags)
2743 {
2744         bch2_trans_iter_init_common(trans, iter, btree_id, pos, 0, 0,
2745                                bch2_btree_iter_flags(trans, btree_id, flags),
2746                                _RET_IP_);
2747 }
2748
2749 void bch2_trans_iter_init_outlined(struct btree_trans *trans,
2750                           struct btree_iter *iter,
2751                           unsigned btree_id, struct bpos pos,
2752                           unsigned flags)
2753 {
2754         bch2_trans_iter_init_common(trans, iter, btree_id, pos, 0, 0,
2755                                bch2_btree_iter_flags(trans, btree_id, flags),
2756                                _RET_IP_);
2757 }
2758
2759 void bch2_trans_node_iter_init(struct btree_trans *trans,
2760                                struct btree_iter *iter,
2761                                enum btree_id btree_id,
2762                                struct bpos pos,
2763                                unsigned locks_want,
2764                                unsigned depth,
2765                                unsigned flags)
2766 {
2767        flags |= BTREE_ITER_NOT_EXTENTS;
2768        flags |= __BTREE_ITER_ALL_SNAPSHOTS;
2769        flags |= BTREE_ITER_ALL_SNAPSHOTS;
2770
2771         bch2_trans_iter_init_common(trans, iter, btree_id, pos, locks_want, depth,
2772                                __bch2_btree_iter_flags(trans, btree_id, flags),
2773                                _RET_IP_);
2774
2775         iter->min_depth = depth;
2776
2777         BUG_ON(iter->path->locks_want    < min(locks_want, BTREE_MAX_DEPTH));
2778         BUG_ON(iter->path->level        != depth);
2779         BUG_ON(iter->min_depth          != depth);
2780 }
2781
2782 void bch2_trans_copy_iter(struct btree_iter *dst, struct btree_iter *src)
2783 {
2784         *dst = *src;
2785         if (src->path)
2786                 __btree_path_get(src->path, src->flags & BTREE_ITER_INTENT);
2787         if (src->update_path)
2788                 __btree_path_get(src->update_path, src->flags & BTREE_ITER_INTENT);
2789         dst->key_cache_path = NULL;
2790 }
2791
2792 void *__bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
2793 {
2794         unsigned new_top = trans->mem_top + size;
2795         size_t old_bytes = trans->mem_bytes;
2796         size_t new_bytes = roundup_pow_of_two(new_top);
2797         void *new_mem;
2798         void *p;
2799
2800         trans->mem_max = max(trans->mem_max, new_top);
2801
2802         WARN_ON_ONCE(new_bytes > BTREE_TRANS_MEM_MAX);
2803
2804         new_mem = krealloc(trans->mem, new_bytes, GFP_NOFS);
2805         if (!new_mem && new_bytes <= BTREE_TRANS_MEM_MAX) {
2806                 new_mem = mempool_alloc(&trans->c->btree_trans_mem_pool, GFP_KERNEL);
2807                 new_bytes = BTREE_TRANS_MEM_MAX;
2808                 kfree(trans->mem);
2809         }
2810
2811         if (!new_mem)
2812                 return ERR_PTR(-BCH_ERR_ENOMEM_trans_kmalloc);
2813
2814         trans->mem = new_mem;
2815         trans->mem_bytes = new_bytes;
2816
2817         if (old_bytes) {
2818                 trace_and_count(trans->c, trans_restart_mem_realloced, trans, _RET_IP_, new_bytes);
2819                 return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_mem_realloced));
2820         }
2821
2822         p = trans->mem + trans->mem_top;
2823         trans->mem_top += size;
2824         memset(p, 0, size);
2825         return p;
2826 }
2827
2828 static noinline void bch2_trans_reset_srcu_lock(struct btree_trans *trans)
2829 {
2830         struct bch_fs *c = trans->c;
2831         struct btree_path *path;
2832
2833         trans_for_each_path(trans, path)
2834                 if (path->cached && !btree_node_locked(path, 0))
2835                         path->l[0].b = ERR_PTR(-BCH_ERR_no_btree_node_srcu_reset);
2836
2837         srcu_read_unlock(&c->btree_trans_barrier, trans->srcu_idx);
2838         trans->srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
2839         trans->srcu_lock_time   = jiffies;
2840 }
2841
2842 /**
2843  * bch2_trans_begin() - reset a transaction after a interrupted attempt
2844  * @trans: transaction to reset
2845  *
2846  * While iterating over nodes or updating nodes a attempt to lock a btree node
2847  * may return BCH_ERR_transaction_restart when the trylock fails. When this
2848  * occurs bch2_trans_begin() should be called and the transaction retried.
2849  */
2850 u32 bch2_trans_begin(struct btree_trans *trans)
2851 {
2852         struct btree_path *path;
2853
2854         bch2_trans_reset_updates(trans);
2855
2856         trans->restart_count++;
2857         trans->mem_top                  = 0;
2858
2859         trans_for_each_path(trans, path) {
2860                 path->should_be_locked = false;
2861
2862                 /*
2863                  * If the transaction wasn't restarted, we're presuming to be
2864                  * doing something new: dont keep iterators excpt the ones that
2865                  * are in use - except for the subvolumes btree:
2866                  */
2867                 if (!trans->restarted && path->btree_id != BTREE_ID_subvolumes)
2868                         path->preserve = false;
2869
2870                 /*
2871                  * XXX: we probably shouldn't be doing this if the transaction
2872                  * was restarted, but currently we still overflow transaction
2873                  * iterators if we do that
2874                  */
2875                 if (!path->ref && !path->preserve)
2876                         __bch2_path_free(trans, path);
2877                 else
2878                         path->preserve = false;
2879         }
2880
2881         if (!trans->restarted &&
2882             (need_resched() ||
2883              local_clock() - trans->last_begin_time > BTREE_TRANS_MAX_LOCK_HOLD_TIME_NS)) {
2884                 bch2_trans_unlock(trans);
2885                 cond_resched();
2886                 bch2_trans_relock(trans);
2887         }
2888
2889         if (unlikely(time_after(jiffies, trans->srcu_lock_time + msecs_to_jiffies(10))))
2890                 bch2_trans_reset_srcu_lock(trans);
2891
2892         trans->last_begin_ip = _RET_IP_;
2893         if (trans->restarted) {
2894                 bch2_btree_path_traverse_all(trans);
2895                 trans->notrace_relock_fail = false;
2896         }
2897
2898         trans->last_begin_time = local_clock();
2899         return trans->restart_count;
2900 }
2901
2902 static void bch2_trans_alloc_paths(struct btree_trans *trans, struct bch_fs *c)
2903 {
2904         size_t paths_bytes      = sizeof(struct btree_path) * BTREE_ITER_MAX;
2905         size_t updates_bytes    = sizeof(struct btree_insert_entry) * BTREE_ITER_MAX;
2906         void *p = NULL;
2907
2908         BUG_ON(trans->used_mempool);
2909
2910 #ifdef __KERNEL__
2911         p = this_cpu_xchg(c->btree_paths_bufs->path, NULL);
2912 #endif
2913         if (!p)
2914                 p = mempool_alloc(&trans->c->btree_paths_pool, GFP_NOFS);
2915
2916         trans->paths            = p; p += paths_bytes;
2917         trans->updates          = p; p += updates_bytes;
2918 }
2919
2920 const char *bch2_btree_transaction_fns[BCH_TRANSACTIONS_NR];
2921
2922 unsigned bch2_trans_get_fn_idx(const char *fn)
2923 {
2924         unsigned i;
2925
2926         for (i = 0; i < ARRAY_SIZE(bch2_btree_transaction_fns); i++)
2927                 if (!bch2_btree_transaction_fns[i] ||
2928                     bch2_btree_transaction_fns[i] == fn) {
2929                         bch2_btree_transaction_fns[i] = fn;
2930                         return i;
2931                 }
2932
2933         pr_warn_once("BCH_TRANSACTIONS_NR not big enough!");
2934         return i;
2935 }
2936
2937 void __bch2_trans_init(struct btree_trans *trans, struct bch_fs *c, unsigned fn_idx)
2938         __acquires(&c->btree_trans_barrier)
2939 {
2940         struct btree_transaction_stats *s;
2941
2942         bch2_assert_btree_nodes_not_locked();
2943
2944         memset(trans, 0, sizeof(*trans));
2945         trans->c                = c;
2946         trans->fn               = fn_idx < ARRAY_SIZE(bch2_btree_transaction_fns)
2947                 ? bch2_btree_transaction_fns[fn_idx] : NULL;
2948         trans->last_begin_time  = local_clock();
2949         trans->fn_idx           = fn_idx;
2950         trans->locking_wait.task = current;
2951         trans->journal_replay_not_finished =
2952                 !test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags);
2953         closure_init_stack(&trans->ref);
2954
2955         bch2_trans_alloc_paths(trans, c);
2956
2957         s = btree_trans_stats(trans);
2958         if (s && s->max_mem) {
2959                 unsigned expected_mem_bytes = roundup_pow_of_two(s->max_mem);
2960
2961                 trans->mem = kmalloc(expected_mem_bytes, GFP_KERNEL);
2962
2963                 if (!unlikely(trans->mem)) {
2964                         trans->mem = mempool_alloc(&c->btree_trans_mem_pool, GFP_KERNEL);
2965                         trans->mem_bytes = BTREE_TRANS_MEM_MAX;
2966                 } else {
2967                         trans->mem_bytes = expected_mem_bytes;
2968                 }
2969         }
2970
2971         if (s) {
2972                 trans->nr_max_paths = s->nr_max_paths;
2973                 trans->wb_updates_size = s->wb_updates_size;
2974         }
2975
2976         trans->srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
2977         trans->srcu_lock_time   = jiffies;
2978
2979         if (IS_ENABLED(CONFIG_BCACHEFS_DEBUG_TRANSACTIONS)) {
2980                 struct btree_trans *pos;
2981
2982                 mutex_lock(&c->btree_trans_lock);
2983                 list_for_each_entry(pos, &c->btree_trans_list, list) {
2984                         /*
2985                          * We'd much prefer to be stricter here and completely
2986                          * disallow multiple btree_trans in the same thread -
2987                          * but the data move path calls bch2_write when we
2988                          * already have a btree_trans initialized.
2989                          */
2990                         BUG_ON(trans->locking_wait.task->pid == pos->locking_wait.task->pid &&
2991                                bch2_trans_locked(pos));
2992
2993                         if (trans->locking_wait.task->pid < pos->locking_wait.task->pid) {
2994                                 list_add_tail(&trans->list, &pos->list);
2995                                 goto list_add_done;
2996                         }
2997                 }
2998                 list_add_tail(&trans->list, &c->btree_trans_list);
2999 list_add_done:
3000                 mutex_unlock(&c->btree_trans_lock);
3001         }
3002 }
3003
3004 static void check_btree_paths_leaked(struct btree_trans *trans)
3005 {
3006 #ifdef CONFIG_BCACHEFS_DEBUG
3007         struct bch_fs *c = trans->c;
3008         struct btree_path *path;
3009
3010         trans_for_each_path(trans, path)
3011                 if (path->ref)
3012                         goto leaked;
3013         return;
3014 leaked:
3015         bch_err(c, "btree paths leaked from %s!", trans->fn);
3016         trans_for_each_path(trans, path)
3017                 if (path->ref)
3018                         printk(KERN_ERR "  btree %s %pS\n",
3019                                bch2_btree_ids[path->btree_id],
3020                                (void *) path->ip_allocated);
3021         /* Be noisy about this: */
3022         bch2_fatal_error(c);
3023 #endif
3024 }
3025
3026 void bch2_trans_exit(struct btree_trans *trans)
3027         __releases(&c->btree_trans_barrier)
3028 {
3029         struct btree_insert_entry *i;
3030         struct bch_fs *c = trans->c;
3031         struct btree_transaction_stats *s = btree_trans_stats(trans);
3032
3033         bch2_trans_unlock(trans);
3034
3035         closure_sync(&trans->ref);
3036
3037         if (s)
3038                 s->max_mem = max(s->max_mem, trans->mem_max);
3039
3040         trans_for_each_update(trans, i)
3041                 __btree_path_put(i->path, true);
3042         trans->nr_updates               = 0;
3043
3044         check_btree_paths_leaked(trans);
3045
3046         if (IS_ENABLED(CONFIG_BCACHEFS_DEBUG_TRANSACTIONS)) {
3047                 mutex_lock(&c->btree_trans_lock);
3048                 list_del(&trans->list);
3049                 mutex_unlock(&c->btree_trans_lock);
3050         }
3051
3052         srcu_read_unlock(&c->btree_trans_barrier, trans->srcu_idx);
3053
3054         bch2_journal_preres_put(&c->journal, &trans->journal_preres);
3055
3056         kfree(trans->extra_journal_entries.data);
3057
3058         if (trans->fs_usage_deltas) {
3059                 if (trans->fs_usage_deltas->size + sizeof(trans->fs_usage_deltas) ==
3060                     REPLICAS_DELTA_LIST_MAX)
3061                         mempool_free(trans->fs_usage_deltas,
3062                                      &c->replicas_delta_pool);
3063                 else
3064                         kfree(trans->fs_usage_deltas);
3065         }
3066
3067         if (trans->mem_bytes == BTREE_TRANS_MEM_MAX)
3068                 mempool_free(trans->mem, &c->btree_trans_mem_pool);
3069         else
3070                 kfree(trans->mem);
3071
3072 #ifdef __KERNEL__
3073         /*
3074          * Userspace doesn't have a real percpu implementation:
3075          */
3076         trans->paths = this_cpu_xchg(c->btree_paths_bufs->path, trans->paths);
3077 #endif
3078
3079         if (trans->paths)
3080                 mempool_free(trans->paths, &c->btree_paths_pool);
3081
3082         trans->mem      = (void *) 0x1;
3083         trans->paths    = (void *) 0x1;
3084 }
3085
3086 static void __maybe_unused
3087 bch2_btree_bkey_cached_common_to_text(struct printbuf *out,
3088                                       struct btree_bkey_cached_common *b)
3089 {
3090         struct six_lock_count c = six_lock_counts(&b->lock);
3091         struct task_struct *owner;
3092         pid_t pid;
3093
3094         rcu_read_lock();
3095         owner = READ_ONCE(b->lock.owner);
3096         pid = owner ? owner->pid : 0;
3097         rcu_read_unlock();
3098
3099         prt_tab(out);
3100         prt_printf(out, "%px %c l=%u %s:", b, b->cached ? 'c' : 'b',
3101                    b->level, bch2_btree_ids[b->btree_id]);
3102         bch2_bpos_to_text(out, btree_node_pos(b));
3103
3104         prt_tab(out);
3105         prt_printf(out, " locks %u:%u:%u held by pid %u",
3106                    c.n[0], c.n[1], c.n[2], pid);
3107 }
3108
3109 void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans)
3110 {
3111         struct btree_path *path;
3112         struct btree_bkey_cached_common *b;
3113         static char lock_types[] = { 'r', 'i', 'w' };
3114         unsigned l;
3115
3116         if (!out->nr_tabstops) {
3117                 printbuf_tabstop_push(out, 16);
3118                 printbuf_tabstop_push(out, 32);
3119         }
3120
3121         prt_printf(out, "%i %s\n", trans->locking_wait.task->pid, trans->fn);
3122
3123         trans_for_each_path(trans, path) {
3124                 if (!path->nodes_locked)
3125                         continue;
3126
3127                 prt_printf(out, "  path %u %c l=%u %s:",
3128                        path->idx,
3129                        path->cached ? 'c' : 'b',
3130                        path->level,
3131                        bch2_btree_ids[path->btree_id]);
3132                 bch2_bpos_to_text(out, path->pos);
3133                 prt_newline(out);
3134
3135                 for (l = 0; l < BTREE_MAX_DEPTH; l++) {
3136                         if (btree_node_locked(path, l) &&
3137                             !IS_ERR_OR_NULL(b = (void *) READ_ONCE(path->l[l].b))) {
3138                                 prt_printf(out, "    %c l=%u ",
3139                                            lock_types[btree_node_locked_type(path, l)], l);
3140                                 bch2_btree_bkey_cached_common_to_text(out, b);
3141                                 prt_newline(out);
3142                         }
3143                 }
3144         }
3145
3146         b = READ_ONCE(trans->locking);
3147         if (b) {
3148                 prt_printf(out, "  blocked for %lluus on",
3149                            div_u64(local_clock() - trans->locking_wait.start_time,
3150                                    1000));
3151                 prt_newline(out);
3152                 prt_printf(out, "    %c", lock_types[trans->locking_wait.lock_want]);
3153                 bch2_btree_bkey_cached_common_to_text(out, b);
3154                 prt_newline(out);
3155         }
3156 }
3157
3158 void bch2_fs_btree_iter_exit(struct bch_fs *c)
3159 {
3160         struct btree_transaction_stats *s;
3161
3162         for (s = c->btree_transaction_stats;
3163              s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
3164              s++) {
3165                 kfree(s->max_paths_text);
3166                 bch2_time_stats_exit(&s->lock_hold_times);
3167         }
3168
3169         if (c->btree_trans_barrier_initialized)
3170                 cleanup_srcu_struct(&c->btree_trans_barrier);
3171         mempool_exit(&c->btree_trans_mem_pool);
3172         mempool_exit(&c->btree_paths_pool);
3173 }
3174
3175 int bch2_fs_btree_iter_init(struct bch_fs *c)
3176 {
3177         struct btree_transaction_stats *s;
3178         unsigned nr = BTREE_ITER_MAX;
3179         int ret;
3180
3181         for (s = c->btree_transaction_stats;
3182              s < c->btree_transaction_stats + ARRAY_SIZE(c->btree_transaction_stats);
3183              s++) {
3184                 bch2_time_stats_init(&s->lock_hold_times);
3185                 mutex_init(&s->lock);
3186         }
3187
3188         INIT_LIST_HEAD(&c->btree_trans_list);
3189         mutex_init(&c->btree_trans_lock);
3190
3191         ret   = mempool_init_kmalloc_pool(&c->btree_paths_pool, 1,
3192                         sizeof(struct btree_path) * nr +
3193                         sizeof(struct btree_insert_entry) * nr) ?:
3194                 mempool_init_kmalloc_pool(&c->btree_trans_mem_pool, 1,
3195                                           BTREE_TRANS_MEM_MAX) ?:
3196                 init_srcu_struct(&c->btree_trans_barrier);
3197         if (!ret)
3198                 c->btree_trans_barrier_initialized = true;
3199         return ret;
3200 }