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/prefetch.h>
  20 #include <trace/events/bcachefs.h>
  21
  22 static void btree_trans_verify_sorted(struct btree_trans *);
  23 inline void bch2_btree_path_check_sort(struct btree_trans *, struct btree_path *, int);
  24
  25 static inline void btree_path_list_remove(struct btree_trans *, struct btree_path *);
  26 static inline void btree_path_list_add(struct btree_trans *, struct btree_path *,
  27                                        struct btree_path *);
  28
  29 static inline unsigned long btree_iter_ip_allocated(struct btree_iter *iter)
  30 {
  31 #ifdef CONFIG_BCACHEFS_DEBUG
  32         return iter->ip_allocated;
  33 #else
  34         return 0;
  35 #endif
  36 }
  37
  38 static struct btree_path *btree_path_alloc(struct btree_trans *, struct btree_path *);
  39
  40 /*
  41  * Unlocks before scheduling
  42  * Note: does not revalidate iterator
  43  */
  44 static inline int bch2_trans_cond_resched(struct btree_trans *trans)
  45 {
  46         if (need_resched() || race_fault()) {
  47                 bch2_trans_unlock(trans);
  48                 schedule();
  49                 return bch2_trans_relock(trans) ? 0 : -EINTR;
  50         } else {
  51                 return 0;
  52         }
  53 }
  54
  55 static inline int __btree_path_cmp(const struct btree_path *l,
  56                                    enum btree_id        r_btree_id,
  57                                    bool                 r_cached,
  58                                    struct bpos          r_pos,
  59                                    unsigned             r_level)
  60 {
  61         /*
  62          * Must match lock ordering as defined by __bch2_btree_node_lock:
  63          */
  64         return   cmp_int(l->btree_id,   r_btree_id) ?:
  65                  cmp_int((int) l->cached,       (int) r_cached) ?:
  66                  bpos_cmp(l->pos,       r_pos) ?:
  67                 -cmp_int(l->level,      r_level);
  68 }
  69
  70 static inline int btree_path_cmp(const struct btree_path *l,
  71                                  const struct btree_path *r)
  72 {
  73         return __btree_path_cmp(l, r->btree_id, r->cached, r->pos, r->level);
  74 }
  75
  76 static inline struct bpos bkey_successor(struct btree_iter *iter, struct bpos p)
  77 {
  78         /* Are we iterating over keys in all snapshots? */
  79         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  80                 p = bpos_successor(p);
  81         } else {
  82                 p = bpos_nosnap_successor(p);
  83                 p.snapshot = iter->snapshot;
  84         }
  85
  86         return p;
  87 }
  88
  89 static inline struct bpos bkey_predecessor(struct btree_iter *iter, struct bpos p)
  90 {
  91         /* Are we iterating over keys in all snapshots? */
  92         if (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) {
  93                 p = bpos_predecessor(p);
  94         } else {
  95                 p = bpos_nosnap_predecessor(p);
  96                 p.snapshot = iter->snapshot;
  97         }
  98
  99         return p;
 100 }
 101
 102 static inline bool is_btree_node(struct btree_path *path, unsigned l)
 103 {
 104         return l < BTREE_MAX_DEPTH &&
 105                 (unsigned long) path->l[l].b >= 128;
 106 }
 107
 108 static inline struct bpos btree_iter_search_key(struct btree_iter *iter)
 109 {
 110         struct bpos pos = iter->pos;
 111
 112         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
 113             bkey_cmp(pos, POS_MAX))
 114                 pos = bkey_successor(iter, pos);
 115         return pos;
 116 }
 117
 118 static inline bool btree_path_pos_before_node(struct btree_path *path,
 119                                               struct btree *b)
 120 {
 121         return bpos_cmp(path->pos, b->data->min_key) < 0;
 122 }
 123
 124 static inline bool btree_path_pos_after_node(struct btree_path *path,
 125                                              struct btree *b)
 126 {
 127         return bpos_cmp(b->key.k.p, path->pos) < 0;
 128 }
 129
 130 static inline bool btree_path_pos_in_node(struct btree_path *path,
 131                                           struct btree *b)
 132 {
 133         return path->btree_id == b->c.btree_id &&
 134                 !btree_path_pos_before_node(path, b) &&
 135                 !btree_path_pos_after_node(path, b);
 136 }
 137
 138 /* Btree node locking: */
 139
 140 void bch2_btree_node_unlock_write(struct btree_trans *trans,
 141                         struct btree_path *path, struct btree *b)
 142 {
 143         bch2_btree_node_unlock_write_inlined(trans, path, b);
 144 }
 145
 146 void __bch2_btree_node_lock_write(struct btree_trans *trans, struct btree *b)
 147 {
 148         struct btree_path *linked;
 149         unsigned readers = 0;
 150
 151         trans_for_each_path(trans, linked)
 152                 if (linked->l[b->c.level].b == b &&
 153                     btree_node_read_locked(linked, b->c.level))
 154                         readers++;
 155
 156         /*
 157          * Must drop our read locks before calling six_lock_write() -
 158          * six_unlock() won't do wakeups until the reader count
 159          * goes to 0, and it's safe because we have the node intent
 160          * locked:
 161          */
 162         if (!b->c.lock.readers)
 163                 atomic64_sub(__SIX_VAL(read_lock, readers),
 164                              &b->c.lock.state.counter);
 165         else
 166                 this_cpu_sub(*b->c.lock.readers, readers);
 167
 168         six_lock_write(&b->c.lock, NULL, NULL);
 169
 170         if (!b->c.lock.readers)
 171                 atomic64_add(__SIX_VAL(read_lock, readers),
 172                              &b->c.lock.state.counter);
 173         else
 174                 this_cpu_add(*b->c.lock.readers, readers);
 175 }
 176
 177 bool __bch2_btree_node_relock(struct btree_trans *trans,
 178                               struct btree_path *path, unsigned level)
 179 {
 180         struct btree *b = btree_path_node(path, level);
 181         int want = __btree_lock_want(path, level);
 182
 183         if (!is_btree_node(path, level))
 184                 goto fail;
 185
 186         if (race_fault())
 187                 goto fail;
 188
 189         if (six_relock_type(&b->c.lock, want, path->l[level].lock_seq) ||
 190             (btree_node_lock_seq_matches(path, b, level) &&
 191              btree_node_lock_increment(trans, b, level, want))) {
 192                 mark_btree_node_locked(trans, path, level, want);
 193                 return true;
 194         }
 195 fail:
 196         trace_btree_node_relock_fail(trans->fn, _RET_IP_,
 197                                      path->btree_id,
 198                                      &path->pos,
 199                                      (unsigned long) b,
 200                                      path->l[level].lock_seq,
 201                                      is_btree_node(path, level) ? b->c.lock.state.seq : 0);
 202         return false;
 203 }
 204
 205 bool bch2_btree_node_upgrade(struct btree_trans *trans,
 206                              struct btree_path *path, unsigned level)
 207 {
 208         struct btree *b = path->l[level].b;
 209
 210         if (!is_btree_node(path, level))
 211                 return false;
 212
 213         switch (btree_lock_want(path, level)) {
 214         case BTREE_NODE_UNLOCKED:
 215                 BUG_ON(btree_node_locked(path, level));
 216                 return true;
 217         case BTREE_NODE_READ_LOCKED:
 218                 BUG_ON(btree_node_intent_locked(path, level));
 219                 return bch2_btree_node_relock(trans, path, level);
 220         case BTREE_NODE_INTENT_LOCKED:
 221                 break;
 222         }
 223
 224         if (btree_node_intent_locked(path, level))
 225                 return true;
 226
 227         if (race_fault())
 228                 return false;
 229
 230         if (btree_node_locked(path, level)
 231             ? six_lock_tryupgrade(&b->c.lock)
 232             : six_relock_type(&b->c.lock, SIX_LOCK_intent, path->l[level].lock_seq))
 233                 goto success;
 234
 235         if (btree_node_lock_seq_matches(path, b, level) &&
 236             btree_node_lock_increment(trans, b, level, BTREE_NODE_INTENT_LOCKED)) {
 237                 btree_node_unlock(path, level);
 238                 goto success;
 239         }
 240
 241         return false;
 242 success:
 243         mark_btree_node_intent_locked(trans, path, level);
 244         return true;
 245 }
 246
 247 static inline bool btree_path_get_locks(struct btree_trans *trans,
 248                                         struct btree_path *path,
 249                                         bool upgrade)
 250 {
 251         unsigned l = path->level;
 252         int fail_idx = -1;
 253
 254         do {
 255                 if (!btree_path_node(path, l))
 256                         break;
 257
 258                 if (!(upgrade
 259                       ? bch2_btree_node_upgrade(trans, path, l)
 260                       : bch2_btree_node_relock(trans, path, l)))
 261                         fail_idx = l;
 262
 263                 l++;
 264         } while (l < path->locks_want);
 265
 266         /*
 267          * When we fail to get a lock, we have to ensure that any child nodes
 268          * can't be relocked so bch2_btree_path_traverse has to walk back up to
 269          * the node that we failed to relock:
 270          */
 271         if (fail_idx >= 0) {
 272                 __bch2_btree_path_unlock(path);
 273                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
 274
 275                 do {
 276                         path->l[fail_idx].b = BTREE_ITER_NO_NODE_GET_LOCKS;
 277                         --fail_idx;
 278                 } while (fail_idx >= 0);
 279         }
 280
 281         if (path->uptodate == BTREE_ITER_NEED_RELOCK)
 282                 path->uptodate = BTREE_ITER_UPTODATE;
 283
 284         bch2_trans_verify_locks(trans);
 285
 286         return path->uptodate < BTREE_ITER_NEED_RELOCK;
 287 }
 288
 289 static struct bpos btree_node_pos(struct btree_bkey_cached_common *_b,
 290                                   bool cached)
 291 {
 292         return !cached
 293                 ? container_of(_b, struct btree, c)->key.k.p
 294                 : container_of(_b, struct bkey_cached, c)->key.pos;
 295 }
 296
 297 /* Slowpath: */
 298 bool __bch2_btree_node_lock(struct btree_trans *trans,
 299                             struct btree_path *path,
 300                             struct btree *b,
 301                             struct bpos pos, unsigned level,
 302                             enum six_lock_type type,
 303                             six_lock_should_sleep_fn should_sleep_fn, void *p,
 304                             unsigned long ip)
 305 {
 306         struct btree_path *linked;
 307         unsigned reason;
 308
 309         /* Check if it's safe to block: */
 310         trans_for_each_path(trans, linked) {
 311                 if (!linked->nodes_locked)
 312                         continue;
 313
 314                 /*
 315                  * Can't block taking an intent lock if we have _any_ nodes read
 316                  * locked:
 317                  *
 318                  * - Our read lock blocks another thread with an intent lock on
 319                  *   the same node from getting a write lock, and thus from
 320                  *   dropping its intent lock
 321                  *
 322                  * - And the other thread may have multiple nodes intent locked:
 323                  *   both the node we want to intent lock, and the node we
 324                  *   already have read locked - deadlock:
 325                  */
 326                 if (type == SIX_LOCK_intent &&
 327                     linked->nodes_locked != linked->nodes_intent_locked) {
 328                         reason = 1;
 329                         goto deadlock;
 330                 }
 331
 332                 if (linked->btree_id != path->btree_id) {
 333                         if (linked->btree_id < path->btree_id)
 334                                 continue;
 335
 336                         reason = 3;
 337                         goto deadlock;
 338                 }
 339
 340                 /*
 341                  * Within the same btree, non-cached paths come before cached
 342                  * paths:
 343                  */
 344                 if (linked->cached != path->cached) {
 345                         if (!linked->cached)
 346                                 continue;
 347
 348                         reason = 4;
 349                         goto deadlock;
 350                 }
 351
 352                 /*
 353                  * Interior nodes must be locked before their descendants: if
 354                  * another path has possible descendants locked of the node
 355                  * we're about to lock, it must have the ancestors locked too:
 356                  */
 357                 if (level > __fls(linked->nodes_locked)) {
 358                         reason = 5;
 359                         goto deadlock;
 360                 }
 361
 362                 /* Must lock btree nodes in key order: */
 363                 if (btree_node_locked(linked, level) &&
 364                     bpos_cmp(pos, btree_node_pos((void *) linked->l[level].b,
 365                                                  linked->cached)) <= 0) {
 366                         BUG_ON(trans->in_traverse_all);
 367                         reason = 7;
 368                         goto deadlock;
 369                 }
 370         }
 371
 372         return btree_node_lock_type(trans, path, b, pos, level,
 373                                     type, should_sleep_fn, p);
 374 deadlock:
 375         trace_trans_restart_would_deadlock(trans->fn, ip,
 376                         trans->in_traverse_all, reason,
 377                         linked->btree_id,
 378                         linked->cached,
 379                         &linked->pos,
 380                         path->btree_id,
 381                         path->cached,
 382                         &pos);
 383         btree_trans_restart(trans);
 384         return false;
 385 }
 386
 387 /* Btree iterator locking: */
 388
 389 #ifdef CONFIG_BCACHEFS_DEBUG
 390
 391 static void bch2_btree_path_verify_locks(struct btree_path *path)
 392 {
 393         unsigned l;
 394
 395         if (!path->nodes_locked) {
 396                 BUG_ON(path->uptodate == BTREE_ITER_UPTODATE &&
 397                        btree_path_node(path, path->level));
 398                 return;
 399         }
 400
 401         for (l = 0; btree_path_node(path, l); l++)
 402                 BUG_ON(btree_lock_want(path, l) !=
 403                        btree_node_locked_type(path, l));
 404 }
 405
 406 void bch2_trans_verify_locks(struct btree_trans *trans)
 407 {
 408         struct btree_path *path;
 409
 410         trans_for_each_path(trans, path)
 411                 bch2_btree_path_verify_locks(path);
 412 }
 413 #else
 414 static inline void bch2_btree_path_verify_locks(struct btree_path *path) {}
 415 #endif
 416
 417 /* Btree path locking: */
 418
 419 /*
 420  * Only for btree_cache.c - only relocks intent locks
 421  */
 422 bool bch2_btree_path_relock_intent(struct btree_trans *trans,
 423                                    struct btree_path *path)
 424 {
 425         unsigned l;
 426
 427         for (l = path->level;
 428              l < path->locks_want && btree_path_node(path, l);
 429              l++) {
 430                 if (!bch2_btree_node_relock(trans, path, l)) {
 431                         __bch2_btree_path_unlock(path);
 432                         btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
 433                         trace_trans_restart_relock_path_intent(trans->fn, _RET_IP_,
 434                                                    path->btree_id, &path->pos);
 435                         btree_trans_restart(trans);
 436                         return false;
 437                 }
 438         }
 439
 440         return true;
 441 }
 442
 443 __flatten
 444 static bool bch2_btree_path_relock(struct btree_trans *trans,
 445                         struct btree_path *path, unsigned long trace_ip)
 446 {
 447         bool ret = btree_path_get_locks(trans, path, false);
 448
 449         if (!ret) {
 450                 trace_trans_restart_relock_path(trans->fn, trace_ip,
 451                                                 path->btree_id, &path->pos);
 452                 btree_trans_restart(trans);
 453         }
 454         return ret;
 455 }
 456
 457 bool __bch2_btree_path_upgrade(struct btree_trans *trans,
 458                                struct btree_path *path,
 459                                unsigned new_locks_want)
 460 {
 461         struct btree_path *linked;
 462
 463         EBUG_ON(path->locks_want >= new_locks_want);
 464
 465         path->locks_want = new_locks_want;
 466
 467         if (btree_path_get_locks(trans, path, true))
 468                 return true;
 469
 470         /*
 471          * XXX: this is ugly - we'd prefer to not be mucking with other
 472          * iterators in the btree_trans here.
 473          *
 474          * On failure to upgrade the iterator, setting iter->locks_want and
 475          * calling get_locks() is sufficient to make bch2_btree_path_traverse()
 476          * get the locks we want on transaction restart.
 477          *
 478          * But if this iterator was a clone, on transaction restart what we did
 479          * to this iterator isn't going to be preserved.
 480          *
 481          * Possibly we could add an iterator field for the parent iterator when
 482          * an iterator is a copy - for now, we'll just upgrade any other
 483          * iterators with the same btree id.
 484          *
 485          * The code below used to be needed to ensure ancestor nodes get locked
 486          * before interior nodes - now that's handled by
 487          * bch2_btree_path_traverse_all().
 488          */
 489         if (!path->cached && !trans->in_traverse_all)
 490                 trans_for_each_path(trans, linked)
 491                         if (linked != path &&
 492                             linked->cached == path->cached &&
 493                             linked->btree_id == path->btree_id &&
 494                             linked->locks_want < new_locks_want) {
 495                                 linked->locks_want = new_locks_want;
 496                                 btree_path_get_locks(trans, linked, true);
 497                         }
 498
 499         return false;
 500 }
 501
 502 void __bch2_btree_path_downgrade(struct btree_path *path,
 503                                  unsigned new_locks_want)
 504 {
 505         unsigned l;
 506
 507         EBUG_ON(path->locks_want < new_locks_want);
 508
 509         path->locks_want = new_locks_want;
 510
 511         while (path->nodes_locked &&
 512                (l = __fls(path->nodes_locked)) >= path->locks_want) {
 513                 if (l > path->level) {
 514                         btree_node_unlock(path, l);
 515                 } else {
 516                         if (btree_node_intent_locked(path, l)) {
 517                                 six_lock_downgrade(&path->l[l].b->c.lock);
 518                                 path->nodes_intent_locked ^= 1 << l;
 519                         }
 520                         break;
 521                 }
 522         }
 523
 524         bch2_btree_path_verify_locks(path);
 525 }
 526
 527 void bch2_trans_downgrade(struct btree_trans *trans)
 528 {
 529         struct btree_path *path;
 530
 531         trans_for_each_path(trans, path)
 532                 bch2_btree_path_downgrade(path);
 533 }
 534
 535 /* Btree transaction locking: */
 536
 537 bool bch2_trans_relock(struct btree_trans *trans)
 538 {
 539         struct btree_path *path;
 540
 541         if (unlikely(trans->restarted))
 542                 return false;
 543
 544         trans_for_each_path(trans, path)
 545                 if (path->should_be_locked &&
 546                     !bch2_btree_path_relock(trans, path, _RET_IP_)) {
 547                         trace_trans_restart_relock(trans->fn, _RET_IP_,
 548                                         path->btree_id, &path->pos);
 549                         BUG_ON(!trans->restarted);
 550                         return false;
 551                 }
 552         return true;
 553 }
 554
 555 void bch2_trans_unlock(struct btree_trans *trans)
 556 {
 557         struct btree_path *path;
 558
 559         trans_for_each_path(trans, path)
 560                 __bch2_btree_path_unlock(path);
 561
 562         /*
 563          * bch2_gc_btree_init_recurse() doesn't use btree iterators for walking
 564          * btree nodes, it implements its own walking:
 565          */
 566         BUG_ON(!trans->is_initial_gc &&
 567                lock_class_is_held(&bch2_btree_node_lock_key));
 568 }
 569
 570 /* Btree iterator: */
 571
 572 #ifdef CONFIG_BCACHEFS_DEBUG
 573
 574 static void bch2_btree_path_verify_cached(struct btree_trans *trans,
 575                                           struct btree_path *path)
 576 {
 577         struct bkey_cached *ck;
 578         bool locked = btree_node_locked(path, 0);
 579
 580         if (!bch2_btree_node_relock(trans, path, 0))
 581                 return;
 582
 583         ck = (void *) path->l[0].b;
 584         BUG_ON(ck->key.btree_id != path->btree_id ||
 585                bkey_cmp(ck->key.pos, path->pos));
 586
 587         if (!locked)
 588                 btree_node_unlock(path, 0);
 589 }
 590
 591 static void bch2_btree_path_verify_level(struct btree_trans *trans,
 592                                 struct btree_path *path, unsigned level)
 593 {
 594         struct btree_path_level *l;
 595         struct btree_node_iter tmp;
 596         bool locked;
 597         struct bkey_packed *p, *k;
 598         struct printbuf buf1 = PRINTBUF;
 599         struct printbuf buf2 = PRINTBUF;
 600         struct printbuf buf3 = PRINTBUF;
 601         const char *msg;
 602
 603         if (!bch2_debug_check_iterators)
 604                 return;
 605
 606         l       = &path->l[level];
 607         tmp     = l->iter;
 608         locked  = btree_node_locked(path, level);
 609
 610         if (path->cached) {
 611                 if (!level)
 612                         bch2_btree_path_verify_cached(trans, path);
 613                 return;
 614         }
 615
 616         if (!btree_path_node(path, level))
 617                 return;
 618
 619         if (!bch2_btree_node_relock(trans, path, level))
 620                 return;
 621
 622         BUG_ON(!btree_path_pos_in_node(path, l->b));
 623
 624         bch2_btree_node_iter_verify(&l->iter, l->b);
 625
 626         /*
 627          * For interior nodes, the iterator will have skipped past deleted keys:
 628          */
 629         p = level
 630                 ? bch2_btree_node_iter_prev(&tmp, l->b)
 631                 : bch2_btree_node_iter_prev_all(&tmp, l->b);
 632         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
 633
 634         if (p && bkey_iter_pos_cmp(l->b, p, &path->pos) >= 0) {
 635                 msg = "before";
 636                 goto err;
 637         }
 638
 639         if (k && bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
 640                 msg = "after";
 641                 goto err;
 642         }
 643
 644         if (!locked)
 645                 btree_node_unlock(path, level);
 646         return;
 647 err:
 648         bch2_bpos_to_text(&buf1, path->pos);
 649
 650         if (p) {
 651                 struct bkey uk = bkey_unpack_key(l->b, p);
 652                 bch2_bkey_to_text(&buf2, &uk);
 653         } else {
 654                 pr_buf(&buf2, "(none)");
 655         }
 656
 657         if (k) {
 658                 struct bkey uk = bkey_unpack_key(l->b, k);
 659                 bch2_bkey_to_text(&buf3, &uk);
 660         } else {
 661                 pr_buf(&buf3, "(none)");
 662         }
 663
 664         panic("path should be %s key at level %u:\n"
 665               "path pos %s\n"
 666               "prev key %s\n"
 667               "cur  key %s\n",
 668               msg, level, buf1.buf, buf2.buf, buf3.buf);
 669 }
 670
 671 static void bch2_btree_path_verify(struct btree_trans *trans,
 672                                    struct btree_path *path)
 673 {
 674         struct bch_fs *c = trans->c;
 675         unsigned i;
 676
 677         EBUG_ON(path->btree_id >= BTREE_ID_NR);
 678
 679         for (i = 0; i < (!path->cached ? BTREE_MAX_DEPTH : 1); i++) {
 680                 if (!path->l[i].b) {
 681                         BUG_ON(!path->cached &&
 682                                c->btree_roots[path->btree_id].b->c.level > i);
 683                         break;
 684                 }
 685
 686                 bch2_btree_path_verify_level(trans, path, i);
 687         }
 688
 689         bch2_btree_path_verify_locks(path);
 690 }
 691
 692 void bch2_trans_verify_paths(struct btree_trans *trans)
 693 {
 694         struct btree_path *path;
 695
 696         trans_for_each_path(trans, path)
 697                 bch2_btree_path_verify(trans, path);
 698 }
 699
 700 static void bch2_btree_iter_verify(struct btree_iter *iter)
 701 {
 702         struct btree_trans *trans = iter->trans;
 703
 704         BUG_ON(iter->btree_id >= BTREE_ID_NR);
 705
 706         BUG_ON(!!(iter->flags & BTREE_ITER_CACHED) != iter->path->cached);
 707
 708         BUG_ON((iter->flags & BTREE_ITER_IS_EXTENTS) &&
 709                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS));
 710
 711         BUG_ON(!(iter->flags & __BTREE_ITER_ALL_SNAPSHOTS) &&
 712                (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 713                !btree_type_has_snapshots(iter->btree_id));
 714
 715         if (iter->update_path)
 716                 bch2_btree_path_verify(trans, iter->update_path);
 717         bch2_btree_path_verify(trans, iter->path);
 718 }
 719
 720 static void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter)
 721 {
 722         BUG_ON((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
 723                !iter->pos.snapshot);
 724
 725         BUG_ON(!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&
 726                iter->pos.snapshot != iter->snapshot);
 727
 728         BUG_ON(bkey_cmp(iter->pos, bkey_start_pos(&iter->k)) < 0 ||
 729                bkey_cmp(iter->pos, iter->k.p) > 0);
 730 }
 731
 732 static int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k)
 733 {
 734         struct btree_trans *trans = iter->trans;
 735         struct btree_iter copy;
 736         struct bkey_s_c prev;
 737         int ret = 0;
 738
 739         if (!bch2_debug_check_iterators)
 740                 return 0;
 741
 742         if (!(iter->flags & BTREE_ITER_FILTER_SNAPSHOTS))
 743                 return 0;
 744
 745         if (bkey_err(k) || !k.k)
 746                 return 0;
 747
 748         BUG_ON(!bch2_snapshot_is_ancestor(trans->c,
 749                                           iter->snapshot,
 750                                           k.k->p.snapshot));
 751
 752         bch2_trans_iter_init(trans, &copy, iter->btree_id, iter->pos,
 753                              BTREE_ITER_NOPRESERVE|
 754                              BTREE_ITER_ALL_SNAPSHOTS);
 755         prev = bch2_btree_iter_prev(&copy);
 756         if (!prev.k)
 757                 goto out;
 758
 759         ret = bkey_err(prev);
 760         if (ret)
 761                 goto out;
 762
 763         if (!bkey_cmp(prev.k->p, k.k->p) &&
 764             bch2_snapshot_is_ancestor(trans->c, iter->snapshot,
 765                                       prev.k->p.snapshot) > 0) {
 766                 struct printbuf buf1 = PRINTBUF, buf2 = PRINTBUF;
 767
 768                 bch2_bkey_to_text(&buf1, k.k);
 769                 bch2_bkey_to_text(&buf2, prev.k);
 770
 771                 panic("iter snap %u\n"
 772                       "k    %s\n"
 773                       "prev %s\n",
 774                       iter->snapshot,
 775                       buf1.buf, buf2.buf);
 776         }
 777 out:
 778         bch2_trans_iter_exit(trans, &copy);
 779         return ret;
 780 }
 781
 782 void bch2_assert_pos_locked(struct btree_trans *trans, enum btree_id id,
 783                             struct bpos pos, bool key_cache)
 784 {
 785         struct btree_path *path;
 786         unsigned idx;
 787         struct printbuf buf = PRINTBUF;
 788
 789         trans_for_each_path_inorder(trans, path, idx) {
 790                 int cmp = cmp_int(path->btree_id, id) ?:
 791                         cmp_int(path->cached, key_cache);
 792
 793                 if (cmp > 0)
 794                         break;
 795                 if (cmp < 0)
 796                         continue;
 797
 798                 if (!(path->nodes_locked & 1) ||
 799                     !path->should_be_locked)
 800                         continue;
 801
 802                 if (!key_cache) {
 803                         if (bkey_cmp(pos, path->l[0].b->data->min_key) >= 0 &&
 804                             bkey_cmp(pos, path->l[0].b->key.k.p) <= 0)
 805                                 return;
 806                 } else {
 807                         if (!bkey_cmp(pos, path->pos))
 808                                 return;
 809                 }
 810         }
 811
 812         bch2_dump_trans_paths_updates(trans);
 813         bch2_bpos_to_text(&buf, pos);
 814
 815         panic("not locked: %s %s%s\n",
 816               bch2_btree_ids[id], buf.buf,
 817               key_cache ? " cached" : "");
 818 }
 819
 820 #else
 821
 822 static inline void bch2_btree_path_verify_level(struct btree_trans *trans,
 823                                                 struct btree_path *path, unsigned l) {}
 824 static inline void bch2_btree_path_verify(struct btree_trans *trans,
 825                                           struct btree_path *path) {}
 826 static inline void bch2_btree_iter_verify(struct btree_iter *iter) {}
 827 static inline void bch2_btree_iter_verify_entry_exit(struct btree_iter *iter) {}
 828 static inline int bch2_btree_iter_verify_ret(struct btree_iter *iter, struct bkey_s_c k) { return 0; }
 829
 830 #endif
 831
 832 /* Btree path: fixups after btree updates */
 833
 834 static void btree_node_iter_set_set_pos(struct btree_node_iter *iter,
 835                                         struct btree *b,
 836                                         struct bset_tree *t,
 837                                         struct bkey_packed *k)
 838 {
 839         struct btree_node_iter_set *set;
 840
 841         btree_node_iter_for_each(iter, set)
 842                 if (set->end == t->end_offset) {
 843                         set->k = __btree_node_key_to_offset(b, k);
 844                         bch2_btree_node_iter_sort(iter, b);
 845                         return;
 846                 }
 847
 848         bch2_btree_node_iter_push(iter, b, k, btree_bkey_last(b, t));
 849 }
 850
 851 static void __bch2_btree_path_fix_key_modified(struct btree_path *path,
 852                                                struct btree *b,
 853                                                struct bkey_packed *where)
 854 {
 855         struct btree_path_level *l = &path->l[b->c.level];
 856
 857         if (where != bch2_btree_node_iter_peek_all(&l->iter, l->b))
 858                 return;
 859
 860         if (bkey_iter_pos_cmp(l->b, where, &path->pos) < 0)
 861                 bch2_btree_node_iter_advance(&l->iter, l->b);
 862 }
 863
 864 void bch2_btree_path_fix_key_modified(struct btree_trans *trans,
 865                                       struct btree *b,
 866                                       struct bkey_packed *where)
 867 {
 868         struct btree_path *path;
 869
 870         trans_for_each_path_with_node(trans, b, path) {
 871                 __bch2_btree_path_fix_key_modified(path, b, where);
 872                 bch2_btree_path_verify_level(trans, path, b->c.level);
 873         }
 874 }
 875
 876 static void __bch2_btree_node_iter_fix(struct btree_path *path,
 877                                        struct btree *b,
 878                                        struct btree_node_iter *node_iter,
 879                                        struct bset_tree *t,
 880                                        struct bkey_packed *where,
 881                                        unsigned clobber_u64s,
 882                                        unsigned new_u64s)
 883 {
 884         const struct bkey_packed *end = btree_bkey_last(b, t);
 885         struct btree_node_iter_set *set;
 886         unsigned offset = __btree_node_key_to_offset(b, where);
 887         int shift = new_u64s - clobber_u64s;
 888         unsigned old_end = t->end_offset - shift;
 889         unsigned orig_iter_pos = node_iter->data[0].k;
 890         bool iter_current_key_modified =
 891                 orig_iter_pos >= offset &&
 892                 orig_iter_pos <= offset + clobber_u64s;
 893
 894         btree_node_iter_for_each(node_iter, set)
 895                 if (set->end == old_end)
 896                         goto found;
 897
 898         /* didn't find the bset in the iterator - might have to readd it: */
 899         if (new_u64s &&
 900             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 901                 bch2_btree_node_iter_push(node_iter, b, where, end);
 902                 goto fixup_done;
 903         } else {
 904                 /* Iterator is after key that changed */
 905                 return;
 906         }
 907 found:
 908         set->end = t->end_offset;
 909
 910         /* Iterator hasn't gotten to the key that changed yet: */
 911         if (set->k < offset)
 912                 return;
 913
 914         if (new_u64s &&
 915             bkey_iter_pos_cmp(b, where, &path->pos) >= 0) {
 916                 set->k = offset;
 917         } else if (set->k < offset + clobber_u64s) {
 918                 set->k = offset + new_u64s;
 919                 if (set->k == set->end)
 920                         bch2_btree_node_iter_set_drop(node_iter, set);
 921         } else {
 922                 /* Iterator is after key that changed */
 923                 set->k = (int) set->k + shift;
 924                 return;
 925         }
 926
 927         bch2_btree_node_iter_sort(node_iter, b);
 928 fixup_done:
 929         if (node_iter->data[0].k != orig_iter_pos)
 930                 iter_current_key_modified = true;
 931
 932         /*
 933          * When a new key is added, and the node iterator now points to that
 934          * key, the iterator might have skipped past deleted keys that should
 935          * come after the key the iterator now points to. We have to rewind to
 936          * before those deleted keys - otherwise
 937          * bch2_btree_node_iter_prev_all() breaks:
 938          */
 939         if (!bch2_btree_node_iter_end(node_iter) &&
 940             iter_current_key_modified &&
 941             b->c.level) {
 942                 struct bset_tree *t;
 943                 struct bkey_packed *k, *k2, *p;
 944
 945                 k = bch2_btree_node_iter_peek_all(node_iter, b);
 946
 947                 for_each_bset(b, t) {
 948                         bool set_pos = false;
 949
 950                         if (node_iter->data[0].end == t->end_offset)
 951                                 continue;
 952
 953                         k2 = bch2_btree_node_iter_bset_pos(node_iter, b, t);
 954
 955                         while ((p = bch2_bkey_prev_all(b, t, k2)) &&
 956                                bkey_iter_cmp(b, k, p) < 0) {
 957                                 k2 = p;
 958                                 set_pos = true;
 959                         }
 960
 961                         if (set_pos)
 962                                 btree_node_iter_set_set_pos(node_iter,
 963                                                             b, t, k2);
 964                 }
 965         }
 966 }
 967
 968 void bch2_btree_node_iter_fix(struct btree_trans *trans,
 969                               struct btree_path *path,
 970                               struct btree *b,
 971                               struct btree_node_iter *node_iter,
 972                               struct bkey_packed *where,
 973                               unsigned clobber_u64s,
 974                               unsigned new_u64s)
 975 {
 976         struct bset_tree *t = bch2_bkey_to_bset(b, where);
 977         struct btree_path *linked;
 978
 979         if (node_iter != &path->l[b->c.level].iter) {
 980                 __bch2_btree_node_iter_fix(path, b, node_iter, t,
 981                                            where, clobber_u64s, new_u64s);
 982
 983                 if (bch2_debug_check_iterators)
 984                         bch2_btree_node_iter_verify(node_iter, b);
 985         }
 986
 987         trans_for_each_path_with_node(trans, b, linked) {
 988                 __bch2_btree_node_iter_fix(linked, b,
 989                                            &linked->l[b->c.level].iter, t,
 990                                            where, clobber_u64s, new_u64s);
 991                 bch2_btree_path_verify_level(trans, linked, b->c.level);
 992         }
 993 }
 994
 995 /* Btree path level: pointer to a particular btree node and node iter */
 996
 997 static inline struct bkey_s_c __btree_iter_unpack(struct bch_fs *c,
 998                                                   struct btree_path_level *l,
 999                                                   struct bkey *u,
1000                                                   struct bkey_packed *k)
1001 {
1002         if (unlikely(!k)) {
1003                 /*
1004                  * signal to bch2_btree_iter_peek_slot() that we're currently at
1005                  * a hole
1006                  */
1007                 u->type = KEY_TYPE_deleted;
1008                 return bkey_s_c_null;
1009         }
1010
1011         return bkey_disassemble(l->b, k, u);
1012 }
1013
1014 static inline struct bkey_s_c btree_path_level_peek_all(struct bch_fs *c,
1015                                                         struct btree_path_level *l,
1016                                                         struct bkey *u)
1017 {
1018         return __btree_iter_unpack(c, l, u,
1019                         bch2_btree_node_iter_peek_all(&l->iter, l->b));
1020 }
1021
1022 static inline struct bkey_s_c btree_path_level_peek(struct bch_fs *c,
1023                                                     struct btree_path *path,
1024                                                     struct btree_path_level *l,
1025                                                     struct bkey *u)
1026 {
1027         struct bkey_s_c k = __btree_iter_unpack(c, l, u,
1028                         bch2_btree_node_iter_peek(&l->iter, l->b));
1029
1030         path->pos = k.k ? k.k->p : l->b->key.k.p;
1031         return k;
1032 }
1033
1034 static inline struct bkey_s_c btree_path_level_prev(struct bch_fs *c,
1035                                                     struct btree_path *path,
1036                                                     struct btree_path_level *l,
1037                                                     struct bkey *u)
1038 {
1039         struct bkey_s_c k = __btree_iter_unpack(c, l, u,
1040                         bch2_btree_node_iter_prev(&l->iter, l->b));
1041
1042         path->pos = k.k ? k.k->p : l->b->data->min_key;
1043         return k;
1044 }
1045
1046 static inline bool btree_path_advance_to_pos(struct btree_path *path,
1047                                              struct btree_path_level *l,
1048                                              int max_advance)
1049 {
1050         struct bkey_packed *k;
1051         int nr_advanced = 0;
1052
1053         while ((k = bch2_btree_node_iter_peek_all(&l->iter, l->b)) &&
1054                bkey_iter_pos_cmp(l->b, k, &path->pos) < 0) {
1055                 if (max_advance > 0 && nr_advanced >= max_advance)
1056                         return false;
1057
1058                 bch2_btree_node_iter_advance(&l->iter, l->b);
1059                 nr_advanced++;
1060         }
1061
1062         return true;
1063 }
1064
1065 /*
1066  * Verify that iterator for parent node points to child node:
1067  */
1068 static void btree_path_verify_new_node(struct btree_trans *trans,
1069                                        struct btree_path *path, struct btree *b)
1070 {
1071         struct bch_fs *c = trans->c;
1072         struct btree_path_level *l;
1073         unsigned plevel;
1074         bool parent_locked;
1075         struct bkey_packed *k;
1076
1077         if (!IS_ENABLED(CONFIG_BCACHEFS_DEBUG))
1078                 return;
1079
1080         if (!test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags))
1081                 return;
1082
1083         plevel = b->c.level + 1;
1084         if (!btree_path_node(path, plevel))
1085                 return;
1086
1087         parent_locked = btree_node_locked(path, plevel);
1088
1089         if (!bch2_btree_node_relock(trans, path, plevel))
1090                 return;
1091
1092         l = &path->l[plevel];
1093         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
1094         if (!k ||
1095             bkey_deleted(k) ||
1096             bkey_cmp_left_packed(l->b, k, &b->key.k.p)) {
1097                 struct printbuf buf1 = PRINTBUF;
1098                 struct printbuf buf2 = PRINTBUF;
1099                 struct printbuf buf3 = PRINTBUF;
1100                 struct printbuf buf4 = PRINTBUF;
1101                 struct bkey uk = bkey_unpack_key(b, k);
1102
1103                 bch2_dump_btree_node(c, l->b);
1104                 bch2_bpos_to_text(&buf1, path->pos);
1105                 bch2_bkey_to_text(&buf2, &uk);
1106                 bch2_bpos_to_text(&buf3, b->data->min_key);
1107                 bch2_bpos_to_text(&buf3, b->data->max_key);
1108                 panic("parent iter doesn't point to new node:\n"
1109                       "iter pos %s %s\n"
1110                       "iter key %s\n"
1111                       "new node %s-%s\n",
1112                       bch2_btree_ids[path->btree_id],
1113                       buf1.buf, buf2.buf, buf3.buf, buf4.buf);
1114         }
1115
1116         if (!parent_locked)
1117                 btree_node_unlock(path, plevel);
1118 }
1119
1120 static inline void __btree_path_level_init(struct btree_path *path,
1121                                            unsigned level)
1122 {
1123         struct btree_path_level *l = &path->l[level];
1124
1125         bch2_btree_node_iter_init(&l->iter, l->b, &path->pos);
1126
1127         /*
1128          * Iterators to interior nodes should always be pointed at the first non
1129          * whiteout:
1130          */
1131         if (level)
1132                 bch2_btree_node_iter_peek(&l->iter, l->b);
1133 }
1134
1135 static inline void btree_path_level_init(struct btree_trans *trans,
1136                                          struct btree_path *path,
1137                                          struct btree *b)
1138 {
1139         BUG_ON(path->cached);
1140
1141         btree_path_verify_new_node(trans, path, b);
1142
1143         EBUG_ON(!btree_path_pos_in_node(path, b));
1144         EBUG_ON(b->c.lock.state.seq & 1);
1145
1146         path->l[b->c.level].lock_seq = b->c.lock.state.seq;
1147         path->l[b->c.level].b = b;
1148         __btree_path_level_init(path, b->c.level);
1149 }
1150
1151 /* Btree path: fixups after btree node updates: */
1152
1153 /*
1154  * A btree node is being replaced - update the iterator to point to the new
1155  * node:
1156  */
1157 void bch2_trans_node_add(struct btree_trans *trans, struct btree *b)
1158 {
1159         struct btree_path *path;
1160
1161         trans_for_each_path(trans, path)
1162                 if (!path->cached &&
1163                     btree_path_pos_in_node(path, b)) {
1164                         enum btree_node_locked_type t =
1165                                 btree_lock_want(path, b->c.level);
1166
1167                         if (path->nodes_locked &&
1168                             t != BTREE_NODE_UNLOCKED) {
1169                                 btree_node_unlock(path, b->c.level);
1170                                 six_lock_increment(&b->c.lock, t);
1171                                 mark_btree_node_locked(trans, path, b->c.level, t);
1172                         }
1173
1174                         btree_path_level_init(trans, path, b);
1175                 }
1176 }
1177
1178 /*
1179  * A btree node has been modified in such a way as to invalidate iterators - fix
1180  * them:
1181  */
1182 void bch2_trans_node_reinit_iter(struct btree_trans *trans, struct btree *b)
1183 {
1184         struct btree_path *path;
1185
1186         trans_for_each_path_with_node(trans, b, path)
1187                 __btree_path_level_init(path, b->c.level);
1188 }
1189
1190 /* Btree path: traverse, set_pos: */
1191
1192 static int lock_root_check_fn(struct six_lock *lock, void *p)
1193 {
1194         struct btree *b = container_of(lock, struct btree, c.lock);
1195         struct btree **rootp = p;
1196
1197         return b == *rootp ? 0 : -1;
1198 }
1199
1200 static inline int btree_path_lock_root(struct btree_trans *trans,
1201                                        struct btree_path *path,
1202                                        unsigned depth_want,
1203                                        unsigned long trace_ip)
1204 {
1205         struct bch_fs *c = trans->c;
1206         struct btree *b, **rootp = &c->btree_roots[path->btree_id].b;
1207         enum six_lock_type lock_type;
1208         unsigned i;
1209
1210         EBUG_ON(path->nodes_locked);
1211
1212         while (1) {
1213                 b = READ_ONCE(*rootp);
1214                 path->level = READ_ONCE(b->c.level);
1215
1216                 if (unlikely(path->level < depth_want)) {
1217                         /*
1218                          * the root is at a lower depth than the depth we want:
1219                          * got to the end of the btree, or we're walking nodes
1220                          * greater than some depth and there are no nodes >=
1221                          * that depth
1222                          */
1223                         path->level = depth_want;
1224                         for (i = path->level; i < BTREE_MAX_DEPTH; i++)
1225                                 path->l[i].b = NULL;
1226                         return 1;
1227                 }
1228
1229                 lock_type = __btree_lock_want(path, path->level);
1230                 if (unlikely(!btree_node_lock(trans, path, b, SPOS_MAX,
1231                                               path->level, lock_type,
1232                                               lock_root_check_fn, rootp,
1233                                               trace_ip))) {
1234                         if (trans->restarted)
1235                                 return -EINTR;
1236                         continue;
1237                 }
1238
1239                 if (likely(b == READ_ONCE(*rootp) &&
1240                            b->c.level == path->level &&
1241                            !race_fault())) {
1242                         for (i = 0; i < path->level; i++)
1243                                 path->l[i].b = BTREE_ITER_NO_NODE_LOCK_ROOT;
1244                         path->l[path->level].b = b;
1245                         for (i = path->level + 1; i < BTREE_MAX_DEPTH; i++)
1246                                 path->l[i].b = NULL;
1247
1248                         mark_btree_node_locked(trans, path, path->level, lock_type);
1249                         btree_path_level_init(trans, path, b);
1250                         return 0;
1251                 }
1252
1253                 six_unlock_type(&b->c.lock, lock_type);
1254         }
1255 }
1256
1257 noinline
1258 static int btree_path_prefetch(struct btree_trans *trans, struct btree_path *path)
1259 {
1260         struct bch_fs *c = trans->c;
1261         struct btree_path_level *l = path_l(path);
1262         struct btree_node_iter node_iter = l->iter;
1263         struct bkey_packed *k;
1264         struct bkey_buf tmp;
1265         unsigned nr = test_bit(BCH_FS_STARTED, &c->flags)
1266                 ? (path->level > 1 ? 0 :  2)
1267                 : (path->level > 1 ? 1 : 16);
1268         bool was_locked = btree_node_locked(path, path->level);
1269         int ret = 0;
1270
1271         bch2_bkey_buf_init(&tmp);
1272
1273         while (nr && !ret) {
1274                 if (!bch2_btree_node_relock(trans, path, path->level))
1275                         break;
1276
1277                 bch2_btree_node_iter_advance(&node_iter, l->b);
1278                 k = bch2_btree_node_iter_peek(&node_iter, l->b);
1279                 if (!k)
1280                         break;
1281
1282                 bch2_bkey_buf_unpack(&tmp, c, l->b, k);
1283                 ret = bch2_btree_node_prefetch(c, trans, path, tmp.k, path->btree_id,
1284                                                path->level - 1);
1285         }
1286
1287         if (!was_locked)
1288                 btree_node_unlock(path, path->level);
1289
1290         bch2_bkey_buf_exit(&tmp, c);
1291         return ret;
1292 }
1293
1294 static int btree_path_prefetch_j(struct btree_trans *trans, struct btree_path *path,
1295                                  struct btree_and_journal_iter *jiter)
1296 {
1297         struct bch_fs *c = trans->c;
1298         struct bkey_s_c k;
1299         struct bkey_buf tmp;
1300         unsigned nr = test_bit(BCH_FS_STARTED, &c->flags)
1301                 ? (path->level > 1 ? 0 :  2)
1302                 : (path->level > 1 ? 1 : 16);
1303         bool was_locked = btree_node_locked(path, path->level);
1304         int ret = 0;
1305
1306         bch2_bkey_buf_init(&tmp);
1307
1308         while (nr && !ret) {
1309                 if (!bch2_btree_node_relock(trans, path, path->level))
1310                         break;
1311
1312                 bch2_btree_and_journal_iter_advance(jiter);
1313                 k = bch2_btree_and_journal_iter_peek(jiter);
1314                 if (!k.k)
1315                         break;
1316
1317                 bch2_bkey_buf_reassemble(&tmp, c, k);
1318                 ret = bch2_btree_node_prefetch(c, trans, path, tmp.k, path->btree_id,
1319                                                path->level - 1);
1320         }
1321
1322         if (!was_locked)
1323                 btree_node_unlock(path, path->level);
1324
1325         bch2_bkey_buf_exit(&tmp, c);
1326         return ret;
1327 }
1328
1329 static noinline void btree_node_mem_ptr_set(struct btree_trans *trans,
1330                                             struct btree_path *path,
1331                                             unsigned plevel, struct btree *b)
1332 {
1333         struct btree_path_level *l = &path->l[plevel];
1334         bool locked = btree_node_locked(path, plevel);
1335         struct bkey_packed *k;
1336         struct bch_btree_ptr_v2 *bp;
1337
1338         if (!bch2_btree_node_relock(trans, path, plevel))
1339                 return;
1340
1341         k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
1342         BUG_ON(k->type != KEY_TYPE_btree_ptr_v2);
1343
1344         bp = (void *) bkeyp_val(&l->b->format, k);
1345         bp->mem_ptr = (unsigned long)b;
1346
1347         if (!locked)
1348                 btree_node_unlock(path, plevel);
1349 }
1350
1351 static noinline int btree_node_iter_and_journal_peek(struct btree_trans *trans,
1352                                                      struct btree_path *path,
1353                                                      unsigned flags,
1354                                                      struct bkey_buf *out)
1355 {
1356         struct bch_fs *c = trans->c;
1357         struct btree_path_level *l = path_l(path);
1358         struct btree_and_journal_iter jiter;
1359         struct bkey_s_c k;
1360         int ret = 0;
1361
1362         __bch2_btree_and_journal_iter_init_node_iter(&jiter, c, l->b, l->iter, path->pos);
1363
1364         k = bch2_btree_and_journal_iter_peek(&jiter);
1365
1366         bch2_bkey_buf_reassemble(out, c, k);
1367
1368         if (flags & BTREE_ITER_PREFETCH)
1369                 ret = btree_path_prefetch_j(trans, path, &jiter);
1370
1371         bch2_btree_and_journal_iter_exit(&jiter);
1372         return ret;
1373 }
1374
1375 static __always_inline int btree_path_down(struct btree_trans *trans,
1376                                            struct btree_path *path,
1377                                            unsigned flags,
1378                                            unsigned long trace_ip)
1379 {
1380         struct bch_fs *c = trans->c;
1381         struct btree_path_level *l = path_l(path);
1382         struct btree *b;
1383         unsigned level = path->level - 1;
1384         enum six_lock_type lock_type = __btree_lock_want(path, level);
1385         bool replay_done = test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags);
1386         struct bkey_buf tmp;
1387         int ret;
1388
1389         EBUG_ON(!btree_node_locked(path, path->level));
1390
1391         bch2_bkey_buf_init(&tmp);
1392
1393         if (unlikely(!replay_done)) {
1394                 ret = btree_node_iter_and_journal_peek(trans, path, flags, &tmp);
1395                 if (ret)
1396                         goto err;
1397         } else {
1398                 bch2_bkey_buf_unpack(&tmp, c, l->b,
1399                                  bch2_btree_node_iter_peek(&l->iter, l->b));
1400
1401                 if (flags & BTREE_ITER_PREFETCH) {
1402                         ret = btree_path_prefetch(trans, path);
1403                         if (ret)
1404                                 goto err;
1405                 }
1406         }
1407
1408         b = bch2_btree_node_get(trans, path, tmp.k, level, lock_type, trace_ip);
1409         ret = PTR_ERR_OR_ZERO(b);
1410         if (unlikely(ret))
1411                 goto err;
1412
1413         mark_btree_node_locked(trans, path, level, lock_type);
1414         btree_path_level_init(trans, path, b);
1415
1416         if (likely(replay_done && tmp.k->k.type == KEY_TYPE_btree_ptr_v2) &&
1417             unlikely(b != btree_node_mem_ptr(tmp.k)))
1418                 btree_node_mem_ptr_set(trans, path, level + 1, b);
1419
1420         if (btree_node_read_locked(path, level + 1))
1421                 btree_node_unlock(path, level + 1);
1422         path->level = level;
1423
1424         bch2_btree_path_verify_locks(path);
1425 err:
1426         bch2_bkey_buf_exit(&tmp, c);
1427         return ret;
1428 }
1429
1430 static int btree_path_traverse_one(struct btree_trans *, struct btree_path *,
1431                                    unsigned, unsigned long);
1432
1433 static int bch2_btree_path_traverse_all(struct btree_trans *trans)
1434 {
1435         struct bch_fs *c = trans->c;
1436         struct btree_path *path;
1437         unsigned long trace_ip = _RET_IP_;
1438         int i, ret = 0;
1439
1440         if (trans->in_traverse_all)
1441                 return -EINTR;
1442
1443         trans->in_traverse_all = true;
1444 retry_all:
1445         trans->restarted = false;
1446         trans->traverse_all_idx = U8_MAX;
1447
1448         trans_for_each_path(trans, path)
1449                 path->should_be_locked = false;
1450
1451         btree_trans_verify_sorted(trans);
1452
1453         for (i = trans->nr_sorted - 2; i >= 0; --i) {
1454                 struct btree_path *path1 = trans->paths + trans->sorted[i];
1455                 struct btree_path *path2 = trans->paths + trans->sorted[i + 1];
1456
1457                 if (path1->btree_id == path2->btree_id &&
1458                     path1->locks_want < path2->locks_want)
1459                         __bch2_btree_path_upgrade(trans, path1, path2->locks_want);
1460                 else if (!path1->locks_want && path2->locks_want)
1461                         __bch2_btree_path_upgrade(trans, path1, 1);
1462         }
1463
1464         bch2_trans_unlock(trans);
1465         cond_resched();
1466
1467         if (unlikely(trans->memory_allocation_failure)) {
1468                 struct closure cl;
1469
1470                 closure_init_stack(&cl);
1471
1472                 do {
1473                         ret = bch2_btree_cache_cannibalize_lock(c, &cl);
1474                         closure_sync(&cl);
1475                 } while (ret);
1476         }
1477
1478         /* Now, redo traversals in correct order: */
1479         trans->traverse_all_idx = 0;
1480         while (trans->traverse_all_idx < trans->nr_sorted) {
1481                 path = trans->paths + trans->sorted[trans->traverse_all_idx];
1482
1483                 /*
1484                  * Traversing a path can cause another path to be added at about
1485                  * the same position:
1486                  */
1487                 if (path->uptodate) {
1488                         ret = btree_path_traverse_one(trans, path, 0, _THIS_IP_);
1489                         if (ret == -EINTR || ret == -ENOMEM)
1490                                 goto retry_all;
1491                         if (ret)
1492                                 goto err;
1493                         BUG_ON(path->uptodate);
1494                 } else {
1495                         trans->traverse_all_idx++;
1496                 }
1497         }
1498
1499         /*
1500          * BTREE_ITER_NEED_RELOCK is ok here - if we called bch2_trans_unlock()
1501          * and relock(), relock() won't relock since path->should_be_locked
1502          * isn't set yet, which is all fine
1503          */
1504         trans_for_each_path(trans, path)
1505                 BUG_ON(path->uptodate >= BTREE_ITER_NEED_TRAVERSE);
1506 err:
1507         bch2_btree_cache_cannibalize_unlock(c);
1508
1509         trans->in_traverse_all = false;
1510
1511         trace_trans_traverse_all(trans->fn, trace_ip);
1512         return ret;
1513 }
1514
1515 static inline bool btree_path_good_node(struct btree_trans *trans,
1516                                         struct btree_path *path,
1517                                         unsigned l, int check_pos)
1518 {
1519         if (!is_btree_node(path, l) ||
1520             !bch2_btree_node_relock(trans, path, l))
1521                 return false;
1522
1523         if (check_pos < 0 && btree_path_pos_before_node(path, path->l[l].b))
1524                 return false;
1525         if (check_pos > 0 && btree_path_pos_after_node(path, path->l[l].b))
1526                 return false;
1527         return true;
1528 }
1529
1530 static inline unsigned btree_path_up_until_good_node(struct btree_trans *trans,
1531                                                      struct btree_path *path,
1532                                                      int check_pos)
1533 {
1534         unsigned i, l = path->level;
1535
1536         while (btree_path_node(path, l) &&
1537                !btree_path_good_node(trans, path, l, check_pos)) {
1538                 btree_node_unlock(path, l);
1539                 path->l[l].b = BTREE_ITER_NO_NODE_UP;
1540                 l++;
1541         }
1542
1543         /* If we need intent locks, take them too: */
1544         for (i = l + 1;
1545              i < path->locks_want && btree_path_node(path, i);
1546              i++)
1547                 if (!bch2_btree_node_relock(trans, path, i))
1548                         while (l <= i) {
1549                                 btree_node_unlock(path, l);
1550                                 path->l[l].b = BTREE_ITER_NO_NODE_UP;
1551                                 l++;
1552                         }
1553
1554         return l;
1555 }
1556
1557 /*
1558  * This is the main state machine for walking down the btree - walks down to a
1559  * specified depth
1560  *
1561  * Returns 0 on success, -EIO on error (error reading in a btree node).
1562  *
1563  * On error, caller (peek_node()/peek_key()) must return NULL; the error is
1564  * stashed in the iterator and returned from bch2_trans_exit().
1565  */
1566 static int btree_path_traverse_one(struct btree_trans *trans,
1567                                    struct btree_path *path,
1568                                    unsigned flags,
1569                                    unsigned long trace_ip)
1570 {
1571         unsigned depth_want = path->level;
1572         int ret = 0;
1573
1574         if (unlikely(trans->restarted)) {
1575                 ret = -EINTR;
1576                 goto out;
1577         }
1578
1579         /*
1580          * Ensure we obey path->should_be_locked: if it's set, we can't unlock
1581          * and re-traverse the path without a transaction restart:
1582          */
1583         if (path->should_be_locked) {
1584                 ret = bch2_btree_path_relock(trans, path, trace_ip) ? 0 : -EINTR;
1585                 goto out;
1586         }
1587
1588         if (path->cached) {
1589                 ret = bch2_btree_path_traverse_cached(trans, path, flags);
1590                 goto out;
1591         }
1592
1593         if (unlikely(path->level >= BTREE_MAX_DEPTH))
1594                 goto out;
1595
1596         path->level = btree_path_up_until_good_node(trans, path, 0);
1597
1598         /*
1599          * Note: path->nodes[path->level] may be temporarily NULL here - that
1600          * would indicate to other code that we got to the end of the btree,
1601          * here it indicates that relocking the root failed - it's critical that
1602          * btree_path_lock_root() comes next and that it can't fail
1603          */
1604         while (path->level > depth_want) {
1605                 ret = btree_path_node(path, path->level)
1606                         ? btree_path_down(trans, path, flags, trace_ip)
1607                         : btree_path_lock_root(trans, path, depth_want, trace_ip);
1608                 if (unlikely(ret)) {
1609                         if (ret == 1) {
1610                                 /*
1611                                  * No nodes at this level - got to the end of
1612                                  * the btree:
1613                                  */
1614                                 ret = 0;
1615                                 goto out;
1616                         }
1617
1618                         __bch2_btree_path_unlock(path);
1619                         path->level = depth_want;
1620
1621                         if (ret == -EIO)
1622                                 path->l[path->level].b =
1623                                         BTREE_ITER_NO_NODE_ERROR;
1624                         else
1625                                 path->l[path->level].b =
1626                                         BTREE_ITER_NO_NODE_DOWN;
1627                         goto out;
1628                 }
1629         }
1630
1631         path->uptodate = BTREE_ITER_UPTODATE;
1632 out:
1633         BUG_ON((ret == -EINTR) != !!trans->restarted);
1634         bch2_btree_path_verify(trans, path);
1635         return ret;
1636 }
1637
1638 int __must_check bch2_btree_path_traverse(struct btree_trans *trans,
1639                                           struct btree_path *path, unsigned flags)
1640 {
1641         if (path->uptodate < BTREE_ITER_NEED_RELOCK)
1642                 return 0;
1643
1644         return  bch2_trans_cond_resched(trans) ?:
1645                 btree_path_traverse_one(trans, path, flags, _RET_IP_);
1646 }
1647
1648 static void btree_path_copy(struct btree_trans *trans, struct btree_path *dst,
1649                             struct btree_path *src)
1650 {
1651         unsigned i;
1652
1653         memcpy(&dst->pos, &src->pos,
1654                sizeof(struct btree_path) - offsetof(struct btree_path, pos));
1655
1656         for (i = 0; i < BTREE_MAX_DEPTH; i++)
1657                 if (btree_node_locked(dst, i))
1658                         six_lock_increment(&dst->l[i].b->c.lock,
1659                                            __btree_lock_want(dst, i));
1660
1661         bch2_btree_path_check_sort(trans, dst, 0);
1662 }
1663
1664 static struct btree_path *btree_path_clone(struct btree_trans *trans, struct btree_path *src,
1665                                            bool intent)
1666 {
1667         struct btree_path *new = btree_path_alloc(trans, src);
1668
1669         btree_path_copy(trans, new, src);
1670         __btree_path_get(new, intent);
1671         return new;
1672 }
1673
1674 inline struct btree_path * __must_check
1675 bch2_btree_path_make_mut(struct btree_trans *trans,
1676                          struct btree_path *path, bool intent,
1677                          unsigned long ip)
1678 {
1679         if (path->ref > 1 || path->preserve) {
1680                 __btree_path_put(path, intent);
1681                 path = btree_path_clone(trans, path, intent);
1682                 path->preserve = false;
1683 #ifdef CONFIG_BCACHEFS_DEBUG
1684                 path->ip_allocated = ip;
1685 #endif
1686                 btree_trans_verify_sorted(trans);
1687         }
1688
1689         return path;
1690 }
1691
1692 struct btree_path * __must_check
1693 bch2_btree_path_set_pos(struct btree_trans *trans,
1694                    struct btree_path *path, struct bpos new_pos,
1695                    bool intent, unsigned long ip)
1696 {
1697         int cmp = bpos_cmp(new_pos, path->pos);
1698         unsigned l = path->level;
1699
1700         EBUG_ON(trans->restarted);
1701         EBUG_ON(!path->ref);
1702
1703         if (!cmp)
1704                 return path;
1705
1706         path = bch2_btree_path_make_mut(trans, path, intent, ip);
1707
1708         path->pos               = new_pos;
1709         path->should_be_locked  = false;
1710
1711         bch2_btree_path_check_sort(trans, path, cmp);
1712
1713         if (unlikely(path->cached)) {
1714                 btree_node_unlock(path, 0);
1715                 path->l[0].b = BTREE_ITER_NO_NODE_CACHED;
1716                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1717                 goto out;
1718         }
1719
1720         l = btree_path_up_until_good_node(trans, path, cmp);
1721
1722         if (btree_path_node(path, l)) {
1723                 /*
1724                  * We might have to skip over many keys, or just a few: try
1725                  * advancing the node iterator, and if we have to skip over too
1726                  * many keys just reinit it (or if we're rewinding, since that
1727                  * is expensive).
1728                  */
1729                 if (cmp < 0 ||
1730                     !btree_path_advance_to_pos(path, &path->l[l], 8))
1731                         __btree_path_level_init(path, l);
1732         }
1733
1734         if (l != path->level) {
1735                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
1736                 __bch2_btree_path_unlock(path);
1737         }
1738 out:
1739         bch2_btree_path_verify(trans, path);
1740         return path;
1741 }
1742
1743 /* Btree path: main interface: */
1744
1745 static struct btree_path *have_path_at_pos(struct btree_trans *trans, struct btree_path *path)
1746 {
1747         struct btree_path *next;
1748
1749         next = prev_btree_path(trans, path);
1750         if (next && !btree_path_cmp(next, path))
1751                 return next;
1752
1753         next = next_btree_path(trans, path);
1754         if (next && !btree_path_cmp(next, path))
1755                 return next;
1756
1757         return NULL;
1758 }
1759
1760 static struct btree_path *have_node_at_pos(struct btree_trans *trans, struct btree_path *path)
1761 {
1762         struct btree_path *next;
1763
1764         next = prev_btree_path(trans, path);
1765         if (next && next->level == path->level && path_l(next)->b == path_l(path)->b)
1766                 return next;
1767
1768         next = next_btree_path(trans, path);
1769         if (next && next->level == path->level && path_l(next)->b == path_l(path)->b)
1770                 return next;
1771
1772         return NULL;
1773 }
1774
1775 static inline void __bch2_path_free(struct btree_trans *trans, struct btree_path *path)
1776 {
1777         __bch2_btree_path_unlock(path);
1778         btree_path_list_remove(trans, path);
1779         trans->paths_allocated &= ~(1ULL << path->idx);
1780 }
1781
1782 void bch2_path_put(struct btree_trans *trans, struct btree_path *path, bool intent)
1783 {
1784         struct btree_path *dup;
1785
1786         EBUG_ON(trans->paths + path->idx != path);
1787         EBUG_ON(!path->ref);
1788
1789         if (!__btree_path_put(path, intent))
1790                 return;
1791
1792         /*
1793          * Perhaps instead we should check for duplicate paths in traverse_all:
1794          */
1795         if (path->preserve &&
1796             (dup = have_path_at_pos(trans, path))) {
1797                 dup->preserve = true;
1798                 path->preserve = false;
1799                 goto free;
1800         }
1801
1802         if (!path->preserve &&
1803             (dup = have_node_at_pos(trans, path)))
1804                 goto free;
1805         return;
1806 free:
1807         if (path->should_be_locked &&
1808             !btree_node_locked(dup, path->level))
1809                 return;
1810
1811         dup->should_be_locked |= path->should_be_locked;
1812         __bch2_path_free(trans, path);
1813 }
1814
1815 void bch2_trans_updates_to_text(struct printbuf *buf, struct btree_trans *trans)
1816 {
1817         struct btree_insert_entry *i;
1818
1819         pr_buf(buf, "transaction updates for %s journal seq %llu\n",
1820                trans->fn, trans->journal_res.seq);
1821
1822         trans_for_each_update(trans, i) {
1823                 struct bkey_s_c old = { &i->old_k, i->old_v };
1824
1825                 pr_buf(buf, "update: btree %s %pS\n  old ",
1826                        bch2_btree_ids[i->btree_id],
1827                        (void *) i->ip_allocated);
1828
1829                 bch2_bkey_val_to_text(buf, trans->c, old);
1830                 pr_buf(buf, "\n  new ");
1831                 bch2_bkey_val_to_text(buf, trans->c, bkey_i_to_s_c(i->k));
1832                 pr_buf(buf, "\n");
1833         }
1834 }
1835
1836 noinline __cold
1837 void bch2_dump_trans_updates(struct btree_trans *trans)
1838 {
1839         struct printbuf buf = PRINTBUF;
1840
1841         bch2_trans_updates_to_text(&buf, trans);
1842         bch_err(trans->c, "%s", buf.buf);
1843         printbuf_exit(&buf);
1844 }
1845
1846 noinline __cold
1847 void bch2_dump_trans_paths_updates(struct btree_trans *trans)
1848 {
1849         struct btree_path *path;
1850         struct printbuf buf = PRINTBUF;
1851         unsigned idx;
1852
1853         trans_for_each_path_inorder(trans, path, idx) {
1854                 printbuf_reset(&buf);
1855
1856                 bch2_bpos_to_text(&buf, path->pos);
1857
1858                 printk(KERN_ERR "path: idx %u ref %u:%u%s%s btree=%s l=%u pos %s locks %u %pS\n",
1859                        path->idx, path->ref, path->intent_ref,
1860                        path->should_be_locked ? " S" : "",
1861                        path->preserve ? " P" : "",
1862                        bch2_btree_ids[path->btree_id],
1863                        path->level,
1864                        buf.buf,
1865                        path->nodes_locked,
1866 #ifdef CONFIG_BCACHEFS_DEBUG
1867                        (void *) path->ip_allocated
1868 #else
1869                        NULL
1870 #endif
1871                        );
1872         }
1873
1874         printbuf_exit(&buf);
1875
1876         bch2_dump_trans_updates(trans);
1877 }
1878
1879 static struct btree_path *btree_path_alloc(struct btree_trans *trans,
1880                                            struct btree_path *pos)
1881 {
1882         struct btree_path *path;
1883         unsigned idx;
1884
1885         if (unlikely(trans->paths_allocated ==
1886                      ~((~0ULL << 1) << (BTREE_ITER_MAX - 1)))) {
1887                 bch2_dump_trans_paths_updates(trans);
1888                 panic("trans path oveflow\n");
1889         }
1890
1891         idx = __ffs64(~trans->paths_allocated);
1892         trans->paths_allocated |= 1ULL << idx;
1893
1894         path = &trans->paths[idx];
1895
1896         path->idx               = idx;
1897         path->ref               = 0;
1898         path->intent_ref        = 0;
1899         path->nodes_locked      = 0;
1900         path->nodes_intent_locked = 0;
1901
1902         btree_path_list_add(trans, pos, path);
1903         return path;
1904 }
1905
1906 struct btree_path *bch2_path_get(struct btree_trans *trans,
1907                                  enum btree_id btree_id, struct bpos pos,
1908                                  unsigned locks_want, unsigned level,
1909                                  unsigned flags, unsigned long ip)
1910 {
1911         struct btree_path *path, *path_pos = NULL;
1912         bool cached = flags & BTREE_ITER_CACHED;
1913         bool intent = flags & BTREE_ITER_INTENT;
1914         int i;
1915
1916         BUG_ON(trans->restarted);
1917         btree_trans_verify_sorted(trans);
1918
1919         trans_for_each_path_inorder(trans, path, i) {
1920                 if (__btree_path_cmp(path,
1921                                      btree_id,
1922                                      cached,
1923                                      pos,
1924                                      level) > 0)
1925                         break;
1926
1927                 path_pos = path;
1928         }
1929
1930         if (path_pos &&
1931             path_pos->cached    == cached &&
1932             path_pos->btree_id  == btree_id &&
1933             path_pos->level     == level) {
1934                 __btree_path_get(path_pos, intent);
1935                 path = bch2_btree_path_set_pos(trans, path_pos, pos, intent, ip);
1936         } else {
1937                 path = btree_path_alloc(trans, path_pos);
1938                 path_pos = NULL;
1939
1940                 __btree_path_get(path, intent);
1941                 path->pos                       = pos;
1942                 path->btree_id                  = btree_id;
1943                 path->cached                    = cached;
1944                 path->uptodate                  = BTREE_ITER_NEED_TRAVERSE;
1945                 path->should_be_locked          = false;
1946                 path->level                     = level;
1947                 path->locks_want                = locks_want;
1948                 path->nodes_locked              = 0;
1949                 path->nodes_intent_locked       = 0;
1950                 for (i = 0; i < ARRAY_SIZE(path->l); i++)
1951                         path->l[i].b            = BTREE_ITER_NO_NODE_INIT;
1952 #ifdef CONFIG_BCACHEFS_DEBUG
1953                 path->ip_allocated              = ip;
1954 #endif
1955                 btree_trans_verify_sorted(trans);
1956         }
1957
1958         if (!(flags & BTREE_ITER_NOPRESERVE))
1959                 path->preserve = true;
1960
1961         if (path->intent_ref)
1962                 locks_want = max(locks_want, level + 1);
1963
1964         /*
1965          * If the path has locks_want greater than requested, we don't downgrade
1966          * it here - on transaction restart because btree node split needs to
1967          * upgrade locks, we might be putting/getting the iterator again.
1968          * Downgrading iterators only happens via bch2_trans_downgrade(), after
1969          * a successful transaction commit.
1970          */
1971
1972         locks_want = min(locks_want, BTREE_MAX_DEPTH);
1973         if (locks_want > path->locks_want) {
1974                 path->locks_want = locks_want;
1975                 btree_path_get_locks(trans, path, true);
1976         }
1977
1978         return path;
1979 }
1980
1981 inline struct bkey_s_c bch2_btree_path_peek_slot(struct btree_path *path, struct bkey *u)
1982 {
1983
1984         struct bkey_s_c k;
1985
1986         if (!path->cached) {
1987                 struct btree_path_level *l = path_l(path);
1988                 struct bkey_packed *_k;
1989
1990                 EBUG_ON(path->uptodate != BTREE_ITER_UPTODATE);
1991
1992                 _k = bch2_btree_node_iter_peek_all(&l->iter, l->b);
1993                 k = _k ? bkey_disassemble(l->b, _k, u) : bkey_s_c_null;
1994
1995                 EBUG_ON(k.k && bkey_deleted(k.k) && bpos_cmp(k.k->p, path->pos) == 0);
1996
1997                 if (!k.k || bpos_cmp(path->pos, k.k->p))
1998                         goto hole;
1999         } else {
2000                 struct bkey_cached *ck = (void *) path->l[0].b;
2001
2002                 EBUG_ON(ck &&
2003                         (path->btree_id != ck->key.btree_id ||
2004                          bkey_cmp(path->pos, ck->key.pos)));
2005
2006                 /* BTREE_ITER_CACHED_NOFILL|BTREE_ITER_CACHED_NOCREATE? */
2007                 if (unlikely(!ck || !ck->valid))
2008                         return bkey_s_c_null;
2009
2010                 EBUG_ON(path->uptodate != BTREE_ITER_UPTODATE);
2011
2012                 *u = ck->k->k;
2013                 k = bkey_i_to_s_c(ck->k);
2014         }
2015
2016         return k;
2017 hole:
2018         bkey_init(u);
2019         u->p = path->pos;
2020         return (struct bkey_s_c) { u, NULL };
2021 }
2022
2023 /* Btree iterators: */
2024
2025 int __must_check
2026 __bch2_btree_iter_traverse(struct btree_iter *iter)
2027 {
2028         return bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
2029 }
2030
2031 int __must_check
2032 bch2_btree_iter_traverse(struct btree_iter *iter)
2033 {
2034         int ret;
2035
2036         iter->path = bch2_btree_path_set_pos(iter->trans, iter->path,
2037                                         btree_iter_search_key(iter),
2038                                         iter->flags & BTREE_ITER_INTENT,
2039                                         btree_iter_ip_allocated(iter));
2040
2041         ret = bch2_btree_path_traverse(iter->trans, iter->path, iter->flags);
2042         if (ret)
2043                 return ret;
2044
2045         iter->path->should_be_locked = true;
2046         return 0;
2047 }
2048
2049 /* Iterate across nodes (leaf and interior nodes) */
2050
2051 struct btree *bch2_btree_iter_peek_node(struct btree_iter *iter)
2052 {
2053         struct btree_trans *trans = iter->trans;
2054         struct btree *b = NULL;
2055         int ret;
2056
2057         EBUG_ON(iter->path->cached);
2058         bch2_btree_iter_verify(iter);
2059
2060         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2061         if (ret)
2062                 goto err;
2063
2064         b = btree_path_node(iter->path, iter->path->level);
2065         if (!b)
2066                 goto out;
2067
2068         BUG_ON(bpos_cmp(b->key.k.p, iter->pos) < 0);
2069
2070         bkey_init(&iter->k);
2071         iter->k.p = iter->pos = b->key.k.p;
2072
2073         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
2074                                         iter->flags & BTREE_ITER_INTENT,
2075                                         btree_iter_ip_allocated(iter));
2076         iter->path->should_be_locked = true;
2077         BUG_ON(iter->path->uptodate);
2078 out:
2079         bch2_btree_iter_verify_entry_exit(iter);
2080         bch2_btree_iter_verify(iter);
2081
2082         return b;
2083 err:
2084         b = ERR_PTR(ret);
2085         goto out;
2086 }
2087
2088 struct btree *bch2_btree_iter_next_node(struct btree_iter *iter)
2089 {
2090         struct btree_trans *trans = iter->trans;
2091         struct btree_path *path = iter->path;
2092         struct btree *b = NULL;
2093         unsigned l;
2094         int ret;
2095
2096         BUG_ON(trans->restarted);
2097         EBUG_ON(iter->path->cached);
2098         bch2_btree_iter_verify(iter);
2099
2100         /* already at end? */
2101         if (!btree_path_node(path, path->level))
2102                 return NULL;
2103
2104         /* got to end? */
2105         if (!btree_path_node(path, path->level + 1)) {
2106                 btree_node_unlock(path, path->level);
2107                 path->l[path->level].b = BTREE_ITER_NO_NODE_UP;
2108                 path->level++;
2109                 return NULL;
2110         }
2111
2112         if (!bch2_btree_node_relock(trans, path, path->level + 1)) {
2113                 __bch2_btree_path_unlock(path);
2114                 path->l[path->level].b = BTREE_ITER_NO_NODE_GET_LOCKS;
2115                 path->l[path->level + 1].b = BTREE_ITER_NO_NODE_GET_LOCKS;
2116                 trace_trans_restart_relock_next_node(trans->fn, _THIS_IP_,
2117                                            path->btree_id, &path->pos);
2118                 btree_trans_restart(trans);
2119                 ret = -EINTR;
2120                 goto err;
2121         }
2122
2123         b = btree_path_node(path, path->level + 1);
2124
2125         if (!bpos_cmp(iter->pos, b->key.k.p)) {
2126                 btree_node_unlock(path, path->level);
2127                 path->l[path->level].b = BTREE_ITER_NO_NODE_UP;
2128                 path->level++;
2129         } else {
2130                 /*
2131                  * Haven't gotten to the end of the parent node: go back down to
2132                  * the next child node
2133                  */
2134                 path = iter->path =
2135                         bch2_btree_path_set_pos(trans, path, bpos_successor(iter->pos),
2136                                            iter->flags & BTREE_ITER_INTENT,
2137                                            btree_iter_ip_allocated(iter));
2138
2139                 path->level = iter->min_depth;
2140
2141                 for (l = path->level + 1; l < BTREE_MAX_DEPTH; l++)
2142                         if (btree_lock_want(path, l) == BTREE_NODE_UNLOCKED)
2143                                 btree_node_unlock(path, l);
2144
2145                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
2146                 bch2_btree_iter_verify(iter);
2147
2148                 ret = bch2_btree_path_traverse(trans, path, iter->flags);
2149                 if (ret)
2150                         goto err;
2151
2152                 b = path->l[path->level].b;
2153         }
2154
2155         bkey_init(&iter->k);
2156         iter->k.p = iter->pos = b->key.k.p;
2157
2158         iter->path = bch2_btree_path_set_pos(trans, iter->path, b->key.k.p,
2159                                         iter->flags & BTREE_ITER_INTENT,
2160                                         btree_iter_ip_allocated(iter));
2161         iter->path->should_be_locked = true;
2162         BUG_ON(iter->path->uptodate);
2163 out:
2164         bch2_btree_iter_verify_entry_exit(iter);
2165         bch2_btree_iter_verify(iter);
2166
2167         return b;
2168 err:
2169         b = ERR_PTR(ret);
2170         goto out;
2171 }
2172
2173 /* Iterate across keys (in leaf nodes only) */
2174
2175 inline bool bch2_btree_iter_advance(struct btree_iter *iter)
2176 {
2177         struct bpos pos = iter->k.p;
2178         bool ret = (iter->flags & BTREE_ITER_ALL_SNAPSHOTS
2179                     ? bpos_cmp(pos, SPOS_MAX)
2180                     : bkey_cmp(pos, SPOS_MAX)) != 0;
2181
2182         if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
2183                 pos = bkey_successor(iter, pos);
2184         bch2_btree_iter_set_pos(iter, pos);
2185         return ret;
2186 }
2187
2188 inline bool bch2_btree_iter_rewind(struct btree_iter *iter)
2189 {
2190         struct bpos pos = bkey_start_pos(&iter->k);
2191         bool ret = (iter->flags & BTREE_ITER_ALL_SNAPSHOTS
2192                     ? bpos_cmp(pos, POS_MIN)
2193                     : bkey_cmp(pos, POS_MIN)) != 0;
2194
2195         if (ret && !(iter->flags & BTREE_ITER_IS_EXTENTS))
2196                 pos = bkey_predecessor(iter, pos);
2197         bch2_btree_iter_set_pos(iter, pos);
2198         return ret;
2199 }
2200
2201 static inline struct bkey_i *btree_trans_peek_updates(struct btree_trans *trans,
2202                                                       enum btree_id btree_id,
2203                                                       struct bpos pos)
2204 {
2205         struct btree_insert_entry *i;
2206
2207         trans_for_each_update(trans, i)
2208                 if ((cmp_int(btree_id,  i->btree_id) ?:
2209                      bpos_cmp(pos,      i->k->k.p)) <= 0) {
2210                         if (btree_id == i->btree_id)
2211                                 return i->k;
2212                         break;
2213                 }
2214
2215         return NULL;
2216 }
2217
2218 static noinline
2219 struct bkey_s_c btree_trans_peek_journal(struct btree_trans *trans,
2220                                          struct btree_iter *iter,
2221                                          struct bkey_s_c k)
2222 {
2223         struct bkey_i *next_journal =
2224                 bch2_journal_keys_peek(trans->c, iter->btree_id, 0,
2225                                        iter->path->pos);
2226
2227         if (next_journal &&
2228             bpos_cmp(next_journal->k.p,
2229                      k.k ? k.k->p : iter->path->l[0].b->key.k.p) <= 0) {
2230                 iter->k = next_journal->k;
2231                 k = bkey_i_to_s_c(next_journal);
2232         }
2233
2234         return k;
2235 }
2236
2237 /*
2238  * Checks btree key cache for key at iter->pos and returns it if present, or
2239  * bkey_s_c_null:
2240  */
2241 static noinline
2242 struct bkey_s_c btree_trans_peek_key_cache(struct btree_iter *iter, struct bpos pos)
2243 {
2244         struct btree_trans *trans = iter->trans;
2245         struct bch_fs *c = trans->c;
2246         struct bkey u;
2247         int ret;
2248
2249         if (!bch2_btree_key_cache_find(c, iter->btree_id, pos))
2250                 return bkey_s_c_null;
2251
2252         if (!iter->key_cache_path)
2253                 iter->key_cache_path = bch2_path_get(trans, iter->btree_id, pos,
2254                                                      iter->flags & BTREE_ITER_INTENT, 0,
2255                                                      iter->flags|BTREE_ITER_CACHED,
2256                                                      _THIS_IP_);
2257
2258         iter->key_cache_path = bch2_btree_path_set_pos(trans, iter->key_cache_path, pos,
2259                                         iter->flags & BTREE_ITER_INTENT,
2260                                         btree_iter_ip_allocated(iter));
2261
2262         ret = bch2_btree_path_traverse(trans, iter->key_cache_path, iter->flags|BTREE_ITER_CACHED);
2263         if (unlikely(ret))
2264                 return bkey_s_c_err(ret);
2265
2266         iter->key_cache_path->should_be_locked = true;
2267
2268         return bch2_btree_path_peek_slot(iter->key_cache_path, &u);
2269 }
2270
2271 static struct bkey_s_c __bch2_btree_iter_peek(struct btree_iter *iter, struct bpos search_key)
2272 {
2273         struct btree_trans *trans = iter->trans;
2274         struct bkey_i *next_update;
2275         struct bkey_s_c k, k2;
2276         int ret;
2277
2278         EBUG_ON(iter->path->cached || iter->path->level);
2279         bch2_btree_iter_verify(iter);
2280
2281         while (1) {
2282                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2283                                         iter->flags & BTREE_ITER_INTENT,
2284                                         btree_iter_ip_allocated(iter));
2285
2286                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2287                 if (unlikely(ret)) {
2288                         /* ensure that iter->k is consistent with iter->pos: */
2289                         bch2_btree_iter_set_pos(iter, iter->pos);
2290                         k = bkey_s_c_err(ret);
2291                         goto out;
2292                 }
2293
2294                 iter->path->should_be_locked = true;
2295
2296                 k = btree_path_level_peek_all(trans->c, &iter->path->l[0], &iter->k);
2297
2298                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
2299                     k.k &&
2300                     (k2 = btree_trans_peek_key_cache(iter, k.k->p)).k) {
2301                         ret = bkey_err(k2);
2302                         if (ret) {
2303                                 k = k2;
2304                                 bch2_btree_iter_set_pos(iter, iter->pos);
2305                                 goto out;
2306                         }
2307
2308                         k = k2;
2309                         iter->k = *k.k;
2310                 }
2311
2312                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL))
2313                         k = btree_trans_peek_journal(trans, iter, k);
2314
2315                 next_update = iter->flags & BTREE_ITER_WITH_UPDATES
2316                         ? btree_trans_peek_updates(trans, iter->btree_id, search_key)
2317                         : NULL;
2318                 if (next_update &&
2319                     bpos_cmp(next_update->k.p,
2320                              k.k ? k.k->p : iter->path->l[0].b->key.k.p) <= 0) {
2321                         iter->k = next_update->k;
2322                         k = bkey_i_to_s_c(next_update);
2323                 }
2324
2325                 if (k.k && bkey_deleted(k.k)) {
2326                         /*
2327                          * If we've got a whiteout, and it's after the search
2328                          * key, advance the search key to the whiteout instead
2329                          * of just after the whiteout - it might be a btree
2330                          * whiteout, with a real key at the same position, since
2331                          * in the btree deleted keys sort before non deleted.
2332                          */
2333                         search_key = bpos_cmp(search_key, k.k->p)
2334                                 ? k.k->p
2335                                 : bpos_successor(k.k->p);
2336                         continue;
2337                 }
2338
2339                 if (likely(k.k)) {
2340                         break;
2341                 } else if (likely(bpos_cmp(iter->path->l[0].b->key.k.p, SPOS_MAX))) {
2342                         /* Advance to next leaf node: */
2343                         search_key = bpos_successor(iter->path->l[0].b->key.k.p);
2344                 } else {
2345                         /* End of btree: */
2346                         bch2_btree_iter_set_pos(iter, SPOS_MAX);
2347                         k = bkey_s_c_null;
2348                         goto out;
2349                 }
2350         }
2351 out:
2352         bch2_btree_iter_verify(iter);
2353
2354         return k;
2355 }
2356
2357 /**
2358  * bch2_btree_iter_peek: returns first key greater than or equal to iterator's
2359  * current position
2360  */
2361 struct bkey_s_c bch2_btree_iter_peek_upto(struct btree_iter *iter, struct bpos end)
2362 {
2363         struct btree_trans *trans = iter->trans;
2364         struct bpos search_key = btree_iter_search_key(iter);
2365         struct bkey_s_c k;
2366         struct bpos iter_pos;
2367         int ret;
2368
2369         if (iter->update_path) {
2370                 bch2_path_put(trans, iter->update_path,
2371                               iter->flags & BTREE_ITER_INTENT);
2372                 iter->update_path = NULL;
2373         }
2374
2375         bch2_btree_iter_verify_entry_exit(iter);
2376
2377         while (1) {
2378                 k = __bch2_btree_iter_peek(iter, search_key);
2379                 if (!k.k || bkey_err(k))
2380                         goto out;
2381
2382                 /*
2383                  * iter->pos should be mononotically increasing, and always be
2384                  * equal to the key we just returned - except extents can
2385                  * straddle iter->pos:
2386                  */
2387                 if (!(iter->flags & BTREE_ITER_IS_EXTENTS))
2388                         iter_pos = k.k->p;
2389                 else if (bkey_cmp(bkey_start_pos(k.k), iter->pos) > 0)
2390                         iter_pos = bkey_start_pos(k.k);
2391                 else
2392                         iter_pos = iter->pos;
2393
2394                 if (bkey_cmp(iter_pos, end) > 0) {
2395                         bch2_btree_iter_set_pos(iter, end);
2396                         k = bkey_s_c_null;
2397                         goto out;
2398                 }
2399
2400                 if (iter->update_path &&
2401                     bkey_cmp(iter->update_path->pos, k.k->p)) {
2402                         bch2_path_put(trans, iter->update_path,
2403                                       iter->flags & BTREE_ITER_INTENT);
2404                         iter->update_path = NULL;
2405                 }
2406
2407                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2408                     (iter->flags & BTREE_ITER_INTENT) &&
2409                     !(iter->flags & BTREE_ITER_IS_EXTENTS) &&
2410                     !iter->update_path) {
2411                         struct bpos pos = k.k->p;
2412
2413                         if (pos.snapshot < iter->snapshot) {
2414                                 search_key = bpos_successor(k.k->p);
2415                                 continue;
2416                         }
2417
2418                         pos.snapshot = iter->snapshot;
2419
2420                         /*
2421                          * advance, same as on exit for iter->path, but only up
2422                          * to snapshot
2423                          */
2424                         __btree_path_get(iter->path, iter->flags & BTREE_ITER_INTENT);
2425                         iter->update_path = iter->path;
2426
2427                         iter->update_path = bch2_btree_path_set_pos(trans,
2428                                                 iter->update_path, pos,
2429                                                 iter->flags & BTREE_ITER_INTENT,
2430                                                 _THIS_IP_);
2431                 }
2432
2433                 /*
2434                  * We can never have a key in a leaf node at POS_MAX, so
2435                  * we don't have to check these successor() calls:
2436                  */
2437                 if ((iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) &&
2438                     !bch2_snapshot_is_ancestor(trans->c,
2439                                                iter->snapshot,
2440                                                k.k->p.snapshot)) {
2441                         search_key = bpos_successor(k.k->p);
2442                         continue;
2443                 }
2444
2445                 if (bkey_whiteout(k.k) &&
2446                     !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS)) {
2447                         search_key = bkey_successor(iter, k.k->p);
2448                         continue;
2449                 }
2450
2451                 break;
2452         }
2453
2454         iter->pos = iter_pos;
2455
2456         iter->path = bch2_btree_path_set_pos(trans, iter->path, k.k->p,
2457                                 iter->flags & BTREE_ITER_INTENT,
2458                                 btree_iter_ip_allocated(iter));
2459         BUG_ON(!iter->path->nodes_locked);
2460 out:
2461         if (iter->update_path) {
2462                 if (iter->update_path->uptodate &&
2463                     !bch2_btree_path_relock(trans, iter->update_path, _THIS_IP_)) {
2464                         k = bkey_s_c_err(-EINTR);
2465                 } else {
2466                         BUG_ON(!(iter->update_path->nodes_locked & 1));
2467                         iter->update_path->should_be_locked = true;
2468                 }
2469         }
2470         iter->path->should_be_locked = true;
2471
2472         if (!(iter->flags & BTREE_ITER_ALL_SNAPSHOTS))
2473                 iter->pos.snapshot = iter->snapshot;
2474
2475         ret = bch2_btree_iter_verify_ret(iter, k);
2476         if (unlikely(ret)) {
2477                 bch2_btree_iter_set_pos(iter, iter->pos);
2478                 k = bkey_s_c_err(ret);
2479         }
2480
2481         bch2_btree_iter_verify_entry_exit(iter);
2482
2483         return k;
2484 }
2485
2486 /**
2487  * bch2_btree_iter_next: returns first key greater than iterator's current
2488  * position
2489  */
2490 struct bkey_s_c bch2_btree_iter_next(struct btree_iter *iter)
2491 {
2492         if (!bch2_btree_iter_advance(iter))
2493                 return bkey_s_c_null;
2494
2495         return bch2_btree_iter_peek(iter);
2496 }
2497
2498 /**
2499  * bch2_btree_iter_peek_prev: returns first key less than or equal to
2500  * iterator's current position
2501  */
2502 struct bkey_s_c bch2_btree_iter_peek_prev(struct btree_iter *iter)
2503 {
2504         struct btree_trans *trans = iter->trans;
2505         struct bpos search_key = iter->pos;
2506         struct btree_path *saved_path = NULL;
2507         struct bkey_s_c k;
2508         struct bkey saved_k;
2509         const struct bch_val *saved_v;
2510         int ret;
2511
2512         EBUG_ON(iter->path->cached || iter->path->level);
2513         EBUG_ON(iter->flags & BTREE_ITER_WITH_UPDATES);
2514
2515         if (iter->flags & BTREE_ITER_WITH_JOURNAL)
2516                 return bkey_s_c_err(-EIO);
2517
2518         bch2_btree_iter_verify(iter);
2519         bch2_btree_iter_verify_entry_exit(iter);
2520
2521         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2522                 search_key.snapshot = U32_MAX;
2523
2524         while (1) {
2525                 iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2526                                                 iter->flags & BTREE_ITER_INTENT,
2527                                                 btree_iter_ip_allocated(iter));
2528
2529                 ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2530                 if (unlikely(ret)) {
2531                         /* ensure that iter->k is consistent with iter->pos: */
2532                         bch2_btree_iter_set_pos(iter, iter->pos);
2533                         k = bkey_s_c_err(ret);
2534                         goto out;
2535                 }
2536
2537                 k = btree_path_level_peek(trans->c, iter->path,
2538                                           &iter->path->l[0], &iter->k);
2539                 if (!k.k ||
2540                     ((iter->flags & BTREE_ITER_IS_EXTENTS)
2541                      ? bpos_cmp(bkey_start_pos(k.k), search_key) >= 0
2542                      : bpos_cmp(k.k->p, search_key) > 0))
2543                         k = btree_path_level_prev(trans->c, iter->path,
2544                                                   &iter->path->l[0], &iter->k);
2545
2546                 bch2_btree_path_check_sort(trans, iter->path, 0);
2547
2548                 if (likely(k.k)) {
2549                         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS) {
2550                                 if (k.k->p.snapshot == iter->snapshot)
2551                                         goto got_key;
2552
2553                                 /*
2554                                  * If we have a saved candidate, and we're no
2555                                  * longer at the same _key_ (not pos), return
2556                                  * that candidate
2557                                  */
2558                                 if (saved_path && bkey_cmp(k.k->p, saved_k.p)) {
2559                                         bch2_path_put(trans, iter->path,
2560                                                       iter->flags & BTREE_ITER_INTENT);
2561                                         iter->path = saved_path;
2562                                         saved_path = NULL;
2563                                         iter->k = saved_k;
2564                                         k.v     = saved_v;
2565                                         goto got_key;
2566                                 }
2567
2568                                 if (bch2_snapshot_is_ancestor(iter->trans->c,
2569                                                               iter->snapshot,
2570                                                               k.k->p.snapshot)) {
2571                                         if (saved_path)
2572                                                 bch2_path_put(trans, saved_path,
2573                                                       iter->flags & BTREE_ITER_INTENT);
2574                                         saved_path = btree_path_clone(trans, iter->path,
2575                                                                 iter->flags & BTREE_ITER_INTENT);
2576                                         saved_k = *k.k;
2577                                         saved_v = k.v;
2578                                 }
2579
2580                                 search_key = bpos_predecessor(k.k->p);
2581                                 continue;
2582                         }
2583 got_key:
2584                         if (bkey_whiteout(k.k) &&
2585                             !(iter->flags & BTREE_ITER_ALL_SNAPSHOTS)) {
2586                                 search_key = bkey_predecessor(iter, k.k->p);
2587                                 if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2588                                         search_key.snapshot = U32_MAX;
2589                                 continue;
2590                         }
2591
2592                         break;
2593                 } else if (likely(bpos_cmp(iter->path->l[0].b->data->min_key, POS_MIN))) {
2594                         /* Advance to previous leaf node: */
2595                         search_key = bpos_predecessor(iter->path->l[0].b->data->min_key);
2596                 } else {
2597                         /* Start of btree: */
2598                         bch2_btree_iter_set_pos(iter, POS_MIN);
2599                         k = bkey_s_c_null;
2600                         goto out;
2601                 }
2602         }
2603
2604         EBUG_ON(bkey_cmp(bkey_start_pos(k.k), iter->pos) > 0);
2605
2606         /* Extents can straddle iter->pos: */
2607         if (bkey_cmp(k.k->p, iter->pos) < 0)
2608                 iter->pos = k.k->p;
2609
2610         if (iter->flags & BTREE_ITER_FILTER_SNAPSHOTS)
2611                 iter->pos.snapshot = iter->snapshot;
2612 out:
2613         if (saved_path)
2614                 bch2_path_put(trans, saved_path, iter->flags & BTREE_ITER_INTENT);
2615         iter->path->should_be_locked = true;
2616
2617         bch2_btree_iter_verify_entry_exit(iter);
2618         bch2_btree_iter_verify(iter);
2619
2620         return k;
2621 }
2622
2623 /**
2624  * bch2_btree_iter_prev: returns first key less than iterator's current
2625  * position
2626  */
2627 struct bkey_s_c bch2_btree_iter_prev(struct btree_iter *iter)
2628 {
2629         if (!bch2_btree_iter_rewind(iter))
2630                 return bkey_s_c_null;
2631
2632         return bch2_btree_iter_peek_prev(iter);
2633 }
2634
2635 struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_iter *iter)
2636 {
2637         struct btree_trans *trans = iter->trans;
2638         struct bpos search_key;
2639         struct bkey_s_c k;
2640         int ret;
2641
2642         EBUG_ON(iter->path->level);
2643         bch2_btree_iter_verify(iter);
2644         bch2_btree_iter_verify_entry_exit(iter);
2645
2646         /* extents can't span inode numbers: */
2647         if ((iter->flags & BTREE_ITER_IS_EXTENTS) &&
2648             unlikely(iter->pos.offset == KEY_OFFSET_MAX)) {
2649                 if (iter->pos.inode == KEY_INODE_MAX)
2650                         return bkey_s_c_null;
2651
2652                 bch2_btree_iter_set_pos(iter, bpos_nosnap_successor(iter->pos));
2653         }
2654
2655         search_key = btree_iter_search_key(iter);
2656         iter->path = bch2_btree_path_set_pos(trans, iter->path, search_key,
2657                                         iter->flags & BTREE_ITER_INTENT,
2658                                         btree_iter_ip_allocated(iter));
2659
2660         ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
2661         if (unlikely(ret))
2662                 return bkey_s_c_err(ret);
2663
2664         if ((iter->flags & BTREE_ITER_CACHED) ||
2665             !(iter->flags & (BTREE_ITER_IS_EXTENTS|BTREE_ITER_FILTER_SNAPSHOTS))) {
2666                 struct bkey_i *next_update;
2667
2668                 if ((iter->flags & BTREE_ITER_WITH_UPDATES) &&
2669                     (next_update = btree_trans_peek_updates(trans,
2670                                                 iter->btree_id, search_key)) &&
2671                     !bpos_cmp(next_update->k.p, iter->pos)) {
2672                         iter->k = next_update->k;
2673                         k = bkey_i_to_s_c(next_update);
2674                         goto out;
2675                 }
2676
2677                 if (unlikely(iter->flags & BTREE_ITER_WITH_JOURNAL) &&
2678                     (next_update = bch2_journal_keys_peek(trans->c, iter->btree_id,
2679                                                           0, iter->pos)) &&
2680                     !bpos_cmp(next_update->k.p, iter->pos)) {
2681                         iter->k = next_update->k;
2682                         k = bkey_i_to_s_c(next_update);
2683                         goto out;
2684                 }
2685
2686                 if (unlikely(iter->flags & BTREE_ITER_WITH_KEY_CACHE) &&
2687                     (k = btree_trans_peek_key_cache(iter, iter->pos)).k) {
2688                         if (!bkey_err(k))
2689                                 iter->k = *k.k;
2690                         goto out;
2691                 }
2692
2693                 k = bch2_btree_path_peek_slot(iter->path, &iter->k);
2694         } else {
2695                 struct bpos next;
2696
2697                 if (iter->flags & BTREE_ITER_INTENT) {
2698                         struct btree_iter iter2;
2699                         struct bpos end = iter->pos;
2700
2701                         if (iter->flags & BTREE_ITER_IS_EXTENTS)
2702                                 end.offset = U64_MAX;
2703
2704                         bch2_trans_copy_iter(&iter2, iter);
2705                         k = bch2_btree_iter_peek_upto(&iter2, end);
2706
2707                         if (k.k && !bkey_err(k)) {
2708                                 iter->k = iter2.k;
2709                                 k.k = &iter->k;
2710                         }
2711                         bch2_trans_iter_exit(trans, &iter2);
2712                 } else {
2713                         struct bpos pos = iter->pos;
2714
2715                         k = bch2_btree_iter_peek(iter);
2716                         iter->pos = pos;
2717                 }
2718
2719                 if (unlikely(bkey_err(k)))
2720                         return k;
2721
2722                 next = k.k ? bkey_start_pos(k.k) : POS_MAX;
2723
2724                 if (bkey_cmp(iter->pos, next) < 0) {
2725                         bkey_init(&iter->k);
2726                         iter->k.p = iter->pos;
2727
2728                         if (iter->flags & BTREE_ITER_IS_EXTENTS) {
2729                                 bch2_key_resize(&iter->k,
2730                                                 min_t(u64, KEY_SIZE_MAX,
2731                                                       (next.inode == iter->pos.inode
2732                                                        ? next.offset
2733                                                        : KEY_OFFSET_MAX) -
2734                                                       iter->pos.offset));
2735                                 EBUG_ON(!iter->k.size);
2736                         }
2737
2738                         k = (struct bkey_s_c) { &iter->k, NULL };
2739                 }
2740         }
2741 out:
2742         iter->path->should_be_locked = true;
2743
2744         bch2_btree_iter_verify_entry_exit(iter);
2745         bch2_btree_iter_verify(iter);
2746         ret = bch2_btree_iter_verify_ret(iter, k);
2747         if (unlikely(ret))
2748                 return bkey_s_c_err(ret);
2749
2750         return k;
2751 }
2752
2753 struct bkey_s_c bch2_btree_iter_next_slot(struct btree_iter *iter)
2754 {
2755         if (!bch2_btree_iter_advance(iter))
2756                 return bkey_s_c_null;
2757
2758         return bch2_btree_iter_peek_slot(iter);
2759 }
2760
2761 struct bkey_s_c bch2_btree_iter_prev_slot(struct btree_iter *iter)
2762 {
2763         if (!bch2_btree_iter_rewind(iter))
2764                 return bkey_s_c_null;
2765
2766         return bch2_btree_iter_peek_slot(iter);
2767 }
2768
2769 /* new transactional stuff: */
2770
2771 static inline void btree_path_verify_sorted_ref(struct btree_trans *trans,
2772                                                 struct btree_path *path)
2773 {
2774         EBUG_ON(path->sorted_idx >= trans->nr_sorted);
2775         EBUG_ON(trans->sorted[path->sorted_idx] != path->idx);
2776         EBUG_ON(!(trans->paths_allocated & (1ULL << path->idx)));
2777 }
2778
2779 static inline void btree_trans_verify_sorted_refs(struct btree_trans *trans)
2780 {
2781 #ifdef CONFIG_BCACHEFS_DEBUG
2782         unsigned i;
2783
2784         for (i = 0; i < trans->nr_sorted; i++)
2785                 btree_path_verify_sorted_ref(trans, trans->paths + trans->sorted[i]);
2786 #endif
2787 }
2788
2789 static void btree_trans_verify_sorted(struct btree_trans *trans)
2790 {
2791 #ifdef CONFIG_BCACHEFS_DEBUG
2792         struct btree_path *path, *prev = NULL;
2793         unsigned i;
2794
2795         trans_for_each_path_inorder(trans, path, i) {
2796                 if (prev && btree_path_cmp(prev, path) > 0) {
2797                         bch2_dump_trans_paths_updates(trans);
2798                         panic("trans paths out of order!\n");
2799                 }
2800                 prev = path;
2801         }
2802 #endif
2803 }
2804
2805 static inline void btree_path_swap(struct btree_trans *trans,
2806                                    struct btree_path *l, struct btree_path *r)
2807 {
2808         swap(l->sorted_idx, r->sorted_idx);
2809         swap(trans->sorted[l->sorted_idx],
2810              trans->sorted[r->sorted_idx]);
2811
2812         btree_path_verify_sorted_ref(trans, l);
2813         btree_path_verify_sorted_ref(trans, r);
2814 }
2815
2816 inline void bch2_btree_path_check_sort(struct btree_trans *trans, struct btree_path *path,
2817                                        int cmp)
2818 {
2819         struct btree_path *n;
2820
2821         if (cmp <= 0) {
2822                 n = prev_btree_path(trans, path);
2823                 if (n && btree_path_cmp(n, path) > 0) {
2824                         do {
2825                                 btree_path_swap(trans, n, path);
2826                                 n = prev_btree_path(trans, path);
2827                         } while (n && btree_path_cmp(n, path) > 0);
2828
2829                         goto out;
2830                 }
2831         }
2832
2833         if (cmp >= 0) {
2834                 n = next_btree_path(trans, path);
2835                 if (n && btree_path_cmp(path, n) > 0) {
2836                         do {
2837                                 btree_path_swap(trans, path, n);
2838                                 n = next_btree_path(trans, path);
2839                         } while (n && btree_path_cmp(path, n) > 0);
2840                 }
2841         }
2842 out:
2843         btree_trans_verify_sorted(trans);
2844 }
2845
2846 static inline void btree_path_list_remove(struct btree_trans *trans,
2847                                           struct btree_path *path)
2848 {
2849         unsigned i;
2850
2851         EBUG_ON(path->sorted_idx >= trans->nr_sorted);
2852
2853         array_remove_item(trans->sorted, trans->nr_sorted, path->sorted_idx);
2854
2855         for (i = path->sorted_idx; i < trans->nr_sorted; i++)
2856                 trans->paths[trans->sorted[i]].sorted_idx = i;
2857
2858         path->sorted_idx = U8_MAX;
2859
2860         btree_trans_verify_sorted_refs(trans);
2861 }
2862
2863 static inline void btree_path_list_add(struct btree_trans *trans,
2864                                        struct btree_path *pos,
2865                                        struct btree_path *path)
2866 {
2867         unsigned i;
2868
2869         btree_trans_verify_sorted_refs(trans);
2870
2871         path->sorted_idx = pos ? pos->sorted_idx + 1 : 0;
2872
2873         if (trans->in_traverse_all &&
2874             trans->traverse_all_idx != U8_MAX &&
2875             trans->traverse_all_idx >= path->sorted_idx)
2876                 trans->traverse_all_idx++;
2877
2878         array_insert_item(trans->sorted, trans->nr_sorted, path->sorted_idx, path->idx);
2879
2880         for (i = path->sorted_idx; i < trans->nr_sorted; i++)
2881                 trans->paths[trans->sorted[i]].sorted_idx = i;
2882
2883         btree_trans_verify_sorted_refs(trans);
2884 }
2885
2886 void bch2_trans_iter_exit(struct btree_trans *trans, struct btree_iter *iter)
2887 {
2888         if (iter->path)
2889                 bch2_path_put(trans, iter->path,
2890                               iter->flags & BTREE_ITER_INTENT);
2891         if (iter->update_path)
2892                 bch2_path_put(trans, iter->update_path,
2893                               iter->flags & BTREE_ITER_INTENT);
2894         if (iter->key_cache_path)
2895                 bch2_path_put(trans, iter->key_cache_path,
2896                               iter->flags & BTREE_ITER_INTENT);
2897         iter->path = NULL;
2898         iter->update_path = NULL;
2899         iter->key_cache_path = NULL;
2900 }
2901
2902 static void __bch2_trans_iter_init(struct btree_trans *trans,
2903                                    struct btree_iter *iter,
2904                                    unsigned btree_id, struct bpos pos,
2905                                    unsigned locks_want,
2906                                    unsigned depth,
2907                                    unsigned flags,
2908                                    unsigned long ip)
2909 {
2910         EBUG_ON(trans->restarted);
2911
2912         if (!(flags & (BTREE_ITER_ALL_SNAPSHOTS|BTREE_ITER_NOT_EXTENTS)) &&
2913             btree_node_type_is_extents(btree_id))
2914                 flags |= BTREE_ITER_IS_EXTENTS;
2915
2916         if (!(flags & __BTREE_ITER_ALL_SNAPSHOTS) &&
2917             !btree_type_has_snapshots(btree_id))
2918                 flags &= ~BTREE_ITER_ALL_SNAPSHOTS;
2919
2920         if (!(flags & BTREE_ITER_ALL_SNAPSHOTS) &&
2921             btree_type_has_snapshots(btree_id))
2922                 flags |= BTREE_ITER_FILTER_SNAPSHOTS;
2923
2924         if (!test_bit(JOURNAL_REPLAY_DONE, &trans->c->journal.flags))
2925                 flags |= BTREE_ITER_WITH_JOURNAL;
2926
2927         if (!btree_id_cached(trans->c, btree_id)) {
2928                 flags &= ~BTREE_ITER_CACHED;
2929                 flags &= ~BTREE_ITER_WITH_KEY_CACHE;
2930         } else if (!(flags & BTREE_ITER_CACHED))
2931                 flags |= BTREE_ITER_WITH_KEY_CACHE;
2932
2933         iter->trans     = trans;
2934         iter->path      = NULL;
2935         iter->update_path = NULL;
2936         iter->key_cache_path = NULL;
2937         iter->btree_id  = btree_id;
2938         iter->min_depth = depth;
2939         iter->flags     = flags;
2940         iter->snapshot  = pos.snapshot;
2941         iter->pos       = pos;
2942         iter->k.type    = KEY_TYPE_deleted;
2943         iter->k.p       = pos;
2944         iter->k.size    = 0;
2945 #ifdef CONFIG_BCACHEFS_DEBUG
2946         iter->ip_allocated = ip;
2947 #endif
2948
2949         iter->path = bch2_path_get(trans, btree_id, iter->pos,
2950                                    locks_want, depth, flags, ip);
2951 }
2952
2953 void bch2_trans_iter_init(struct btree_trans *trans,
2954                           struct btree_iter *iter,
2955                           unsigned btree_id, struct bpos pos,
2956                           unsigned flags)
2957 {
2958         __bch2_trans_iter_init(trans, iter, btree_id, pos,
2959                                0, 0, flags, _RET_IP_);
2960 }
2961
2962 void bch2_trans_node_iter_init(struct btree_trans *trans,
2963                                struct btree_iter *iter,
2964                                enum btree_id btree_id,
2965                                struct bpos pos,
2966                                unsigned locks_want,
2967                                unsigned depth,
2968                                unsigned flags)
2969 {
2970         __bch2_trans_iter_init(trans, iter, btree_id, pos, locks_want, depth,
2971                                BTREE_ITER_NOT_EXTENTS|
2972                                __BTREE_ITER_ALL_SNAPSHOTS|
2973                                BTREE_ITER_ALL_SNAPSHOTS|
2974                                flags, _RET_IP_);
2975         BUG_ON(iter->path->locks_want    < min(locks_want, BTREE_MAX_DEPTH));
2976         BUG_ON(iter->path->level        != depth);
2977         BUG_ON(iter->min_depth          != depth);
2978 }
2979
2980 void bch2_trans_copy_iter(struct btree_iter *dst, struct btree_iter *src)
2981 {
2982         *dst = *src;
2983         if (src->path)
2984                 __btree_path_get(src->path, src->flags & BTREE_ITER_INTENT);
2985         if (src->update_path)
2986                 __btree_path_get(src->update_path, src->flags & BTREE_ITER_INTENT);
2987         dst->key_cache_path = NULL;
2988 }
2989
2990 void *bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
2991 {
2992         size_t new_top = trans->mem_top + size;
2993         void *p;
2994
2995         if (new_top > trans->mem_bytes) {
2996                 size_t old_bytes = trans->mem_bytes;
2997                 size_t new_bytes = roundup_pow_of_two(new_top);
2998                 void *new_mem;
2999
3000                 WARN_ON_ONCE(new_bytes > BTREE_TRANS_MEM_MAX);
3001
3002                 new_mem = krealloc(trans->mem, new_bytes, GFP_NOFS);
3003                 if (!new_mem && new_bytes <= BTREE_TRANS_MEM_MAX) {
3004                         new_mem = mempool_alloc(&trans->c->btree_trans_mem_pool, GFP_KERNEL);
3005                         new_bytes = BTREE_TRANS_MEM_MAX;
3006                         kfree(trans->mem);
3007                 }
3008
3009                 if (!new_mem)
3010                         return ERR_PTR(-ENOMEM);
3011
3012                 trans->mem = new_mem;
3013                 trans->mem_bytes = new_bytes;
3014
3015                 if (old_bytes) {
3016                         trace_trans_restart_mem_realloced(trans->fn, _RET_IP_, new_bytes);
3017                         btree_trans_restart(trans);
3018                         return ERR_PTR(-EINTR);
3019                 }
3020         }
3021
3022         p = trans->mem + trans->mem_top;
3023         trans->mem_top += size;
3024         memset(p, 0, size);
3025         return p;
3026 }
3027
3028 /**
3029  * bch2_trans_begin() - reset a transaction after a interrupted attempt
3030  * @trans: transaction to reset
3031  *
3032  * While iterating over nodes or updating nodes a attempt to lock a btree
3033  * node may return EINTR when the trylock fails. When this occurs
3034  * bch2_trans_begin() should be called and the transaction retried.
3035  */
3036 void bch2_trans_begin(struct btree_trans *trans)
3037 {
3038         struct btree_insert_entry *i;
3039         struct btree_path *path;
3040
3041         trans_for_each_update(trans, i)
3042                 __btree_path_put(i->path, true);
3043
3044         memset(&trans->journal_res, 0, sizeof(trans->journal_res));
3045         trans->extra_journal_res        = 0;
3046         trans->nr_updates               = 0;
3047         trans->mem_top                  = 0;
3048
3049         trans->hooks                    = NULL;
3050         trans->extra_journal_entries    = NULL;
3051         trans->extra_journal_entry_u64s = 0;
3052
3053         if (trans->fs_usage_deltas) {
3054                 trans->fs_usage_deltas->used = 0;
3055                 memset(&trans->fs_usage_deltas->memset_start, 0,
3056                        (void *) &trans->fs_usage_deltas->memset_end -
3057                        (void *) &trans->fs_usage_deltas->memset_start);
3058         }
3059
3060         trans_for_each_path(trans, path) {
3061                 path->should_be_locked = false;
3062
3063                 /*
3064                  * If the transaction wasn't restarted, we're presuming to be
3065                  * doing something new: dont keep iterators excpt the ones that
3066                  * are in use - except for the subvolumes btree:
3067                  */
3068                 if (!trans->restarted && path->btree_id != BTREE_ID_subvolumes)
3069                         path->preserve = false;
3070
3071                 /*
3072                  * XXX: we probably shouldn't be doing this if the transaction
3073                  * was restarted, but currently we still overflow transaction
3074                  * iterators if we do that
3075                  */
3076                 if (!path->ref && !path->preserve)
3077                         __bch2_path_free(trans, path);
3078                 else
3079                         path->preserve = false;
3080         }
3081
3082         bch2_trans_cond_resched(trans);
3083
3084         if (trans->restarted)
3085                 bch2_btree_path_traverse_all(trans);
3086
3087         trans->restarted = false;
3088 }
3089
3090 static void bch2_trans_alloc_paths(struct btree_trans *trans, struct bch_fs *c)
3091 {
3092         size_t paths_bytes      = sizeof(struct btree_path) * BTREE_ITER_MAX;
3093         size_t updates_bytes    = sizeof(struct btree_insert_entry) * BTREE_ITER_MAX;
3094         void *p = NULL;
3095
3096         BUG_ON(trans->used_mempool);
3097
3098 #ifdef __KERNEL__
3099         p = this_cpu_xchg(c->btree_paths_bufs->path , NULL);
3100 #endif
3101         if (!p)
3102                 p = mempool_alloc(&trans->c->btree_paths_pool, GFP_NOFS);
3103
3104         trans->paths            = p; p += paths_bytes;
3105         trans->updates          = p; p += updates_bytes;
3106 }
3107
3108 void __bch2_trans_init(struct btree_trans *trans, struct bch_fs *c,
3109                        unsigned expected_nr_iters,
3110                        size_t expected_mem_bytes,
3111                        const char *fn)
3112         __acquires(&c->btree_trans_barrier)
3113 {
3114         BUG_ON(lock_class_is_held(&bch2_btree_node_lock_key));
3115
3116         memset(trans, 0, sizeof(*trans));
3117         trans->c                = c;
3118         trans->fn               = fn;
3119
3120         bch2_trans_alloc_paths(trans, c);
3121
3122         if (expected_mem_bytes) {
3123                 trans->mem_bytes = roundup_pow_of_two(expected_mem_bytes);
3124                 trans->mem = kmalloc(trans->mem_bytes, GFP_KERNEL|__GFP_NOFAIL);
3125
3126                 if (!unlikely(trans->mem)) {
3127                         trans->mem = mempool_alloc(&c->btree_trans_mem_pool, GFP_KERNEL);
3128                         trans->mem_bytes = BTREE_TRANS_MEM_MAX;
3129                 }
3130         }
3131
3132         trans->srcu_idx = srcu_read_lock(&c->btree_trans_barrier);
3133
3134         trans->pid = current->pid;
3135         mutex_lock(&c->btree_trans_lock);
3136         list_add(&trans->list, &c->btree_trans_list);
3137         mutex_unlock(&c->btree_trans_lock);
3138 }
3139
3140 static void check_btree_paths_leaked(struct btree_trans *trans)
3141 {
3142 #ifdef CONFIG_BCACHEFS_DEBUG
3143         struct bch_fs *c = trans->c;
3144         struct btree_path *path;
3145
3146         trans_for_each_path(trans, path)
3147                 if (path->ref)
3148                         goto leaked;
3149         return;
3150 leaked:
3151         bch_err(c, "btree paths leaked from %s!", trans->fn);
3152         trans_for_each_path(trans, path)
3153                 if (path->ref)
3154                         printk(KERN_ERR "  btree %s %pS\n",
3155                                bch2_btree_ids[path->btree_id],
3156                                (void *) path->ip_allocated);
3157         /* Be noisy about this: */
3158         bch2_fatal_error(c);
3159 #endif
3160 }
3161
3162 void bch2_trans_exit(struct btree_trans *trans)
3163         __releases(&c->btree_trans_barrier)
3164 {
3165         struct btree_insert_entry *i;
3166         struct bch_fs *c = trans->c;
3167
3168         bch2_trans_unlock(trans);
3169
3170         trans_for_each_update(trans, i)
3171                 __btree_path_put(i->path, true);
3172         trans->nr_updates               = 0;
3173
3174         check_btree_paths_leaked(trans);
3175
3176         mutex_lock(&c->btree_trans_lock);
3177         list_del(&trans->list);
3178         mutex_unlock(&c->btree_trans_lock);
3179
3180         srcu_read_unlock(&c->btree_trans_barrier, trans->srcu_idx);
3181
3182         bch2_journal_preres_put(&c->journal, &trans->journal_preres);
3183
3184         if (trans->fs_usage_deltas) {
3185                 if (trans->fs_usage_deltas->size + sizeof(trans->fs_usage_deltas) ==
3186                     REPLICAS_DELTA_LIST_MAX)
3187                         mempool_free(trans->fs_usage_deltas,
3188                                      &c->replicas_delta_pool);
3189                 else
3190                         kfree(trans->fs_usage_deltas);
3191         }
3192
3193         if (trans->mem_bytes == BTREE_TRANS_MEM_MAX)
3194                 mempool_free(trans->mem, &c->btree_trans_mem_pool);
3195         else
3196                 kfree(trans->mem);
3197
3198 #ifdef __KERNEL__
3199         /*
3200          * Userspace doesn't have a real percpu implementation:
3201          */
3202         trans->paths = this_cpu_xchg(c->btree_paths_bufs->path, trans->paths);
3203 #endif
3204
3205         if (trans->paths)
3206                 mempool_free(trans->paths, &c->btree_paths_pool);
3207
3208         trans->mem      = (void *) 0x1;
3209         trans->paths    = (void *) 0x1;
3210 }
3211
3212 static void __maybe_unused
3213 bch2_btree_path_node_to_text(struct printbuf *out,
3214                              struct btree_bkey_cached_common *_b,
3215                              bool cached)
3216 {
3217         pr_buf(out, "    l=%u %s:",
3218                _b->level, bch2_btree_ids[_b->btree_id]);
3219         bch2_bpos_to_text(out, btree_node_pos(_b, cached));
3220 }
3221
3222 static bool trans_has_locks(struct btree_trans *trans)
3223 {
3224         struct btree_path *path;
3225
3226         trans_for_each_path(trans, path)
3227                 if (path->nodes_locked)
3228                         return true;
3229         return false;
3230 }
3231
3232 void bch2_btree_trans_to_text(struct printbuf *out, struct bch_fs *c)
3233 {
3234         struct btree_trans *trans;
3235         struct btree_path *path;
3236         struct btree *b;
3237         static char lock_types[] = { 'r', 'i', 'w' };
3238         unsigned l;
3239
3240         mutex_lock(&c->btree_trans_lock);
3241         list_for_each_entry(trans, &c->btree_trans_list, list) {
3242                 if (!trans_has_locks(trans))
3243                         continue;
3244
3245                 pr_buf(out, "%i %s\n", trans->pid, trans->fn);
3246
3247                 trans_for_each_path(trans, path) {
3248                         if (!path->nodes_locked)
3249                                 continue;
3250
3251                         pr_buf(out, "  path %u %c l=%u %s:",
3252                                path->idx,
3253                                path->cached ? 'c' : 'b',
3254                                path->level,
3255                                bch2_btree_ids[path->btree_id]);
3256                         bch2_bpos_to_text(out, path->pos);
3257                         pr_buf(out, "\n");
3258
3259                         for (l = 0; l < BTREE_MAX_DEPTH; l++) {
3260                                 if (btree_node_locked(path, l)) {
3261                                         pr_buf(out, "    %s l=%u ",
3262                                                btree_node_intent_locked(path, l) ? "i" : "r", l);
3263                                         bch2_btree_path_node_to_text(out,
3264                                                         (void *) path->l[l].b,
3265                                                         path->cached);
3266                                         pr_buf(out, "\n");
3267                                 }
3268                         }
3269                 }
3270
3271                 b = READ_ONCE(trans->locking);
3272                 if (b) {
3273                         path = &trans->paths[trans->locking_path_idx];
3274                         pr_buf(out, "  locking path %u %c l=%u %c %s:",
3275                                trans->locking_path_idx,
3276                                path->cached ? 'c' : 'b',
3277                                trans->locking_level,
3278                                lock_types[trans->locking_lock_type],
3279                                bch2_btree_ids[trans->locking_btree_id]);
3280                         bch2_bpos_to_text(out, trans->locking_pos);
3281
3282                         pr_buf(out, " node ");
3283                         bch2_btree_path_node_to_text(out,
3284                                         (void *) b, path->cached);
3285                         pr_buf(out, "\n");
3286                 }
3287         }
3288         mutex_unlock(&c->btree_trans_lock);
3289 }
3290
3291 void bch2_fs_btree_iter_exit(struct bch_fs *c)
3292 {
3293         if (c->btree_trans_barrier_initialized)
3294                 cleanup_srcu_struct(&c->btree_trans_barrier);
3295         mempool_exit(&c->btree_trans_mem_pool);
3296         mempool_exit(&c->btree_paths_pool);
3297 }
3298
3299 int bch2_fs_btree_iter_init(struct bch_fs *c)
3300 {
3301         unsigned nr = BTREE_ITER_MAX;
3302         int ret;
3303
3304         INIT_LIST_HEAD(&c->btree_trans_list);
3305         mutex_init(&c->btree_trans_lock);
3306
3307         ret   = mempool_init_kmalloc_pool(&c->btree_paths_pool, 1,
3308                         sizeof(struct btree_path) * nr +
3309                         sizeof(struct btree_insert_entry) * nr) ?:
3310                 mempool_init_kmalloc_pool(&c->btree_trans_mem_pool, 1,
3311                                           BTREE_TRANS_MEM_MAX) ?:
3312                 init_srcu_struct(&c->btree_trans_barrier);
3313         if (!ret)
3314                 c->btree_trans_barrier_initialized = true;
3315         return ret;
3316 }