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