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

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include "bcachefs.h"
   4 #include "btree_locking.h"
   5 #include "btree_types.h"
   6
   7 struct lock_class_key bch2_btree_node_lock_key;
   8
   9 /* Btree node locking: */
  10
  11 static inline void six_lock_readers_add(struct six_lock *lock, int nr)
  12 {
  13         if (lock->readers)
  14                 this_cpu_add(*lock->readers, nr);
  15         else if (nr > 0)
  16                 atomic64_add(__SIX_VAL(read_lock, nr), &lock->state.counter);
  17         else
  18                 atomic64_sub(__SIX_VAL(read_lock, -nr), &lock->state.counter);
  19 }
  20
  21 struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *trans,
  22                                                   struct btree_path *skip,
  23                                                   struct btree_bkey_cached_common *b,
  24                                                   unsigned level)
  25 {
  26         struct btree_path *path;
  27         struct six_lock_count ret;
  28
  29         memset(&ret, 0, sizeof(ret));
  30
  31         if (IS_ERR_OR_NULL(b))
  32                 return ret;
  33
  34         trans_for_each_path(trans, path)
  35                 if (path != skip && &path->l[level].b->c == b) {
  36                         int t = btree_node_locked_type(path, level);
  37
  38                         if (t != BTREE_NODE_UNLOCKED)
  39                                 ret.n[t]++;
  40                 }
  41
  42         return ret;
  43 }
  44
  45 /* unlock */
  46
  47 void bch2_btree_node_unlock_write(struct btree_trans *trans,
  48                         struct btree_path *path, struct btree *b)
  49 {
  50         bch2_btree_node_unlock_write_inlined(trans, path, b);
  51 }
  52
  53 /* lock */
  54
  55 /*
  56  * @trans wants to lock @b with type @type
  57  */
  58 struct trans_waiting_for_lock {
  59         struct btree_trans              *trans;
  60         struct btree_bkey_cached_common *node_want;
  61         enum six_lock_type              lock_want;
  62
  63         /* for iterating over held locks :*/
  64         u8                              path_idx;
  65         u8                              level;
  66         u64                             lock_start_time;
  67 };
  68
  69 struct lock_graph {
  70         struct trans_waiting_for_lock   g[8];
  71         unsigned                        nr;
  72 };
  73
  74 static noinline void print_cycle(struct printbuf *out, struct lock_graph *g)
  75 {
  76         struct trans_waiting_for_lock *i;
  77
  78         prt_printf(out, "Found lock cycle (%u entries):", g->nr);
  79         prt_newline(out);
  80
  81         for (i = g->g; i < g->g + g->nr; i++)
  82                 bch2_btree_trans_to_text(out, i->trans);
  83 }
  84
  85 static noinline void print_chain(struct printbuf *out, struct lock_graph *g)
  86 {
  87         struct trans_waiting_for_lock *i;
  88
  89         for (i = g->g; i != g->g + g->nr; i++) {
  90                 if (i != g->g)
  91                         prt_str(out, "<- ");
  92                 prt_printf(out, "%u ", i->trans->locking_wait.task->pid);
  93         }
  94         prt_newline(out);
  95 }
  96
  97 static void lock_graph_up(struct lock_graph *g)
  98 {
  99         closure_put(&g->g[--g->nr].trans->ref);
 100 }
 101
 102 static noinline void lock_graph_pop_all(struct lock_graph *g)
 103 {
 104         while (g->nr)
 105                 lock_graph_up(g);
 106 }
 107
 108 static void lock_graph_down(struct lock_graph *g, struct btree_trans *trans)
 109 {
 110         closure_get(&trans->ref);
 111
 112         g->g[g->nr++] = (struct trans_waiting_for_lock) {
 113                 .trans          = trans,
 114                 .node_want      = trans->locking,
 115                 .lock_want      = trans->locking_wait.lock_want,
 116         };
 117 }
 118
 119 static bool lock_graph_remove_non_waiters(struct lock_graph *g)
 120 {
 121         struct trans_waiting_for_lock *i;
 122
 123         for (i = g->g + 1; i < g->g + g->nr; i++)
 124                 if (i->trans->locking != i->node_want ||
 125                     i->trans->locking_wait.start_time != i[-1].lock_start_time) {
 126                         while (g->g + g->nr > i)
 127                                 lock_graph_up(g);
 128                         return true;
 129                 }
 130
 131         return false;
 132 }
 133
 134 static int abort_lock(struct lock_graph *g, struct trans_waiting_for_lock *i)
 135 {
 136         if (i == g->g) {
 137                 trace_and_count(i->trans->c, trans_restart_would_deadlock, i->trans, _RET_IP_);
 138                 return btree_trans_restart(i->trans, BCH_ERR_transaction_restart_would_deadlock);
 139         } else {
 140                 i->trans->lock_must_abort = true;
 141                 wake_up_process(i->trans->locking_wait.task);
 142                 return 0;
 143         }
 144 }
 145
 146 static int btree_trans_abort_preference(struct btree_trans *trans)
 147 {
 148         if (trans->lock_may_not_fail)
 149                 return 0;
 150         if (trans->locking_wait.lock_want == SIX_LOCK_write)
 151                 return 1;
 152         if (!trans->in_traverse_all)
 153                 return 2;
 154         return 3;
 155 }
 156
 157 static noinline int break_cycle(struct lock_graph *g, struct printbuf *cycle)
 158 {
 159         struct trans_waiting_for_lock *i, *abort = NULL;
 160         unsigned best = 0, pref;
 161         int ret;
 162
 163         if (lock_graph_remove_non_waiters(g))
 164                 return 0;
 165
 166         /* Only checking, for debugfs: */
 167         if (cycle) {
 168                 print_cycle(cycle, g);
 169                 ret = -1;
 170                 goto out;
 171         }
 172
 173         for (i = g->g; i < g->g + g->nr; i++) {
 174                 pref = btree_trans_abort_preference(i->trans);
 175                 if (pref > best) {
 176                         abort = i;
 177                         best = pref;
 178                 }
 179         }
 180
 181         if (unlikely(!best)) {
 182                 struct printbuf buf = PRINTBUF;
 183
 184                 prt_printf(&buf, bch2_fmt(g->g->trans->c, "cycle of nofail locks"));
 185
 186                 for (i = g->g; i < g->g + g->nr; i++) {
 187                         struct btree_trans *trans = i->trans;
 188
 189                         bch2_btree_trans_to_text(&buf, trans);
 190
 191                         prt_printf(&buf, "backtrace:");
 192                         prt_newline(&buf);
 193                         printbuf_indent_add(&buf, 2);
 194                         bch2_prt_task_backtrace(&buf, trans->locking_wait.task);
 195                         printbuf_indent_sub(&buf, 2);
 196                         prt_newline(&buf);
 197                 }
 198
 199                 bch2_print_string_as_lines(KERN_ERR, buf.buf);
 200                 printbuf_exit(&buf);
 201                 BUG();
 202         }
 203
 204         ret = abort_lock(g, abort);
 205 out:
 206         if (ret)
 207                 while (g->nr)
 208                         lock_graph_up(g);
 209         return ret;
 210 }
 211
 212 static int lock_graph_descend(struct lock_graph *g, struct btree_trans *trans,
 213                               struct printbuf *cycle)
 214 {
 215         struct btree_trans *orig_trans = g->g->trans;
 216         struct trans_waiting_for_lock *i;
 217
 218         for (i = g->g; i < g->g + g->nr; i++)
 219                 if (i->trans == trans)
 220                         return break_cycle(g, cycle);
 221
 222         if (g->nr == ARRAY_SIZE(g->g)) {
 223                 if (orig_trans->lock_may_not_fail)
 224                         return 0;
 225
 226                 while (g->nr)
 227                         lock_graph_up(g);
 228
 229                 if (cycle)
 230                         return 0;
 231
 232                 trace_and_count(trans->c, trans_restart_would_deadlock_recursion_limit, trans, _RET_IP_);
 233                 return btree_trans_restart(orig_trans, BCH_ERR_transaction_restart_deadlock_recursion_limit);
 234         }
 235
 236         lock_graph_down(g, trans);
 237         return 0;
 238 }
 239
 240 static bool lock_type_conflicts(enum six_lock_type t1, enum six_lock_type t2)
 241 {
 242         return t1 + t2 > 1;
 243 }
 244
 245 int bch2_check_for_deadlock(struct btree_trans *trans, struct printbuf *cycle)
 246 {
 247         struct lock_graph g;
 248         struct trans_waiting_for_lock *top;
 249         struct btree_bkey_cached_common *b;
 250         struct btree_path *path;
 251         int ret;
 252
 253         if (trans->lock_must_abort) {
 254                 if (cycle)
 255                         return -1;
 256
 257                 trace_and_count(trans->c, trans_restart_would_deadlock, trans, _RET_IP_);
 258                 return btree_trans_restart(trans, BCH_ERR_transaction_restart_would_deadlock);
 259         }
 260
 261         g.nr = 0;
 262         lock_graph_down(&g, trans);
 263 next:
 264         if (!g.nr)
 265                 return 0;
 266
 267         top = &g.g[g.nr - 1];
 268
 269         trans_for_each_path_from(top->trans, path, top->path_idx) {
 270                 if (!path->nodes_locked)
 271                         continue;
 272
 273                 if (top->path_idx != path->idx) {
 274                         top->path_idx           = path->idx;
 275                         top->level              = 0;
 276                         top->lock_start_time    = 0;
 277                 }
 278
 279                 for (;
 280                      top->level < BTREE_MAX_DEPTH;
 281                      top->level++, top->lock_start_time = 0) {
 282                         int lock_held = btree_node_locked_type(path, top->level);
 283
 284                         if (lock_held == BTREE_NODE_UNLOCKED)
 285                                 continue;
 286
 287                         b = &READ_ONCE(path->l[top->level].b)->c;
 288
 289                         if (IS_ERR_OR_NULL(b)) {
 290                                 /*
 291                                  * If we get here, it means we raced with the
 292                                  * other thread updating its btree_path
 293                                  * structures - which means it can't be blocked
 294                                  * waiting on a lock:
 295                                  */
 296                                 if (!lock_graph_remove_non_waiters(&g)) {
 297                                         /*
 298                                          * If lock_graph_remove_non_waiters()
 299                                          * didn't do anything, it must be
 300                                          * because we're being called by debugfs
 301                                          * checking for lock cycles, which
 302                                          * invokes us on btree_transactions that
 303                                          * aren't actually waiting on anything.
 304                                          * Just bail out:
 305                                          */
 306                                         lock_graph_pop_all(&g);
 307                                 }
 308
 309                                 goto next;
 310                         }
 311
 312                         if (list_empty_careful(&b->lock.wait_list))
 313                                 continue;
 314
 315                         raw_spin_lock(&b->lock.wait_lock);
 316                         list_for_each_entry(trans, &b->lock.wait_list, locking_wait.list) {
 317                                 BUG_ON(b != trans->locking);
 318
 319                                 if (top->lock_start_time &&
 320                                     time_after_eq64(top->lock_start_time, trans->locking_wait.start_time))
 321                                         continue;
 322
 323                                 top->lock_start_time = trans->locking_wait.start_time;
 324
 325                                 /* Don't check for self deadlock: */
 326                                 if (trans == top->trans ||
 327                                     !lock_type_conflicts(lock_held, trans->locking_wait.lock_want))
 328                                         continue;
 329
 330                                 ret = lock_graph_descend(&g, trans, cycle);
 331                                 raw_spin_unlock(&b->lock.wait_lock);
 332
 333                                 if (ret)
 334                                         return ret;
 335                                 goto next;
 336
 337                         }
 338                         raw_spin_unlock(&b->lock.wait_lock);
 339                 }
 340         }
 341
 342         if (g.nr > 1 && cycle)
 343                 print_chain(cycle, &g);
 344         lock_graph_up(&g);
 345         goto next;
 346 }
 347
 348 int bch2_six_check_for_deadlock(struct six_lock *lock, void *p)
 349 {
 350         struct btree_trans *trans = p;
 351
 352         return bch2_check_for_deadlock(trans, NULL);
 353 }
 354
 355 int __bch2_btree_node_lock_write(struct btree_trans *trans, struct btree_path *path,
 356                                  struct btree_bkey_cached_common *b,
 357                                  bool lock_may_not_fail)
 358 {
 359         int readers = bch2_btree_node_lock_counts(trans, NULL, b, b->level).n[SIX_LOCK_read];
 360         int ret;
 361
 362         /*
 363          * Must drop our read locks before calling six_lock_write() -
 364          * six_unlock() won't do wakeups until the reader count
 365          * goes to 0, and it's safe because we have the node intent
 366          * locked:
 367          */
 368         six_lock_readers_add(&b->lock, -readers);
 369         ret = __btree_node_lock_nopath(trans, b, SIX_LOCK_write,
 370                                        lock_may_not_fail, _RET_IP_);
 371         six_lock_readers_add(&b->lock, readers);
 372
 373         if (ret)
 374                 mark_btree_node_locked_noreset(path, b->level, SIX_LOCK_intent);
 375
 376         return ret;
 377 }
 378
 379 /* relock */
 380
 381 static inline bool btree_path_get_locks(struct btree_trans *trans,
 382                                         struct btree_path *path,
 383                                         bool upgrade)
 384 {
 385         unsigned l = path->level;
 386         int fail_idx = -1;
 387
 388         do {
 389                 if (!btree_path_node(path, l))
 390                         break;
 391
 392                 if (!(upgrade
 393                       ? bch2_btree_node_upgrade(trans, path, l)
 394                       : bch2_btree_node_relock(trans, path, l)))
 395                         fail_idx = l;
 396
 397                 l++;
 398         } while (l < path->locks_want);
 399
 400         /*
 401          * When we fail to get a lock, we have to ensure that any child nodes
 402          * can't be relocked so bch2_btree_path_traverse has to walk back up to
 403          * the node that we failed to relock:
 404          */
 405         if (fail_idx >= 0) {
 406                 __bch2_btree_path_unlock(trans, path);
 407                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
 408
 409                 do {
 410                         path->l[fail_idx].b = upgrade
 411                                 ? ERR_PTR(-BCH_ERR_no_btree_node_upgrade)
 412                                 : ERR_PTR(-BCH_ERR_no_btree_node_relock);
 413                         --fail_idx;
 414                 } while (fail_idx >= 0);
 415         }
 416
 417         if (path->uptodate == BTREE_ITER_NEED_RELOCK)
 418                 path->uptodate = BTREE_ITER_UPTODATE;
 419
 420         bch2_trans_verify_locks(trans);
 421
 422         return path->uptodate < BTREE_ITER_NEED_RELOCK;
 423 }
 424
 425 bool __bch2_btree_node_relock(struct btree_trans *trans,
 426                               struct btree_path *path, unsigned level,
 427                               bool trace)
 428 {
 429         struct btree *b = btree_path_node(path, level);
 430         int want = __btree_lock_want(path, level);
 431
 432         if (race_fault())
 433                 goto fail;
 434
 435         if (six_relock_type(&b->c.lock, want, path->l[level].lock_seq) ||
 436             (btree_node_lock_seq_matches(path, b, level) &&
 437              btree_node_lock_increment(trans, &b->c, level, want))) {
 438                 mark_btree_node_locked(trans, path, level, want);
 439                 return true;
 440         }
 441 fail:
 442         if (trace && !trans->notrace_relock_fail)
 443                 trace_and_count(trans->c, btree_path_relock_fail, trans, _RET_IP_, path, level);
 444         return false;
 445 }
 446
 447 /* upgrade */
 448
 449 bool bch2_btree_node_upgrade(struct btree_trans *trans,
 450                              struct btree_path *path, unsigned level)
 451 {
 452         struct btree *b = path->l[level].b;
 453         struct six_lock_count count = bch2_btree_node_lock_counts(trans, path, &b->c, level);
 454
 455         if (!is_btree_node(path, level))
 456                 return false;
 457
 458         switch (btree_lock_want(path, level)) {
 459         case BTREE_NODE_UNLOCKED:
 460                 BUG_ON(btree_node_locked(path, level));
 461                 return true;
 462         case BTREE_NODE_READ_LOCKED:
 463                 BUG_ON(btree_node_intent_locked(path, level));
 464                 return bch2_btree_node_relock(trans, path, level);
 465         case BTREE_NODE_INTENT_LOCKED:
 466                 break;
 467         case BTREE_NODE_WRITE_LOCKED:
 468                 BUG();
 469         }
 470
 471         if (btree_node_intent_locked(path, level))
 472                 return true;
 473
 474         if (race_fault())
 475                 return false;
 476
 477         if (btree_node_locked(path, level)) {
 478                 bool ret;
 479
 480                 six_lock_readers_add(&b->c.lock, -count.n[SIX_LOCK_read]);
 481                 ret = six_lock_tryupgrade(&b->c.lock);
 482                 six_lock_readers_add(&b->c.lock, count.n[SIX_LOCK_read]);
 483
 484                 if (ret)
 485                         goto success;
 486         } else {
 487                 if (six_relock_type(&b->c.lock, SIX_LOCK_intent, path->l[level].lock_seq))
 488                         goto success;
 489         }
 490
 491         /*
 492          * Do we already have an intent lock via another path? If so, just bump
 493          * lock count:
 494          */
 495         if (btree_node_lock_seq_matches(path, b, level) &&
 496             btree_node_lock_increment(trans, &b->c, level, BTREE_NODE_INTENT_LOCKED)) {
 497                 btree_node_unlock(trans, path, level);
 498                 goto success;
 499         }
 500
 501         trace_and_count(trans->c, btree_path_upgrade_fail, trans, _RET_IP_, path, level);
 502         return false;
 503 success:
 504         mark_btree_node_locked_noreset(path, level, SIX_LOCK_intent);
 505         return true;
 506 }
 507
 508 /* Btree path locking: */
 509
 510 /*
 511  * Only for btree_cache.c - only relocks intent locks
 512  */
 513 int bch2_btree_path_relock_intent(struct btree_trans *trans,
 514                                   struct btree_path *path)
 515 {
 516         unsigned l;
 517
 518         for (l = path->level;
 519              l < path->locks_want && btree_path_node(path, l);
 520              l++) {
 521                 if (!bch2_btree_node_relock(trans, path, l)) {
 522                         __bch2_btree_path_unlock(trans, path);
 523                         btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
 524                         trace_and_count(trans->c, trans_restart_relock_path_intent, trans, _RET_IP_, path);
 525                         return btree_trans_restart(trans, BCH_ERR_transaction_restart_relock_path_intent);
 526                 }
 527         }
 528
 529         return 0;
 530 }
 531
 532 __flatten
 533 bool bch2_btree_path_relock_norestart(struct btree_trans *trans,
 534                         struct btree_path *path, unsigned long trace_ip)
 535 {
 536         return btree_path_get_locks(trans, path, false);
 537 }
 538
 539 int __bch2_btree_path_relock(struct btree_trans *trans,
 540                         struct btree_path *path, unsigned long trace_ip)
 541 {
 542         if (!bch2_btree_path_relock_norestart(trans, path, trace_ip)) {
 543                 trace_and_count(trans->c, trans_restart_relock_path, trans, trace_ip, path);
 544                 return btree_trans_restart(trans, BCH_ERR_transaction_restart_relock_path);
 545         }
 546
 547         return 0;
 548 }
 549
 550 __flatten
 551 bool bch2_btree_path_upgrade_norestart(struct btree_trans *trans,
 552                         struct btree_path *path, unsigned long trace_ip)
 553 {
 554         return btree_path_get_locks(trans, path, true);
 555 }
 556
 557 bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *trans,
 558                                struct btree_path *path,
 559                                unsigned new_locks_want)
 560 {
 561         EBUG_ON(path->locks_want >= new_locks_want);
 562
 563         path->locks_want = new_locks_want;
 564
 565         return btree_path_get_locks(trans, path, true);
 566 }
 567
 568 bool __bch2_btree_path_upgrade(struct btree_trans *trans,
 569                                struct btree_path *path,
 570                                unsigned new_locks_want)
 571 {
 572         struct btree_path *linked;
 573
 574         if (bch2_btree_path_upgrade_noupgrade_sibs(trans, path, new_locks_want))
 575                 return true;
 576
 577         /*
 578          * XXX: this is ugly - we'd prefer to not be mucking with other
 579          * iterators in the btree_trans here.
 580          *
 581          * On failure to upgrade the iterator, setting iter->locks_want and
 582          * calling get_locks() is sufficient to make bch2_btree_path_traverse()
 583          * get the locks we want on transaction restart.
 584          *
 585          * But if this iterator was a clone, on transaction restart what we did
 586          * to this iterator isn't going to be preserved.
 587          *
 588          * Possibly we could add an iterator field for the parent iterator when
 589          * an iterator is a copy - for now, we'll just upgrade any other
 590          * iterators with the same btree id.
 591          *
 592          * The code below used to be needed to ensure ancestor nodes get locked
 593          * before interior nodes - now that's handled by
 594          * bch2_btree_path_traverse_all().
 595          */
 596         if (!path->cached && !trans->in_traverse_all)
 597                 trans_for_each_path(trans, linked)
 598                         if (linked != path &&
 599                             linked->cached == path->cached &&
 600                             linked->btree_id == path->btree_id &&
 601                             linked->locks_want < new_locks_want) {
 602                                 linked->locks_want = new_locks_want;
 603                                 btree_path_get_locks(trans, linked, true);
 604                         }
 605
 606         return false;
 607 }
 608
 609 void __bch2_btree_path_downgrade(struct btree_trans *trans,
 610                                  struct btree_path *path,
 611                                  unsigned new_locks_want)
 612 {
 613         unsigned l;
 614
 615         EBUG_ON(path->locks_want < new_locks_want);
 616
 617         path->locks_want = new_locks_want;
 618
 619         while (path->nodes_locked &&
 620                (l = btree_path_highest_level_locked(path)) >= path->locks_want) {
 621                 if (l > path->level) {
 622                         btree_node_unlock(trans, path, l);
 623                 } else {
 624                         if (btree_node_intent_locked(path, l)) {
 625                                 six_lock_downgrade(&path->l[l].b->c.lock);
 626                                 mark_btree_node_locked_noreset(path, l, SIX_LOCK_read);
 627                         }
 628                         break;
 629                 }
 630         }
 631
 632         bch2_btree_path_verify_locks(path);
 633 }
 634
 635 /* Btree transaction locking: */
 636
 637 void bch2_trans_downgrade(struct btree_trans *trans)
 638 {
 639         struct btree_path *path;
 640
 641         trans_for_each_path(trans, path)
 642                 bch2_btree_path_downgrade(trans, path);
 643 }
 644
 645 int bch2_trans_relock(struct btree_trans *trans)
 646 {
 647         struct btree_path *path;
 648
 649         if (unlikely(trans->restarted))
 650                 return -((int) trans->restarted);
 651
 652         trans_for_each_path(trans, path)
 653                 if (path->should_be_locked &&
 654                     !bch2_btree_path_relock_norestart(trans, path, _RET_IP_)) {
 655                         trace_and_count(trans->c, trans_restart_relock, trans, _RET_IP_, path);
 656                         return btree_trans_restart(trans, BCH_ERR_transaction_restart_relock);
 657                 }
 658         return 0;
 659 }
 660
 661 int bch2_trans_relock_notrace(struct btree_trans *trans)
 662 {
 663         struct btree_path *path;
 664
 665         if (unlikely(trans->restarted))
 666                 return -((int) trans->restarted);
 667
 668         trans_for_each_path(trans, path)
 669                 if (path->should_be_locked &&
 670                     !bch2_btree_path_relock_norestart(trans, path, _RET_IP_)) {
 671                         return btree_trans_restart(trans, BCH_ERR_transaction_restart_relock);
 672                 }
 673         return 0;
 674 }
 675
 676 void bch2_trans_unlock(struct btree_trans *trans)
 677 {
 678         struct btree_path *path;
 679
 680         trans_for_each_path(trans, path)
 681                 __bch2_btree_path_unlock(trans, path);
 682
 683         /*
 684          * bch2_gc_btree_init_recurse() doesn't use btree iterators for walking
 685          * btree nodes, it implements its own walking:
 686          */
 687         EBUG_ON(!trans->is_initial_gc &&
 688                 lock_class_is_held(&bch2_btree_node_lock_key));
 689 }
 690
 691 bool bch2_trans_locked(struct btree_trans *trans)
 692 {
 693         struct btree_path *path;
 694
 695         trans_for_each_path(trans, path)
 696                 if (path->nodes_locked)
 697                         return true;
 698         return false;
 699 }
 700
 701 /* Debug */
 702
 703 #ifdef CONFIG_BCACHEFS_DEBUG
 704
 705 void bch2_btree_path_verify_locks(struct btree_path *path)
 706 {
 707         unsigned l;
 708
 709         if (!path->nodes_locked) {
 710                 BUG_ON(path->uptodate == BTREE_ITER_UPTODATE &&
 711                        btree_path_node(path, path->level));
 712                 return;
 713         }
 714
 715         for (l = 0; l < BTREE_MAX_DEPTH; l++) {
 716                 int want = btree_lock_want(path, l);
 717                 int have = btree_node_locked_type(path, l);
 718
 719                 BUG_ON(!is_btree_node(path, l) && have != BTREE_NODE_UNLOCKED);
 720
 721                 BUG_ON(is_btree_node(path, l) &&
 722                        (want == BTREE_NODE_UNLOCKED ||
 723                         have != BTREE_NODE_WRITE_LOCKED) &&
 724                        want != have);
 725         }
 726 }
 727
 728 void bch2_trans_verify_locks(struct btree_trans *trans)
 729 {
 730         struct btree_path *path;
 731
 732         trans_for_each_path(trans, path)
 733                 bch2_btree_path_verify_locks(path);
 734 }
 735
 736 #endif