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 static struct lock_class_key bch2_btree_node_lock_key;
   8
   9 void bch2_btree_lock_init(struct btree_bkey_cached_common *b,
  10                           enum six_lock_init_flags flags)
  11 {
  12         __six_lock_init(&b->lock, "b->c.lock", &bch2_btree_node_lock_key, flags);
  13 }
  14
  15 #ifdef CONFIG_LOCKDEP
  16 void bch2_assert_btree_nodes_not_locked(void)
  17 {
  18         BUG_ON(lock_class_is_held(&bch2_btree_node_lock_key));
  19 }
  20 #endif
  21
  22 /* Btree node locking: */
  23
  24 struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *trans,
  25                                                   struct btree_path *skip,
  26                                                   struct btree_bkey_cached_common *b,
  27                                                   unsigned level)
  28 {
  29         struct btree_path *path;
  30         struct six_lock_count ret;
  31
  32         memset(&ret, 0, sizeof(ret));
  33
  34         if (IS_ERR_OR_NULL(b))
  35                 return ret;
  36
  37         trans_for_each_path(trans, path)
  38                 if (path != skip && &path->l[level].b->c == b) {
  39                         int t = btree_node_locked_type(path, level);
  40
  41                         if (t != BTREE_NODE_UNLOCKED)
  42                                 ret.n[t]++;
  43                 }
  44
  45         return ret;
  46 }
  47
  48 /* unlock */
  49
  50 void bch2_btree_node_unlock_write(struct btree_trans *trans,
  51                         struct btree_path *path, struct btree *b)
  52 {
  53         bch2_btree_node_unlock_write_inlined(trans, path, b);
  54 }
  55
  56 /* lock */
  57
  58 /*
  59  * @trans wants to lock @b with type @type
  60  */
  61 struct trans_waiting_for_lock {
  62         struct btree_trans              *trans;
  63         struct btree_bkey_cached_common *node_want;
  64         enum six_lock_type              lock_want;
  65
  66         /* for iterating over held locks :*/
  67         u8                              path_idx;
  68         u8                              level;
  69         u64                             lock_start_time;
  70 };
  71
  72 struct lock_graph {
  73         struct trans_waiting_for_lock   g[8];
  74         unsigned                        nr;
  75 };
  76
  77 static noinline void print_cycle(struct printbuf *out, struct lock_graph *g)
  78 {
  79         struct trans_waiting_for_lock *i;
  80
  81         prt_printf(out, "Found lock cycle (%u entries):", g->nr);
  82         prt_newline(out);
  83
  84         for (i = g->g; i < g->g + g->nr; i++)
  85                 bch2_btree_trans_to_text(out, i->trans);
  86 }
  87
  88 static noinline void print_chain(struct printbuf *out, struct lock_graph *g)
  89 {
  90         struct trans_waiting_for_lock *i;
  91
  92         for (i = g->g; i != g->g + g->nr; i++) {
  93                 if (i != g->g)
  94                         prt_str(out, "<- ");
  95                 prt_printf(out, "%u ", i->trans->locking_wait.task->pid);
  96         }
  97         prt_newline(out);
  98 }
  99
 100 static void lock_graph_up(struct lock_graph *g)
 101 {
 102         closure_put(&g->g[--g->nr].trans->ref);
 103 }
 104
 105 static noinline void lock_graph_pop_all(struct lock_graph *g)
 106 {
 107         while (g->nr)
 108                 lock_graph_up(g);
 109 }
 110
 111 static void lock_graph_down(struct lock_graph *g, struct btree_trans *trans)
 112 {
 113         closure_get(&trans->ref);
 114
 115         g->g[g->nr++] = (struct trans_waiting_for_lock) {
 116                 .trans          = trans,
 117                 .node_want      = trans->locking,
 118                 .lock_want      = trans->locking_wait.lock_want,
 119         };
 120 }
 121
 122 static bool lock_graph_remove_non_waiters(struct lock_graph *g)
 123 {
 124         struct trans_waiting_for_lock *i;
 125
 126         for (i = g->g + 1; i < g->g + g->nr; i++)
 127                 if (i->trans->locking != i->node_want ||
 128                     i->trans->locking_wait.start_time != i[-1].lock_start_time) {
 129                         while (g->g + g->nr > i)
 130                                 lock_graph_up(g);
 131                         return true;
 132                 }
 133
 134         return false;
 135 }
 136
 137 static int abort_lock(struct lock_graph *g, struct trans_waiting_for_lock *i)
 138 {
 139         if (i == g->g) {
 140                 trace_and_count(i->trans->c, trans_restart_would_deadlock, i->trans, _RET_IP_);
 141                 return btree_trans_restart(i->trans, BCH_ERR_transaction_restart_would_deadlock);
 142         } else {
 143                 i->trans->lock_must_abort = true;
 144                 wake_up_process(i->trans->locking_wait.task);
 145                 return 0;
 146         }
 147 }
 148
 149 static int btree_trans_abort_preference(struct btree_trans *trans)
 150 {
 151         if (trans->lock_may_not_fail)
 152                 return 0;
 153         if (trans->locking_wait.lock_want == SIX_LOCK_write)
 154                 return 1;
 155         if (!trans->in_traverse_all)
 156                 return 2;
 157         return 3;
 158 }
 159
 160 static noinline int break_cycle(struct lock_graph *g, struct printbuf *cycle)
 161 {
 162         struct trans_waiting_for_lock *i, *abort = NULL;
 163         unsigned best = 0, pref;
 164         int ret;
 165
 166         if (lock_graph_remove_non_waiters(g))
 167                 return 0;
 168
 169         /* Only checking, for debugfs: */
 170         if (cycle) {
 171                 print_cycle(cycle, g);
 172                 ret = -1;
 173                 goto out;
 174         }
 175
 176         for (i = g->g; i < g->g + g->nr; i++) {
 177                 pref = btree_trans_abort_preference(i->trans);
 178                 if (pref > best) {
 179                         abort = i;
 180                         best = pref;
 181                 }
 182         }
 183
 184         if (unlikely(!best)) {
 185                 struct printbuf buf = PRINTBUF;
 186
 187                 prt_printf(&buf, bch2_fmt(g->g->trans->c, "cycle of nofail locks"));
 188
 189                 for (i = g->g; i < g->g + g->nr; i++) {
 190                         struct btree_trans *trans = i->trans;
 191
 192                         bch2_btree_trans_to_text(&buf, trans);
 193
 194                         prt_printf(&buf, "backtrace:");
 195                         prt_newline(&buf);
 196                         printbuf_indent_add(&buf, 2);
 197                         bch2_prt_task_backtrace(&buf, trans->locking_wait.task);
 198                         printbuf_indent_sub(&buf, 2);
 199                         prt_newline(&buf);
 200                 }
 201
 202                 bch2_print_string_as_lines(KERN_ERR, buf.buf);
 203                 printbuf_exit(&buf);
 204                 BUG();
 205         }
 206
 207         ret = abort_lock(g, abort);
 208 out:
 209         if (ret)
 210                 while (g->nr)
 211                         lock_graph_up(g);
 212         return ret;
 213 }
 214
 215 static int lock_graph_descend(struct lock_graph *g, struct btree_trans *trans,
 216                               struct printbuf *cycle)
 217 {
 218         struct btree_trans *orig_trans = g->g->trans;
 219         struct trans_waiting_for_lock *i;
 220
 221         for (i = g->g; i < g->g + g->nr; i++)
 222                 if (i->trans == trans)
 223                         return break_cycle(g, cycle);
 224
 225         if (g->nr == ARRAY_SIZE(g->g)) {
 226                 if (orig_trans->lock_may_not_fail)
 227                         return 0;
 228
 229                 while (g->nr)
 230                         lock_graph_up(g);
 231
 232                 if (cycle)
 233                         return 0;
 234
 235                 trace_and_count(trans->c, trans_restart_would_deadlock_recursion_limit, trans, _RET_IP_);
 236                 return btree_trans_restart(orig_trans, BCH_ERR_transaction_restart_deadlock_recursion_limit);
 237         }
 238
 239         lock_graph_down(g, trans);
 240         return 0;
 241 }
 242
 243 static bool lock_type_conflicts(enum six_lock_type t1, enum six_lock_type t2)
 244 {
 245         return t1 + t2 > 1;
 246 }
 247
 248 int bch2_check_for_deadlock(struct btree_trans *trans, struct printbuf *cycle)
 249 {
 250         struct lock_graph g;
 251         struct trans_waiting_for_lock *top;
 252         struct btree_bkey_cached_common *b;
 253         struct btree_path *path;
 254         int ret;
 255
 256         if (trans->lock_must_abort) {
 257                 if (cycle)
 258                         return -1;
 259
 260                 trace_and_count(trans->c, trans_restart_would_deadlock, trans, _RET_IP_);
 261                 return btree_trans_restart(trans, BCH_ERR_transaction_restart_would_deadlock);
 262         }
 263
 264         g.nr = 0;
 265         lock_graph_down(&g, trans);
 266 next:
 267         if (!g.nr)
 268                 return 0;
 269
 270         top = &g.g[g.nr - 1];
 271
 272         trans_for_each_path_from(top->trans, path, top->path_idx) {
 273                 if (!path->nodes_locked)
 274                         continue;
 275
 276                 if (top->path_idx != path->idx) {
 277                         top->path_idx           = path->idx;
 278                         top->level              = 0;
 279                         top->lock_start_time    = 0;
 280                 }
 281
 282                 for (;
 283                      top->level < BTREE_MAX_DEPTH;
 284                      top->level++, top->lock_start_time = 0) {
 285                         int lock_held = btree_node_locked_type(path, top->level);
 286
 287                         if (lock_held == BTREE_NODE_UNLOCKED)
 288                                 continue;
 289
 290                         b = &READ_ONCE(path->l[top->level].b)->c;
 291
 292                         if (IS_ERR_OR_NULL(b)) {
 293                                 /*
 294                                  * If we get here, it means we raced with the
 295                                  * other thread updating its btree_path
 296                                  * structures - which means it can't be blocked
 297                                  * waiting on a lock:
 298                                  */
 299                                 if (!lock_graph_remove_non_waiters(&g)) {
 300                                         /*
 301                                          * If lock_graph_remove_non_waiters()
 302                                          * didn't do anything, it must be
 303                                          * because we're being called by debugfs
 304                                          * checking for lock cycles, which
 305                                          * invokes us on btree_transactions that
 306                                          * aren't actually waiting on anything.
 307                                          * Just bail out:
 308                                          */
 309                                         lock_graph_pop_all(&g);
 310                                 }
 311
 312                                 goto next;
 313                         }
 314
 315                         if (list_empty_careful(&b->lock.wait_list))
 316                                 continue;
 317
 318                         raw_spin_lock(&b->lock.wait_lock);
 319                         list_for_each_entry(trans, &b->lock.wait_list, locking_wait.list) {
 320                                 BUG_ON(b != trans->locking);
 321
 322                                 if (top->lock_start_time &&
 323                                     time_after_eq64(top->lock_start_time, trans->locking_wait.start_time))
 324                                         continue;
 325
 326                                 top->lock_start_time = trans->locking_wait.start_time;
 327
 328                                 /* Don't check for self deadlock: */
 329                                 if (trans == top->trans ||
 330                                     !lock_type_conflicts(lock_held, trans->locking_wait.lock_want))
 331                                         continue;
 332
 333                                 ret = lock_graph_descend(&g, trans, cycle);
 334                                 raw_spin_unlock(&b->lock.wait_lock);
 335
 336                                 if (ret)
 337                                         return ret;
 338                                 goto next;
 339
 340                         }
 341                         raw_spin_unlock(&b->lock.wait_lock);
 342                 }
 343         }
 344
 345         if (g.nr > 1 && cycle)
 346                 print_chain(cycle, &g);
 347         lock_graph_up(&g);
 348         goto next;
 349 }
 350
 351 int bch2_six_check_for_deadlock(struct six_lock *lock, void *p)
 352 {
 353         struct btree_trans *trans = p;
 354
 355         return bch2_check_for_deadlock(trans, NULL);
 356 }
 357
 358 int __bch2_btree_node_lock_write(struct btree_trans *trans, struct btree_path *path,
 359                                  struct btree_bkey_cached_common *b,
 360                                  bool lock_may_not_fail)
 361 {
 362         int readers = bch2_btree_node_lock_counts(trans, NULL, b, b->level).n[SIX_LOCK_read];
 363         int ret;
 364
 365         /*
 366          * Must drop our read locks before calling six_lock_write() -
 367          * six_unlock() won't do wakeups until the reader count
 368          * goes to 0, and it's safe because we have the node intent
 369          * locked:
 370          */
 371         six_lock_readers_add(&b->lock, -readers);
 372         ret = __btree_node_lock_nopath(trans, b, SIX_LOCK_write,
 373                                        lock_may_not_fail, _RET_IP_);
 374         six_lock_readers_add(&b->lock, readers);
 375
 376         if (ret)
 377                 mark_btree_node_locked_noreset(path, b->level, SIX_LOCK_intent);
 378
 379         return ret;
 380 }
 381
 382 void bch2_btree_node_lock_write_nofail(struct btree_trans *trans,
 383                                        struct btree_path *path,
 384                                        struct btree_bkey_cached_common *b)
 385 {
 386         struct btree_path *linked;
 387         unsigned i;
 388         int ret;
 389
 390         /*
 391          * XXX BIG FAT NOTICE
 392          *
 393          * Drop all read locks before taking a write lock:
 394          *
 395          * This is a hack, because bch2_btree_node_lock_write_nofail() is a
 396          * hack - but by dropping read locks first, this should never fail, and
 397          * we only use this in code paths where whatever read locks we've
 398          * already taken are no longer needed:
 399          */
 400
 401         trans_for_each_path(trans, linked) {
 402                 if (!linked->nodes_locked)
 403                         continue;
 404
 405                 for (i = 0; i < BTREE_MAX_DEPTH; i++)
 406                         if (btree_node_read_locked(linked, i)) {
 407                                 btree_node_unlock(trans, linked, i);
 408                                 btree_path_set_dirty(linked, BTREE_ITER_NEED_RELOCK);
 409                         }
 410         }
 411
 412         ret = __btree_node_lock_write(trans, path, b, true);
 413         BUG_ON(ret);
 414 }
 415
 416 /* relock */
 417
 418 static inline bool btree_path_get_locks(struct btree_trans *trans,
 419                                         struct btree_path *path,
 420                                         bool upgrade)
 421 {
 422         unsigned l = path->level;
 423         int fail_idx = -1;
 424
 425         do {
 426                 if (!btree_path_node(path, l))
 427                         break;
 428
 429                 if (!(upgrade
 430                       ? bch2_btree_node_upgrade(trans, path, l)
 431                       : bch2_btree_node_relock(trans, path, l)))
 432                         fail_idx = l;
 433
 434                 l++;
 435         } while (l < path->locks_want);
 436
 437         /*
 438          * When we fail to get a lock, we have to ensure that any child nodes
 439          * can't be relocked so bch2_btree_path_traverse has to walk back up to
 440          * the node that we failed to relock:
 441          */
 442         if (fail_idx >= 0) {
 443                 __bch2_btree_path_unlock(trans, path);
 444                 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
 445
 446                 do {
 447                         path->l[fail_idx].b = upgrade
 448                                 ? ERR_PTR(-BCH_ERR_no_btree_node_upgrade)
 449                                 : ERR_PTR(-BCH_ERR_no_btree_node_relock);
 450                         --fail_idx;
 451                 } while (fail_idx >= 0);
 452         }
 453
 454         if (path->uptodate == BTREE_ITER_NEED_RELOCK)
 455                 path->uptodate = BTREE_ITER_UPTODATE;
 456
 457         bch2_trans_verify_locks(trans);
 458
 459         return path->uptodate < BTREE_ITER_NEED_RELOCK;
 460 }
 461
 462 bool __bch2_btree_node_relock(struct btree_trans *trans,
 463                               struct btree_path *path, unsigned level,
 464                               bool trace)
 465 {
 466         struct btree *b = btree_path_node(path, level);
 467         int want = __btree_lock_want(path, level);
 468
 469         if (race_fault())
 470                 goto fail;
 471
 472         if (six_relock_type(&b->c.lock, want, path->l[level].lock_seq) ||
 473             (btree_node_lock_seq_matches(path, b, level) &&
 474              btree_node_lock_increment(trans, &b->c, level, want))) {
 475                 mark_btree_node_locked(trans, path, level, want);
 476                 return true;
 477         }
 478 fail:
 479         if (trace && !trans->notrace_relock_fail)
 480                 trace_and_count(trans->c, btree_path_relock_fail, trans, _RET_IP_, path, level);
 481         return false;
 482 }
 483
 484 /* upgrade */
 485
 486 bool bch2_btree_node_upgrade(struct btree_trans *trans,
 487                              struct btree_path *path, unsigned level)
 488 {
 489         struct btree *b = path->l[level].b;
 490         struct six_lock_count count = bch2_btree_node_lock_counts(trans, path, &b->c, level);
 491
 492         if (!is_btree_node(path, level))
 493                 return false;
 494
 495         switch (btree_lock_want(path, level)) {
 496         case BTREE_NODE_UNLOCKED:
 497                 BUG_ON(btree_node_locked(path, level));
 498                 return true;
 499         case BTREE_NODE_READ_LOCKED:
 500                 BUG_ON(btree_node_intent_locked(path, level));
 501                 return bch2_btree_node_relock(trans, path, level);
 502         case BTREE_NODE_INTENT_LOCKED:
 503                 break;
 504         case BTREE_NODE_WRITE_LOCKED:
 505                 BUG();
 506         }
 507
 508         if (btree_node_intent_locked(path, level))
 509                 return true;
 510
 511         if (race_fault())
 512                 return false;
 513
 514         if (btree_node_locked(path, level)) {
 515                 bool ret;
 516
 517                 six_lock_readers_add(&b->c.lock, -count.n[SIX_LOCK_read]);
 518                 ret = six_lock_tryupgrade(&b->c.lock);
 519                 six_lock_readers_add(&b->c.lock, count.n[SIX_LOCK_read]);
 520
 521                 if (ret)
 522                         goto success;
 523         } else {
 524                 if (six_relock_type(&b->c.lock, SIX_LOCK_intent, path->l[level].lock_seq))
 525                         goto success;
 526         }
 527
 528         /*
 529          * Do we already have an intent lock via another path? If so, just bump
 530          * lock count:
 531          */
 532         if (btree_node_lock_seq_matches(path, b, level) &&
 533             btree_node_lock_increment(trans, &b->c, level, BTREE_NODE_INTENT_LOCKED)) {
 534                 btree_node_unlock(trans, path, level);
 535                 goto success;
 536         }
 537
 538         trace_and_count(trans->c, btree_path_upgrade_fail, trans, _RET_IP_, path, level);
 539         return false;
 540 success:
 541         mark_btree_node_locked_noreset(path, level, SIX_LOCK_intent);
 542         return true;
 543 }
 544
 545 /* Btree path locking: */
 546
 547 /*
 548  * Only for btree_cache.c - only relocks intent locks
 549  */
 550 int bch2_btree_path_relock_intent(struct btree_trans *trans,
 551                                   struct btree_path *path)
 552 {
 553         unsigned l;
 554
 555         for (l = path->level;
 556              l < path->locks_want && btree_path_node(path, l);
 557              l++) {
 558                 if (!bch2_btree_node_relock(trans, path, l)) {
 559                         __bch2_btree_path_unlock(trans, path);
 560                         btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
 561                         trace_and_count(trans->c, trans_restart_relock_path_intent, trans, _RET_IP_, path);
 562                         return btree_trans_restart(trans, BCH_ERR_transaction_restart_relock_path_intent);
 563                 }
 564         }
 565
 566         return 0;
 567 }
 568
 569 __flatten
 570 bool bch2_btree_path_relock_norestart(struct btree_trans *trans,
 571                         struct btree_path *path, unsigned long trace_ip)
 572 {
 573         return btree_path_get_locks(trans, path, false);
 574 }
 575
 576 int __bch2_btree_path_relock(struct btree_trans *trans,
 577                         struct btree_path *path, unsigned long trace_ip)
 578 {
 579         if (!bch2_btree_path_relock_norestart(trans, path, trace_ip)) {
 580                 trace_and_count(trans->c, trans_restart_relock_path, trans, trace_ip, path);
 581                 return btree_trans_restart(trans, BCH_ERR_transaction_restart_relock_path);
 582         }
 583
 584         return 0;
 585 }
 586
 587 __flatten
 588 bool bch2_btree_path_upgrade_norestart(struct btree_trans *trans,
 589                         struct btree_path *path, unsigned long trace_ip)
 590 {
 591         return btree_path_get_locks(trans, path, true);
 592 }
 593
 594 bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *trans,
 595                                struct btree_path *path,
 596                                unsigned new_locks_want)
 597 {
 598         EBUG_ON(path->locks_want >= new_locks_want);
 599
 600         path->locks_want = new_locks_want;
 601
 602         return btree_path_get_locks(trans, path, true);
 603 }
 604
 605 bool __bch2_btree_path_upgrade(struct btree_trans *trans,
 606                                struct btree_path *path,
 607                                unsigned new_locks_want)
 608 {
 609         struct btree_path *linked;
 610
 611         if (bch2_btree_path_upgrade_noupgrade_sibs(trans, path, new_locks_want))
 612                 return true;
 613
 614         /*
 615          * XXX: this is ugly - we'd prefer to not be mucking with other
 616          * iterators in the btree_trans here.
 617          *
 618          * On failure to upgrade the iterator, setting iter->locks_want and
 619          * calling get_locks() is sufficient to make bch2_btree_path_traverse()
 620          * get the locks we want on transaction restart.
 621          *
 622          * But if this iterator was a clone, on transaction restart what we did
 623          * to this iterator isn't going to be preserved.
 624          *
 625          * Possibly we could add an iterator field for the parent iterator when
 626          * an iterator is a copy - for now, we'll just upgrade any other
 627          * iterators with the same btree id.
 628          *
 629          * The code below used to be needed to ensure ancestor nodes get locked
 630          * before interior nodes - now that's handled by
 631          * bch2_btree_path_traverse_all().
 632          */
 633         if (!path->cached && !trans->in_traverse_all)
 634                 trans_for_each_path(trans, linked)
 635                         if (linked != path &&
 636                             linked->cached == path->cached &&
 637                             linked->btree_id == path->btree_id &&
 638                             linked->locks_want < new_locks_want) {
 639                                 linked->locks_want = new_locks_want;
 640                                 btree_path_get_locks(trans, linked, true);
 641                         }
 642
 643         return false;
 644 }
 645
 646 void __bch2_btree_path_downgrade(struct btree_trans *trans,
 647                                  struct btree_path *path,
 648                                  unsigned new_locks_want)
 649 {
 650         unsigned l;
 651
 652         EBUG_ON(path->locks_want < new_locks_want);
 653
 654         path->locks_want = new_locks_want;
 655
 656         while (path->nodes_locked &&
 657                (l = btree_path_highest_level_locked(path)) >= path->locks_want) {
 658                 if (l > path->level) {
 659                         btree_node_unlock(trans, path, l);
 660                 } else {
 661                         if (btree_node_intent_locked(path, l)) {
 662                                 six_lock_downgrade(&path->l[l].b->c.lock);
 663                                 mark_btree_node_locked_noreset(path, l, SIX_LOCK_read);
 664                         }
 665                         break;
 666                 }
 667         }
 668
 669         bch2_btree_path_verify_locks(path);
 670 }
 671
 672 /* Btree transaction locking: */
 673
 674 void bch2_trans_downgrade(struct btree_trans *trans)
 675 {
 676         struct btree_path *path;
 677
 678         trans_for_each_path(trans, path)
 679                 bch2_btree_path_downgrade(trans, path);
 680 }
 681
 682 int bch2_trans_relock(struct btree_trans *trans)
 683 {
 684         struct btree_path *path;
 685
 686         if (unlikely(trans->restarted))
 687                 return -((int) trans->restarted);
 688
 689         trans_for_each_path(trans, path)
 690                 if (path->should_be_locked &&
 691                     !bch2_btree_path_relock_norestart(trans, path, _RET_IP_)) {
 692                         trace_and_count(trans->c, trans_restart_relock, trans, _RET_IP_, path);
 693                         return btree_trans_restart(trans, BCH_ERR_transaction_restart_relock);
 694                 }
 695         return 0;
 696 }
 697
 698 int bch2_trans_relock_notrace(struct btree_trans *trans)
 699 {
 700         struct btree_path *path;
 701
 702         if (unlikely(trans->restarted))
 703                 return -((int) trans->restarted);
 704
 705         trans_for_each_path(trans, path)
 706                 if (path->should_be_locked &&
 707                     !bch2_btree_path_relock_norestart(trans, path, _RET_IP_)) {
 708                         return btree_trans_restart(trans, BCH_ERR_transaction_restart_relock);
 709                 }
 710         return 0;
 711 }
 712
 713 void bch2_trans_unlock(struct btree_trans *trans)
 714 {
 715         struct btree_path *path;
 716
 717         trans_for_each_path(trans, path)
 718                 __bch2_btree_path_unlock(trans, path);
 719
 720         /*
 721          * bch2_gc_btree_init_recurse() doesn't use btree iterators for walking
 722          * btree nodes, it implements its own walking:
 723          */
 724         if (!trans->is_initial_gc)
 725                 bch2_assert_btree_nodes_not_locked();
 726 }
 727
 728 bool bch2_trans_locked(struct btree_trans *trans)
 729 {
 730         struct btree_path *path;
 731
 732         trans_for_each_path(trans, path)
 733                 if (path->nodes_locked)
 734                         return true;
 735         return false;
 736 }
 737
 738 int __bch2_trans_mutex_lock(struct btree_trans *trans,
 739                             struct mutex *lock)
 740 {
 741         int ret;
 742
 743         bch2_trans_unlock(trans);
 744         mutex_lock(lock);
 745         ret = bch2_trans_relock(trans);
 746         if (ret)
 747                 mutex_unlock(lock);
 748         return ret;
 749 }
 750
 751 /* Debug */
 752
 753 #ifdef CONFIG_BCACHEFS_DEBUG
 754
 755 void bch2_btree_path_verify_locks(struct btree_path *path)
 756 {
 757         unsigned l;
 758
 759         if (!path->nodes_locked) {
 760                 BUG_ON(path->uptodate == BTREE_ITER_UPTODATE &&
 761                        btree_path_node(path, path->level));
 762                 return;
 763         }
 764
 765         for (l = 0; l < BTREE_MAX_DEPTH; l++) {
 766                 int want = btree_lock_want(path, l);
 767                 int have = btree_node_locked_type(path, l);
 768
 769                 BUG_ON(!is_btree_node(path, l) && have != BTREE_NODE_UNLOCKED);
 770
 771                 BUG_ON(is_btree_node(path, l) &&
 772                        (want == BTREE_NODE_UNLOCKED ||
 773                         have != BTREE_NODE_WRITE_LOCKED) &&
 774                        want != have);
 775         }
 776 }
 777
 778 void bch2_trans_verify_locks(struct btree_trans *trans)
 779 {
 780         struct btree_path *path;
 781
 782         trans_for_each_path(trans, path)
 783                 bch2_btree_path_verify_locks(path);
 784 }
 785
 786 #endif