1// SPDX-License-Identifier: GPL-2.0
2
3#include "bcachefs.h"
4#include "btree_locking.h"
5#include "btree_types.h"
6
7static struct lock_class_key bch2_btree_node_lock_key;
8
9void bch2_btree_lock_init(struct btree_bkey_cached_common *b,
10 enum six_lock_init_flags flags)
11{
12 __six_lock_init(lock: &b->lock, name: "b->c.lock", key: &bch2_btree_node_lock_key, flags);
13 lockdep_set_novalidate_class(&b->lock);
14}
15
16#ifdef CONFIG_LOCKDEP
17void bch2_assert_btree_nodes_not_locked(void)
18{
19#if 0
20 //Re-enable when lock_class_is_held() is merged:
21 BUG_ON(lock_class_is_held(&bch2_btree_node_lock_key));
22#endif
23}
24#endif
25
26/* Btree node locking: */
27
28struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *trans,
29 struct btree_path *skip,
30 struct btree_bkey_cached_common *b,
31 unsigned level)
32{
33 struct btree_path *path;
34 struct six_lock_count ret;
35 unsigned i;
36
37 memset(&ret, 0, sizeof(ret));
38
39 if (IS_ERR_OR_NULL(ptr: b))
40 return ret;
41
42 trans_for_each_path(trans, path, i)
43 if (path != skip && &path->l[level].b->c == b) {
44 int t = btree_node_locked_type(path, level);
45
46 if (t != BTREE_NODE_UNLOCKED)
47 ret.n[t]++;
48 }
49
50 return ret;
51}
52
53/* unlock */
54
55void bch2_btree_node_unlock_write(struct btree_trans *trans,
56 struct btree_path *path, struct btree *b)
57{
58 bch2_btree_node_unlock_write_inlined(trans, path, b);
59}
60
61/* lock */
62
63/*
64 * @trans wants to lock @b with type @type
65 */
66struct trans_waiting_for_lock {
67 struct btree_trans *trans;
68 struct btree_bkey_cached_common *node_want;
69 enum six_lock_type lock_want;
70
71 /* for iterating over held locks :*/
72 u8 path_idx;
73 u8 level;
74 u64 lock_start_time;
75};
76
77struct lock_graph {
78 struct trans_waiting_for_lock g[8];
79 unsigned nr;
80};
81
82static noinline void print_cycle(struct printbuf *out, struct lock_graph *g)
83{
84 struct trans_waiting_for_lock *i;
85
86 prt_printf(out, "Found lock cycle (%u entries):", g->nr);
87 prt_newline(out);
88
89 for (i = g->g; i < g->g + g->nr; i++) {
90 struct task_struct *task = READ_ONCE(i->trans->locking_wait.task);
91 if (!task)
92 continue;
93
94 bch2_btree_trans_to_text(out, i->trans);
95 bch2_prt_task_backtrace(out, task, i == g->g ? 5 : 1, GFP_NOWAIT);
96 }
97}
98
99static noinline void print_chain(struct printbuf *out, struct lock_graph *g)
100{
101 struct trans_waiting_for_lock *i;
102
103 for (i = g->g; i != g->g + g->nr; i++) {
104 struct task_struct *task = i->trans->locking_wait.task;
105 if (i != g->g)
106 prt_str(out, str: "<- ");
107 prt_printf(out, "%u ", task ?task->pid : 0);
108 }
109 prt_newline(out);
110}
111
112static void lock_graph_up(struct lock_graph *g)
113{
114 closure_put(cl: &g->g[--g->nr].trans->ref);
115}
116
117static noinline void lock_graph_pop_all(struct lock_graph *g)
118{
119 while (g->nr)
120 lock_graph_up(g);
121}
122
123static void __lock_graph_down(struct lock_graph *g, struct btree_trans *trans)
124{
125 g->g[g->nr++] = (struct trans_waiting_for_lock) {
126 .trans = trans,
127 .node_want = trans->locking,
128 .lock_want = trans->locking_wait.lock_want,
129 };
130}
131
132static void lock_graph_down(struct lock_graph *g, struct btree_trans *trans)
133{
134 closure_get(cl: &trans->ref);
135 __lock_graph_down(g, trans);
136}
137
138static bool lock_graph_remove_non_waiters(struct lock_graph *g)
139{
140 struct trans_waiting_for_lock *i;
141
142 for (i = g->g + 1; i < g->g + g->nr; i++)
143 if (i->trans->locking != i->node_want ||
144 i->trans->locking_wait.start_time != i[-1].lock_start_time) {
145 while (g->g + g->nr > i)
146 lock_graph_up(g);
147 return true;
148 }
149
150 return false;
151}
152
153static void trace_would_deadlock(struct lock_graph *g, struct btree_trans *trans)
154{
155 struct bch_fs *c = trans->c;
156
157 count_event(c, trans_restart_would_deadlock);
158
159 if (trace_trans_restart_would_deadlock_enabled()) {
160 struct printbuf buf = PRINTBUF;
161
162 buf.atomic++;
163 print_cycle(out: &buf, g);
164
165 trace_trans_restart_would_deadlock(trans, cycle: buf.buf);
166 printbuf_exit(&buf);
167 }
168}
169
170static int abort_lock(struct lock_graph *g, struct trans_waiting_for_lock *i)
171{
172 if (i == g->g) {
173 trace_would_deadlock(g, trans: i->trans);
174 return btree_trans_restart(trans: i->trans, err: BCH_ERR_transaction_restart_would_deadlock);
175 } else {
176 i->trans->lock_must_abort = true;
177 wake_up_process(tsk: i->trans->locking_wait.task);
178 return 0;
179 }
180}
181
182static int btree_trans_abort_preference(struct btree_trans *trans)
183{
184 if (trans->lock_may_not_fail)
185 return 0;
186 if (trans->locking_wait.lock_want == SIX_LOCK_write)
187 return 1;
188 if (!trans->in_traverse_all)
189 return 2;
190 return 3;
191}
192
193static noinline int break_cycle(struct lock_graph *g, struct printbuf *cycle)
194{
195 struct trans_waiting_for_lock *i, *abort = NULL;
196 unsigned best = 0, pref;
197 int ret;
198
199 if (lock_graph_remove_non_waiters(g))
200 return 0;
201
202 /* Only checking, for debugfs: */
203 if (cycle) {
204 print_cycle(out: cycle, g);
205 ret = -1;
206 goto out;
207 }
208
209 for (i = g->g; i < g->g + g->nr; i++) {
210 pref = btree_trans_abort_preference(trans: i->trans);
211 if (pref > best) {
212 abort = i;
213 best = pref;
214 }
215 }
216
217 if (unlikely(!best)) {
218 struct printbuf buf = PRINTBUF;
219
220 prt_printf(&buf, bch2_fmt(g->g->trans->c, "cycle of nofail locks"));
221
222 for (i = g->g; i < g->g + g->nr; i++) {
223 struct btree_trans *trans = i->trans;
224
225 bch2_btree_trans_to_text(&buf, trans);
226
227 prt_printf(&buf, "backtrace:");
228 prt_newline(&buf);
229 printbuf_indent_add(&buf, 2);
230 bch2_prt_task_backtrace(&buf, trans->locking_wait.task, 2, GFP_NOWAIT);
231 printbuf_indent_sub(&buf, 2);
232 prt_newline(&buf);
233 }
234
235 bch2_print_string_as_lines(KERN_ERR, lines: buf.buf);
236 printbuf_exit(&buf);
237 BUG();
238 }
239
240 ret = abort_lock(g, i: abort);
241out:
242 if (ret)
243 while (g->nr)
244 lock_graph_up(g);
245 return ret;
246}
247
248static int lock_graph_descend(struct lock_graph *g, struct btree_trans *trans,
249 struct printbuf *cycle)
250{
251 struct btree_trans *orig_trans = g->g->trans;
252 struct trans_waiting_for_lock *i;
253
254 for (i = g->g; i < g->g + g->nr; i++)
255 if (i->trans == trans) {
256 closure_put(cl: &trans->ref);
257 return break_cycle(g, cycle);
258 }
259
260 if (g->nr == ARRAY_SIZE(g->g)) {
261 closure_put(cl: &trans->ref);
262
263 if (orig_trans->lock_may_not_fail)
264 return 0;
265
266 while (g->nr)
267 lock_graph_up(g);
268
269 if (cycle)
270 return 0;
271
272 trace_and_count(trans->c, trans_restart_would_deadlock_recursion_limit, trans, _RET_IP_);
273 return btree_trans_restart(trans: orig_trans, err: BCH_ERR_transaction_restart_deadlock_recursion_limit);
274 }
275
276 __lock_graph_down(g, trans);
277 return 0;
278}
279
280static bool lock_type_conflicts(enum six_lock_type t1, enum six_lock_type t2)
281{
282 return t1 + t2 > 1;
283}
284
285int bch2_check_for_deadlock(struct btree_trans *trans, struct printbuf *cycle)
286{
287 struct lock_graph g;
288 struct trans_waiting_for_lock *top;
289 struct btree_bkey_cached_common *b;
290 btree_path_idx_t path_idx;
291 int ret = 0;
292
293 g.nr = 0;
294
295 if (trans->lock_must_abort) {
296 if (cycle)
297 return -1;
298
299 trace_would_deadlock(g: &g, trans);
300 return btree_trans_restart(trans, err: BCH_ERR_transaction_restart_would_deadlock);
301 }
302
303 lock_graph_down(g: &g, trans);
304
305 /* trans->paths is rcu protected vs. freeing */
306 rcu_read_lock();
307 if (cycle)
308 cycle->atomic++;
309next:
310 if (!g.nr)
311 goto out;
312
313 top = &g.g[g.nr - 1];
314
315 struct btree_path *paths = rcu_dereference(top->trans->paths);
316 if (!paths)
317 goto up;
318
319 unsigned long *paths_allocated = trans_paths_allocated(paths);
320
321 trans_for_each_path_idx_from(paths_allocated, *trans_paths_nr(paths),
322 path_idx, top->path_idx) {
323 struct btree_path *path = paths + path_idx;
324 if (!path->nodes_locked)
325 continue;
326
327 if (path_idx != top->path_idx) {
328 top->path_idx = path_idx;
329 top->level = 0;
330 top->lock_start_time = 0;
331 }
332
333 for (;
334 top->level < BTREE_MAX_DEPTH;
335 top->level++, top->lock_start_time = 0) {
336 int lock_held = btree_node_locked_type(path, level: top->level);
337
338 if (lock_held == BTREE_NODE_UNLOCKED)
339 continue;
340
341 b = &READ_ONCE(path->l[top->level].b)->c;
342
343 if (IS_ERR_OR_NULL(ptr: b)) {
344 /*
345 * If we get here, it means we raced with the
346 * other thread updating its btree_path
347 * structures - which means it can't be blocked
348 * waiting on a lock:
349 */
350 if (!lock_graph_remove_non_waiters(g: &g)) {
351 /*
352 * If lock_graph_remove_non_waiters()
353 * didn't do anything, it must be
354 * because we're being called by debugfs
355 * checking for lock cycles, which
356 * invokes us on btree_transactions that
357 * aren't actually waiting on anything.
358 * Just bail out:
359 */
360 lock_graph_pop_all(g: &g);
361 }
362
363 goto next;
364 }
365
366 if (list_empty_careful(head: &b->lock.wait_list))
367 continue;
368
369 raw_spin_lock(&b->lock.wait_lock);
370 list_for_each_entry(trans, &b->lock.wait_list, locking_wait.list) {
371 BUG_ON(b != trans->locking);
372
373 if (top->lock_start_time &&
374 time_after_eq64(top->lock_start_time, trans->locking_wait.start_time))
375 continue;
376
377 top->lock_start_time = trans->locking_wait.start_time;
378
379 /* Don't check for self deadlock: */
380 if (trans == top->trans ||
381 !lock_type_conflicts(t1: lock_held, t2: trans->locking_wait.lock_want))
382 continue;
383
384 closure_get(cl: &trans->ref);
385 raw_spin_unlock(&b->lock.wait_lock);
386
387 ret = lock_graph_descend(g: &g, trans, cycle);
388 if (ret)
389 goto out;
390 goto next;
391
392 }
393 raw_spin_unlock(&b->lock.wait_lock);
394 }
395 }
396up:
397 if (g.nr > 1 && cycle)
398 print_chain(out: cycle, g: &g);
399 lock_graph_up(g: &g);
400 goto next;
401out:
402 if (cycle)
403 --cycle->atomic;
404 rcu_read_unlock();
405 return ret;
406}
407
408int bch2_six_check_for_deadlock(struct six_lock *lock, void *p)
409{
410 struct btree_trans *trans = p;
411
412 return bch2_check_for_deadlock(trans, NULL);
413}
414
415int __bch2_btree_node_lock_write(struct btree_trans *trans, struct btree_path *path,
416 struct btree_bkey_cached_common *b,
417 bool lock_may_not_fail)
418{
419 int readers = bch2_btree_node_lock_counts(trans, NULL, b, level: b->level).n[SIX_LOCK_read];
420 int ret;
421
422 /*
423 * Must drop our read locks before calling six_lock_write() -
424 * six_unlock() won't do wakeups until the reader count
425 * goes to 0, and it's safe because we have the node intent
426 * locked:
427 */
428 six_lock_readers_add(&b->lock, -readers);
429 ret = __btree_node_lock_nopath(trans, b, type: SIX_LOCK_write,
430 lock_may_not_fail, _RET_IP_);
431 six_lock_readers_add(&b->lock, readers);
432
433 if (ret)
434 mark_btree_node_locked_noreset(path, level: b->level, type: BTREE_NODE_INTENT_LOCKED);
435
436 return ret;
437}
438
439void bch2_btree_node_lock_write_nofail(struct btree_trans *trans,
440 struct btree_path *path,
441 struct btree_bkey_cached_common *b)
442{
443 int ret = __btree_node_lock_write(trans, path, b, lock_may_not_fail: true);
444 BUG_ON(ret);
445}
446
447/* relock */
448
449static inline bool btree_path_get_locks(struct btree_trans *trans,
450 struct btree_path *path,
451 bool upgrade,
452 struct get_locks_fail *f)
453{
454 unsigned l = path->level;
455 int fail_idx = -1;
456
457 do {
458 if (!btree_path_node(path, level: l))
459 break;
460
461 if (!(upgrade
462 ? bch2_btree_node_upgrade(trans, path, l)
463 : bch2_btree_node_relock(trans, path, level: l))) {
464 fail_idx = l;
465
466 if (f) {
467 f->l = l;
468 f->b = path->l[l].b;
469 }
470 }
471
472 l++;
473 } while (l < path->locks_want);
474
475 /*
476 * When we fail to get a lock, we have to ensure that any child nodes
477 * can't be relocked so bch2_btree_path_traverse has to walk back up to
478 * the node that we failed to relock:
479 */
480 if (fail_idx >= 0) {
481 __bch2_btree_path_unlock(trans, path);
482 btree_path_set_dirty(path, u: BTREE_ITER_NEED_TRAVERSE);
483
484 do {
485 path->l[fail_idx].b = upgrade
486 ? ERR_PTR(error: -BCH_ERR_no_btree_node_upgrade)
487 : ERR_PTR(error: -BCH_ERR_no_btree_node_relock);
488 --fail_idx;
489 } while (fail_idx >= 0);
490 }
491
492 if (path->uptodate == BTREE_ITER_NEED_RELOCK)
493 path->uptodate = BTREE_ITER_UPTODATE;
494
495 bch2_trans_verify_locks(trans);
496
497 return path->uptodate < BTREE_ITER_NEED_RELOCK;
498}
499
500bool __bch2_btree_node_relock(struct btree_trans *trans,
501 struct btree_path *path, unsigned level,
502 bool trace)
503{
504 struct btree *b = btree_path_node(path, level);
505 int want = __btree_lock_want(path, level);
506
507 if (race_fault())
508 goto fail;
509
510 if (six_relock_type(lock: &b->c.lock, type: want, seq: path->l[level].lock_seq) ||
511 (btree_node_lock_seq_matches(path, b, level) &&
512 btree_node_lock_increment(trans, b: &b->c, level, want))) {
513 mark_btree_node_locked(trans, path, level, type: want);
514 return true;
515 }
516fail:
517 if (trace && !trans->notrace_relock_fail)
518 trace_and_count(trans->c, btree_path_relock_fail, trans, _RET_IP_, path, level);
519 return false;
520}
521
522/* upgrade */
523
524bool bch2_btree_node_upgrade(struct btree_trans *trans,
525 struct btree_path *path, unsigned level)
526{
527 struct btree *b = path->l[level].b;
528 struct six_lock_count count = bch2_btree_node_lock_counts(trans, skip: path, b: &b->c, level);
529
530 if (!is_btree_node(path, l: level))
531 return false;
532
533 switch (btree_lock_want(path, level)) {
534 case BTREE_NODE_UNLOCKED:
535 BUG_ON(btree_node_locked(path, level));
536 return true;
537 case BTREE_NODE_READ_LOCKED:
538 BUG_ON(btree_node_intent_locked(path, level));
539 return bch2_btree_node_relock(trans, path, level);
540 case BTREE_NODE_INTENT_LOCKED:
541 break;
542 case BTREE_NODE_WRITE_LOCKED:
543 BUG();
544 }
545
546 if (btree_node_intent_locked(path, l: level))
547 return true;
548
549 if (race_fault())
550 return false;
551
552 if (btree_node_locked(path, level)) {
553 bool ret;
554
555 six_lock_readers_add(&b->c.lock, -count.n[SIX_LOCK_read]);
556 ret = six_lock_tryupgrade(&b->c.lock);
557 six_lock_readers_add(&b->c.lock, count.n[SIX_LOCK_read]);
558
559 if (ret)
560 goto success;
561 } else {
562 if (six_relock_type(lock: &b->c.lock, type: SIX_LOCK_intent, seq: path->l[level].lock_seq))
563 goto success;
564 }
565
566 /*
567 * Do we already have an intent lock via another path? If so, just bump
568 * lock count:
569 */
570 if (btree_node_lock_seq_matches(path, b, level) &&
571 btree_node_lock_increment(trans, b: &b->c, level, want: BTREE_NODE_INTENT_LOCKED)) {
572 btree_node_unlock(trans, path, level);
573 goto success;
574 }
575
576 trace_and_count(trans->c, btree_path_upgrade_fail, trans, _RET_IP_, path, level);
577 return false;
578success:
579 mark_btree_node_locked_noreset(path, level, type: BTREE_NODE_INTENT_LOCKED);
580 return true;
581}
582
583/* Btree path locking: */
584
585/*
586 * Only for btree_cache.c - only relocks intent locks
587 */
588int bch2_btree_path_relock_intent(struct btree_trans *trans,
589 struct btree_path *path)
590{
591 unsigned l;
592
593 for (l = path->level;
594 l < path->locks_want && btree_path_node(path, level: l);
595 l++) {
596 if (!bch2_btree_node_relock(trans, path, level: l)) {
597 __bch2_btree_path_unlock(trans, path);
598 btree_path_set_dirty(path, u: BTREE_ITER_NEED_TRAVERSE);
599 trace_and_count(trans->c, trans_restart_relock_path_intent, trans, _RET_IP_, path);
600 return btree_trans_restart(trans, err: BCH_ERR_transaction_restart_relock_path_intent);
601 }
602 }
603
604 return 0;
605}
606
607__flatten
608bool bch2_btree_path_relock_norestart(struct btree_trans *trans, struct btree_path *path)
609{
610 struct get_locks_fail f;
611
612 return btree_path_get_locks(trans, path, upgrade: false, f: &f);
613}
614
615int __bch2_btree_path_relock(struct btree_trans *trans,
616 struct btree_path *path, unsigned long trace_ip)
617{
618 if (!bch2_btree_path_relock_norestart(trans, path)) {
619 trace_and_count(trans->c, trans_restart_relock_path, trans, trace_ip, path);
620 return btree_trans_restart(trans, err: BCH_ERR_transaction_restart_relock_path);
621 }
622
623 return 0;
624}
625
626bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *trans,
627 struct btree_path *path,
628 unsigned new_locks_want,
629 struct get_locks_fail *f)
630{
631 EBUG_ON(path->locks_want >= new_locks_want);
632
633 path->locks_want = new_locks_want;
634
635 return btree_path_get_locks(trans, path, upgrade: true, f);
636}
637
638bool __bch2_btree_path_upgrade(struct btree_trans *trans,
639 struct btree_path *path,
640 unsigned new_locks_want,
641 struct get_locks_fail *f)
642{
643 if (bch2_btree_path_upgrade_noupgrade_sibs(trans, path, new_locks_want, f))
644 return true;
645
646 /*
647 * XXX: this is ugly - we'd prefer to not be mucking with other
648 * iterators in the btree_trans here.
649 *
650 * On failure to upgrade the iterator, setting iter->locks_want and
651 * calling get_locks() is sufficient to make bch2_btree_path_traverse()
652 * get the locks we want on transaction restart.
653 *
654 * But if this iterator was a clone, on transaction restart what we did
655 * to this iterator isn't going to be preserved.
656 *
657 * Possibly we could add an iterator field for the parent iterator when
658 * an iterator is a copy - for now, we'll just upgrade any other
659 * iterators with the same btree id.
660 *
661 * The code below used to be needed to ensure ancestor nodes get locked
662 * before interior nodes - now that's handled by
663 * bch2_btree_path_traverse_all().
664 */
665 if (!path->cached && !trans->in_traverse_all) {
666 struct btree_path *linked;
667 unsigned i;
668
669 trans_for_each_path(trans, linked, i)
670 if (linked != path &&
671 linked->cached == path->cached &&
672 linked->btree_id == path->btree_id &&
673 linked->locks_want < new_locks_want) {
674 linked->locks_want = new_locks_want;
675 btree_path_get_locks(trans, path: linked, upgrade: true, NULL);
676 }
677 }
678
679 return false;
680}
681
682void __bch2_btree_path_downgrade(struct btree_trans *trans,
683 struct btree_path *path,
684 unsigned new_locks_want)
685{
686 unsigned l, old_locks_want = path->locks_want;
687
688 if (trans->restarted)
689 return;
690
691 EBUG_ON(path->locks_want < new_locks_want);
692
693 path->locks_want = new_locks_want;
694
695 while (path->nodes_locked &&
696 (l = btree_path_highest_level_locked(path)) >= path->locks_want) {
697 if (l > path->level) {
698 btree_node_unlock(trans, path, level: l);
699 } else {
700 if (btree_node_intent_locked(path, l)) {
701 six_lock_downgrade(&path->l[l].b->c.lock);
702 mark_btree_node_locked_noreset(path, level: l, type: BTREE_NODE_READ_LOCKED);
703 }
704 break;
705 }
706 }
707
708 bch2_btree_path_verify_locks(path);
709
710 trace_path_downgrade(trans, _RET_IP_, path, old_locks_want);
711}
712
713/* Btree transaction locking: */
714
715void bch2_trans_downgrade(struct btree_trans *trans)
716{
717 struct btree_path *path;
718 unsigned i;
719
720 if (trans->restarted)
721 return;
722
723 trans_for_each_path(trans, path, i)
724 if (path->ref)
725 bch2_btree_path_downgrade(trans, path);
726}
727
728int bch2_trans_relock(struct btree_trans *trans)
729{
730 struct btree_path *path;
731 unsigned i;
732
733 if (unlikely(trans->restarted))
734 return -((int) trans->restarted);
735
736 trans_for_each_path(trans, path, i) {
737 struct get_locks_fail f;
738
739 if (path->should_be_locked &&
740 !btree_path_get_locks(trans, path, upgrade: false, f: &f)) {
741 if (trace_trans_restart_relock_enabled()) {
742 struct printbuf buf = PRINTBUF;
743
744 bch2_bpos_to_text(&buf, path->pos);
745 prt_printf(&buf, " l=%u seq=%u node seq=",
746 f.l, path->l[f.l].lock_seq);
747 if (IS_ERR_OR_NULL(ptr: f.b)) {
748 prt_str(out: &buf, str: bch2_err_str(PTR_ERR(ptr: f.b)));
749 } else {
750 prt_printf(&buf, "%u", f.b->c.lock.seq);
751
752 struct six_lock_count c =
753 bch2_btree_node_lock_counts(trans, NULL, b: &f.b->c, level: f.l);
754 prt_printf(&buf, " self locked %u.%u.%u", c.n[0], c.n[1], c.n[2]);
755
756 c = six_lock_counts(&f.b->c.lock);
757 prt_printf(&buf, " total locked %u.%u.%u", c.n[0], c.n[1], c.n[2]);
758 }
759
760 trace_trans_restart_relock(trans, _RET_IP_, str: buf.buf);
761 printbuf_exit(&buf);
762 }
763
764 count_event(trans->c, trans_restart_relock);
765 return btree_trans_restart(trans, err: BCH_ERR_transaction_restart_relock);
766 }
767 }
768
769 return 0;
770}
771
772int bch2_trans_relock_notrace(struct btree_trans *trans)
773{
774 struct btree_path *path;
775 unsigned i;
776
777 if (unlikely(trans->restarted))
778 return -((int) trans->restarted);
779
780 trans_for_each_path(trans, path, i)
781 if (path->should_be_locked &&
782 !bch2_btree_path_relock_norestart(trans, path)) {
783 return btree_trans_restart(trans, err: BCH_ERR_transaction_restart_relock);
784 }
785 return 0;
786}
787
788void bch2_trans_unlock_noassert(struct btree_trans *trans)
789{
790 struct btree_path *path;
791 unsigned i;
792
793 trans_for_each_path(trans, path, i)
794 __bch2_btree_path_unlock(trans, path);
795}
796
797void bch2_trans_unlock(struct btree_trans *trans)
798{
799 struct btree_path *path;
800 unsigned i;
801
802 trans_for_each_path(trans, path, i)
803 __bch2_btree_path_unlock(trans, path);
804}
805
806void bch2_trans_unlock_long(struct btree_trans *trans)
807{
808 bch2_trans_unlock(trans);
809 bch2_trans_srcu_unlock(trans);
810}
811
812bool bch2_trans_locked(struct btree_trans *trans)
813{
814 struct btree_path *path;
815 unsigned i;
816
817 trans_for_each_path(trans, path, i)
818 if (path->nodes_locked)
819 return true;
820 return false;
821}
822
823int __bch2_trans_mutex_lock(struct btree_trans *trans,
824 struct mutex *lock)
825{
826 int ret = drop_locks_do(trans, (mutex_lock(lock), 0));
827
828 if (ret)
829 mutex_unlock(lock);
830 return ret;
831}
832
833/* Debug */
834
835#ifdef CONFIG_BCACHEFS_DEBUG
836
837void bch2_btree_path_verify_locks(struct btree_path *path)
838{
839 unsigned l;
840
841 if (!path->nodes_locked) {
842 BUG_ON(path->uptodate == BTREE_ITER_UPTODATE &&
843 btree_path_node(path, path->level));
844 return;
845 }
846
847 for (l = 0; l < BTREE_MAX_DEPTH; l++) {
848 int want = btree_lock_want(path, level: l);
849 int have = btree_node_locked_type(path, level: l);
850
851 BUG_ON(!is_btree_node(path, l) && have != BTREE_NODE_UNLOCKED);
852
853 BUG_ON(is_btree_node(path, l) &&
854 (want == BTREE_NODE_UNLOCKED ||
855 have != BTREE_NODE_WRITE_LOCKED) &&
856 want != have);
857 }
858}
859
860void bch2_trans_verify_locks(struct btree_trans *trans)
861{
862 struct btree_path *path;
863 unsigned i;
864
865 trans_for_each_path(trans, path, i)
866 bch2_btree_path_verify_locks(path);
867}
868
869#endif
870

source code of linux/fs/bcachefs/btree_locking.c