1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _BCACHEFS_BTREE_LOCKING_H
3 #define _BCACHEFS_BTREE_LOCKING_H
6 * Only for internal btree use:
8 * The btree iterator tracks what locks it wants to take, and what locks it
9 * currently has - here we have wrappers for locking/unlocking btree nodes and
10 * updating the iterator state
13 #include <linux/six.h>
15 #include "btree_iter.h"
17 void bch2_btree_lock_init(struct btree_bkey_cached_common *, enum six_lock_init_flags);
20 void bch2_assert_btree_nodes_not_locked(void);
22 static inline void bch2_assert_btree_nodes_not_locked(void) {}
25 void bch2_trans_unlock_noassert(struct btree_trans *);
27 static inline bool is_btree_node(struct btree_path *path, unsigned l)
29 return l < BTREE_MAX_DEPTH && !IS_ERR_OR_NULL(path->l[l].b);
32 static inline struct btree_transaction_stats *btree_trans_stats(struct btree_trans *trans)
34 return trans->fn_idx < ARRAY_SIZE(trans->c->btree_transaction_stats)
35 ? &trans->c->btree_transaction_stats[trans->fn_idx]
39 /* matches six lock types */
40 enum btree_node_locked_type {
41 BTREE_NODE_UNLOCKED = -1,
42 BTREE_NODE_READ_LOCKED = SIX_LOCK_read,
43 BTREE_NODE_INTENT_LOCKED = SIX_LOCK_intent,
44 BTREE_NODE_WRITE_LOCKED = SIX_LOCK_write,
47 static inline int btree_node_locked_type(struct btree_path *path,
50 return BTREE_NODE_UNLOCKED + ((path->nodes_locked >> (level << 1)) & 3);
53 static inline bool btree_node_write_locked(struct btree_path *path, unsigned l)
55 return btree_node_locked_type(path, l) == BTREE_NODE_WRITE_LOCKED;
58 static inline bool btree_node_intent_locked(struct btree_path *path, unsigned l)
60 return btree_node_locked_type(path, l) == BTREE_NODE_INTENT_LOCKED;
63 static inline bool btree_node_read_locked(struct btree_path *path, unsigned l)
65 return btree_node_locked_type(path, l) == BTREE_NODE_READ_LOCKED;
68 static inline bool btree_node_locked(struct btree_path *path, unsigned level)
70 return btree_node_locked_type(path, level) != BTREE_NODE_UNLOCKED;
73 static inline void mark_btree_node_locked_noreset(struct btree_path *path,
75 enum btree_node_locked_type type)
77 /* relying on this to avoid a branch */
78 BUILD_BUG_ON(SIX_LOCK_read != 0);
79 BUILD_BUG_ON(SIX_LOCK_intent != 1);
81 path->nodes_locked &= ~(3U << (level << 1));
82 path->nodes_locked |= (type + 1) << (level << 1);
85 static inline void mark_btree_node_unlocked(struct btree_path *path,
88 EBUG_ON(btree_node_write_locked(path, level));
89 mark_btree_node_locked_noreset(path, level, BTREE_NODE_UNLOCKED);
92 static inline void mark_btree_node_locked(struct btree_trans *trans,
93 struct btree_path *path,
95 enum six_lock_type type)
97 mark_btree_node_locked_noreset(path, level, type);
98 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
99 path->l[level].lock_taken_time = local_clock();
103 static inline enum six_lock_type __btree_lock_want(struct btree_path *path, int level)
105 return level < path->locks_want
110 static inline enum btree_node_locked_type
111 btree_lock_want(struct btree_path *path, int level)
113 if (level < path->level)
114 return BTREE_NODE_UNLOCKED;
115 if (level < path->locks_want)
116 return BTREE_NODE_INTENT_LOCKED;
117 if (level == path->level)
118 return BTREE_NODE_READ_LOCKED;
119 return BTREE_NODE_UNLOCKED;
122 static void btree_trans_lock_hold_time_update(struct btree_trans *trans,
123 struct btree_path *path, unsigned level)
125 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
126 struct btree_transaction_stats *s = btree_trans_stats(trans);
129 __bch2_time_stats_update(&s->lock_hold_times,
130 path->l[level].lock_taken_time,
137 static inline void btree_node_unlock(struct btree_trans *trans,
138 struct btree_path *path, unsigned level)
140 int lock_type = btree_node_locked_type(path, level);
142 EBUG_ON(level >= BTREE_MAX_DEPTH);
144 if (lock_type != BTREE_NODE_UNLOCKED) {
145 six_unlock_type(&path->l[level].b->c.lock, lock_type);
146 btree_trans_lock_hold_time_update(trans, path, level);
148 mark_btree_node_unlocked(path, level);
151 static inline int btree_path_lowest_level_locked(struct btree_path *path)
153 return __ffs(path->nodes_locked) >> 1;
156 static inline int btree_path_highest_level_locked(struct btree_path *path)
158 return __fls(path->nodes_locked) >> 1;
161 static inline void __bch2_btree_path_unlock(struct btree_trans *trans,
162 struct btree_path *path)
164 btree_path_set_dirty(path, BTREE_ITER_NEED_RELOCK);
166 while (path->nodes_locked)
167 btree_node_unlock(trans, path, btree_path_lowest_level_locked(path));
171 * Updates the saved lock sequence number, so that bch2_btree_node_relock() will
175 bch2_btree_node_unlock_write_inlined(struct btree_trans *trans, struct btree_path *path,
178 struct btree_path *linked;
180 EBUG_ON(path->l[b->c.level].b != b);
181 EBUG_ON(path->l[b->c.level].lock_seq != six_lock_seq(&b->c.lock));
182 EBUG_ON(btree_node_locked_type(path, b->c.level) != SIX_LOCK_write);
184 mark_btree_node_locked_noreset(path, b->c.level, SIX_LOCK_intent);
186 trans_for_each_path_with_node(trans, b, linked)
187 linked->l[b->c.level].lock_seq++;
189 six_unlock_write(&b->c.lock);
192 void bch2_btree_node_unlock_write(struct btree_trans *,
193 struct btree_path *, struct btree *);
195 int bch2_six_check_for_deadlock(struct six_lock *lock, void *p);
199 static inline int __btree_node_lock_nopath(struct btree_trans *trans,
200 struct btree_bkey_cached_common *b,
201 enum six_lock_type type,
202 bool lock_may_not_fail,
207 trans->lock_may_not_fail = lock_may_not_fail;
208 trans->lock_must_abort = false;
211 ret = six_lock_ip_waiter(&b->lock, type, &trans->locking_wait,
212 bch2_six_check_for_deadlock, trans, ip);
213 WRITE_ONCE(trans->locking, NULL);
214 WRITE_ONCE(trans->locking_wait.start_time, 0);
218 static inline int __must_check
219 btree_node_lock_nopath(struct btree_trans *trans,
220 struct btree_bkey_cached_common *b,
221 enum six_lock_type type,
224 return __btree_node_lock_nopath(trans, b, type, false, ip);
227 static inline void btree_node_lock_nopath_nofail(struct btree_trans *trans,
228 struct btree_bkey_cached_common *b,
229 enum six_lock_type type)
231 int ret = __btree_node_lock_nopath(trans, b, type, true, _THIS_IP_);
237 * Lock a btree node if we already have it locked on one of our linked
240 static inline bool btree_node_lock_increment(struct btree_trans *trans,
241 struct btree_bkey_cached_common *b,
243 enum btree_node_locked_type want)
245 struct btree_path *path;
247 trans_for_each_path(trans, path)
248 if (&path->l[level].b->c == b &&
249 btree_node_locked_type(path, level) >= want) {
250 six_lock_increment(&b->lock, want);
257 static inline int btree_node_lock(struct btree_trans *trans,
258 struct btree_path *path,
259 struct btree_bkey_cached_common *b,
261 enum six_lock_type type,
266 EBUG_ON(level >= BTREE_MAX_DEPTH);
267 EBUG_ON(!(trans->paths_allocated & (1ULL << path->idx)));
269 if (likely(six_trylock_type(&b->lock, type)) ||
270 btree_node_lock_increment(trans, b, level, type) ||
271 !(ret = btree_node_lock_nopath(trans, b, type, btree_path_ip_allocated(path)))) {
272 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
273 path->l[b->level].lock_taken_time = local_clock();
280 int __bch2_btree_node_lock_write(struct btree_trans *, struct btree_path *,
281 struct btree_bkey_cached_common *b, bool);
283 static inline int __btree_node_lock_write(struct btree_trans *trans,
284 struct btree_path *path,
285 struct btree_bkey_cached_common *b,
286 bool lock_may_not_fail)
288 EBUG_ON(&path->l[b->level].b->c != b);
289 EBUG_ON(path->l[b->level].lock_seq != six_lock_seq(&b->lock));
290 EBUG_ON(!btree_node_intent_locked(path, b->level));
293 * six locks are unfair, and read locks block while a thread wants a
294 * write lock: thus, we need to tell the cycle detector we have a write
295 * lock _before_ taking the lock:
297 mark_btree_node_locked_noreset(path, b->level, SIX_LOCK_write);
299 return likely(six_trylock_write(&b->lock))
301 : __bch2_btree_node_lock_write(trans, path, b, lock_may_not_fail);
304 static inline int __must_check
305 bch2_btree_node_lock_write(struct btree_trans *trans,
306 struct btree_path *path,
307 struct btree_bkey_cached_common *b)
309 return __btree_node_lock_write(trans, path, b, false);
312 void bch2_btree_node_lock_write_nofail(struct btree_trans *,
314 struct btree_bkey_cached_common *);
318 bool bch2_btree_path_relock_norestart(struct btree_trans *,
319 struct btree_path *, unsigned long);
320 int __bch2_btree_path_relock(struct btree_trans *,
321 struct btree_path *, unsigned long);
323 static inline int bch2_btree_path_relock(struct btree_trans *trans,
324 struct btree_path *path, unsigned long trace_ip)
326 return btree_node_locked(path, path->level)
328 : __bch2_btree_path_relock(trans, path, trace_ip);
331 bool __bch2_btree_node_relock(struct btree_trans *, struct btree_path *, unsigned, bool trace);
333 static inline bool bch2_btree_node_relock(struct btree_trans *trans,
334 struct btree_path *path, unsigned level)
336 EBUG_ON(btree_node_locked(path, level) &&
337 !btree_node_write_locked(path, level) &&
338 btree_node_locked_type(path, level) != __btree_lock_want(path, level));
340 return likely(btree_node_locked(path, level)) ||
341 (!IS_ERR_OR_NULL(path->l[level].b) &&
342 __bch2_btree_node_relock(trans, path, level, true));
345 static inline bool bch2_btree_node_relock_notrace(struct btree_trans *trans,
346 struct btree_path *path, unsigned level)
348 EBUG_ON(btree_node_locked(path, level) &&
349 !btree_node_write_locked(path, level) &&
350 btree_node_locked_type(path, level) != __btree_lock_want(path, level));
352 return likely(btree_node_locked(path, level)) ||
353 (!IS_ERR_OR_NULL(path->l[level].b) &&
354 __bch2_btree_node_relock(trans, path, level, false));
359 bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *,
360 struct btree_path *, unsigned);
361 bool __bch2_btree_path_upgrade(struct btree_trans *,
362 struct btree_path *, unsigned);
364 static inline int bch2_btree_path_upgrade(struct btree_trans *trans,
365 struct btree_path *path,
366 unsigned new_locks_want)
368 unsigned old_locks_want = path->locks_want;
370 new_locks_want = min(new_locks_want, BTREE_MAX_DEPTH);
372 if (path->locks_want < new_locks_want
373 ? __bch2_btree_path_upgrade(trans, path, new_locks_want)
374 : path->uptodate == BTREE_ITER_UPTODATE)
377 trace_and_count(trans->c, trans_restart_upgrade, trans, _THIS_IP_, path,
378 old_locks_want, new_locks_want);
379 return btree_trans_restart(trans, BCH_ERR_transaction_restart_upgrade);
384 static inline void btree_path_set_should_be_locked(struct btree_path *path)
386 EBUG_ON(!btree_node_locked(path, path->level));
387 EBUG_ON(path->uptodate);
389 path->should_be_locked = true;
392 static inline void __btree_path_set_level_up(struct btree_trans *trans,
393 struct btree_path *path,
396 btree_node_unlock(trans, path, l);
397 path->l[l].b = ERR_PTR(-BCH_ERR_no_btree_node_up);
400 static inline void btree_path_set_level_up(struct btree_trans *trans,
401 struct btree_path *path)
403 __btree_path_set_level_up(trans, path, path->level++);
404 btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE);
409 struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *,
411 struct btree_bkey_cached_common *b,
414 int bch2_check_for_deadlock(struct btree_trans *, struct printbuf *);
416 #ifdef CONFIG_BCACHEFS_DEBUG
417 void bch2_btree_path_verify_locks(struct btree_path *);
418 void bch2_trans_verify_locks(struct btree_trans *);
420 static inline void bch2_btree_path_verify_locks(struct btree_path *path) {}
421 static inline void bch2_trans_verify_locks(struct btree_trans *trans) {}
424 #endif /* _BCACHEFS_BTREE_LOCKING_H */