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 "btree_iter.h"
16 void bch2_btree_lock_init(struct btree_bkey_cached_common *, enum six_lock_init_flags);
19 void bch2_assert_btree_nodes_not_locked(void);
21 static inline void bch2_assert_btree_nodes_not_locked(void) {}
24 void bch2_trans_unlock_noassert(struct btree_trans *);
26 static inline bool is_btree_node(struct btree_path *path, unsigned l)
28 return l < BTREE_MAX_DEPTH && !IS_ERR_OR_NULL(path->l[l].b);
31 static inline struct btree_transaction_stats *btree_trans_stats(struct btree_trans *trans)
33 return trans->fn_idx < ARRAY_SIZE(trans->c->btree_transaction_stats)
34 ? &trans->c->btree_transaction_stats[trans->fn_idx]
38 /* matches six lock types */
39 enum btree_node_locked_type {
40 BTREE_NODE_UNLOCKED = -1,
41 BTREE_NODE_READ_LOCKED = SIX_LOCK_read,
42 BTREE_NODE_INTENT_LOCKED = SIX_LOCK_intent,
43 BTREE_NODE_WRITE_LOCKED = SIX_LOCK_write,
46 static inline int btree_node_locked_type(struct btree_path *path,
49 return BTREE_NODE_UNLOCKED + ((path->nodes_locked >> (level << 1)) & 3);
52 static inline bool btree_node_write_locked(struct btree_path *path, unsigned l)
54 return btree_node_locked_type(path, l) == BTREE_NODE_WRITE_LOCKED;
57 static inline bool btree_node_intent_locked(struct btree_path *path, unsigned l)
59 return btree_node_locked_type(path, l) == BTREE_NODE_INTENT_LOCKED;
62 static inline bool btree_node_read_locked(struct btree_path *path, unsigned l)
64 return btree_node_locked_type(path, l) == BTREE_NODE_READ_LOCKED;
67 static inline bool btree_node_locked(struct btree_path *path, unsigned level)
69 return btree_node_locked_type(path, level) != BTREE_NODE_UNLOCKED;
72 static inline void mark_btree_node_locked_noreset(struct btree_path *path,
74 enum btree_node_locked_type type)
76 /* relying on this to avoid a branch */
77 BUILD_BUG_ON(SIX_LOCK_read != 0);
78 BUILD_BUG_ON(SIX_LOCK_intent != 1);
80 path->nodes_locked &= ~(3U << (level << 1));
81 path->nodes_locked |= (type + 1) << (level << 1);
84 static inline void mark_btree_node_unlocked(struct btree_path *path,
87 EBUG_ON(btree_node_write_locked(path, level));
88 mark_btree_node_locked_noreset(path, level, BTREE_NODE_UNLOCKED);
91 static inline void mark_btree_node_locked(struct btree_trans *trans,
92 struct btree_path *path,
94 enum btree_node_locked_type type)
96 mark_btree_node_locked_noreset(path, level, (enum btree_node_locked_type) type);
97 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
98 path->l[level].lock_taken_time = local_clock();
102 static inline enum six_lock_type __btree_lock_want(struct btree_path *path, int level)
104 return level < path->locks_want
109 static inline enum btree_node_locked_type
110 btree_lock_want(struct btree_path *path, int level)
112 if (level < path->level)
113 return BTREE_NODE_UNLOCKED;
114 if (level < path->locks_want)
115 return BTREE_NODE_INTENT_LOCKED;
116 if (level == path->level)
117 return BTREE_NODE_READ_LOCKED;
118 return BTREE_NODE_UNLOCKED;
121 static void btree_trans_lock_hold_time_update(struct btree_trans *trans,
122 struct btree_path *path, unsigned level)
124 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
125 __bch2_time_stats_update(&btree_trans_stats(trans)->lock_hold_times,
126 path->l[level].lock_taken_time,
133 static inline void btree_node_unlock(struct btree_trans *trans,
134 struct btree_path *path, unsigned level)
136 int lock_type = btree_node_locked_type(path, level);
138 EBUG_ON(level >= BTREE_MAX_DEPTH);
140 if (lock_type != BTREE_NODE_UNLOCKED) {
141 six_unlock_type(&path->l[level].b->c.lock, lock_type);
142 btree_trans_lock_hold_time_update(trans, path, level);
144 mark_btree_node_unlocked(path, level);
147 static inline int btree_path_lowest_level_locked(struct btree_path *path)
149 return __ffs(path->nodes_locked) >> 1;
152 static inline int btree_path_highest_level_locked(struct btree_path *path)
154 return __fls(path->nodes_locked) >> 1;
157 static inline void __bch2_btree_path_unlock(struct btree_trans *trans,
158 struct btree_path *path)
160 btree_path_set_dirty(path, BTREE_ITER_NEED_RELOCK);
162 while (path->nodes_locked)
163 btree_node_unlock(trans, path, btree_path_lowest_level_locked(path));
167 * Updates the saved lock sequence number, so that bch2_btree_node_relock() will
171 bch2_btree_node_unlock_write_inlined(struct btree_trans *trans, struct btree_path *path,
174 struct btree_path *linked;
177 EBUG_ON(path->l[b->c.level].b != b);
178 EBUG_ON(path->l[b->c.level].lock_seq != six_lock_seq(&b->c.lock));
179 EBUG_ON(btree_node_locked_type(path, b->c.level) != SIX_LOCK_write);
181 mark_btree_node_locked_noreset(path, b->c.level, BTREE_NODE_INTENT_LOCKED);
183 trans_for_each_path_with_node(trans, b, linked, i)
184 linked->l[b->c.level].lock_seq++;
186 six_unlock_write(&b->c.lock);
189 void bch2_btree_node_unlock_write(struct btree_trans *,
190 struct btree_path *, struct btree *);
192 int bch2_six_check_for_deadlock(struct six_lock *lock, void *p);
196 static inline int __btree_node_lock_nopath(struct btree_trans *trans,
197 struct btree_bkey_cached_common *b,
198 enum six_lock_type type,
199 bool lock_may_not_fail,
204 trans->lock_may_not_fail = lock_may_not_fail;
205 trans->lock_must_abort = false;
208 ret = six_lock_ip_waiter(&b->lock, type, &trans->locking_wait,
209 bch2_six_check_for_deadlock, trans, ip);
210 WRITE_ONCE(trans->locking, NULL);
211 WRITE_ONCE(trans->locking_wait.start_time, 0);
215 static inline int __must_check
216 btree_node_lock_nopath(struct btree_trans *trans,
217 struct btree_bkey_cached_common *b,
218 enum six_lock_type type,
221 return __btree_node_lock_nopath(trans, b, type, false, ip);
224 static inline void btree_node_lock_nopath_nofail(struct btree_trans *trans,
225 struct btree_bkey_cached_common *b,
226 enum six_lock_type type)
228 int ret = __btree_node_lock_nopath(trans, b, type, true, _THIS_IP_);
234 * Lock a btree node if we already have it locked on one of our linked
237 static inline bool btree_node_lock_increment(struct btree_trans *trans,
238 struct btree_bkey_cached_common *b,
240 enum btree_node_locked_type want)
242 struct btree_path *path;
245 trans_for_each_path(trans, path, i)
246 if (&path->l[level].b->c == b &&
247 btree_node_locked_type(path, level) >= want) {
248 six_lock_increment(&b->lock, (enum six_lock_type) want);
255 static inline int btree_node_lock(struct btree_trans *trans,
256 struct btree_path *path,
257 struct btree_bkey_cached_common *b,
259 enum six_lock_type type,
264 EBUG_ON(level >= BTREE_MAX_DEPTH);
266 if (likely(six_trylock_type(&b->lock, type)) ||
267 btree_node_lock_increment(trans, b, level, (enum btree_node_locked_type) type) ||
268 !(ret = btree_node_lock_nopath(trans, b, type, btree_path_ip_allocated(path)))) {
269 #ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
270 path->l[b->level].lock_taken_time = local_clock();
277 int __bch2_btree_node_lock_write(struct btree_trans *, struct btree_path *,
278 struct btree_bkey_cached_common *b, bool);
280 static inline int __btree_node_lock_write(struct btree_trans *trans,
281 struct btree_path *path,
282 struct btree_bkey_cached_common *b,
283 bool lock_may_not_fail)
285 EBUG_ON(&path->l[b->level].b->c != b);
286 EBUG_ON(path->l[b->level].lock_seq != six_lock_seq(&b->lock));
287 EBUG_ON(!btree_node_intent_locked(path, b->level));
290 * six locks are unfair, and read locks block while a thread wants a
291 * write lock: thus, we need to tell the cycle detector we have a write
292 * lock _before_ taking the lock:
294 mark_btree_node_locked_noreset(path, b->level, BTREE_NODE_WRITE_LOCKED);
296 return likely(six_trylock_write(&b->lock))
298 : __bch2_btree_node_lock_write(trans, path, b, lock_may_not_fail);
301 static inline int __must_check
302 bch2_btree_node_lock_write(struct btree_trans *trans,
303 struct btree_path *path,
304 struct btree_bkey_cached_common *b)
306 return __btree_node_lock_write(trans, path, b, false);
309 void bch2_btree_node_lock_write_nofail(struct btree_trans *,
311 struct btree_bkey_cached_common *);
315 bool bch2_btree_path_relock_norestart(struct btree_trans *, struct btree_path *);
316 int __bch2_btree_path_relock(struct btree_trans *,
317 struct btree_path *, unsigned long);
319 static inline int bch2_btree_path_relock(struct btree_trans *trans,
320 struct btree_path *path, unsigned long trace_ip)
322 return btree_node_locked(path, path->level)
324 : __bch2_btree_path_relock(trans, path, trace_ip);
327 bool __bch2_btree_node_relock(struct btree_trans *, struct btree_path *, unsigned, bool trace);
329 static inline bool bch2_btree_node_relock(struct btree_trans *trans,
330 struct btree_path *path, unsigned level)
332 EBUG_ON(btree_node_locked(path, level) &&
333 !btree_node_write_locked(path, level) &&
334 btree_node_locked_type(path, level) != __btree_lock_want(path, level));
336 return likely(btree_node_locked(path, level)) ||
337 (!IS_ERR_OR_NULL(path->l[level].b) &&
338 __bch2_btree_node_relock(trans, path, level, true));
341 static inline bool bch2_btree_node_relock_notrace(struct btree_trans *trans,
342 struct btree_path *path, unsigned level)
344 EBUG_ON(btree_node_locked(path, level) &&
345 !btree_node_write_locked(path, level) &&
346 btree_node_locked_type(path, level) != __btree_lock_want(path, level));
348 return likely(btree_node_locked(path, level)) ||
349 (!IS_ERR_OR_NULL(path->l[level].b) &&
350 __bch2_btree_node_relock(trans, path, level, false));
355 bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *,
356 struct btree_path *, unsigned,
357 struct get_locks_fail *);
359 bool __bch2_btree_path_upgrade(struct btree_trans *,
360 struct btree_path *, unsigned,
361 struct get_locks_fail *);
363 static inline int bch2_btree_path_upgrade(struct btree_trans *trans,
364 struct btree_path *path,
365 unsigned new_locks_want)
367 struct get_locks_fail f;
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, &f)
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, &f);
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 */