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 /* matches six lock types */
18 enum btree_node_locked_type {
19 BTREE_NODE_UNLOCKED = -1,
20 BTREE_NODE_READ_LOCKED = SIX_LOCK_read,
21 BTREE_NODE_INTENT_LOCKED = SIX_LOCK_intent,
24 static inline int btree_node_locked_type(struct btree_iter *iter,
28 * We're relying on the fact that if nodes_intent_locked is set
29 * nodes_locked must be set as well, so that we can compute without
32 return BTREE_NODE_UNLOCKED +
33 ((iter->nodes_locked >> level) & 1) +
34 ((iter->nodes_intent_locked >> level) & 1);
37 static inline bool btree_node_intent_locked(struct btree_iter *iter,
40 return btree_node_locked_type(iter, level) == BTREE_NODE_INTENT_LOCKED;
43 static inline bool btree_node_read_locked(struct btree_iter *iter,
46 return btree_node_locked_type(iter, level) == BTREE_NODE_READ_LOCKED;
49 static inline bool btree_node_locked(struct btree_iter *iter, unsigned level)
51 return iter->nodes_locked & (1 << level);
54 static inline void mark_btree_node_unlocked(struct btree_iter *iter,
57 iter->nodes_locked &= ~(1 << level);
58 iter->nodes_intent_locked &= ~(1 << level);
61 static inline void mark_btree_node_locked(struct btree_iter *iter,
63 enum six_lock_type type)
65 /* relying on this to avoid a branch */
66 BUILD_BUG_ON(SIX_LOCK_read != 0);
67 BUILD_BUG_ON(SIX_LOCK_intent != 1);
69 iter->nodes_locked |= 1 << level;
70 iter->nodes_intent_locked |= type << level;
73 static inline void mark_btree_node_intent_locked(struct btree_iter *iter,
76 mark_btree_node_locked(iter, level, SIX_LOCK_intent);
79 static inline enum six_lock_type __btree_lock_want(struct btree_iter *iter, int level)
81 return level < iter->locks_want
86 static inline enum btree_node_locked_type
87 btree_lock_want(struct btree_iter *iter, int level)
89 if (level < iter->level)
90 return BTREE_NODE_UNLOCKED;
91 if (level < iter->locks_want)
92 return BTREE_NODE_INTENT_LOCKED;
93 if (level == iter->level)
94 return BTREE_NODE_READ_LOCKED;
95 return BTREE_NODE_UNLOCKED;
98 static inline void __btree_node_unlock(struct btree_iter *iter, unsigned level)
100 int lock_type = btree_node_locked_type(iter, level);
102 EBUG_ON(level >= BTREE_MAX_DEPTH);
104 if (lock_type != BTREE_NODE_UNLOCKED)
105 six_unlock_type(&iter->l[level].b->lock, lock_type);
106 mark_btree_node_unlocked(iter, level);
109 static inline void btree_node_unlock(struct btree_iter *iter, unsigned level)
111 EBUG_ON(!level && iter->trans->nounlock);
113 __btree_node_unlock(iter, level);
116 static inline void __bch2_btree_iter_unlock(struct btree_iter *iter)
118 btree_iter_set_dirty(iter, BTREE_ITER_NEED_RELOCK);
120 while (iter->nodes_locked)
121 btree_node_unlock(iter, __ffs(iter->nodes_locked));
124 static inline enum bch_time_stats lock_to_time_stat(enum six_lock_type type)
128 return BCH_TIME_btree_lock_contended_read;
129 case SIX_LOCK_intent:
130 return BCH_TIME_btree_lock_contended_intent;
132 return BCH_TIME_btree_lock_contended_write;
139 * wrapper around six locks that just traces lock contended time
141 static inline void __btree_node_lock_type(struct bch_fs *c, struct btree *b,
142 enum six_lock_type type)
144 u64 start_time = local_clock();
146 six_lock_type(&b->lock, type);
147 bch2_time_stats_update(&c->times[lock_to_time_stat(type)], start_time);
150 static inline void btree_node_lock_type(struct bch_fs *c, struct btree *b,
151 enum six_lock_type type)
153 if (!six_trylock_type(&b->lock, type))
154 __btree_node_lock_type(c, b, type);
158 * Lock a btree node if we already have it locked on one of our linked
161 static inline bool btree_node_lock_increment(struct btree_iter *iter,
162 struct btree *b, unsigned level,
163 enum btree_node_locked_type want)
165 struct btree_iter *linked;
167 trans_for_each_iter(iter->trans, linked)
168 if (linked != iter &&
169 linked->l[level].b == b &&
170 btree_node_locked_type(linked, level) >= want) {
171 six_lock_increment(&b->lock, want);
178 bool __bch2_btree_node_lock(struct btree *, struct bpos, unsigned,
179 struct btree_iter *, enum six_lock_type);
181 static inline bool btree_node_lock(struct btree *b, struct bpos pos,
183 struct btree_iter *iter,
184 enum six_lock_type type)
186 EBUG_ON(level >= BTREE_MAX_DEPTH);
188 return likely(six_trylock_type(&b->lock, type)) ||
189 btree_node_lock_increment(iter, b, level, type) ||
190 __bch2_btree_node_lock(b, pos, level, iter, type);
193 bool __bch2_btree_node_relock(struct btree_iter *, unsigned);
195 static inline bool bch2_btree_node_relock(struct btree_iter *iter,
198 EBUG_ON(btree_node_locked(iter, level) &&
199 btree_node_locked_type(iter, level) !=
200 __btree_lock_want(iter, level));
202 return likely(btree_node_locked(iter, level)) ||
203 __bch2_btree_node_relock(iter, level);
207 * Updates the saved lock sequence number, so that bch2_btree_node_relock() will
211 bch2_btree_node_unlock_write_inlined(struct btree *b, struct btree_iter *iter)
213 struct btree_iter *linked;
215 EBUG_ON(iter->l[b->level].b != b);
216 EBUG_ON(iter->l[b->level].lock_seq + 1 != b->lock.state.seq);
218 trans_for_each_iter_with_node(iter->trans, b, linked)
219 linked->l[b->level].lock_seq += 2;
221 six_unlock_write(&b->lock);
224 void bch2_btree_node_unlock_write(struct btree *, struct btree_iter *);
226 void __bch2_btree_node_lock_write(struct btree *, struct btree_iter *);
228 static inline void bch2_btree_node_lock_write(struct btree *b, struct btree_iter *iter)
230 EBUG_ON(iter->l[b->level].b != b);
231 EBUG_ON(iter->l[b->level].lock_seq != b->lock.state.seq);
233 if (unlikely(!six_trylock_write(&b->lock)))
234 __bch2_btree_node_lock_write(b, iter);
237 #endif /* _BCACHEFS_BTREE_LOCKING_H */