X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libbcachefs%2Fbtree_locking.h;h=f3e58aa2774d7d91c1537af99e3ffda83fb43c38;hb=73bf371f4c2b7b5323cef9b6813fc813ac9d385b;hp=0945ea89bca043488f5e7fbffed218d8935dd986;hpb=64c325ef483c863c720a7f53c6b3126e583e05a0;p=bcachefs-tools-debian diff --git a/libbcachefs/btree_locking.h b/libbcachefs/btree_locking.h index 0945ea8..f3e58aa 100644 --- a/libbcachefs/btree_locking.h +++ b/libbcachefs/btree_locking.h @@ -1,5 +1,6 @@ -#ifndef _BCACHE_BTREE_LOCKING_H -#define _BCACHE_BTREE_LOCKING_H +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _BCACHEFS_BTREE_LOCKING_H +#define _BCACHEFS_BTREE_LOCKING_H /* * Only for internal btree use: @@ -9,107 +10,415 @@ * updating the iterator state */ +#include + #include "btree_iter.h" -#include "six.h" + +void bch2_btree_lock_init(struct btree_bkey_cached_common *, enum six_lock_init_flags); + +#ifdef CONFIG_LOCKDEP +void bch2_assert_btree_nodes_not_locked(void); +#else +static inline void bch2_assert_btree_nodes_not_locked(void) {} +#endif + +void bch2_trans_unlock_noassert(struct btree_trans *); + +static inline bool is_btree_node(struct btree_path *path, unsigned l) +{ + return l < BTREE_MAX_DEPTH && !IS_ERR_OR_NULL(path->l[l].b); +} + +static inline struct btree_transaction_stats *btree_trans_stats(struct btree_trans *trans) +{ + return trans->fn_idx < ARRAY_SIZE(trans->c->btree_transaction_stats) + ? &trans->c->btree_transaction_stats[trans->fn_idx] + : NULL; +} /* matches six lock types */ enum btree_node_locked_type { BTREE_NODE_UNLOCKED = -1, BTREE_NODE_READ_LOCKED = SIX_LOCK_read, BTREE_NODE_INTENT_LOCKED = SIX_LOCK_intent, + BTREE_NODE_WRITE_LOCKED = SIX_LOCK_write, }; -static inline int btree_node_locked_type(struct btree_iter *iter, +static inline int btree_node_locked_type(struct btree_path *path, unsigned level) { - /* - * We're relying on the fact that if nodes_intent_locked is set - * nodes_locked must be set as well, so that we can compute without - * branches: - */ - return BTREE_NODE_UNLOCKED + - ((iter->nodes_locked >> level) & 1) + - ((iter->nodes_intent_locked >> level) & 1); + return BTREE_NODE_UNLOCKED + ((path->nodes_locked >> (level << 1)) & 3); } -static inline bool btree_node_intent_locked(struct btree_iter *iter, - unsigned level) +static inline bool btree_node_write_locked(struct btree_path *path, unsigned l) { - return btree_node_locked_type(iter, level) == BTREE_NODE_INTENT_LOCKED; + return btree_node_locked_type(path, l) == BTREE_NODE_WRITE_LOCKED; } -static inline bool btree_node_read_locked(struct btree_iter *iter, - unsigned level) +static inline bool btree_node_intent_locked(struct btree_path *path, unsigned l) { - return btree_node_locked_type(iter, level) == BTREE_NODE_READ_LOCKED; + return btree_node_locked_type(path, l) == BTREE_NODE_INTENT_LOCKED; } -static inline bool btree_node_locked(struct btree_iter *iter, unsigned level) +static inline bool btree_node_read_locked(struct btree_path *path, unsigned l) { - return iter->nodes_locked & (1 << level); + return btree_node_locked_type(path, l) == BTREE_NODE_READ_LOCKED; } -static inline void mark_btree_node_unlocked(struct btree_iter *iter, - unsigned level) +static inline bool btree_node_locked(struct btree_path *path, unsigned level) { - iter->nodes_locked &= ~(1 << level); - iter->nodes_intent_locked &= ~(1 << level); + return btree_node_locked_type(path, level) != BTREE_NODE_UNLOCKED; } -static inline void mark_btree_node_locked(struct btree_iter *iter, - unsigned level, - enum six_lock_type type) +static inline void mark_btree_node_locked_noreset(struct btree_path *path, + unsigned level, + enum btree_node_locked_type type) { /* relying on this to avoid a branch */ BUILD_BUG_ON(SIX_LOCK_read != 0); BUILD_BUG_ON(SIX_LOCK_intent != 1); - iter->nodes_locked |= 1 << level; - iter->nodes_intent_locked |= type << level; + path->nodes_locked &= ~(3U << (level << 1)); + path->nodes_locked |= (type + 1) << (level << 1); +} + +static inline void mark_btree_node_unlocked(struct btree_path *path, + unsigned level) +{ + EBUG_ON(btree_node_write_locked(path, level)); + mark_btree_node_locked_noreset(path, level, BTREE_NODE_UNLOCKED); } -static inline void mark_btree_node_intent_locked(struct btree_iter *iter, - unsigned level) +static inline void mark_btree_node_locked(struct btree_trans *trans, + struct btree_path *path, + unsigned level, + enum six_lock_type type) { - mark_btree_node_locked(iter, level, SIX_LOCK_intent); + mark_btree_node_locked_noreset(path, level, (enum btree_node_locked_type) type); +#ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS + path->l[level].lock_taken_time = local_clock(); +#endif } -static inline int btree_lock_want(struct btree_iter *iter, int level) +static inline enum six_lock_type __btree_lock_want(struct btree_path *path, int level) { - return level < iter->locks_want + return level < path->locks_want ? SIX_LOCK_intent : SIX_LOCK_read; } -static inline bool btree_want_intent(struct btree_iter *iter, int level) +static inline enum btree_node_locked_type +btree_lock_want(struct btree_path *path, int level) +{ + if (level < path->level) + return BTREE_NODE_UNLOCKED; + if (level < path->locks_want) + return BTREE_NODE_INTENT_LOCKED; + if (level == path->level) + return BTREE_NODE_READ_LOCKED; + return BTREE_NODE_UNLOCKED; +} + +static void btree_trans_lock_hold_time_update(struct btree_trans *trans, + struct btree_path *path, unsigned level) +{ +#ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS + struct btree_transaction_stats *s = btree_trans_stats(trans); + + if (s) + __bch2_time_stats_update(&s->lock_hold_times, + path->l[level].lock_taken_time, + local_clock()); +#endif +} + +/* unlock: */ + +static inline void btree_node_unlock(struct btree_trans *trans, + struct btree_path *path, unsigned level) +{ + int lock_type = btree_node_locked_type(path, level); + + EBUG_ON(level >= BTREE_MAX_DEPTH); + + if (lock_type != BTREE_NODE_UNLOCKED) { + six_unlock_type(&path->l[level].b->c.lock, lock_type); + btree_trans_lock_hold_time_update(trans, path, level); + } + mark_btree_node_unlocked(path, level); +} + +static inline int btree_path_lowest_level_locked(struct btree_path *path) +{ + return __ffs(path->nodes_locked) >> 1; +} + +static inline int btree_path_highest_level_locked(struct btree_path *path) +{ + return __fls(path->nodes_locked) >> 1; +} + +static inline void __bch2_btree_path_unlock(struct btree_trans *trans, + struct btree_path *path) +{ + btree_path_set_dirty(path, BTREE_ITER_NEED_RELOCK); + + while (path->nodes_locked) + btree_node_unlock(trans, path, btree_path_lowest_level_locked(path)); +} + +/* + * Updates the saved lock sequence number, so that bch2_btree_node_relock() will + * succeed: + */ +static inline void +bch2_btree_node_unlock_write_inlined(struct btree_trans *trans, struct btree_path *path, + struct btree *b) +{ + struct btree_path *linked; + + EBUG_ON(path->l[b->c.level].b != b); + EBUG_ON(path->l[b->c.level].lock_seq != six_lock_seq(&b->c.lock)); + EBUG_ON(btree_node_locked_type(path, b->c.level) != SIX_LOCK_write); + + mark_btree_node_locked_noreset(path, b->c.level, SIX_LOCK_intent); + + trans_for_each_path_with_node(trans, b, linked) + linked->l[b->c.level].lock_seq++; + + six_unlock_write(&b->c.lock); +} + +void bch2_btree_node_unlock_write(struct btree_trans *, + struct btree_path *, struct btree *); + +int bch2_six_check_for_deadlock(struct six_lock *lock, void *p); + +/* lock: */ + +static inline int __btree_node_lock_nopath(struct btree_trans *trans, + struct btree_bkey_cached_common *b, + enum six_lock_type type, + bool lock_may_not_fail, + unsigned long ip) +{ + int ret; + + trans->lock_may_not_fail = lock_may_not_fail; + trans->lock_must_abort = false; + trans->locking = b; + + ret = six_lock_ip_waiter(&b->lock, type, &trans->locking_wait, + bch2_six_check_for_deadlock, trans, ip); + WRITE_ONCE(trans->locking, NULL); + WRITE_ONCE(trans->locking_wait.start_time, 0); + return ret; +} + +static inline int __must_check +btree_node_lock_nopath(struct btree_trans *trans, + struct btree_bkey_cached_common *b, + enum six_lock_type type, + unsigned long ip) +{ + return __btree_node_lock_nopath(trans, b, type, false, ip); +} + +static inline void btree_node_lock_nopath_nofail(struct btree_trans *trans, + struct btree_bkey_cached_common *b, + enum six_lock_type type) +{ + int ret = __btree_node_lock_nopath(trans, b, type, true, _THIS_IP_); + + BUG_ON(ret); +} + +/* + * Lock a btree node if we already have it locked on one of our linked + * iterators: + */ +static inline bool btree_node_lock_increment(struct btree_trans *trans, + struct btree_bkey_cached_common *b, + unsigned level, + enum btree_node_locked_type want) +{ + struct btree_path *path; + + trans_for_each_path(trans, path) + if (&path->l[level].b->c == b && + btree_node_locked_type(path, level) >= want) { + six_lock_increment(&b->lock, (enum six_lock_type) want); + return true; + } + + return false; +} + +static inline int btree_node_lock(struct btree_trans *trans, + struct btree_path *path, + struct btree_bkey_cached_common *b, + unsigned level, + enum six_lock_type type, + unsigned long ip) { - return btree_lock_want(iter, level) == SIX_LOCK_intent; + int ret = 0; + + EBUG_ON(level >= BTREE_MAX_DEPTH); + EBUG_ON(!(trans->paths_allocated & (1ULL << path->idx))); + + if (likely(six_trylock_type(&b->lock, type)) || + btree_node_lock_increment(trans, b, level, (enum btree_node_locked_type) type) || + !(ret = btree_node_lock_nopath(trans, b, type, btree_path_ip_allocated(path)))) { +#ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS + path->l[b->level].lock_taken_time = local_clock(); +#endif + } + + return ret; } -static inline void btree_node_unlock(struct btree_iter *iter, unsigned level) +int __bch2_btree_node_lock_write(struct btree_trans *, struct btree_path *, + struct btree_bkey_cached_common *b, bool); + +static inline int __btree_node_lock_write(struct btree_trans *trans, + struct btree_path *path, + struct btree_bkey_cached_common *b, + bool lock_may_not_fail) { - int lock_type = btree_node_locked_type(iter, level); + EBUG_ON(&path->l[b->level].b->c != b); + EBUG_ON(path->l[b->level].lock_seq != six_lock_seq(&b->lock)); + EBUG_ON(!btree_node_intent_locked(path, b->level)); - if (lock_type != BTREE_NODE_UNLOCKED) - six_unlock_type(&iter->nodes[level]->lock, lock_type); - mark_btree_node_unlocked(iter, level); + /* + * six locks are unfair, and read locks block while a thread wants a + * write lock: thus, we need to tell the cycle detector we have a write + * lock _before_ taking the lock: + */ + mark_btree_node_locked_noreset(path, b->level, SIX_LOCK_write); + + return likely(six_trylock_write(&b->lock)) + ? 0 + : __bch2_btree_node_lock_write(trans, path, b, lock_may_not_fail); +} + +static inline int __must_check +bch2_btree_node_lock_write(struct btree_trans *trans, + struct btree_path *path, + struct btree_bkey_cached_common *b) +{ + return __btree_node_lock_write(trans, path, b, false); } -bool __bch2_btree_node_lock(struct btree *, struct bpos, unsigned, - struct btree_iter *, enum six_lock_type); +void bch2_btree_node_lock_write_nofail(struct btree_trans *, + struct btree_path *, + struct btree_bkey_cached_common *); -static inline bool btree_node_lock(struct btree *b, struct bpos pos, - unsigned level, - struct btree_iter *iter, - enum six_lock_type type) +/* relock: */ + +bool bch2_btree_path_relock_norestart(struct btree_trans *, + struct btree_path *, unsigned long); +int __bch2_btree_path_relock(struct btree_trans *, + struct btree_path *, unsigned long); + +static inline int bch2_btree_path_relock(struct btree_trans *trans, + struct btree_path *path, unsigned long trace_ip) { - return likely(six_trylock_type(&b->lock, type)) || - __bch2_btree_node_lock(b, pos, level, iter, type); + return btree_node_locked(path, path->level) + ? 0 + : __bch2_btree_path_relock(trans, path, trace_ip); } -bool bch2_btree_node_relock(struct btree_iter *, unsigned); +bool __bch2_btree_node_relock(struct btree_trans *, struct btree_path *, unsigned, bool trace); + +static inline bool bch2_btree_node_relock(struct btree_trans *trans, + struct btree_path *path, unsigned level) +{ + EBUG_ON(btree_node_locked(path, level) && + !btree_node_write_locked(path, level) && + btree_node_locked_type(path, level) != __btree_lock_want(path, level)); + + return likely(btree_node_locked(path, level)) || + (!IS_ERR_OR_NULL(path->l[level].b) && + __bch2_btree_node_relock(trans, path, level, true)); +} + +static inline bool bch2_btree_node_relock_notrace(struct btree_trans *trans, + struct btree_path *path, unsigned level) +{ + EBUG_ON(btree_node_locked(path, level) && + !btree_node_write_locked(path, level) && + btree_node_locked_type(path, level) != __btree_lock_want(path, level)); + + return likely(btree_node_locked(path, level)) || + (!IS_ERR_OR_NULL(path->l[level].b) && + __bch2_btree_node_relock(trans, path, level, false)); +} + +/* upgrade */ + +bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *, + struct btree_path *, unsigned); +bool __bch2_btree_path_upgrade(struct btree_trans *, + struct btree_path *, unsigned); + +static inline int bch2_btree_path_upgrade(struct btree_trans *trans, + struct btree_path *path, + unsigned new_locks_want) +{ + unsigned old_locks_want = path->locks_want; + + new_locks_want = min(new_locks_want, BTREE_MAX_DEPTH); + + if (path->locks_want < new_locks_want + ? __bch2_btree_path_upgrade(trans, path, new_locks_want) + : path->uptodate == BTREE_ITER_UPTODATE) + return 0; + + trace_and_count(trans->c, trans_restart_upgrade, trans, _THIS_IP_, path, + old_locks_want, new_locks_want); + return btree_trans_restart(trans, BCH_ERR_transaction_restart_upgrade); +} + +/* misc: */ + +static inline void btree_path_set_should_be_locked(struct btree_path *path) +{ + EBUG_ON(!btree_node_locked(path, path->level)); + EBUG_ON(path->uptodate); + + path->should_be_locked = true; +} + +static inline void __btree_path_set_level_up(struct btree_trans *trans, + struct btree_path *path, + unsigned l) +{ + btree_node_unlock(trans, path, l); + path->l[l].b = ERR_PTR(-BCH_ERR_no_btree_node_up); +} + +static inline void btree_path_set_level_up(struct btree_trans *trans, + struct btree_path *path) +{ + __btree_path_set_level_up(trans, path, path->level++); + btree_path_set_dirty(path, BTREE_ITER_NEED_TRAVERSE); +} + +/* debug */ + +struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *, + struct btree_path *, + struct btree_bkey_cached_common *b, + unsigned); + +int bch2_check_for_deadlock(struct btree_trans *, struct printbuf *); -void bch2_btree_node_unlock_write(struct btree *, struct btree_iter *); -void bch2_btree_node_lock_write(struct btree *, struct btree_iter *); +#ifdef CONFIG_BCACHEFS_DEBUG +void bch2_btree_path_verify_locks(struct btree_path *); +void bch2_trans_verify_locks(struct btree_trans *); +#else +static inline void bch2_btree_path_verify_locks(struct btree_path *path) {} +static inline void bch2_trans_verify_locks(struct btree_trans *trans) {} +#endif -#endif /* _BCACHE_BTREE_LOCKING_H */ +#endif /* _BCACHEFS_BTREE_LOCKING_H */