diff options
Diffstat (limited to 'fs/bcachefs/btree_locking.h')
| -rw-r--r-- | fs/bcachefs/btree_locking.h | 433 |
1 files changed, 433 insertions, 0 deletions
diff --git a/fs/bcachefs/btree_locking.h b/fs/bcachefs/btree_locking.h new file mode 100644 index 0000000000..11b0a2c8cd --- /dev/null +++ b/fs/bcachefs/btree_locking.h @@ -0,0 +1,433 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _BCACHEFS_BTREE_LOCKING_H +#define _BCACHEFS_BTREE_LOCKING_H + +/* + * Only for internal btree use: + * + * The btree iterator tracks what locks it wants to take, and what locks it + * currently has - here we have wrappers for locking/unlocking btree nodes and + * updating the iterator state + */ + +#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_path *path, + unsigned level) +{ + return BTREE_NODE_UNLOCKED + ((path->nodes_locked >> (level << 1)) & 3); +} + +static inline bool btree_node_write_locked(struct btree_path *path, unsigned l) +{ + return btree_node_locked_type(path, l) == BTREE_NODE_WRITE_LOCKED; +} + +static inline bool btree_node_intent_locked(struct btree_path *path, unsigned l) +{ + return btree_node_locked_type(path, l) == BTREE_NODE_INTENT_LOCKED; +} + +static inline bool btree_node_read_locked(struct btree_path *path, unsigned l) +{ + return btree_node_locked_type(path, l) == BTREE_NODE_READ_LOCKED; +} + +static inline bool btree_node_locked(struct btree_path *path, unsigned level) +{ + return btree_node_locked_type(path, level) != BTREE_NODE_UNLOCKED; +} + +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); + + 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_locked(struct btree_trans *trans, + struct btree_path *path, + unsigned level, + enum btree_node_locked_type type) +{ + 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 enum six_lock_type __btree_lock_want(struct btree_path *path, int level) +{ + return level < path->locks_want + ? SIX_LOCK_intent + : SIX_LOCK_read; +} + +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, BTREE_NODE_INTENT_LOCKED); + + 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) +{ + 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; +} + +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) +{ + 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)); + + /* + * 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, BTREE_NODE_WRITE_LOCKED); + + 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); +} + +void bch2_btree_node_lock_write_nofail(struct btree_trans *, + struct btree_path *, + struct btree_bkey_cached_common *); + +/* 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 btree_node_locked(path, path->level) + ? 0 + : __bch2_btree_path_relock(trans, path, trace_ip); +} + +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 */ + + +struct get_locks_fail { + unsigned l; + struct btree *b; +}; + +bool bch2_btree_path_upgrade_noupgrade_sibs(struct btree_trans *, + struct btree_path *, unsigned, + struct get_locks_fail *); + +bool __bch2_btree_path_upgrade(struct btree_trans *, + struct btree_path *, unsigned, + struct get_locks_fail *); + +static inline int bch2_btree_path_upgrade(struct btree_trans *trans, + struct btree_path *path, + unsigned new_locks_want) +{ + struct get_locks_fail f; + 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, &f) + : 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, &f); + 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 *); + +#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 /* _BCACHEFS_BTREE_LOCKING_H */ |