/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _BCACHEFS_TWO_STATE_LOCK_H #define _BCACHEFS_TWO_STATE_LOCK_H #include #include #include #include "util.h" /* * Two-state lock - can be taken for add or block - both states are shared, * like read side of rwsem, but conflict with other state: */ typedef struct { atomic_long_t v; wait_queue_head_t wait; } two_state_lock_t; static inline void two_state_lock_init(two_state_lock_t *lock) { atomic_long_set(&lock->v, 0); init_waitqueue_head(&lock->wait); } static inline void bch2_two_state_unlock(two_state_lock_t *lock, int s) { long i = s ? 1 : -1; EBUG_ON(atomic_long_read(&lock->v) == 0); if (atomic_long_sub_return_release(i, &lock->v) == 0) wake_up_all(&lock->wait); } static inline bool bch2_two_state_trylock(two_state_lock_t *lock, int s) { long i = s ? 1 : -1; long old; old = atomic_long_read(&lock->v); do { if (i > 0 ? old < 0 : old > 0) return false; } while (!atomic_long_try_cmpxchg_acquire(&lock->v, &old, old + i)); return true; } void __bch2_two_state_lock(two_state_lock_t *, int); static inline void bch2_two_state_lock(two_state_lock_t *lock, int s) { if (!bch2_two_state_trylock(lock, s)) __bch2_two_state_lock(lock, s); } #endif /* _BCACHEFS_TWO_STATE_LOCK_H */