1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _BCACHEFS_TWO_STATE_LOCK_H
3 #define _BCACHEFS_TWO_STATE_LOCK_H
5 #include <linux/atomic.h>
6 #include <linux/sched.h>
7 #include <linux/wait.h>
12 * Two-state lock - can be taken for add or block - both states are shared,
13 * like read side of rwsem, but conflict with other state:
17 wait_queue_head_t wait;
20 static inline void two_state_lock_init(two_state_lock_t *lock)
22 atomic_long_set(&lock->v, 0);
23 init_waitqueue_head(&lock->wait);
26 static inline void bch2_two_state_unlock(two_state_lock_t *lock, int s)
30 EBUG_ON(atomic_long_read(&lock->v) == 0);
32 if (atomic_long_sub_return_release(i, &lock->v) == 0)
33 wake_up_all(&lock->wait);
36 static inline bool bch2_two_state_trylock(two_state_lock_t *lock, int s)
39 long v = atomic_long_read(&lock->v), old;
44 if (i > 0 ? v < 0 : v > 0)
46 } while ((v = atomic_long_cmpxchg_acquire(&lock->v,
47 old, old + i)) != old);
51 void __bch2_two_state_lock(two_state_lock_t *, int);
53 static inline void bch2_two_state_lock(two_state_lock_t *lock, int s)
55 if (!bch2_two_state_trylock(lock, s))
56 __bch2_two_state_lock(lock, s);
59 #endif /* _BCACHEFS_TWO_STATE_LOCK_H */