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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef _BCACHEFS_TWO_STATE_LOCK_H3#define _BCACHEFS_TWO_STATE_LOCK_H4 5#include <linux/atomic.h>6#include <linux/sched.h>7#include <linux/wait.h>8 9#include "util.h"10 11/*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:14 */15typedef struct {16 atomic_long_t v;17 wait_queue_head_t wait;18} two_state_lock_t;19 20static inline void two_state_lock_init(two_state_lock_t *lock)21{22 atomic_long_set(&lock->v, 0);23 init_waitqueue_head(&lock->wait);24}25 26static inline void bch2_two_state_unlock(two_state_lock_t *lock, int s)27{28 long i = s ? 1 : -1;29 30 EBUG_ON(atomic_long_read(&lock->v) == 0);31 32 if (atomic_long_sub_return_release(i, &lock->v) == 0)33 wake_up_all(&lock->wait);34}35 36static inline bool bch2_two_state_trylock(two_state_lock_t *lock, int s)37{38 long i = s ? 1 : -1;39 long old;40 41 old = atomic_long_read(&lock->v);42 do {43 if (i > 0 ? old < 0 : old > 0)44 return false;45 } while (!atomic_long_try_cmpxchg_acquire(&lock->v, &old, old + i));46 47 return true;48}49 50void __bch2_two_state_lock(two_state_lock_t *, int);51 52static inline void bch2_two_state_lock(two_state_lock_t *lock, int s)53{54 if (!bch2_two_state_trylock(lock, s))55 __bch2_two_state_lock(lock, s);56}57 58#endif /* _BCACHEFS_TWO_STATE_LOCK_H */59