1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _BCACHEFS_SEQMUTEX_H 3 #define _BCACHEFS_SEQMUTEX_H 4 5 #include <linux/mutex.h> 6 7 struct seqmutex { 8 struct mutex lock; 9 u32 seq; 10 }; 11 12 #define seqmutex_init(_lock) mutex_init(&(_lock)->lock) 13 14 static inline bool seqmutex_trylock(struct seqmutex *lock) 15 { 16 return mutex_trylock(&lock->lock); 17 } 18 19 static inline void seqmutex_lock(struct seqmutex *lock) 20 { 21 mutex_lock(&lock->lock); 22 lock->seq++; 23 } 24 25 static inline u32 seqmutex_unlock(struct seqmutex *lock) 26 { 27 u32 seq = lock->seq; 28 mutex_unlock(&lock->lock); 29 return seq; 30 } 31 32 static inline bool seqmutex_relock(struct seqmutex *lock, u32 seq) 33 { 34 if (lock->seq != seq || !mutex_trylock(&lock->lock)) 35 return false; 36 37 if (lock->seq != seq) { 38 mutex_unlock(&lock->lock); 39 return false; 40 } 41 42 return true; 43 } 44 45 #endif /* _BCACHEFS_SEQMUTEX_H */ 46