1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef _BCACHEFS_SEQMUTEX_H
 3#define _BCACHEFS_SEQMUTEX_H
 4
 5#include <linux/mutex.h>
 6
 7struct seqmutex {
 8	struct mutex	lock;
 9	u32		seq;
10};
11
12#define seqmutex_init(_lock)	mutex_init(&(_lock)->lock)
13
14static inline bool seqmutex_trylock(struct seqmutex *lock)
15{
16	return mutex_trylock(&lock->lock);
17}
18
19static inline void seqmutex_lock(struct seqmutex *lock)
20{
21	mutex_lock(&lock->lock);
22	lock->seq++;
23}
24
25static inline u32 seqmutex_unlock(struct seqmutex *lock)
26{
27	u32 seq = lock->seq;
28	mutex_unlock(&lock->lock);
29	return seq;
30}
31
32static 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 */