1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 4 * All Rights Reserved.
 5 */
 6#ifndef __XFS_SUPPORT_MRLOCK_H__
 7#define __XFS_SUPPORT_MRLOCK_H__
 8
 9#include <linux/rwsem.h>
10
11typedef struct {
12	struct rw_semaphore	mr_lock;
13#if defined(DEBUG) || defined(XFS_WARN)
14	int			mr_writer;
15#endif
16} mrlock_t;
17
18#if defined(DEBUG) || defined(XFS_WARN)
19#define mrinit(mrp, name)	\
20	do { (mrp)->mr_writer = 0; init_rwsem(&(mrp)->mr_lock); } while (0)
21#else
22#define mrinit(mrp, name)	\
23	do { init_rwsem(&(mrp)->mr_lock); } while (0)
24#endif
25
26#define mrlock_init(mrp, t,n,s)	mrinit(mrp, n)
27#define mrfree(mrp)		do { } while (0)
28
29static inline void mraccess_nested(mrlock_t *mrp, int subclass)
30{
31	down_read_nested(&mrp->mr_lock, subclass);
32}
33
34static inline void mrupdate_nested(mrlock_t *mrp, int subclass)
35{
36	down_write_nested(&mrp->mr_lock, subclass);
37#if defined(DEBUG) || defined(XFS_WARN)
38	mrp->mr_writer = 1;
39#endif
40}
41
42static inline int mrtryaccess(mrlock_t *mrp)
43{
44	return down_read_trylock(&mrp->mr_lock);
45}
46
47static inline int mrtryupdate(mrlock_t *mrp)
48{
49	if (!down_write_trylock(&mrp->mr_lock))
50		return 0;
51#if defined(DEBUG) || defined(XFS_WARN)
52	mrp->mr_writer = 1;
53#endif
54	return 1;
55}
56
57static inline void mrunlock_excl(mrlock_t *mrp)
58{
59#if defined(DEBUG) || defined(XFS_WARN)
60	mrp->mr_writer = 0;
61#endif
62	up_write(&mrp->mr_lock);
63}
64
65static inline void mrunlock_shared(mrlock_t *mrp)
66{
67	up_read(&mrp->mr_lock);
68}
69
70static inline void mrdemote(mrlock_t *mrp)
71{
72#if defined(DEBUG) || defined(XFS_WARN)
73	mrp->mr_writer = 0;
74#endif
75	downgrade_write(&mrp->mr_lock);
76}
77
78#endif /* __XFS_SUPPORT_MRLOCK_H__ */