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(sem: &mrp->mr_lock, subclass);
32}
33
34static inline void mrupdate_nested(mrlock_t *mrp, int subclass)
35{
36 down_write_nested(sem: &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(sem: &mrp->mr_lock);
45}
46
47static inline int mrtryupdate(mrlock_t *mrp)
48{
49 if (!down_write_trylock(sem: &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(sem: &mrp->mr_lock);
63}
64
65static inline void mrunlock_shared(mrlock_t *mrp)
66{
67 up_read(sem: &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(sem: &mrp->mr_lock);
76}
77
78#endif /* __XFS_SUPPORT_MRLOCK_H__ */
79

source code of linux/fs/xfs/mrlock.h