fs/xfs/mrlock.h

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
0004  * All Rights Reserved.
0005  */
0006 #ifndef __XFS_SUPPORT_MRLOCK_H__
0007 #define __XFS_SUPPORT_MRLOCK_H__
0008
0009 #include <linux/rwsem.h>
0010
0011 typedef struct {
0012     struct rw_semaphore mr_lock;
0013 #if defined(DEBUG) || defined(XFS_WARN)
0014     int         mr_writer;
0015 #endif
0016 } mrlock_t;
0017
0018 #if defined(DEBUG) || defined(XFS_WARN)
0019 #define mrinit(mrp, name)   \
0020     do { (mrp)->mr_writer = 0; init_rwsem(&(mrp)->mr_lock); } while (0)
0021 #else
0022 #define mrinit(mrp, name)   \
0023     do { init_rwsem(&(mrp)->mr_lock); } while (0)
0024 #endif
0025
0026 #define mrlock_init(mrp, t,n,s) mrinit(mrp, n)
0027 #define mrfree(mrp)     do { } while (0)
0028
0029 static inline void mraccess_nested(mrlock_t *mrp, int subclass)
0030 {
0031     down_read_nested(&mrp->mr_lock, subclass);
0032 }
0033
0034 static inline void mrupdate_nested(mrlock_t *mrp, int subclass)
0035 {
0036     down_write_nested(&mrp->mr_lock, subclass);
0037 #if defined(DEBUG) || defined(XFS_WARN)
0038     mrp->mr_writer = 1;
0039 #endif
0040 }
0041
0042 static inline int mrtryaccess(mrlock_t *mrp)
0043 {
0044     return down_read_trylock(&mrp->mr_lock);
0045 }
0046
0047 static inline int mrtryupdate(mrlock_t *mrp)
0048 {
0049     if (!down_write_trylock(&mrp->mr_lock))
0050         return 0;
0051 #if defined(DEBUG) || defined(XFS_WARN)
0052     mrp->mr_writer = 1;
0053 #endif
0054     return 1;
0055 }
0056
0057 static inline void mrunlock_excl(mrlock_t *mrp)
0058 {
0059 #if defined(DEBUG) || defined(XFS_WARN)
0060     mrp->mr_writer = 0;
0061 #endif
0062     up_write(&mrp->mr_lock);
0063 }
0064
0065 static inline void mrunlock_shared(mrlock_t *mrp)
0066 {
0067     up_read(&mrp->mr_lock);
0068 }
0069
0070 static inline void mrdemote(mrlock_t *mrp)
0071 {
0072 #if defined(DEBUG) || defined(XFS_WARN)
0073     mrp->mr_writer = 0;
0074 #endif
0075     downgrade_write(&mrp->mr_lock);
0076 }
0077
0078 #endif /* __XFS_SUPPORT_MRLOCK_H__ */