fs/xfs/mrlock.h

   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
  11 typedef 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
  29 static inline void mraccess_nested(mrlock_t *mrp, int subclass)
  30 {
  31         down_read_nested(&mrp->mr_lock, subclass);
  32 }
  33
  34 static 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
  42 static inline int mrtryaccess(mrlock_t *mrp)
  43 {
  44         return down_read_trylock(&mrp->mr_lock);
  45 }
  46
  47 static 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
  57 static 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
  65 static inline void mrunlock_shared(mrlock_t *mrp)
  66 {
  67         up_read(&mrp->mr_lock);
  68 }
  69
  70 static 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__ */