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__ */ 79