1 /* 2 * Copyright (c) 2000-2006 Silicon Graphics, Inc. 3 * All Rights Reserved. 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License as 7 * published by the Free Software Foundation. 8 * 9 * This program is distributed in the hope that it would be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 17 */ 18 #ifndef __XFS_SUPPORT_MRLOCK_H__ 19 #define __XFS_SUPPORT_MRLOCK_H__ 20 21 #include <linux/rwsem.h> 22 23 typedef struct { 24 struct rw_semaphore mr_lock; 25 #if defined(DEBUG) || defined(XFS_WARN) 26 int mr_writer; 27 #endif 28 } mrlock_t; 29 30 #if defined(DEBUG) || defined(XFS_WARN) 31 #define mrinit(mrp, name) \ 32 do { (mrp)->mr_writer = 0; init_rwsem(&(mrp)->mr_lock); } while (0) 33 #else 34 #define mrinit(mrp, name) \ 35 do { init_rwsem(&(mrp)->mr_lock); } while (0) 36 #endif 37 38 #define mrlock_init(mrp, t,n,s) mrinit(mrp, n) 39 #define mrfree(mrp) do { } while (0) 40 41 static inline void mraccess_nested(mrlock_t *mrp, int subclass) 42 { 43 down_read_nested(&mrp->mr_lock, subclass); 44 } 45 46 static inline void mrupdate_nested(mrlock_t *mrp, int subclass) 47 { 48 down_write_nested(&mrp->mr_lock, subclass); 49 #if defined(DEBUG) || defined(XFS_WARN) 50 mrp->mr_writer = 1; 51 #endif 52 } 53 54 static inline int mrtryaccess(mrlock_t *mrp) 55 { 56 return down_read_trylock(&mrp->mr_lock); 57 } 58 59 static inline int mrtryupdate(mrlock_t *mrp) 60 { 61 if (!down_write_trylock(&mrp->mr_lock)) 62 return 0; 63 #if defined(DEBUG) || defined(XFS_WARN) 64 mrp->mr_writer = 1; 65 #endif 66 return 1; 67 } 68 69 static inline void mrunlock_excl(mrlock_t *mrp) 70 { 71 #if defined(DEBUG) || defined(XFS_WARN) 72 mrp->mr_writer = 0; 73 #endif 74 up_write(&mrp->mr_lock); 75 } 76 77 static inline void mrunlock_shared(mrlock_t *mrp) 78 { 79 up_read(&mrp->mr_lock); 80 } 81 82 static inline void mrdemote(mrlock_t *mrp) 83 { 84 #if defined(DEBUG) || defined(XFS_WARN) 85 mrp->mr_writer = 0; 86 #endif 87 downgrade_write(&mrp->mr_lock); 88 } 89 90 #endif /* __XFS_SUPPORT_MRLOCK_H__ */ 91