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 23typedef struct { 24 struct rw_semaphore mr_lock; 25#ifdef DEBUG 26 int mr_writer; 27#endif 28} mrlock_t; 29 30#ifdef DEBUG 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 41static inline void mraccess_nested(mrlock_t *mrp, int subclass) 42{ 43 down_read_nested(&mrp->mr_lock, subclass); 44} 45 46static inline void mrupdate_nested(mrlock_t *mrp, int subclass) 47{ 48 down_write_nested(&mrp->mr_lock, subclass); 49#ifdef DEBUG 50 mrp->mr_writer = 1; 51#endif 52} 53 54static inline int mrtryaccess(mrlock_t *mrp) 55{ 56 return down_read_trylock(&mrp->mr_lock); 57} 58 59static inline int mrtryupdate(mrlock_t *mrp) 60{ 61 if (!down_write_trylock(&mrp->mr_lock)) 62 return 0; 63#ifdef DEBUG 64 mrp->mr_writer = 1; 65#endif 66 return 1; 67} 68 69static inline void mrunlock_excl(mrlock_t *mrp) 70{ 71#ifdef DEBUG 72 mrp->mr_writer = 0; 73#endif 74 up_write(&mrp->mr_lock); 75} 76 77static inline void mrunlock_shared(mrlock_t *mrp) 78{ 79 up_read(&mrp->mr_lock); 80} 81 82static inline void mrdemote(mrlock_t *mrp) 83{ 84#ifdef DEBUG 85 mrp->mr_writer = 0; 86#endif 87 downgrade_write(&mrp->mr_lock); 88} 89 90#endif /* __XFS_SUPPORT_MRLOCK_H__ */ 91