diff options
Diffstat (limited to 'fs/xfs/linux-2.6/mrlock.h')
| -rw-r--r-- | fs/xfs/linux-2.6/mrlock.h | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/fs/xfs/linux-2.6/mrlock.h b/fs/xfs/linux-2.6/mrlock.h new file mode 100644 index 000000000000..d2c11a098ff2 --- /dev/null +++ b/fs/xfs/linux-2.6/mrlock.h @@ -0,0 +1,106 @@ +/* + * Copyright (c) 2000-2004 Silicon Graphics, Inc. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of version 2 of the GNU General Public License as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it would be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. + * + * Further, this software is distributed without any warranty that it is + * free of the rightful claim of any third person regarding infringement + * or the like. Any license provided herein, whether implied or + * otherwise, applies only to this software file. Patent licenses, if + * any, provided herein do not apply to combinations of this program with + * other software, or any other product whatsoever. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write the Free Software Foundation, Inc., 59 + * Temple Place - Suite 330, Boston MA 02111-1307, USA. + * + * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy, + * Mountain View, CA 94043, or: + * + * http://www.sgi.com + * + * For further information regarding this notice, see: + * + * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/ + */ +#ifndef __XFS_SUPPORT_MRLOCK_H__ +#define __XFS_SUPPORT_MRLOCK_H__ + +#include <linux/rwsem.h> + +enum { MR_NONE, MR_ACCESS, MR_UPDATE }; + +typedef struct { + struct rw_semaphore mr_lock; + int mr_writer; +} mrlock_t; + +#define mrinit(mrp, name) \ + ( (mrp)->mr_writer = 0, init_rwsem(&(mrp)->mr_lock) ) +#define mrlock_init(mrp, t,n,s) mrinit(mrp, n) +#define mrfree(mrp) do { } while (0) +#define mraccess(mrp) mraccessf(mrp, 0) +#define mrupdate(mrp) mrupdatef(mrp, 0) + +static inline void mraccessf(mrlock_t *mrp, int flags) +{ + down_read(&mrp->mr_lock); +} + +static inline void mrupdatef(mrlock_t *mrp, int flags) +{ + down_write(&mrp->mr_lock); + mrp->mr_writer = 1; +} + +static inline int mrtryaccess(mrlock_t *mrp) +{ + return down_read_trylock(&mrp->mr_lock); +} + +static inline int mrtryupdate(mrlock_t *mrp) +{ + if (!down_write_trylock(&mrp->mr_lock)) + return 0; + mrp->mr_writer = 1; + return 1; +} + +static inline void mrunlock(mrlock_t *mrp) +{ + if (mrp->mr_writer) { + mrp->mr_writer = 0; + up_write(&mrp->mr_lock); + } else { + up_read(&mrp->mr_lock); + } +} + +static inline void mrdemote(mrlock_t *mrp) +{ + mrp->mr_writer = 0; + downgrade_write(&mrp->mr_lock); +} + +#ifdef DEBUG +/* + * Debug-only routine, without some platform-specific asm code, we can + * now only answer requests regarding whether we hold the lock for write + * (reader state is outside our visibility, we only track writer state). + * Note: means !ismrlocked would give false positivies, so don't do that. + */ +static inline int ismrlocked(mrlock_t *mrp, int type) +{ + if (mrp && type == MR_UPDATE) + return mrp->mr_writer; + return 1; +} +#endif + +#endif /* __XFS_SUPPORT_MRLOCK_H__ */ |