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Update license/copyright notices to match the prefered SGI boilerplate.
Merge of xfs-linux-melb:xfs-kern:23903a by kenmcd.

/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms 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.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef __XFS_COMPAT_MRLOCK_H__
#define __XFS_COMPAT_MRLOCK_H__

#include <linux/rwsem.h>
#ifdef HAVE_DOWNGRADE_WRITE
#include "mrlock_rwsem.h"
#else

#include <linux/time.h>
#include <linux/wait.h>
#include <asm/atomic.h>
#include <asm/semaphore.h>

/*
 * Implement mrlocks on Linux that work for XFS.
 *
 * These are sleep locks and not spinlocks. If one wants read/write spinlocks,
 * use read_lock, write_lock, ... see spinlock.h.
 */

typedef struct mrlock_s {
	int			mr_count;
	unsigned short		mr_reads_waiting;
	unsigned short		mr_writes_waiting;
	wait_queue_head_t	mr_readerq;
	wait_queue_head_t	mr_writerq;
	spinlock_t		mr_lock;
} mrlock_t;

#define MR_ACCESS	1
#define MR_UPDATE	2

#define MRLOCK_BARRIER		0x1
#define MRLOCK_ALLOW_EQUAL_PRI	0x8

/*
 * mraccessf/mrupdatef take flags to be passed in while sleeping;
 * only PLTWAIT is currently supported.
 */

extern void	mraccessf(mrlock_t *, int);
extern void	mrupdatef(mrlock_t *, int);
extern void     mrlock(mrlock_t *, int, int);
extern void     mrunlock(mrlock_t *);
extern void     mraccunlock(mrlock_t *);
extern int      mrtryupdate(mrlock_t *);
extern int      mrtryaccess(mrlock_t *);
extern int	mrtrypromote(mrlock_t *);
extern void     mrdemote(mrlock_t *);

extern int	ismrlocked(mrlock_t *, int);
extern void     mrlock_init(mrlock_t *, int type, char *name, long sequence);
extern void     mrfree(mrlock_t *);

#define mrinit(mrp, name)	mrlock_init(mrp, MRLOCK_BARRIER, name, -1)
#define mraccess(mrp)		mraccessf(mrp, 0) /* grab for READ/ACCESS */
#define mrupdate(mrp)		mrupdatef(mrp, 0) /* grab for WRITE/UPDATE */
#define mrislocked_access(mrp)	((mrp)->mr_count > 0)
#define mrislocked_update(mrp)	((mrp)->mr_count < 0)

#endif	/* !HAVE_DOWNGRADE_WRITE */

#endif /* __XFS_COMPAT_MRLOCK_H__ */