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mraccessf & mrupdatef are supposed to be the "flags" versions of
the functions, but they

a) ignore the flags parameter completely, and
b) are never called directly, only via the flag-less defines anyway

So, drop the #define indirection, and rename mraccessf to mraccess,
etc.
Merge of xfs-linux-melb:xfs-kern:27711a by kenmcd.

  remove flag-less mraccessf/mrupdatef

/*
 * Copyright (c) 2000-2003,2005 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
 */
#include "mrlock.h"

#ifndef HAVE_DOWNGRADE_WRITE

#include <linux/time.h>
#include <linux/sched.h>
#include <asm/system.h>
#include <linux/interrupt.h>
#include <asm/current.h>

#if USE_RW_WAIT_QUEUE_SPINLOCK
# define wq_write_lock		write_lock
# define wq_write_unlock	write_unlock
#else
# define wq_write_lock		spin_lock
# define wq_write_unlock	spin_unlock
#endif

/*
 * We don't seem to need lock_type (only one supported), name, or
 * sequence. But, XFS will pass it so let's leave them here for now.
 */
/* ARGSUSED */
void
mrlock_init(mrlock_t *mrp, int lock_type, char *name, long sequence)
{
	mrp->mr_count = 0;
	mrp->mr_reads_waiting = 0;
	mrp->mr_writes_waiting = 0;
	init_waitqueue_head(&mrp->mr_readerq);
	init_waitqueue_head(&mrp->mr_writerq);
	mrp->mr_lock = SPIN_LOCK_UNLOCKED;
}

/*
 * Macros to lock/unlock the mrlock_t.
 */

#define MRLOCK(m)		spin_lock(&(m)->mr_lock);
#define MRUNLOCK(m)		spin_unlock(&(m)->mr_lock);


/*
 * lock_wait should never be called in an interrupt thread.
 *
 * mrlocks can sleep (i.e. call schedule) and so they can't ever
 * be called from an interrupt thread.
 *
 * threads that wake-up should also never be invoked from interrupt threads.
 *
 * But, waitqueue_lock is locked from interrupt threads - and we are
 * called with interrupts disabled, so it is all OK.
 */

/* ARGSUSED */
void
lock_wait(wait_queue_head_t *q, spinlock_t *lock, int rw)
{
	DECLARE_WAITQUEUE( wait, current );

	__set_current_state(TASK_UNINTERRUPTIBLE);

	wq_write_lock(&q->lock);
	if (rw) {
		__add_wait_queue_tail(q, &wait);
	} else {
		__add_wait_queue(q, &wait);
	}

	wq_write_unlock(&q->lock);
	spin_unlock(lock);

	schedule();

	wq_write_lock(&q->lock);
	__remove_wait_queue(q, &wait);
	wq_write_unlock(&q->lock);

	spin_lock(lock);

	/* return with lock held */
}

/* ARGSUSED */
void
mrfree(mrlock_t *mrp)
{
}

/* ARGSUSED */
void
mrlock(mrlock_t *mrp, int type, int flags)
{
	if (type == MR_ACCESS)
		mraccess(mrp);
	else
		mrupdate(mrp);
}

/* ARGSUSED */
void
mraccess(mrlock_t *mrp)
{
	MRLOCK(mrp);
	if(mrp->mr_writes_waiting > 0) {
		mrp->mr_reads_waiting++;
		lock_wait(&mrp->mr_readerq, &mrp->mr_lock, 0);
		mrp->mr_reads_waiting--;
	}
	while (mrp->mr_count < 0) {
		mrp->mr_reads_waiting++;
		lock_wait(&mrp->mr_readerq, &mrp->mr_lock, 0);
		mrp->mr_reads_waiting--;
	}
	mrp->mr_count++;
	MRUNLOCK(mrp);
}

/* ARGSUSED */
void
mrupdate(mrlock_t *mrp)
{
	MRLOCK(mrp);
	while(mrp->mr_count) {
		mrp->mr_writes_waiting++;
		lock_wait(&mrp->mr_writerq, &mrp->mr_lock, 1);
		mrp->mr_writes_waiting--;
	}

	mrp->mr_count = -1; /* writer on it */
	MRUNLOCK(mrp);
}

int
mrtryaccess(mrlock_t *mrp)
{
	MRLOCK(mrp);
	/*
	 * If anyone is waiting for update access or the lock is held for update
	 * fail the request.
	 */
	if(mrp->mr_writes_waiting > 0 || mrp->mr_count < 0) {
		MRUNLOCK(mrp);
		return 0;
	}
	mrp->mr_count++;
	MRUNLOCK(mrp);
	return 1;
}

int
mrtrypromote(mrlock_t *mrp)
{
	MRLOCK(mrp);

	if(mrp->mr_count == 1) { /* We are the only thread with the lock */
		mrp->mr_count = -1; /* writer on it */
		MRUNLOCK(mrp);
		return 1;
	}

	MRUNLOCK(mrp);
	return 0;
}

int
mrtryupdate(mrlock_t *mrp)
{
	MRLOCK(mrp);

	if(mrp->mr_count) {
		MRUNLOCK(mrp);
		return 0;
	}

	mrp->mr_count = -1; /* writer on it */
	MRUNLOCK(mrp);
	return 1;
}

STATIC_INLINE void mrwake(mrlock_t *mrp)
{
	/*
	 * First, if the count is now 0, we need to wake-up anyone waiting.
	 */
	if (!mrp->mr_count) {
		if (mrp->mr_writes_waiting) {	/* Wake-up first writer waiting */
			wake_up(&mrp->mr_writerq);
		} else if (mrp->mr_reads_waiting) {	/* Wakeup any readers waiting */
			wake_up(&mrp->mr_readerq);
		}
	}
}

void
mraccunlock(mrlock_t *mrp)
{
	MRLOCK(mrp);
	mrp->mr_count--;
	mrwake(mrp);
	MRUNLOCK(mrp);
}

void
mrunlock(mrlock_t *mrp)
{
	MRLOCK(mrp);
	if (mrp->mr_count < 0) {
		mrp->mr_count = 0;
	} else {
		mrp->mr_count--;
	}
	mrwake(mrp);
	MRUNLOCK(mrp);
}

int
ismrlocked(mrlock_t *mrp, int type)	/* No need to lock since info can change */
{
	if (type == MR_ACCESS)
		return (mrp->mr_count > 0); /* Read lock */
	else if (type == MR_UPDATE)
		return (mrp->mr_count < 0); /* Write lock */
	else if (type == (MR_UPDATE | MR_ACCESS))
		return (mrp->mr_count);	/* Any type of lock held */
	else /* Any waiters */
		return (mrp->mr_reads_waiting | mrp->mr_writes_waiting);
}

/*
 * Demote from update to access. We better be the only thread with the
 * lock in update mode so it should be easy to set to 1.
 * Wake-up any readers waiting.
 */

void
mrdemote(mrlock_t *mrp)
{
	MRLOCK(mrp);
	mrp->mr_count = 1;
	if (mrp->mr_reads_waiting) {	/* Wakeup all readers waiting */
		wake_up(&mrp->mr_readerq);
	}
	MRUNLOCK(mrp);
}

#endif	/* !HAVE_DOWNGRADE_WRITE */