/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License (the "License").

 * You may not use this file except in compliance with the License.

 *

 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

 * or http://www.opensolaris.org/os/licensing.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

 * If applicable, add the following below this CDDL HEADER, with the

 * fields enclosed by brackets "[]" replaced with your own identifying

 * information: Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 */

/*

 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

#ifndef	_SYS_FS_ZFS_RLOCK_H

#define	_SYS_FS_ZFS_RLOCK_H

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#ifdef	__cplusplus

extern "C" {

#endif

#ifdef _KERNEL

#include <sys/zfs_znode.h>

typedef enum {

	RL_READER,

	RL_WRITER,

	RL_APPEND

} rl_type_t;

typedef struct rl {

	avl_node_t r_node;	/* avl node link */

	uint64_t r_off;		/* file range offset */

	uint64_t r_len;		/* file range length */

	uint_t r_cnt;		/* range reference count in tree */

	rl_type_t r_type;	/* range type */

	kcondvar_t r_wr_cv;	/* cv for waiting writers */

	kcondvar_t r_rd_cv;	/* cv for waiting readers */

	uint8_t r_proxy;	/* acting for original range */

	uint8_t r_write_wanted;	/* writer wants to lock this range */

	uint8_t r_read_wanted;	/* reader wants to lock this range */

} rl_t;

/*

 * Lock a range (offset, length) as either shared (READER)

 * or exclusive (WRITER or APPEND). APPEND is a special type that

 * is converted to WRITER that specified to lock from the start of the

 * end of file.  zfs_range_lock() returns the range lock structure.

 */

rl_t *zfs_range_lock(znode_t *zp, uint64_t off, uint64_t len, rl_type_t type);

/*

 * Unlock range and destroy range lock structure.

 */

void zfs_range_unlock(znode_t *zp, rl_t *rl);

/*

 * Reduce range locked as RW_WRITER from whole file to specified range.

 * Asserts the whole file was previously locked.

 */

void zfs_range_reduce(znode_t *zp, rl_t *rl, uint64_t off, uint64_t len);

/*

 * AVL comparison function used to compare range locks

 */

int zfs_range_compare(const void *arg1, const void *arg2);

#endif /* _KERNEL */

#ifdef	__cplusplus

}

#endif

#endif	/* _SYS_FS_ZFS_RLOCK_H */