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/*-
* Copyright (c) 2009 Konstantin Belousov <kib@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice unmodified, this list of conditions, and the following
* disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*/
#ifndef _SYS_RANGELOCK_H
#define _SYS_RANGELOCK_H
#include <sys/queue.h>
#define RL_LOCK_READ 0x0001
#define RL_LOCK_WRITE 0x0002
#define RL_LOCK_TYPE_MASK 0x0003
#define RL_LOCK_GRANTED 0x0004
struct rl_q_entry;
/*
* The structure representing the range lock. Caller may request
* read or write access to the range of bytes. Access is granted if
* all existing lock owners are compatible with the request. Two lock
* owners are compatible if their ranges do not overlap, or both
* owners are for read.
*
* Access to the structure itself is synchronized with the externally
* supplied mutex.
*
* rl_waiters is the queue containing in order (a) granted write lock
* requests, (b) granted read lock requests, and (c) in order of arrival,
* lock requests which cannot be granted yet.
*
* rl_currdep is the first lock request that cannot be granted now due
* to the preceding requests conflicting with it (i.e., it points to
* position (c) in the list above).
*/
struct rangelock {
TAILQ_HEAD(, rl_q_entry) rl_waiters;
struct rl_q_entry *rl_currdep;
};
#ifdef _KERNEL
struct mtx;
void rangelock_init(struct rangelock *lock);
void rangelock_destroy(struct rangelock *lock);
void rangelock_unlock(struct rangelock *lock, void *cookie,
struct mtx *ilk);
void *rangelock_unlock_range(struct rangelock *lock, void *cookie,
off_t start, off_t end, struct mtx *ilk);
void *rangelock_rlock(struct rangelock *lock, off_t start, off_t end,
struct mtx *ilk);
void *rangelock_wlock(struct rangelock *lock, off_t start, off_t end,
struct mtx *ilk);
void rlqentry_free(struct rl_q_entry *rlqe);
#endif /* _KERNEL */
#endif /* _SYS_RANGELOCK_H */
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