rangelock.c revision 204076 
1/*-
2 * Copyright (c) 2010 The FreeBSD Foundation
3 * All rights reserved.
4 *
5 * This software was developed by Pawel Jakub Dawidek under sponsorship from
6 * the FreeBSD Foundation.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD: head/sbin/hastd/rangelock.c 204076 2010-02-18 23:16:19Z pjd $");
32
33#include <sys/queue.h>
34
35#include <assert.h>
36#include <stdbool.h>
37#include <stdlib.h>
38#include <unistd.h>
39
40#include "rangelock.h"
41
42#define	RANGELOCKS_MAGIC	0x94310c
43struct rangelocks {
44	int	 rls_magic;		/* Magic value. */
45	TAILQ_HEAD(, rlock) rls_locks;	/* List of locked ranges. */
46};
47
48struct rlock {
49	off_t	rl_start;
50	off_t	rl_end;
51	TAILQ_ENTRY(rlock) rl_next;
52};
53
54int
55rangelock_init(struct rangelocks **rlsp)
56{
57	struct rangelocks *rls;
58
59	assert(rlsp != NULL);
60
61	rls = malloc(sizeof(*rls));
62	if (rls == NULL)
63		return (-1);
64
65	TAILQ_INIT(&rls->rls_locks);
66
67	rls->rls_magic = RANGELOCKS_MAGIC;
68	*rlsp = rls;
69
70	return (0);
71}
72
73void
74rangelock_free(struct rangelocks *rls)
75{
76	struct rlock *rl;
77
78	assert(rls->rls_magic == RANGELOCKS_MAGIC);
79
80	rls->rls_magic = 0;
81
82	while ((rl = TAILQ_FIRST(&rls->rls_locks)) != NULL) {
83		TAILQ_REMOVE(&rls->rls_locks, rl, rl_next);
84		free(rl);
85	}
86	free(rls);
87}
88
89int
90rangelock_add(struct rangelocks *rls, off_t offset, off_t length)
91{
92	struct rlock *rl;
93
94	assert(rls->rls_magic == RANGELOCKS_MAGIC);
95
96	rl = malloc(sizeof(*rl));
97	if (rl == NULL)
98		return (-1);
99	rl->rl_start = offset;
100	rl->rl_end = offset + length;
101	TAILQ_INSERT_TAIL(&rls->rls_locks, rl, rl_next);
102	return (0);
103}
104
105void
106rangelock_del(struct rangelocks *rls, off_t offset, off_t length)
107{
108	struct rlock *rl;
109
110	assert(rls->rls_magic == RANGELOCKS_MAGIC);
111
112	TAILQ_FOREACH(rl, &rls->rls_locks, rl_next) {
113		if (rl->rl_start == offset && rl->rl_end == offset + length)
114			break;
115	}
116	assert(rl != NULL);
117	TAILQ_REMOVE(&rls->rls_locks, rl, rl_next);
118	free(rl);
119}
120
121bool
122rangelock_islocked(struct rangelocks *rls, off_t offset, off_t length)
123{
124	struct rlock *rl;
125
126	assert(rls->rls_magic == RANGELOCKS_MAGIC);
127
128	TAILQ_FOREACH(rl, &rls->rls_locks, rl_next) {
129		if (rl->rl_start >= offset && rl->rl_start < offset + length)
130			break;
131		else if (rl->rl_end > offset && rl->rl_end <= offset + length)
132			break;
133		else if (rl->rl_start < offset && rl->rl_end > offset + length)
134			break;
135	}
136	return (rl != NULL);
137}
138