rangelock.c revision 231525 
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 231525 2012-02-11 16:41:52Z pjd $");
32
33#include <sys/queue.h>
34
35#include <stdbool.h>
36#include <stdlib.h>
37#include <unistd.h>
38
39#include <pjdlog.h>
40
41#include "rangelock.h"
42
43#ifndef	PJDLOG_ASSERT
44#include <assert.h>
45#define	PJDLOG_ASSERT(...)	assert(__VA_ARGS__)
46#endif
47
48#define	RANGELOCKS_MAGIC	0x94310c
49struct rangelocks {
50	int	 rls_magic;		/* Magic value. */
51	TAILQ_HEAD(, rlock) rls_locks;	/* List of locked ranges. */
52};
53
54struct rlock {
55	off_t	rl_start;
56	off_t	rl_end;
57	TAILQ_ENTRY(rlock) rl_next;
58};
59
60int
61rangelock_init(struct rangelocks **rlsp)
62{
63	struct rangelocks *rls;
64
65	PJDLOG_ASSERT(rlsp != NULL);
66
67	rls = malloc(sizeof(*rls));
68	if (rls == NULL)
69		return (-1);
70
71	TAILQ_INIT(&rls->rls_locks);
72
73	rls->rls_magic = RANGELOCKS_MAGIC;
74	*rlsp = rls;
75
76	return (0);
77}
78
79void
80rangelock_free(struct rangelocks *rls)
81{
82	struct rlock *rl;
83
84	PJDLOG_ASSERT(rls->rls_magic == RANGELOCKS_MAGIC);
85
86	rls->rls_magic = 0;
87
88	while ((rl = TAILQ_FIRST(&rls->rls_locks)) != NULL) {
89		TAILQ_REMOVE(&rls->rls_locks, rl, rl_next);
90		free(rl);
91	}
92	free(rls);
93}
94
95int
96rangelock_add(struct rangelocks *rls, off_t offset, off_t length)
97{
98	struct rlock *rl;
99
100	PJDLOG_ASSERT(rls->rls_magic == RANGELOCKS_MAGIC);
101
102	rl = malloc(sizeof(*rl));
103	if (rl == NULL)
104		return (-1);
105	rl->rl_start = offset;
106	rl->rl_end = offset + length;
107	TAILQ_INSERT_TAIL(&rls->rls_locks, rl, rl_next);
108	return (0);
109}
110
111void
112rangelock_del(struct rangelocks *rls, off_t offset, off_t length)
113{
114	struct rlock *rl;
115
116	PJDLOG_ASSERT(rls->rls_magic == RANGELOCKS_MAGIC);
117
118	TAILQ_FOREACH(rl, &rls->rls_locks, rl_next) {
119		if (rl->rl_start == offset && rl->rl_end == offset + length)
120			break;
121	}
122	PJDLOG_ASSERT(rl != NULL);
123	TAILQ_REMOVE(&rls->rls_locks, rl, rl_next);
124	free(rl);
125}
126
127bool
128rangelock_islocked(struct rangelocks *rls, off_t offset, off_t length)
129{
130	struct rlock *rl;
131	off_t end;
132
133	PJDLOG_ASSERT(rls->rls_magic == RANGELOCKS_MAGIC);
134
135	end = offset + length;
136	TAILQ_FOREACH(rl, &rls->rls_locks, rl_next) {
137		if (rl->rl_start < end && rl->rl_end > offset)
138			break;
139	}
140	return (rl != NULL);
141}
142