geom_stats.c revision 319018 
1/*-
2 * Copyright (c) 2003 Poul-Henning Kamp
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. The names of the authors may not be used to endorse or promote
14 *    products derived from this software without specific prior written
15 *    permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 * $FreeBSD: stable/10/lib/libgeom/geom_stats.c 319018 2017-05-28 00:25:44Z ngie $
30 */
31
32#include <sys/types.h>
33#include <sys/devicestat.h>
34#include <sys/mman.h>
35#include <sys/time.h>
36#include <errno.h>
37#include <fcntl.h>
38#include <paths.h>
39#include <stdlib.h>
40#include <string.h>
41#include <unistd.h>
42#include <libgeom.h>
43
44/************************************************************/
45static uint npages, pagesize, spp;
46static int statsfd = -1;
47static u_char *statp;
48
49void
50geom_stats_close(void)
51{
52	if (statsfd == -1)
53		return;
54	munmap(statp, npages *pagesize);
55	statp = NULL;
56	close (statsfd);
57	statsfd = -1;
58}
59
60void
61geom_stats_resync(void)
62{
63	void *p;
64
65	if (statsfd == -1)
66		return;
67	for (;;) {
68		p = mmap(statp, (npages + 1) * pagesize,
69		    PROT_READ, MAP_SHARED, statsfd, 0);
70		if (p == MAP_FAILED)
71			break;
72		else
73			statp = p;
74		npages++;
75	}
76}
77
78int
79geom_stats_open(void)
80{
81	int error;
82	void *p;
83
84	if (statsfd != -1)
85		return (EBUSY);
86	statsfd = open(_PATH_DEV DEVSTAT_DEVICE_NAME, O_RDONLY);
87	if (statsfd < 0)
88		return (errno);
89	pagesize = getpagesize();
90	spp = pagesize / sizeof(struct devstat);
91	p = mmap(NULL, pagesize, PROT_READ, MAP_SHARED, statsfd, 0);
92	if (p == MAP_FAILED) {
93		error = errno;
94		close(statsfd);
95		statsfd = -1;
96		errno = error;
97		return (error);
98	}
99	statp = p;
100	npages = 1;
101	geom_stats_resync();
102	return (0);
103}
104
105struct snapshot {
106	u_char		*ptr;
107	uint		pages;
108	uint		pagesize;
109	uint		perpage;
110	struct timespec	time;
111	/* used by getnext: */
112	uint		u, v;
113};
114
115void *
116geom_stats_snapshot_get(void)
117{
118	struct snapshot *sp;
119
120	sp = malloc(sizeof *sp);
121	if (sp == NULL)
122		return (NULL);
123	memset(sp, 0, sizeof *sp);
124	sp->ptr = malloc(pagesize * npages);
125	if (sp->ptr == NULL) {
126		free(sp);
127		return (NULL);
128	}
129	memset(sp->ptr, 0, pagesize * npages); 	/* page in, cache */
130	clock_gettime(CLOCK_REALTIME, &sp->time);
131	memset(sp->ptr, 0, pagesize * npages); 	/* page in, cache */
132	memcpy(sp->ptr, statp, pagesize * npages);
133	sp->pages = npages;
134	sp->perpage = spp;
135	sp->pagesize = pagesize;
136	return (sp);
137}
138
139void
140geom_stats_snapshot_free(void *arg)
141{
142	struct snapshot *sp;
143
144	sp = arg;
145	free(sp->ptr);
146	free(sp);
147}
148
149void
150geom_stats_snapshot_timestamp(void *arg, struct timespec *tp)
151{
152	struct snapshot *sp;
153
154	sp = arg;
155	*tp = sp->time;
156}
157
158void
159geom_stats_snapshot_reset(void *arg)
160{
161	struct snapshot *sp;
162
163	sp = arg;
164	sp->u = sp->v = 0;
165}
166
167struct devstat *
168geom_stats_snapshot_next(void *arg)
169{
170	struct devstat *gsp;
171	struct snapshot *sp;
172
173	sp = arg;
174	gsp = (struct devstat *)
175	    (sp->ptr + sp->u * pagesize + sp->v * sizeof *gsp);
176	if (++sp->v >= sp->perpage) {
177		if (++sp->u >= sp->pages)
178			return (NULL);
179		else
180			sp->v = 0;
181	}
182	return (gsp);
183}
184