1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or https://opensource.org/licenses/CDDL-1.0.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright (c) 2017, Lawrence Livermore National Security, LLC.
24 */
25
26 #include <sys/zfs_ratelimit.h>
27
28 /*
29 * Initialize rate limit struct
30 *
31 * rl: zfs_ratelimit_t struct
32 * burst: Number to allow in an interval before rate limiting
33 * interval: Interval time in seconds
34 */
35 void
zfs_ratelimit_init(zfs_ratelimit_t * rl,unsigned int * burst,unsigned int interval)36 zfs_ratelimit_init(zfs_ratelimit_t *rl, unsigned int *burst,
37 unsigned int interval)
38 {
39 rl->count = 0;
40 rl->start = 0;
41 rl->interval = interval;
42 rl->burst = burst;
43 mutex_init(&rl->lock, NULL, MUTEX_DEFAULT, NULL);
44 }
45
46 /*
47 * Finalize rate limit struct
48 *
49 * rl: zfs_ratelimit_t struct
50 */
51 void
zfs_ratelimit_fini(zfs_ratelimit_t * rl)52 zfs_ratelimit_fini(zfs_ratelimit_t *rl)
53 {
54 mutex_destroy(&rl->lock);
55 }
56
57 /*
58 * Re-implementation of the kernel's __ratelimit() function
59 *
60 * We had to write our own rate limiter because the kernel's __ratelimit()
61 * function annoyingly prints out how many times it rate limited to the kernel
62 * logs (and there's no way to turn it off):
63 *
64 * __ratelimit: 59 callbacks suppressed
65 *
66 * If the kernel ever allows us to disable these prints, we should go back to
67 * using __ratelimit() instead.
68 *
69 * Return values are the same as __ratelimit():
70 *
71 * 0: If we're rate limiting
72 * 1: If we're not rate limiting.
73 */
74 int
zfs_ratelimit(zfs_ratelimit_t * rl)75 zfs_ratelimit(zfs_ratelimit_t *rl)
76 {
77 hrtime_t now;
78
79 hrtime_t elapsed;
80 int error = 1;
81
82 mutex_enter(&rl->lock);
83
84 now = gethrtime();
85 elapsed = now - rl->start;
86
87 rl->count++;
88 if (NSEC2SEC(elapsed) >= rl->interval) {
89 rl->start = now;
90 rl->count = 0;
91 } else {
92 if (rl->count >= *rl->burst) {
93 error = 0; /* We're ratelimiting */
94 }
95 }
96 mutex_exit(&rl->lock);
97
98 return (error);
99 }
100