1 // SPDX-License-Identifier: CDDL-1.0
2 /*
3 * CDDL HEADER START
4 *
5 * The contents of this file are subject to the terms of the
6 * Common Development and Distribution License (the "License").
7 * You may not use this file except in compliance with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or https://opensource.org/licenses/CDDL-1.0.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22
23 /*
24 * Copyright (c) 2017, Lawrence Livermore National Security, LLC.
25 */
26
27 #include <sys/zfs_ratelimit.h>
28
29 /*
30 * Initialize rate limit struct
31 *
32 * rl: zfs_ratelimit_t struct
33 * burst: Number to allow in an interval before rate limiting
34 * interval: Interval time in seconds
35 */
36 void
zfs_ratelimit_init(zfs_ratelimit_t * rl,unsigned int * burst,unsigned int interval)37 zfs_ratelimit_init(zfs_ratelimit_t *rl, unsigned int *burst,
38 unsigned int interval)
39 {
40 rl->count = 0;
41 rl->start = 0;
42 rl->interval = interval;
43 rl->burst = burst;
44 mutex_init(&rl->lock, NULL, MUTEX_DEFAULT, NULL);
45 }
46
47 /*
48 * Finalize rate limit struct
49 *
50 * rl: zfs_ratelimit_t struct
51 */
52 void
zfs_ratelimit_fini(zfs_ratelimit_t * rl)53 zfs_ratelimit_fini(zfs_ratelimit_t *rl)
54 {
55 mutex_destroy(&rl->lock);
56 }
57
58 /*
59 * Re-implementation of the kernel's __ratelimit() function
60 *
61 * We had to write our own rate limiter because the kernel's __ratelimit()
62 * function annoyingly prints out how many times it rate limited to the kernel
63 * logs (and there's no way to turn it off):
64 *
65 * __ratelimit: 59 callbacks suppressed
66 *
67 * If the kernel ever allows us to disable these prints, we should go back to
68 * using __ratelimit() instead.
69 *
70 * Return values are the same as __ratelimit():
71 *
72 * 0: If we're rate limiting
73 * 1: If we're not rate limiting.
74 */
75 int
zfs_ratelimit(zfs_ratelimit_t * rl)76 zfs_ratelimit(zfs_ratelimit_t *rl)
77 {
78 hrtime_t now;
79
80 hrtime_t elapsed;
81 int error = 1;
82
83 mutex_enter(&rl->lock);
84
85 now = gethrtime();
86 elapsed = now - rl->start;
87
88 rl->count++;
89 if (NSEC2SEC(elapsed) >= rl->interval) {
90 rl->start = now;
91 rl->count = 0;
92 } else {
93 if (rl->count >= *rl->burst) {
94 error = 0; /* We're ratelimiting */
95 }
96 }
97 mutex_exit(&rl->lock);
98
99 return (error);
100 }
101