Linux kernel mirror (for testing)
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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* CacheFiles statistics
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/module.h>
9#include <linux/proc_fs.h>
10#include <linux/seq_file.h>
11#include "internal.h"
12
13atomic_t cachefiles_lookup_histogram[HZ];
14atomic_t cachefiles_mkdir_histogram[HZ];
15atomic_t cachefiles_create_histogram[HZ];
16
17/*
18 * display the latency histogram
19 */
20static int cachefiles_histogram_show(struct seq_file *m, void *v)
21{
22 unsigned long index;
23 unsigned x, y, z, t;
24
25 switch ((unsigned long) v) {
26 case 1:
27 seq_puts(m, "JIFS SECS LOOKUPS MKDIRS CREATES\n");
28 return 0;
29 case 2:
30 seq_puts(m, "===== ===== ========= ========= =========\n");
31 return 0;
32 default:
33 index = (unsigned long) v - 3;
34 x = atomic_read(&cachefiles_lookup_histogram[index]);
35 y = atomic_read(&cachefiles_mkdir_histogram[index]);
36 z = atomic_read(&cachefiles_create_histogram[index]);
37 if (x == 0 && y == 0 && z == 0)
38 return 0;
39
40 t = (index * 1000) / HZ;
41
42 seq_printf(m, "%4lu 0.%03u %9u %9u %9u\n", index, t, x, y, z);
43 return 0;
44 }
45}
46
47/*
48 * set up the iterator to start reading from the first line
49 */
50static void *cachefiles_histogram_start(struct seq_file *m, loff_t *_pos)
51{
52 if ((unsigned long long)*_pos >= HZ + 2)
53 return NULL;
54 if (*_pos == 0)
55 *_pos = 1;
56 return (void *)(unsigned long) *_pos;
57}
58
59/*
60 * move to the next line
61 */
62static void *cachefiles_histogram_next(struct seq_file *m, void *v, loff_t *pos)
63{
64 (*pos)++;
65 return (unsigned long long)*pos > HZ + 2 ?
66 NULL : (void *)(unsigned long) *pos;
67}
68
69/*
70 * clean up after reading
71 */
72static void cachefiles_histogram_stop(struct seq_file *m, void *v)
73{
74}
75
76static const struct seq_operations cachefiles_histogram_ops = {
77 .start = cachefiles_histogram_start,
78 .stop = cachefiles_histogram_stop,
79 .next = cachefiles_histogram_next,
80 .show = cachefiles_histogram_show,
81};
82
83/*
84 * initialise the /proc/fs/cachefiles/ directory
85 */
86int __init cachefiles_proc_init(void)
87{
88 _enter("");
89
90 if (!proc_mkdir("fs/cachefiles", NULL))
91 goto error_dir;
92
93 if (!proc_create_seq("fs/cachefiles/histogram", S_IFREG | 0444, NULL,
94 &cachefiles_histogram_ops))
95 goto error_histogram;
96
97 _leave(" = 0");
98 return 0;
99
100error_histogram:
101 remove_proc_entry("fs/cachefiles", NULL);
102error_dir:
103 _leave(" = -ENOMEM");
104 return -ENOMEM;
105}
106
107/*
108 * clean up the /proc/fs/cachefiles/ directory
109 */
110void cachefiles_proc_cleanup(void)
111{
112 remove_proc_entry("fs/cachefiles/histogram", NULL);
113 remove_proc_entry("fs/cachefiles", NULL);
114}