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
13 atomic_t cachefiles_lookup_histogram[HZ];
14 atomic_t cachefiles_mkdir_histogram[HZ];
15 atomic_t cachefiles_create_histogram[HZ];
16
17 /*
18 * display the latency histogram
19 */
cachefiles_histogram_show(struct seq_file * m,void * v)20 static 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 */
cachefiles_histogram_start(struct seq_file * m,loff_t * _pos)50 static 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 */
cachefiles_histogram_next(struct seq_file * m,void * v,loff_t * pos)62 static 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 */
cachefiles_histogram_stop(struct seq_file * m,void * v)72 static void cachefiles_histogram_stop(struct seq_file *m, void *v)
73 {
74 }
75
76 static 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 */
cachefiles_proc_init(void)86 int __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
100 error_histogram:
101 remove_proc_entry("fs/cachefiles", NULL);
102 error_dir:
103 _leave(" = -ENOMEM");
104 return -ENOMEM;
105 }
106
107 /*
108 * clean up the /proc/fs/cachefiles/ directory
109 */
cachefiles_proc_cleanup(void)110 void cachefiles_proc_cleanup(void)
111 {
112 remove_proc_entry("fs/cachefiles/histogram", NULL);
113 remove_proc_entry("fs/cachefiles", NULL);
114 }
115
