1/* CacheFiles statistics
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12#include <linux/module.h>
13#include <linux/proc_fs.h>
14#include <linux/seq_file.h>
15#include "internal.h"
16
17atomic_t cachefiles_lookup_histogram[HZ];
18atomic_t cachefiles_mkdir_histogram[HZ];
19atomic_t cachefiles_create_histogram[HZ];
20
21/*
22 * display the latency histogram
23 */
24static int cachefiles_histogram_show(struct seq_file *m, void *v)
25{
26	unsigned long index;
27	unsigned x, y, z, t;
28
29	switch ((unsigned long) v) {
30	case 1:
31		seq_puts(m, "JIFS  SECS  LOOKUPS   MKDIRS    CREATES\n");
32		return 0;
33	case 2:
34		seq_puts(m, "===== ===== ========= ========= =========\n");
35		return 0;
36	default:
37		index = (unsigned long) v - 3;
38		x = atomic_read(&cachefiles_lookup_histogram[index]);
39		y = atomic_read(&cachefiles_mkdir_histogram[index]);
40		z = atomic_read(&cachefiles_create_histogram[index]);
41		if (x == 0 && y == 0 && z == 0)
42			return 0;
43
44		t = (index * 1000) / HZ;
45
46		seq_printf(m, "%4lu  0.%03u %9u %9u %9u\n", index, t, x, y, z);
47		return 0;
48	}
49}
50
51/*
52 * set up the iterator to start reading from the first line
53 */
54static void *cachefiles_histogram_start(struct seq_file *m, loff_t *_pos)
55{
56	if ((unsigned long long)*_pos >= HZ + 2)
57		return NULL;
58	if (*_pos == 0)
59		*_pos = 1;
60	return (void *)(unsigned long) *_pos;
61}
62
63/*
64 * move to the next line
65 */
66static void *cachefiles_histogram_next(struct seq_file *m, void *v, loff_t *pos)
67{
68	(*pos)++;
69	return (unsigned long long)*pos > HZ + 2 ?
70		NULL : (void *)(unsigned long) *pos;
71}
72
73/*
74 * clean up after reading
75 */
76static void cachefiles_histogram_stop(struct seq_file *m, void *v)
77{
78}
79
80static const struct seq_operations cachefiles_histogram_ops = {
81	.start		= cachefiles_histogram_start,
82	.stop		= cachefiles_histogram_stop,
83	.next		= cachefiles_histogram_next,
84	.show		= cachefiles_histogram_show,
85};
86
87/*
88 * open "/proc/fs/cachefiles/XXX" which provide statistics summaries
89 */
90static int cachefiles_histogram_open(struct inode *inode, struct file *file)
91{
92	return seq_open(file, &cachefiles_histogram_ops);
93}
94
95static const struct file_operations cachefiles_histogram_fops = {
96	.owner		= THIS_MODULE,
97	.open		= cachefiles_histogram_open,
98	.read		= seq_read,
99	.llseek		= seq_lseek,
100	.release	= seq_release,
101};
102
103/*
104 * initialise the /proc/fs/cachefiles/ directory
105 */
106int __init cachefiles_proc_init(void)
107{
108	_enter("");
109
110	if (!proc_mkdir("fs/cachefiles", NULL))
111		goto error_dir;
112
113	if (!proc_create("fs/cachefiles/histogram", S_IFREG | 0444, NULL,
114			 &cachefiles_histogram_fops))
115		goto error_histogram;
116
117	_leave(" = 0");
118	return 0;
119
120error_histogram:
121	remove_proc_entry("fs/cachefiles", NULL);
122error_dir:
123	_leave(" = -ENOMEM");
124	return -ENOMEM;
125}
126
127/*
128 * clean up the /proc/fs/cachefiles/ directory
129 */
130void cachefiles_proc_cleanup(void)
131{
132	remove_proc_entry("fs/cachefiles/histogram", NULL);
133	remove_proc_entry("fs/cachefiles", NULL);
134}
135