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}