oprofilefs.c revision 4fdaa7b682b413dfb7ca9fa74ff45b1e0cb3dade 
1/**
2 * @file oprofilefs.c
3 *
4 * @remark Copyright 2002 OProfile authors
5 * @remark Read the file COPYING
6 *
7 * @author John Levon
8 *
9 * A simple filesystem for configuration and
10 * access of oprofile.
11 */
12
13#include <linux/init.h>
14#include <linux/module.h>
15#include <linux/oprofile.h>
16#include <linux/fs.h>
17#include <linux/pagemap.h>
18#include <asm/uaccess.h>
19
20#include "oprof.h"
21
22#define OPROFILEFS_MAGIC 0x6f70726f
23
24DEFINE_SPINLOCK(oprofilefs_lock);
25
26static struct inode *oprofilefs_get_inode(struct super_block *sb, int mode)
27{
28	struct inode *inode = new_inode(sb);
29
30	if (inode) {
31		inode->i_mode = mode;
32		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
33	}
34	return inode;
35}
36
37
38static const struct super_operations s_ops = {
39	.statfs		= simple_statfs,
40	.drop_inode 	= generic_delete_inode,
41};
42
43
44ssize_t oprofilefs_str_to_user(char const *str, char __user *buf, size_t count, loff_t *offset)
45{
46	return simple_read_from_buffer(buf, count, offset, str, strlen(str));
47}
48
49
50#define TMPBUFSIZE 50
51
52ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user *buf, size_t count, loff_t *offset)
53{
54	char tmpbuf[TMPBUFSIZE];
55	size_t maxlen = snprintf(tmpbuf, TMPBUFSIZE, "%lu\n", val);
56	if (maxlen > TMPBUFSIZE)
57		maxlen = TMPBUFSIZE;
58	return simple_read_from_buffer(buf, count, offset, tmpbuf, maxlen);
59}
60
61
62int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count)
63{
64	char tmpbuf[TMPBUFSIZE];
65	unsigned long flags;
66
67	if (!count)
68		return 0;
69
70	if (count > TMPBUFSIZE - 1)
71		return -EINVAL;
72
73	memset(tmpbuf, 0x0, TMPBUFSIZE);
74
75	if (copy_from_user(tmpbuf, buf, count))
76		return -EFAULT;
77
78	spin_lock_irqsave(&oprofilefs_lock, flags);
79	*val = simple_strtoul(tmpbuf, NULL, 0);
80	spin_unlock_irqrestore(&oprofilefs_lock, flags);
81	return 0;
82}
83
84
85static ssize_t ulong_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
86{
87	unsigned long *val = file->private_data;
88	return oprofilefs_ulong_to_user(*val, buf, count, offset);
89}
90
91
92static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_t count, loff_t *offset)
93{
94	unsigned long *value = file->private_data;
95	int retval;
96
97	if (*offset)
98		return -EINVAL;
99
100	retval = oprofilefs_ulong_from_user(value, buf, count);
101
102	if (retval)
103		return retval;
104	return count;
105}
106
107
108static int default_open(struct inode *inode, struct file *filp)
109{
110	if (inode->i_private)
111		filp->private_data = inode->i_private;
112	return 0;
113}
114
115
116static const struct file_operations ulong_fops = {
117	.read		= ulong_read_file,
118	.write		= ulong_write_file,
119	.open		= default_open,
120};
121
122
123static const struct file_operations ulong_ro_fops = {
124	.read		= ulong_read_file,
125	.open		= default_open,
126};
127
128
129static int __oprofilefs_create_file(struct super_block *sb,
130	struct dentry *root, char const *name, const struct file_operations *fops,
131	int perm, void *priv)
132{
133	struct dentry *dentry;
134	struct inode *inode;
135
136	dentry = d_alloc_name(root, name);
137	if (!dentry)
138		return -ENOMEM;
139	inode = oprofilefs_get_inode(sb, S_IFREG | perm);
140	if (!inode) {
141		dput(dentry);
142		return -ENOMEM;
143	}
144	inode->i_fop = fops;
145	d_add(dentry, inode);
146	dentry->d_inode->i_private = priv;
147	return 0;
148}
149
150
151int oprofilefs_create_ulong(struct super_block *sb, struct dentry *root,
152	char const *name, unsigned long *val)
153{
154	return __oprofilefs_create_file(sb, root, name,
155					&ulong_fops, 0644, val);
156}
157
158
159int oprofilefs_create_ro_ulong(struct super_block *sb, struct dentry *root,
160	char const *name, unsigned long *val)
161{
162	return __oprofilefs_create_file(sb, root, name,
163					&ulong_ro_fops, 0444, val);
164}
165
166
167static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
168{
169	atomic_t *val = file->private_data;
170	return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
171}
172
173
174static const struct file_operations atomic_ro_fops = {
175	.read		= atomic_read_file,
176	.open		= default_open,
177};
178
179
180int oprofilefs_create_ro_atomic(struct super_block *sb, struct dentry *root,
181	char const *name, atomic_t *val)
182{
183	return __oprofilefs_create_file(sb, root, name,
184					&atomic_ro_fops, 0444, val);
185}
186
187
188int oprofilefs_create_file(struct super_block *sb, struct dentry *root,
189	char const *name, const struct file_operations *fops)
190{
191	return __oprofilefs_create_file(sb, root, name, fops, 0644, NULL);
192}
193
194
195int oprofilefs_create_file_perm(struct super_block *sb, struct dentry *root,
196	char const *name, const struct file_operations *fops, int perm)
197{
198	return __oprofilefs_create_file(sb, root, name, fops, perm, NULL);
199}
200
201
202struct dentry *oprofilefs_mkdir(struct super_block *sb,
203	struct dentry *root, char const *name)
204{
205	struct dentry *dentry;
206	struct inode *inode;
207
208	dentry = d_alloc_name(root, name);
209	if (!dentry)
210		return NULL;
211	inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
212	if (!inode) {
213		dput(dentry);
214		return NULL;
215	}
216	inode->i_op = &simple_dir_inode_operations;
217	inode->i_fop = &simple_dir_operations;
218	d_add(dentry, inode);
219	return dentry;
220}
221
222
223static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
224{
225	struct inode *root_inode;
226	struct dentry *root_dentry;
227
228	sb->s_blocksize = PAGE_CACHE_SIZE;
229	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
230	sb->s_magic = OPROFILEFS_MAGIC;
231	sb->s_op = &s_ops;
232	sb->s_time_gran = 1;
233
234	root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
235	if (!root_inode)
236		return -ENOMEM;
237	root_inode->i_op = &simple_dir_inode_operations;
238	root_inode->i_fop = &simple_dir_operations;
239	root_dentry = d_alloc_root(root_inode);
240	if (!root_dentry) {
241		iput(root_inode);
242		return -ENOMEM;
243	}
244
245	sb->s_root = root_dentry;
246
247	oprofile_create_files(sb, root_dentry);
248
249	// FIXME: verify kill_litter_super removes our dentries
250	return 0;
251}
252
253
254static int oprofilefs_get_sb(struct file_system_type *fs_type,
255	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
256{
257	return get_sb_single(fs_type, flags, data, oprofilefs_fill_super, mnt);
258}
259
260
261static struct file_system_type oprofilefs_type = {
262	.owner		= THIS_MODULE,
263	.name		= "oprofilefs",
264	.get_sb		= oprofilefs_get_sb,
265	.kill_sb	= kill_litter_super,
266};
267
268
269int __init oprofilefs_register(void)
270{
271	return register_filesystem(&oprofilefs_type);
272}
273
274
275void __exit oprofilefs_unregister(void)
276{
277	unregister_filesystem(&oprofilefs_type);
278}
279