oprofilefs.c revision 6038f373a3dc1f1c26496e60b6c40b164716f07e 
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	.llseek		= default_llseek,
121};
122
123
124static const struct file_operations ulong_ro_fops = {
125	.read		= ulong_read_file,
126	.open		= default_open,
127	.llseek		= default_llseek,
128};
129
130
131static struct dentry *__oprofilefs_create_file(struct super_block *sb,
132	struct dentry *root, char const *name, const struct file_operations *fops,
133	int perm)
134{
135	struct dentry *dentry;
136	struct inode *inode;
137
138	dentry = d_alloc_name(root, name);
139	if (!dentry)
140		return NULL;
141	inode = oprofilefs_get_inode(sb, S_IFREG | perm);
142	if (!inode) {
143		dput(dentry);
144		return NULL;
145	}
146	inode->i_fop = fops;
147	d_add(dentry, inode);
148	return dentry;
149}
150
151
152int oprofilefs_create_ulong(struct super_block *sb, struct dentry *root,
153	char const *name, unsigned long *val)
154{
155	struct dentry *d = __oprofilefs_create_file(sb, root, name,
156						     &ulong_fops, 0644);
157	if (!d)
158		return -EFAULT;
159
160	d->d_inode->i_private = val;
161	return 0;
162}
163
164
165int oprofilefs_create_ro_ulong(struct super_block *sb, struct dentry *root,
166	char const *name, unsigned long *val)
167{
168	struct dentry *d = __oprofilefs_create_file(sb, root, name,
169						     &ulong_ro_fops, 0444);
170	if (!d)
171		return -EFAULT;
172
173	d->d_inode->i_private = val;
174	return 0;
175}
176
177
178static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
179{
180	atomic_t *val = file->private_data;
181	return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
182}
183
184
185static const struct file_operations atomic_ro_fops = {
186	.read		= atomic_read_file,
187	.open		= default_open,
188	.llseek		= default_llseek,
189};
190
191
192int oprofilefs_create_ro_atomic(struct super_block *sb, struct dentry *root,
193	char const *name, atomic_t *val)
194{
195	struct dentry *d = __oprofilefs_create_file(sb, root, name,
196						     &atomic_ro_fops, 0444);
197	if (!d)
198		return -EFAULT;
199
200	d->d_inode->i_private = val;
201	return 0;
202}
203
204
205int oprofilefs_create_file(struct super_block *sb, struct dentry *root,
206	char const *name, const struct file_operations *fops)
207{
208	if (!__oprofilefs_create_file(sb, root, name, fops, 0644))
209		return -EFAULT;
210	return 0;
211}
212
213
214int oprofilefs_create_file_perm(struct super_block *sb, struct dentry *root,
215	char const *name, const struct file_operations *fops, int perm)
216{
217	if (!__oprofilefs_create_file(sb, root, name, fops, perm))
218		return -EFAULT;
219	return 0;
220}
221
222
223struct dentry *oprofilefs_mkdir(struct super_block *sb,
224	struct dentry *root, char const *name)
225{
226	struct dentry *dentry;
227	struct inode *inode;
228
229	dentry = d_alloc_name(root, name);
230	if (!dentry)
231		return NULL;
232	inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
233	if (!inode) {
234		dput(dentry);
235		return NULL;
236	}
237	inode->i_op = &simple_dir_inode_operations;
238	inode->i_fop = &simple_dir_operations;
239	d_add(dentry, inode);
240	return dentry;
241}
242
243
244static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
245{
246	struct inode *root_inode;
247	struct dentry *root_dentry;
248
249	sb->s_blocksize = PAGE_CACHE_SIZE;
250	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
251	sb->s_magic = OPROFILEFS_MAGIC;
252	sb->s_op = &s_ops;
253	sb->s_time_gran = 1;
254
255	root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
256	if (!root_inode)
257		return -ENOMEM;
258	root_inode->i_op = &simple_dir_inode_operations;
259	root_inode->i_fop = &simple_dir_operations;
260	root_dentry = d_alloc_root(root_inode);
261	if (!root_dentry) {
262		iput(root_inode);
263		return -ENOMEM;
264	}
265
266	sb->s_root = root_dentry;
267
268	oprofile_create_files(sb, root_dentry);
269
270	// FIXME: verify kill_litter_super removes our dentries
271	return 0;
272}
273
274
275static int oprofilefs_get_sb(struct file_system_type *fs_type,
276	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
277{
278	return get_sb_single(fs_type, flags, data, oprofilefs_fill_super, mnt);
279}
280
281
282static struct file_system_type oprofilefs_type = {
283	.owner		= THIS_MODULE,
284	.name		= "oprofilefs",
285	.get_sb		= oprofilefs_get_sb,
286	.kill_sb	= kill_litter_super,
287};
288
289
290int __init oprofilefs_register(void)
291{
292	return register_filesystem(&oprofilefs_type);
293}
294
295
296void __exit oprofilefs_unregister(void)
297{
298	unregister_filesystem(&oprofilefs_type);
299}
300