oprofilefs.c revision d54b1fdb1d9f82e375a299e22bd366aad52d4c34 
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_uid = 0;
33		inode->i_gid = 0;
34		inode->i_blocks = 0;
35		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
36	}
37	return inode;
38}
39
40
41static struct super_operations s_ops = {
42	.statfs		= simple_statfs,
43	.drop_inode 	= generic_delete_inode,
44};
45
46
47ssize_t oprofilefs_str_to_user(char const * str, char __user * buf, size_t count, loff_t * offset)
48{
49	return simple_read_from_buffer(buf, count, offset, str, strlen(str));
50}
51
52
53#define TMPBUFSIZE 50
54
55ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user * buf, size_t count, loff_t * offset)
56{
57	char tmpbuf[TMPBUFSIZE];
58	size_t maxlen = snprintf(tmpbuf, TMPBUFSIZE, "%lu\n", val);
59	if (maxlen > TMPBUFSIZE)
60		maxlen = TMPBUFSIZE;
61	return simple_read_from_buffer(buf, count, offset, tmpbuf, maxlen);
62}
63
64
65int oprofilefs_ulong_from_user(unsigned long * val, char const __user * buf, size_t count)
66{
67	char tmpbuf[TMPBUFSIZE];
68
69	if (!count)
70		return 0;
71
72	if (count > TMPBUFSIZE - 1)
73		return -EINVAL;
74
75	memset(tmpbuf, 0x0, TMPBUFSIZE);
76
77	if (copy_from_user(tmpbuf, buf, count))
78		return -EFAULT;
79
80	spin_lock(&oprofilefs_lock);
81	*val = simple_strtoul(tmpbuf, NULL, 0);
82	spin_unlock(&oprofilefs_lock);
83	return 0;
84}
85
86
87static ssize_t ulong_read_file(struct file * file, char __user * buf, size_t count, loff_t * offset)
88{
89	unsigned long * val = file->private_data;
90	return oprofilefs_ulong_to_user(*val, buf, count, offset);
91}
92
93
94static ssize_t ulong_write_file(struct file * file, char const __user * buf, size_t count, loff_t * offset)
95{
96	unsigned long * value = file->private_data;
97	int retval;
98
99	if (*offset)
100		return -EINVAL;
101
102	retval = oprofilefs_ulong_from_user(value, buf, count);
103
104	if (retval)
105		return retval;
106	return count;
107}
108
109
110static int default_open(struct inode * inode, struct file * filp)
111{
112	if (inode->i_private)
113		filp->private_data = inode->i_private;
114	return 0;
115}
116
117
118static const struct file_operations ulong_fops = {
119	.read		= ulong_read_file,
120	.write		= ulong_write_file,
121	.open		= default_open,
122};
123
124
125static const struct file_operations ulong_ro_fops = {
126	.read		= ulong_read_file,
127	.open		= default_open,
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};
189
190
191int oprofilefs_create_ro_atomic(struct super_block * sb, struct dentry * root,
192	char const * name, atomic_t * val)
193{
194	struct dentry * d = __oprofilefs_create_file(sb, root, name,
195						     &atomic_ro_fops, 0444);
196	if (!d)
197		return -EFAULT;
198
199	d->d_inode->i_private = val;
200	return 0;
201}
202
203
204int oprofilefs_create_file(struct super_block * sb, struct dentry * root,
205	char const * name, const struct file_operations * fops)
206{
207	if (!__oprofilefs_create_file(sb, root, name, fops, 0644))
208		return -EFAULT;
209	return 0;
210}
211
212
213int oprofilefs_create_file_perm(struct super_block * sb, struct dentry * root,
214	char const * name, const struct file_operations * fops, int perm)
215{
216	if (!__oprofilefs_create_file(sb, root, name, fops, perm))
217		return -EFAULT;
218	return 0;
219}
220
221
222struct dentry * oprofilefs_mkdir(struct super_block * sb,
223	struct dentry * root, char const * name)
224{
225	struct dentry * dentry;
226	struct inode * inode;
227
228	dentry = d_alloc_name(root, name);
229	if (!dentry)
230		return NULL;
231	inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
232	if (!inode) {
233		dput(dentry);
234		return NULL;
235	}
236	inode->i_op = &simple_dir_inode_operations;
237	inode->i_fop = &simple_dir_operations;
238	d_add(dentry, inode);
239	return dentry;
240}
241
242
243static int oprofilefs_fill_super(struct super_block * sb, void * data, int silent)
244{
245	struct inode * root_inode;
246	struct dentry * root_dentry;
247
248	sb->s_blocksize = PAGE_CACHE_SIZE;
249	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
250	sb->s_magic = OPROFILEFS_MAGIC;
251	sb->s_op = &s_ops;
252	sb->s_time_gran = 1;
253
254	root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
255	if (!root_inode)
256		return -ENOMEM;
257	root_inode->i_op = &simple_dir_inode_operations;
258	root_inode->i_fop = &simple_dir_operations;
259	root_dentry = d_alloc_root(root_inode);
260	if (!root_dentry) {
261		iput(root_inode);
262		return -ENOMEM;
263	}
264
265	sb->s_root = root_dentry;
266
267	oprofile_create_files(sb, root_dentry);
268
269	// FIXME: verify kill_litter_super removes our dentries
270	return 0;
271}
272
273
274static int oprofilefs_get_sb(struct file_system_type *fs_type,
275	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
276{
277	return get_sb_single(fs_type, flags, data, oprofilefs_fill_super, mnt);
278}
279
280
281static struct file_system_type oprofilefs_type = {
282	.owner		= THIS_MODULE,
283	.name		= "oprofilefs",
284	.get_sb		= oprofilefs_get_sb,
285	.kill_sb	= kill_litter_super,
286};
287
288
289int __init oprofilefs_register(void)
290{
291	return register_filesystem(&oprofilefs_type);
292}
293
294
295void __exit oprofilefs_unregister(void)
296{
297	unregister_filesystem(&oprofilefs_type);
298}
299