oprofilefs.c revision 8e18e2941c53416aa219708e7dcad21fb4bd6794 
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_blksize = PAGE_CACHE_SIZE;
35		inode->i_blocks = 0;
36		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
37	}
38	return inode;
39}
40
41
42static struct super_operations s_ops = {
43	.statfs		= simple_statfs,
44	.drop_inode 	= generic_delete_inode,
45};
46
47
48ssize_t oprofilefs_str_to_user(char const * str, char __user * buf, size_t count, loff_t * offset)
49{
50	return simple_read_from_buffer(buf, count, offset, str, strlen(str));
51}
52
53
54#define TMPBUFSIZE 50
55
56ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user * buf, size_t count, loff_t * offset)
57{
58	char tmpbuf[TMPBUFSIZE];
59	size_t maxlen = snprintf(tmpbuf, TMPBUFSIZE, "%lu\n", val);
60	if (maxlen > TMPBUFSIZE)
61		maxlen = TMPBUFSIZE;
62	return simple_read_from_buffer(buf, count, offset, tmpbuf, maxlen);
63}
64
65
66int oprofilefs_ulong_from_user(unsigned long * val, char const __user * buf, size_t count)
67{
68	char tmpbuf[TMPBUFSIZE];
69
70	if (!count)
71		return 0;
72
73	if (count > TMPBUFSIZE - 1)
74		return -EINVAL;
75
76	memset(tmpbuf, 0x0, TMPBUFSIZE);
77
78	if (copy_from_user(tmpbuf, buf, count))
79		return -EFAULT;
80
81	spin_lock(&oprofilefs_lock);
82	*val = simple_strtoul(tmpbuf, NULL, 0);
83	spin_unlock(&oprofilefs_lock);
84	return 0;
85}
86
87
88static ssize_t ulong_read_file(struct file * file, char __user * buf, size_t count, loff_t * offset)
89{
90	unsigned long * val = file->private_data;
91	return oprofilefs_ulong_to_user(*val, buf, count, offset);
92}
93
94
95static ssize_t ulong_write_file(struct file * file, char const __user * buf, size_t count, loff_t * offset)
96{
97	unsigned long * value = file->private_data;
98	int retval;
99
100	if (*offset)
101		return -EINVAL;
102
103	retval = oprofilefs_ulong_from_user(value, buf, count);
104
105	if (retval)
106		return retval;
107	return count;
108}
109
110
111static int default_open(struct inode * inode, struct file * filp)
112{
113	if (inode->i_private)
114		filp->private_data = inode->i_private;
115	return 0;
116}
117
118
119static struct file_operations ulong_fops = {
120	.read		= ulong_read_file,
121	.write		= ulong_write_file,
122	.open		= default_open,
123};
124
125
126static struct file_operations ulong_ro_fops = {
127	.read		= ulong_read_file,
128	.open		= default_open,
129};
130
131
132static struct dentry * __oprofilefs_create_file(struct super_block * sb,
133	struct dentry * root, char const * name, const struct file_operations * fops,
134	int perm)
135{
136	struct dentry * dentry;
137	struct inode * inode;
138
139	dentry = d_alloc_name(root, name);
140	if (!dentry)
141		return NULL;
142	inode = oprofilefs_get_inode(sb, S_IFREG | perm);
143	if (!inode) {
144		dput(dentry);
145		return NULL;
146	}
147	inode->i_fop = fops;
148	d_add(dentry, inode);
149	return dentry;
150}
151
152
153int oprofilefs_create_ulong(struct super_block * sb, struct dentry * root,
154	char const * name, unsigned long * val)
155{
156	struct dentry * d = __oprofilefs_create_file(sb, root, name,
157						     &ulong_fops, 0644);
158	if (!d)
159		return -EFAULT;
160
161	d->d_inode->i_private = val;
162	return 0;
163}
164
165
166int oprofilefs_create_ro_ulong(struct super_block * sb, struct dentry * root,
167	char const * name, unsigned long * val)
168{
169	struct dentry * d = __oprofilefs_create_file(sb, root, name,
170						     &ulong_ro_fops, 0444);
171	if (!d)
172		return -EFAULT;
173
174	d->d_inode->i_private = val;
175	return 0;
176}
177
178
179static ssize_t atomic_read_file(struct file * file, char __user * buf, size_t count, loff_t * offset)
180{
181	atomic_t * val = file->private_data;
182	return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
183}
184
185
186static struct file_operations atomic_ro_fops = {
187	.read		= atomic_read_file,
188	.open		= default_open,
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