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1da177e4 LT |
1 | /* |
2 | * file.c - part of debugfs, a tiny little debug file system | |
3 | * | |
4 | * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com> | |
5 | * Copyright (C) 2004 IBM Inc. | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License version | |
9 | * 2 as published by the Free Software Foundation. | |
10 | * | |
11 | * debugfs is for people to use instead of /proc or /sys. | |
12 | * See Documentation/DocBook/kernel-api for more details. | |
13 | * | |
14 | */ | |
15 | ||
16 | /* uncomment to get debug messages from the debug filesystem, ah the irony. */ | |
17 | /* #define DEBUG */ | |
18 | ||
19 | #include <linux/config.h> | |
20 | #include <linux/module.h> | |
21 | #include <linux/fs.h> | |
22 | #include <linux/mount.h> | |
23 | #include <linux/pagemap.h> | |
24 | #include <linux/init.h> | |
25 | #include <linux/namei.h> | |
26 | #include <linux/debugfs.h> | |
27 | ||
28 | #define DEBUGFS_MAGIC 0x64626720 | |
29 | ||
30 | /* declared over in file.c */ | |
31 | extern struct file_operations debugfs_file_operations; | |
32 | ||
33 | static struct vfsmount *debugfs_mount; | |
34 | static int debugfs_mount_count; | |
35 | ||
36 | static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev) | |
37 | { | |
38 | struct inode *inode = new_inode(sb); | |
39 | ||
40 | if (inode) { | |
41 | inode->i_mode = mode; | |
42 | inode->i_uid = 0; | |
43 | inode->i_gid = 0; | |
44 | inode->i_blksize = PAGE_CACHE_SIZE; | |
45 | inode->i_blocks = 0; | |
46 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
47 | switch (mode & S_IFMT) { | |
48 | default: | |
49 | init_special_inode(inode, mode, dev); | |
50 | break; | |
51 | case S_IFREG: | |
52 | inode->i_fop = &debugfs_file_operations; | |
53 | break; | |
54 | case S_IFDIR: | |
55 | inode->i_op = &simple_dir_inode_operations; | |
56 | inode->i_fop = &simple_dir_operations; | |
57 | ||
58 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ | |
59 | inode->i_nlink++; | |
60 | break; | |
61 | } | |
62 | } | |
63 | return inode; | |
64 | } | |
65 | ||
66 | /* SMP-safe */ | |
67 | static int debugfs_mknod(struct inode *dir, struct dentry *dentry, | |
68 | int mode, dev_t dev) | |
69 | { | |
71601e2b | 70 | struct inode *inode; |
1da177e4 LT |
71 | int error = -EPERM; |
72 | ||
73 | if (dentry->d_inode) | |
74 | return -EEXIST; | |
75 | ||
71601e2b | 76 | inode = debugfs_get_inode(dir->i_sb, mode, dev); |
1da177e4 LT |
77 | if (inode) { |
78 | d_instantiate(dentry, inode); | |
79 | dget(dentry); | |
80 | error = 0; | |
81 | } | |
82 | return error; | |
83 | } | |
84 | ||
85 | static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) | |
86 | { | |
87 | int res; | |
88 | ||
89 | mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR; | |
90 | res = debugfs_mknod(dir, dentry, mode, 0); | |
91 | if (!res) | |
92 | dir->i_nlink++; | |
93 | return res; | |
94 | } | |
95 | ||
96 | static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode) | |
97 | { | |
98 | mode = (mode & S_IALLUGO) | S_IFREG; | |
99 | return debugfs_mknod(dir, dentry, mode, 0); | |
100 | } | |
101 | ||
102 | static inline int debugfs_positive(struct dentry *dentry) | |
103 | { | |
104 | return dentry->d_inode && !d_unhashed(dentry); | |
105 | } | |
106 | ||
107 | static int debug_fill_super(struct super_block *sb, void *data, int silent) | |
108 | { | |
109 | static struct tree_descr debug_files[] = {{""}}; | |
110 | ||
111 | return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files); | |
112 | } | |
113 | ||
1da177e4 LT |
114 | static struct super_block *debug_get_sb(struct file_system_type *fs_type, |
115 | int flags, const char *dev_name, | |
116 | void *data) | |
117 | { | |
118 | return get_sb_single(fs_type, flags, data, debug_fill_super); | |
119 | } | |
120 | ||
121 | static struct file_system_type debug_fs_type = { | |
122 | .owner = THIS_MODULE, | |
123 | .name = "debugfs", | |
124 | .get_sb = debug_get_sb, | |
125 | .kill_sb = kill_litter_super, | |
126 | }; | |
127 | ||
128 | static int debugfs_create_by_name(const char *name, mode_t mode, | |
129 | struct dentry *parent, | |
130 | struct dentry **dentry) | |
131 | { | |
132 | int error = 0; | |
133 | ||
134 | /* If the parent is not specified, we create it in the root. | |
135 | * We need the root dentry to do this, which is in the super | |
136 | * block. A pointer to that is in the struct vfsmount that we | |
137 | * have around. | |
138 | */ | |
139 | if (!parent ) { | |
140 | if (debugfs_mount && debugfs_mount->mnt_sb) { | |
141 | parent = debugfs_mount->mnt_sb->s_root; | |
142 | } | |
143 | } | |
144 | if (!parent) { | |
145 | pr_debug("debugfs: Ah! can not find a parent!\n"); | |
146 | return -EFAULT; | |
147 | } | |
148 | ||
149 | *dentry = NULL; | |
1b1dcc1b | 150 | mutex_lock(&parent->d_inode->i_mutex); |
5f45f1a7 | 151 | *dentry = lookup_one_len(name, parent, strlen(name)); |
1da177e4 LT |
152 | if (!IS_ERR(dentry)) { |
153 | if ((mode & S_IFMT) == S_IFDIR) | |
154 | error = debugfs_mkdir(parent->d_inode, *dentry, mode); | |
155 | else | |
156 | error = debugfs_create(parent->d_inode, *dentry, mode); | |
157 | } else | |
158 | error = PTR_ERR(dentry); | |
1b1dcc1b | 159 | mutex_unlock(&parent->d_inode->i_mutex); |
1da177e4 LT |
160 | |
161 | return error; | |
162 | } | |
163 | ||
164 | /** | |
165 | * debugfs_create_file - create a file in the debugfs filesystem | |
166 | * | |
167 | * @name: a pointer to a string containing the name of the file to create. | |
168 | * @mode: the permission that the file should have | |
169 | * @parent: a pointer to the parent dentry for this file. This should be a | |
170 | * directory dentry if set. If this paramater is NULL, then the | |
171 | * file will be created in the root of the debugfs filesystem. | |
172 | * @data: a pointer to something that the caller will want to get to later | |
173 | * on. The inode.u.generic_ip pointer will point to this value on | |
174 | * the open() call. | |
175 | * @fops: a pointer to a struct file_operations that should be used for | |
176 | * this file. | |
177 | * | |
178 | * This is the basic "create a file" function for debugfs. It allows for a | |
179 | * wide range of flexibility in createing a file, or a directory (if you | |
180 | * want to create a directory, the debugfs_create_dir() function is | |
181 | * recommended to be used instead.) | |
182 | * | |
183 | * This function will return a pointer to a dentry if it succeeds. This | |
184 | * pointer must be passed to the debugfs_remove() function when the file is | |
185 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
186 | * you are responsible here.) If an error occurs, NULL will be returned. | |
187 | * | |
188 | * If debugfs is not enabled in the kernel, the value -ENODEV will be | |
189 | * returned. It is not wise to check for this value, but rather, check for | |
190 | * NULL or !NULL instead as to eliminate the need for #ifdef in the calling | |
191 | * code. | |
192 | */ | |
193 | struct dentry *debugfs_create_file(const char *name, mode_t mode, | |
194 | struct dentry *parent, void *data, | |
99ac48f5 | 195 | const struct file_operations *fops) |
1da177e4 LT |
196 | { |
197 | struct dentry *dentry = NULL; | |
198 | int error; | |
199 | ||
200 | pr_debug("debugfs: creating file '%s'\n",name); | |
201 | ||
1f5ce9e9 | 202 | error = simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count); |
1da177e4 LT |
203 | if (error) |
204 | goto exit; | |
205 | ||
206 | error = debugfs_create_by_name(name, mode, parent, &dentry); | |
207 | if (error) { | |
208 | dentry = NULL; | |
209 | goto exit; | |
210 | } | |
211 | ||
212 | if (dentry->d_inode) { | |
213 | if (data) | |
214 | dentry->d_inode->u.generic_ip = data; | |
215 | if (fops) | |
216 | dentry->d_inode->i_fop = fops; | |
217 | } | |
218 | exit: | |
219 | return dentry; | |
220 | } | |
221 | EXPORT_SYMBOL_GPL(debugfs_create_file); | |
222 | ||
223 | /** | |
224 | * debugfs_create_dir - create a directory in the debugfs filesystem | |
225 | * | |
226 | * @name: a pointer to a string containing the name of the directory to | |
227 | * create. | |
228 | * @parent: a pointer to the parent dentry for this file. This should be a | |
229 | * directory dentry if set. If this paramater is NULL, then the | |
230 | * directory will be created in the root of the debugfs filesystem. | |
231 | * | |
232 | * This function creates a directory in debugfs with the given name. | |
233 | * | |
234 | * This function will return a pointer to a dentry if it succeeds. This | |
235 | * pointer must be passed to the debugfs_remove() function when the file is | |
236 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
237 | * you are responsible here.) If an error occurs, NULL will be returned. | |
238 | * | |
239 | * If debugfs is not enabled in the kernel, the value -ENODEV will be | |
240 | * returned. It is not wise to check for this value, but rather, check for | |
241 | * NULL or !NULL instead as to eliminate the need for #ifdef in the calling | |
242 | * code. | |
243 | */ | |
244 | struct dentry *debugfs_create_dir(const char *name, struct dentry *parent) | |
245 | { | |
246 | return debugfs_create_file(name, | |
247 | S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, | |
248 | parent, NULL, NULL); | |
249 | } | |
250 | EXPORT_SYMBOL_GPL(debugfs_create_dir); | |
251 | ||
252 | /** | |
253 | * debugfs_remove - removes a file or directory from the debugfs filesystem | |
254 | * | |
255 | * @dentry: a pointer to a the dentry of the file or directory to be | |
256 | * removed. | |
257 | * | |
258 | * This function removes a file or directory in debugfs that was previously | |
259 | * created with a call to another debugfs function (like | |
260 | * debufs_create_file() or variants thereof.) | |
261 | * | |
262 | * This function is required to be called in order for the file to be | |
263 | * removed, no automatic cleanup of files will happen when a module is | |
264 | * removed, you are responsible here. | |
265 | */ | |
266 | void debugfs_remove(struct dentry *dentry) | |
267 | { | |
268 | struct dentry *parent; | |
269 | ||
270 | if (!dentry) | |
271 | return; | |
272 | ||
273 | parent = dentry->d_parent; | |
274 | if (!parent || !parent->d_inode) | |
275 | return; | |
276 | ||
1b1dcc1b | 277 | mutex_lock(&parent->d_inode->i_mutex); |
1da177e4 LT |
278 | if (debugfs_positive(dentry)) { |
279 | if (dentry->d_inode) { | |
280 | if (S_ISDIR(dentry->d_inode->i_mode)) | |
281 | simple_rmdir(parent->d_inode, dentry); | |
282 | else | |
283 | simple_unlink(parent->d_inode, dentry); | |
284 | dput(dentry); | |
285 | } | |
286 | } | |
1b1dcc1b | 287 | mutex_unlock(&parent->d_inode->i_mutex); |
1da177e4 LT |
288 | simple_release_fs(&debugfs_mount, &debugfs_mount_count); |
289 | } | |
290 | EXPORT_SYMBOL_GPL(debugfs_remove); | |
291 | ||
292 | static decl_subsys(debug, NULL, NULL); | |
293 | ||
294 | static int __init debugfs_init(void) | |
295 | { | |
296 | int retval; | |
297 | ||
298 | kset_set_kset_s(&debug_subsys, kernel_subsys); | |
299 | retval = subsystem_register(&debug_subsys); | |
300 | if (retval) | |
301 | return retval; | |
302 | ||
303 | retval = register_filesystem(&debug_fs_type); | |
304 | if (retval) | |
305 | subsystem_unregister(&debug_subsys); | |
306 | return retval; | |
307 | } | |
308 | ||
309 | static void __exit debugfs_exit(void) | |
310 | { | |
311 | simple_release_fs(&debugfs_mount, &debugfs_mount_count); | |
312 | unregister_filesystem(&debug_fs_type); | |
313 | subsystem_unregister(&debug_subsys); | |
314 | } | |
315 | ||
316 | core_initcall(debugfs_init); | |
317 | module_exit(debugfs_exit); | |
318 | MODULE_LICENSE("GPL"); | |
319 |