Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | { |
Jens Axboe | 71601e2 | 2006-06-08 10:26:39 +0200 | [diff] [blame] | 70 | struct inode *inode; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 71 | int error = -EPERM; |
| 72 | |
| 73 | if (dentry->d_inode) |
| 74 | return -EEXIST; |
| 75 | |
Jens Axboe | 71601e2 | 2006-06-08 10:26:39 +0200 | [diff] [blame] | 76 | inode = debugfs_get_inode(dir->i_sb, mode, dev); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
David Howells | 454e239 | 2006-06-23 02:02:57 -0700 | [diff] [blame] | 114 | static int debug_get_sb(struct file_system_type *fs_type, |
| 115 | int flags, const char *dev_name, |
| 116 | void *data, struct vfsmount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 117 | { |
David Howells | 454e239 | 2006-06-23 02:02:57 -0700 | [diff] [blame] | 118 | return get_sb_single(fs_type, flags, data, debug_fill_super, mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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; |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 150 | mutex_lock(&parent->d_inode->i_mutex); |
Christoph Hellwig | 5f45f1a | 2005-06-23 00:09:12 -0700 | [diff] [blame] | 151 | *dentry = lookup_one_len(name, parent, strlen(name)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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); |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 159 | mutex_unlock(&parent->d_inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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, |
Arjan van de Ven | 99ac48f | 2006-03-28 01:56:41 -0800 | [diff] [blame] | 195 | const struct file_operations *fops) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 196 | { |
| 197 | struct dentry *dentry = NULL; |
| 198 | int error; |
| 199 | |
| 200 | pr_debug("debugfs: creating file '%s'\n",name); |
| 201 | |
Trond Myklebust | 1f5ce9e | 2006-06-09 09:34:16 -0400 | [diff] [blame] | 202 | error = simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 277 | mutex_lock(&parent->d_inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | } |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 287 | mutex_unlock(&parent->d_inode->i_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | |