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/module.h> 20 #include <linux/fs.h> 21 #include <linux/mount.h> 22 #include <linux/pagemap.h> 23 #include <linux/init.h> 24 #include <linux/kobject.h> 25 #include <linux/namei.h> 26 #include <linux/debugfs.h> 27 #include <linux/fsnotify.h> 28 #include <linux/string.h> 29 #include <linux/magic.h> 30 #include <linux/slab.h> 31 32 static struct vfsmount *debugfs_mount; 33 static int debugfs_mount_count; 34 static bool debugfs_registered; 35 36 static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev, 37 void *data, const struct file_operations *fops) 38 39 { 40 struct inode *inode = new_inode(sb); 41 42 if (inode) { 43 inode->i_ino = get_next_ino(); 44 inode->i_mode = mode; 45 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 46 switch (mode & S_IFMT) { 47 default: 48 init_special_inode(inode, mode, dev); 49 break; 50 case S_IFREG: 51 inode->i_fop = fops ? fops : &debugfs_file_operations; 52 inode->i_private = data; 53 break; 54 case S_IFLNK: 55 inode->i_op = &debugfs_link_operations; 56 inode->i_fop = fops; 57 inode->i_private = data; 58 break; 59 case S_IFDIR: 60 inode->i_op = &simple_dir_inode_operations; 61 inode->i_fop = fops ? fops : &simple_dir_operations; 62 inode->i_private = data; 63 64 /* directory inodes start off with i_nlink == 2 65 * (for "." entry) */ 66 inc_nlink(inode); 67 break; 68 } 69 } 70 return inode; 71 } 72 73 /* SMP-safe */ 74 static int debugfs_mknod(struct inode *dir, struct dentry *dentry, 75 int mode, dev_t dev, void *data, 76 const struct file_operations *fops) 77 { 78 struct inode *inode; 79 int error = -EPERM; 80 81 if (dentry->d_inode) 82 return -EEXIST; 83 84 inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops); 85 if (inode) { 86 d_instantiate(dentry, inode); 87 dget(dentry); 88 error = 0; 89 } 90 return error; 91 } 92 93 static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode, 94 void *data, const struct file_operations *fops) 95 { 96 int res; 97 98 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR; 99 res = debugfs_mknod(dir, dentry, mode, 0, data, fops); 100 if (!res) { 101 inc_nlink(dir); 102 fsnotify_mkdir(dir, dentry); 103 } 104 return res; 105 } 106 107 static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode, 108 void *data, const struct file_operations *fops) 109 { 110 mode = (mode & S_IALLUGO) | S_IFLNK; 111 return debugfs_mknod(dir, dentry, mode, 0, data, fops); 112 } 113 114 static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode, 115 void *data, const struct file_operations *fops) 116 { 117 int res; 118 119 mode = (mode & S_IALLUGO) | S_IFREG; 120 res = debugfs_mknod(dir, dentry, mode, 0, data, fops); 121 if (!res) 122 fsnotify_create(dir, dentry); 123 return res; 124 } 125 126 static inline int debugfs_positive(struct dentry *dentry) 127 { 128 return dentry->d_inode && !d_unhashed(dentry); 129 } 130 131 static int debug_fill_super(struct super_block *sb, void *data, int silent) 132 { 133 static struct tree_descr debug_files[] = {{""}}; 134 135 return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files); 136 } 137 138 static struct dentry *debug_mount(struct file_system_type *fs_type, 139 int flags, const char *dev_name, 140 void *data) 141 { 142 return mount_single(fs_type, flags, data, debug_fill_super); 143 } 144 145 static struct file_system_type debug_fs_type = { 146 .owner = THIS_MODULE, 147 .name = "debugfs", 148 .mount = debug_mount, 149 .kill_sb = kill_litter_super, 150 }; 151 152 static int debugfs_create_by_name(const char *name, mode_t mode, 153 struct dentry *parent, 154 struct dentry **dentry, 155 void *data, 156 const struct file_operations *fops) 157 { 158 int error = 0; 159 160 /* If the parent is not specified, we create it in the root. 161 * We need the root dentry to do this, which is in the super 162 * block. A pointer to that is in the struct vfsmount that we 163 * have around. 164 */ 165 if (!parent) 166 parent = debugfs_mount->mnt_sb->s_root; 167 168 *dentry = NULL; 169 mutex_lock(&parent->d_inode->i_mutex); 170 *dentry = lookup_one_len(name, parent, strlen(name)); 171 if (!IS_ERR(*dentry)) { 172 switch (mode & S_IFMT) { 173 case S_IFDIR: 174 error = debugfs_mkdir(parent->d_inode, *dentry, mode, 175 data, fops); 176 break; 177 case S_IFLNK: 178 error = debugfs_link(parent->d_inode, *dentry, mode, 179 data, fops); 180 break; 181 default: 182 error = debugfs_create(parent->d_inode, *dentry, mode, 183 data, fops); 184 break; 185 } 186 dput(*dentry); 187 } else 188 error = PTR_ERR(*dentry); 189 mutex_unlock(&parent->d_inode->i_mutex); 190 191 return error; 192 } 193 194 /** 195 * debugfs_create_file - create a file in the debugfs filesystem 196 * @name: a pointer to a string containing the name of the file to create. 197 * @mode: the permission that the file should have. 198 * @parent: a pointer to the parent dentry for this file. This should be a 199 * directory dentry if set. If this paramater is NULL, then the 200 * file will be created in the root of the debugfs filesystem. 201 * @data: a pointer to something that the caller will want to get to later 202 * on. The inode.i_private pointer will point to this value on 203 * the open() call. 204 * @fops: a pointer to a struct file_operations that should be used for 205 * this file. 206 * 207 * This is the basic "create a file" function for debugfs. It allows for a 208 * wide range of flexibility in creating a file, or a directory (if you want 209 * to create a directory, the debugfs_create_dir() function is 210 * recommended to be used instead.) 211 * 212 * This function will return a pointer to a dentry if it succeeds. This 213 * pointer must be passed to the debugfs_remove() function when the file is 214 * to be removed (no automatic cleanup happens if your module is unloaded, 215 * you are responsible here.) If an error occurs, %NULL will be returned. 216 * 217 * If debugfs is not enabled in the kernel, the value -%ENODEV will be 218 * returned. 219 */ 220 struct dentry *debugfs_create_file(const char *name, mode_t mode, 221 struct dentry *parent, void *data, 222 const struct file_operations *fops) 223 { 224 struct dentry *dentry = NULL; 225 int error; 226 227 pr_debug("debugfs: creating file '%s'\n",name); 228 229 error = simple_pin_fs(&debug_fs_type, &debugfs_mount, 230 &debugfs_mount_count); 231 if (error) 232 goto exit; 233 234 error = debugfs_create_by_name(name, mode, parent, &dentry, 235 data, fops); 236 if (error) { 237 dentry = NULL; 238 simple_release_fs(&debugfs_mount, &debugfs_mount_count); 239 goto exit; 240 } 241 exit: 242 return dentry; 243 } 244 EXPORT_SYMBOL_GPL(debugfs_create_file); 245 246 /** 247 * debugfs_create_dir - create a directory in the debugfs filesystem 248 * @name: a pointer to a string containing the name of the directory to 249 * create. 250 * @parent: a pointer to the parent dentry for this file. This should be a 251 * directory dentry if set. If this paramater is NULL, then the 252 * directory will be created in the root of the debugfs filesystem. 253 * 254 * This function creates a directory in debugfs with the given name. 255 * 256 * This function will return a pointer to a dentry if it succeeds. This 257 * pointer must be passed to the debugfs_remove() function when the file is 258 * to be removed (no automatic cleanup happens if your module is unloaded, 259 * you are responsible here.) If an error occurs, %NULL will be returned. 260 * 261 * If debugfs is not enabled in the kernel, the value -%ENODEV will be 262 * returned. 263 */ 264 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent) 265 { 266 return debugfs_create_file(name, 267 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, 268 parent, NULL, NULL); 269 } 270 EXPORT_SYMBOL_GPL(debugfs_create_dir); 271 272 /** 273 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem 274 * @name: a pointer to a string containing the name of the symbolic link to 275 * create. 276 * @parent: a pointer to the parent dentry for this symbolic link. This 277 * should be a directory dentry if set. If this paramater is NULL, 278 * then the symbolic link will be created in the root of the debugfs 279 * filesystem. 280 * @target: a pointer to a string containing the path to the target of the 281 * symbolic link. 282 * 283 * This function creates a symbolic link with the given name in debugfs that 284 * links to the given target path. 285 * 286 * This function will return a pointer to a dentry if it succeeds. This 287 * pointer must be passed to the debugfs_remove() function when the symbolic 288 * link is to be removed (no automatic cleanup happens if your module is 289 * unloaded, you are responsible here.) If an error occurs, %NULL will be 290 * returned. 291 * 292 * If debugfs is not enabled in the kernel, the value -%ENODEV will be 293 * returned. 294 */ 295 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent, 296 const char *target) 297 { 298 struct dentry *result; 299 char *link; 300 301 link = kstrdup(target, GFP_KERNEL); 302 if (!link) 303 return NULL; 304 305 result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link, 306 NULL); 307 if (!result) 308 kfree(link); 309 return result; 310 } 311 EXPORT_SYMBOL_GPL(debugfs_create_symlink); 312 313 static void __debugfs_remove(struct dentry *dentry, struct dentry *parent) 314 { 315 int ret = 0; 316 317 if (debugfs_positive(dentry)) { 318 if (dentry->d_inode) { 319 dget(dentry); 320 switch (dentry->d_inode->i_mode & S_IFMT) { 321 case S_IFDIR: 322 ret = simple_rmdir(parent->d_inode, dentry); 323 break; 324 case S_IFLNK: 325 kfree(dentry->d_inode->i_private); 326 /* fall through */ 327 default: 328 simple_unlink(parent->d_inode, dentry); 329 break; 330 } 331 if (!ret) 332 d_delete(dentry); 333 dput(dentry); 334 } 335 } 336 } 337 338 /** 339 * debugfs_remove - removes a file or directory from the debugfs filesystem 340 * @dentry: a pointer to a the dentry of the file or directory to be 341 * removed. 342 * 343 * This function removes a file or directory in debugfs that was previously 344 * created with a call to another debugfs function (like 345 * debugfs_create_file() or variants thereof.) 346 * 347 * This function is required to be called in order for the file to be 348 * removed, no automatic cleanup of files will happen when a module is 349 * removed, you are responsible here. 350 */ 351 void debugfs_remove(struct dentry *dentry) 352 { 353 struct dentry *parent; 354 355 if (!dentry) 356 return; 357 358 parent = dentry->d_parent; 359 if (!parent || !parent->d_inode) 360 return; 361 362 mutex_lock(&parent->d_inode->i_mutex); 363 __debugfs_remove(dentry, parent); 364 mutex_unlock(&parent->d_inode->i_mutex); 365 simple_release_fs(&debugfs_mount, &debugfs_mount_count); 366 } 367 EXPORT_SYMBOL_GPL(debugfs_remove); 368 369 /** 370 * debugfs_remove_recursive - recursively removes a directory 371 * @dentry: a pointer to a the dentry of the directory to be removed. 372 * 373 * This function recursively removes a directory tree in debugfs that 374 * was previously created with a call to another debugfs function 375 * (like debugfs_create_file() or variants thereof.) 376 * 377 * This function is required to be called in order for the file to be 378 * removed, no automatic cleanup of files will happen when a module is 379 * removed, you are responsible here. 380 */ 381 void debugfs_remove_recursive(struct dentry *dentry) 382 { 383 struct dentry *child; 384 struct dentry *parent; 385 386 if (!dentry) 387 return; 388 389 parent = dentry->d_parent; 390 if (!parent || !parent->d_inode) 391 return; 392 393 parent = dentry; 394 mutex_lock(&parent->d_inode->i_mutex); 395 396 while (1) { 397 /* 398 * When all dentries under "parent" has been removed, 399 * walk up the tree until we reach our starting point. 400 */ 401 if (list_empty(&parent->d_subdirs)) { 402 mutex_unlock(&parent->d_inode->i_mutex); 403 if (parent == dentry) 404 break; 405 parent = parent->d_parent; 406 mutex_lock(&parent->d_inode->i_mutex); 407 } 408 child = list_entry(parent->d_subdirs.next, struct dentry, 409 d_u.d_child); 410 next_sibling: 411 412 /* 413 * If "child" isn't empty, walk down the tree and 414 * remove all its descendants first. 415 */ 416 if (!list_empty(&child->d_subdirs)) { 417 mutex_unlock(&parent->d_inode->i_mutex); 418 parent = child; 419 mutex_lock(&parent->d_inode->i_mutex); 420 continue; 421 } 422 __debugfs_remove(child, parent); 423 if (parent->d_subdirs.next == &child->d_u.d_child) { 424 /* 425 * Try the next sibling. 426 */ 427 if (child->d_u.d_child.next != &parent->d_subdirs) { 428 child = list_entry(child->d_u.d_child.next, 429 struct dentry, 430 d_u.d_child); 431 goto next_sibling; 432 } 433 434 /* 435 * Avoid infinite loop if we fail to remove 436 * one dentry. 437 */ 438 mutex_unlock(&parent->d_inode->i_mutex); 439 break; 440 } 441 simple_release_fs(&debugfs_mount, &debugfs_mount_count); 442 } 443 444 parent = dentry->d_parent; 445 mutex_lock(&parent->d_inode->i_mutex); 446 __debugfs_remove(dentry, parent); 447 mutex_unlock(&parent->d_inode->i_mutex); 448 simple_release_fs(&debugfs_mount, &debugfs_mount_count); 449 } 450 EXPORT_SYMBOL_GPL(debugfs_remove_recursive); 451 452 /** 453 * debugfs_rename - rename a file/directory in the debugfs filesystem 454 * @old_dir: a pointer to the parent dentry for the renamed object. This 455 * should be a directory dentry. 456 * @old_dentry: dentry of an object to be renamed. 457 * @new_dir: a pointer to the parent dentry where the object should be 458 * moved. This should be a directory dentry. 459 * @new_name: a pointer to a string containing the target name. 460 * 461 * This function renames a file/directory in debugfs. The target must not 462 * exist for rename to succeed. 463 * 464 * This function will return a pointer to old_dentry (which is updated to 465 * reflect renaming) if it succeeds. If an error occurs, %NULL will be 466 * returned. 467 * 468 * If debugfs is not enabled in the kernel, the value -%ENODEV will be 469 * returned. 470 */ 471 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry, 472 struct dentry *new_dir, const char *new_name) 473 { 474 int error; 475 struct dentry *dentry = NULL, *trap; 476 const char *old_name; 477 478 trap = lock_rename(new_dir, old_dir); 479 /* Source or destination directories don't exist? */ 480 if (!old_dir->d_inode || !new_dir->d_inode) 481 goto exit; 482 /* Source does not exist, cyclic rename, or mountpoint? */ 483 if (!old_dentry->d_inode || old_dentry == trap || 484 d_mountpoint(old_dentry)) 485 goto exit; 486 dentry = lookup_one_len(new_name, new_dir, strlen(new_name)); 487 /* Lookup failed, cyclic rename or target exists? */ 488 if (IS_ERR(dentry) || dentry == trap || dentry->d_inode) 489 goto exit; 490 491 old_name = fsnotify_oldname_init(old_dentry->d_name.name); 492 493 error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode, 494 dentry); 495 if (error) { 496 fsnotify_oldname_free(old_name); 497 goto exit; 498 } 499 d_move(old_dentry, dentry); 500 fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name, 501 S_ISDIR(old_dentry->d_inode->i_mode), 502 NULL, old_dentry); 503 fsnotify_oldname_free(old_name); 504 unlock_rename(new_dir, old_dir); 505 dput(dentry); 506 return old_dentry; 507 exit: 508 if (dentry && !IS_ERR(dentry)) 509 dput(dentry); 510 unlock_rename(new_dir, old_dir); 511 return NULL; 512 } 513 EXPORT_SYMBOL_GPL(debugfs_rename); 514 515 /** 516 * debugfs_initialized - Tells whether debugfs has been registered 517 */ 518 bool debugfs_initialized(void) 519 { 520 return debugfs_registered; 521 } 522 EXPORT_SYMBOL_GPL(debugfs_initialized); 523 524 525 static struct kobject *debug_kobj; 526 527 static int __init debugfs_init(void) 528 { 529 int retval; 530 531 debug_kobj = kobject_create_and_add("debug", kernel_kobj); 532 if (!debug_kobj) 533 return -EINVAL; 534 535 retval = register_filesystem(&debug_fs_type); 536 if (retval) 537 kobject_put(debug_kobj); 538 else 539 debugfs_registered = true; 540 541 return retval; 542 } 543 544 static void __exit debugfs_exit(void) 545 { 546 debugfs_registered = false; 547 548 simple_release_fs(&debugfs_mount, &debugfs_mount_count); 549 unregister_filesystem(&debug_fs_type); 550 kobject_put(debug_kobj); 551 } 552 553 core_initcall(debugfs_init); 554 module_exit(debugfs_exit); 555 MODULE_LICENSE("GPL"); 556 557