linux/fs/debugfs/inode.c
<<
>>
Prefs
   1/*
   2 *  inode.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#include <linux/module.h>
  17#include <linux/fs.h>
  18#include <linux/mount.h>
  19#include <linux/pagemap.h>
  20#include <linux/init.h>
  21#include <linux/kobject.h>
  22#include <linux/namei.h>
  23#include <linux/debugfs.h>
  24#include <linux/fsnotify.h>
  25#include <linux/string.h>
  26#include <linux/seq_file.h>
  27#include <linux/parser.h>
  28#include <linux/magic.h>
  29#include <linux/slab.h>
  30
  31#define DEBUGFS_DEFAULT_MODE    0755
  32
  33static struct vfsmount *debugfs_mount;
  34static int debugfs_mount_count;
  35static bool debugfs_registered;
  36
  37static struct inode *debugfs_get_inode(struct super_block *sb, umode_t mode, dev_t dev,
  38                                       void *data, const struct file_operations *fops)
  39
  40{
  41        struct inode *inode = new_inode(sb);
  42
  43        if (inode) {
  44                inode->i_ino = get_next_ino();
  45                inode->i_mode = mode;
  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 = fops ? fops : &debugfs_file_operations;
  53                        inode->i_private = data;
  54                        break;
  55                case S_IFLNK:
  56                        inode->i_op = &debugfs_link_operations;
  57                        inode->i_private = data;
  58                        break;
  59                case S_IFDIR:
  60                        inode->i_op = &simple_dir_inode_operations;
  61                        inode->i_fop = &simple_dir_operations;
  62                        inode->i_private = NULL;
  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 */
  74static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
  75                         umode_t 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
  93static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
  94{
  95        int res;
  96
  97        mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
  98        res = debugfs_mknod(dir, dentry, mode, 0, NULL, NULL);
  99        if (!res) {
 100                inc_nlink(dir);
 101                fsnotify_mkdir(dir, dentry);
 102        }
 103        return res;
 104}
 105
 106static int debugfs_link(struct inode *dir, struct dentry *dentry, umode_t mode,
 107                        void *data)
 108{
 109        mode = (mode & S_IALLUGO) | S_IFLNK;
 110        return debugfs_mknod(dir, dentry, mode, 0, data, NULL);
 111}
 112
 113static int debugfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 114                          void *data, const struct file_operations *fops)
 115{
 116        int res;
 117
 118        mode = (mode & S_IALLUGO) | S_IFREG;
 119        res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
 120        if (!res)
 121                fsnotify_create(dir, dentry);
 122        return res;
 123}
 124
 125static inline int debugfs_positive(struct dentry *dentry)
 126{
 127        return dentry->d_inode && !d_unhashed(dentry);
 128}
 129
 130struct debugfs_mount_opts {
 131        uid_t uid;
 132        gid_t gid;
 133        umode_t mode;
 134};
 135
 136enum {
 137        Opt_uid,
 138        Opt_gid,
 139        Opt_mode,
 140        Opt_err
 141};
 142
 143static const match_table_t tokens = {
 144        {Opt_uid, "uid=%u"},
 145        {Opt_gid, "gid=%u"},
 146        {Opt_mode, "mode=%o"},
 147        {Opt_err, NULL}
 148};
 149
 150struct debugfs_fs_info {
 151        struct debugfs_mount_opts mount_opts;
 152};
 153
 154static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
 155{
 156        substring_t args[MAX_OPT_ARGS];
 157        int option;
 158        int token;
 159        char *p;
 160
 161        opts->mode = DEBUGFS_DEFAULT_MODE;
 162
 163        while ((p = strsep(&data, ",")) != NULL) {
 164                if (!*p)
 165                        continue;
 166
 167                token = match_token(p, tokens, args);
 168                switch (token) {
 169                case Opt_uid:
 170                        if (match_int(&args[0], &option))
 171                                return -EINVAL;
 172                        opts->uid = option;
 173                        break;
 174                case Opt_gid:
 175                        if (match_octal(&args[0], &option))
 176                                return -EINVAL;
 177                        opts->gid = option;
 178                        break;
 179                case Opt_mode:
 180                        if (match_octal(&args[0], &option))
 181                                return -EINVAL;
 182                        opts->mode = option & S_IALLUGO;
 183                        break;
 184                /*
 185                 * We might like to report bad mount options here;
 186                 * but traditionally debugfs has ignored all mount options
 187                 */
 188                }
 189        }
 190
 191        return 0;
 192}
 193
 194static int debugfs_apply_options(struct super_block *sb)
 195{
 196        struct debugfs_fs_info *fsi = sb->s_fs_info;
 197        struct inode *inode = sb->s_root->d_inode;
 198        struct debugfs_mount_opts *opts = &fsi->mount_opts;
 199
 200        inode->i_mode &= ~S_IALLUGO;
 201        inode->i_mode |= opts->mode;
 202
 203        inode->i_uid = opts->uid;
 204        inode->i_gid = opts->gid;
 205
 206        return 0;
 207}
 208
 209static int debugfs_remount(struct super_block *sb, int *flags, char *data)
 210{
 211        int err;
 212        struct debugfs_fs_info *fsi = sb->s_fs_info;
 213
 214        err = debugfs_parse_options(data, &fsi->mount_opts);
 215        if (err)
 216                goto fail;
 217
 218        debugfs_apply_options(sb);
 219
 220fail:
 221        return err;
 222}
 223
 224static int debugfs_show_options(struct seq_file *m, struct dentry *root)
 225{
 226        struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
 227        struct debugfs_mount_opts *opts = &fsi->mount_opts;
 228
 229        if (opts->uid != 0)
 230                seq_printf(m, ",uid=%u", opts->uid);
 231        if (opts->gid != 0)
 232                seq_printf(m, ",gid=%u", opts->gid);
 233        if (opts->mode != DEBUGFS_DEFAULT_MODE)
 234                seq_printf(m, ",mode=%o", opts->mode);
 235
 236        return 0;
 237}
 238
 239static const struct super_operations debugfs_super_operations = {
 240        .statfs         = simple_statfs,
 241        .remount_fs     = debugfs_remount,
 242        .show_options   = debugfs_show_options,
 243};
 244
 245static int debug_fill_super(struct super_block *sb, void *data, int silent)
 246{
 247        static struct tree_descr debug_files[] = {{""}};
 248        struct debugfs_fs_info *fsi;
 249        int err;
 250
 251        save_mount_options(sb, data);
 252
 253        fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
 254        sb->s_fs_info = fsi;
 255        if (!fsi) {
 256                err = -ENOMEM;
 257                goto fail;
 258        }
 259
 260        err = debugfs_parse_options(data, &fsi->mount_opts);
 261        if (err)
 262                goto fail;
 263
 264        err  =  simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
 265        if (err)
 266                goto fail;
 267
 268        sb->s_op = &debugfs_super_operations;
 269
 270        debugfs_apply_options(sb);
 271
 272        return 0;
 273
 274fail:
 275        kfree(fsi);
 276        sb->s_fs_info = NULL;
 277        return err;
 278}
 279
 280static struct dentry *debug_mount(struct file_system_type *fs_type,
 281                        int flags, const char *dev_name,
 282                        void *data)
 283{
 284        return mount_single(fs_type, flags, data, debug_fill_super);
 285}
 286
 287static struct file_system_type debug_fs_type = {
 288        .owner =        THIS_MODULE,
 289        .name =         "debugfs",
 290        .mount =        debug_mount,
 291        .kill_sb =      kill_litter_super,
 292};
 293
 294struct dentry *__create_file(const char *name, umode_t mode,
 295                                   struct dentry *parent, void *data,
 296                                   const struct file_operations *fops)
 297{
 298        struct dentry *dentry = NULL;
 299        int error;
 300
 301        pr_debug("debugfs: creating file '%s'\n",name);
 302
 303        error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
 304                              &debugfs_mount_count);
 305        if (error)
 306                goto exit;
 307
 308        /* If the parent is not specified, we create it in the root.
 309         * We need the root dentry to do this, which is in the super 
 310         * block. A pointer to that is in the struct vfsmount that we
 311         * have around.
 312         */
 313        if (!parent)
 314                parent = debugfs_mount->mnt_root;
 315
 316        dentry = NULL;
 317        mutex_lock(&parent->d_inode->i_mutex);
 318        dentry = lookup_one_len(name, parent, strlen(name));
 319        if (!IS_ERR(dentry)) {
 320                switch (mode & S_IFMT) {
 321                case S_IFDIR:
 322                        error = debugfs_mkdir(parent->d_inode, dentry, mode);
 323                                              
 324                        break;
 325                case S_IFLNK:
 326                        error = debugfs_link(parent->d_inode, dentry, mode,
 327                                             data);
 328                        break;
 329                default:
 330                        error = debugfs_create(parent->d_inode, dentry, mode,
 331                                               data, fops);
 332                        break;
 333                }
 334                dput(dentry);
 335        } else
 336                error = PTR_ERR(dentry);
 337        mutex_unlock(&parent->d_inode->i_mutex);
 338
 339        if (error) {
 340                dentry = NULL;
 341                simple_release_fs(&debugfs_mount, &debugfs_mount_count);
 342        }
 343exit:
 344        return dentry;
 345}
 346
 347/**
 348 * debugfs_create_file - create a file in the debugfs filesystem
 349 * @name: a pointer to a string containing the name of the file to create.
 350 * @mode: the permission that the file should have.
 351 * @parent: a pointer to the parent dentry for this file.  This should be a
 352 *          directory dentry if set.  If this paramater is NULL, then the
 353 *          file will be created in the root of the debugfs filesystem.
 354 * @data: a pointer to something that the caller will want to get to later
 355 *        on.  The inode.i_private pointer will point to this value on
 356 *        the open() call.
 357 * @fops: a pointer to a struct file_operations that should be used for
 358 *        this file.
 359 *
 360 * This is the basic "create a file" function for debugfs.  It allows for a
 361 * wide range of flexibility in creating a file, or a directory (if you want
 362 * to create a directory, the debugfs_create_dir() function is
 363 * recommended to be used instead.)
 364 *
 365 * This function will return a pointer to a dentry if it succeeds.  This
 366 * pointer must be passed to the debugfs_remove() function when the file is
 367 * to be removed (no automatic cleanup happens if your module is unloaded,
 368 * you are responsible here.)  If an error occurs, %NULL will be returned.
 369 *
 370 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 371 * returned.
 372 */
 373struct dentry *debugfs_create_file(const char *name, umode_t mode,
 374                                   struct dentry *parent, void *data,
 375                                   const struct file_operations *fops)
 376{
 377        switch (mode & S_IFMT) {
 378        case S_IFREG:
 379        case 0:
 380                break;
 381        default:
 382                BUG();
 383        }
 384
 385        return __create_file(name, mode, parent, data, fops);
 386}
 387EXPORT_SYMBOL_GPL(debugfs_create_file);
 388
 389/**
 390 * debugfs_create_dir - create a directory in the debugfs filesystem
 391 * @name: a pointer to a string containing the name of the directory to
 392 *        create.
 393 * @parent: a pointer to the parent dentry for this file.  This should be a
 394 *          directory dentry if set.  If this paramater is NULL, then the
 395 *          directory will be created in the root of the debugfs filesystem.
 396 *
 397 * This function creates a directory in debugfs with the given name.
 398 *
 399 * This function will return a pointer to a dentry if it succeeds.  This
 400 * pointer must be passed to the debugfs_remove() function when the file is
 401 * to be removed (no automatic cleanup happens if your module is unloaded,
 402 * you are responsible here.)  If an error occurs, %NULL will be returned.
 403 *
 404 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 405 * returned.
 406 */
 407struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
 408{
 409        return __create_file(name, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
 410                                   parent, NULL, NULL);
 411}
 412EXPORT_SYMBOL_GPL(debugfs_create_dir);
 413
 414/**
 415 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
 416 * @name: a pointer to a string containing the name of the symbolic link to
 417 *        create.
 418 * @parent: a pointer to the parent dentry for this symbolic link.  This
 419 *          should be a directory dentry if set.  If this paramater is NULL,
 420 *          then the symbolic link will be created in the root of the debugfs
 421 *          filesystem.
 422 * @target: a pointer to a string containing the path to the target of the
 423 *          symbolic link.
 424 *
 425 * This function creates a symbolic link with the given name in debugfs that
 426 * links to the given target path.
 427 *
 428 * This function will return a pointer to a dentry if it succeeds.  This
 429 * pointer must be passed to the debugfs_remove() function when the symbolic
 430 * link is to be removed (no automatic cleanup happens if your module is
 431 * unloaded, you are responsible here.)  If an error occurs, %NULL will be
 432 * returned.
 433 *
 434 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 435 * returned.
 436 */
 437struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
 438                                      const char *target)
 439{
 440        struct dentry *result;
 441        char *link;
 442
 443        link = kstrdup(target, GFP_KERNEL);
 444        if (!link)
 445                return NULL;
 446
 447        result = __create_file(name, S_IFLNK | S_IRWXUGO, parent, link, NULL);
 448        if (!result)
 449                kfree(link);
 450        return result;
 451}
 452EXPORT_SYMBOL_GPL(debugfs_create_symlink);
 453
 454static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
 455{
 456        int ret = 0;
 457
 458        if (debugfs_positive(dentry)) {
 459                if (dentry->d_inode) {
 460                        dget(dentry);
 461                        switch (dentry->d_inode->i_mode & S_IFMT) {
 462                        case S_IFDIR:
 463                                ret = simple_rmdir(parent->d_inode, dentry);
 464                                break;
 465                        case S_IFLNK:
 466                                kfree(dentry->d_inode->i_private);
 467                                /* fall through */
 468                        default:
 469                                simple_unlink(parent->d_inode, dentry);
 470                                break;
 471                        }
 472                        if (!ret)
 473                                d_delete(dentry);
 474                        dput(dentry);
 475                }
 476        }
 477        return ret;
 478}
 479
 480/**
 481 * debugfs_remove - removes a file or directory from the debugfs filesystem
 482 * @dentry: a pointer to a the dentry of the file or directory to be
 483 *          removed.
 484 *
 485 * This function removes a file or directory in debugfs that was previously
 486 * created with a call to another debugfs function (like
 487 * debugfs_create_file() or variants thereof.)
 488 *
 489 * This function is required to be called in order for the file to be
 490 * removed, no automatic cleanup of files will happen when a module is
 491 * removed, you are responsible here.
 492 */
 493void debugfs_remove(struct dentry *dentry)
 494{
 495        struct dentry *parent;
 496        int ret;
 497
 498        if (IS_ERR_OR_NULL(dentry))
 499                return;
 500
 501        parent = dentry->d_parent;
 502        if (!parent || !parent->d_inode)
 503                return;
 504
 505        mutex_lock(&parent->d_inode->i_mutex);
 506        ret = __debugfs_remove(dentry, parent);
 507        mutex_unlock(&parent->d_inode->i_mutex);
 508        if (!ret)
 509                simple_release_fs(&debugfs_mount, &debugfs_mount_count);
 510}
 511EXPORT_SYMBOL_GPL(debugfs_remove);
 512
 513/**
 514 * debugfs_remove_recursive - recursively removes a directory
 515 * @dentry: a pointer to a the dentry of the directory to be removed.
 516 *
 517 * This function recursively removes a directory tree in debugfs that
 518 * was previously created with a call to another debugfs function
 519 * (like debugfs_create_file() or variants thereof.)
 520 *
 521 * This function is required to be called in order for the file to be
 522 * removed, no automatic cleanup of files will happen when a module is
 523 * removed, you are responsible here.
 524 */
 525void debugfs_remove_recursive(struct dentry *dentry)
 526{
 527        struct dentry *child;
 528        struct dentry *parent;
 529
 530        if (IS_ERR_OR_NULL(dentry))
 531                return;
 532
 533        parent = dentry->d_parent;
 534        if (!parent || !parent->d_inode)
 535                return;
 536
 537        parent = dentry;
 538        mutex_lock(&parent->d_inode->i_mutex);
 539
 540        while (1) {
 541                /*
 542                 * When all dentries under "parent" has been removed,
 543                 * walk up the tree until we reach our starting point.
 544                 */
 545                if (list_empty(&parent->d_subdirs)) {
 546                        mutex_unlock(&parent->d_inode->i_mutex);
 547                        if (parent == dentry)
 548                                break;
 549                        parent = parent->d_parent;
 550                        mutex_lock(&parent->d_inode->i_mutex);
 551                }
 552                child = list_entry(parent->d_subdirs.next, struct dentry,
 553                                d_u.d_child);
 554 next_sibling:
 555
 556                /*
 557                 * If "child" isn't empty, walk down the tree and
 558                 * remove all its descendants first.
 559                 */
 560                if (!list_empty(&child->d_subdirs)) {
 561                        mutex_unlock(&parent->d_inode->i_mutex);
 562                        parent = child;
 563                        mutex_lock(&parent->d_inode->i_mutex);
 564                        continue;
 565                }
 566                __debugfs_remove(child, parent);
 567                if (parent->d_subdirs.next == &child->d_u.d_child) {
 568                        /*
 569                         * Try the next sibling.
 570                         */
 571                        if (child->d_u.d_child.next != &parent->d_subdirs) {
 572                                child = list_entry(child->d_u.d_child.next,
 573                                                   struct dentry,
 574                                                   d_u.d_child);
 575                                goto next_sibling;
 576                        }
 577
 578                        /*
 579                         * Avoid infinite loop if we fail to remove
 580                         * one dentry.
 581                         */
 582                        mutex_unlock(&parent->d_inode->i_mutex);
 583                        break;
 584                }
 585                simple_release_fs(&debugfs_mount, &debugfs_mount_count);
 586        }
 587
 588        parent = dentry->d_parent;
 589        mutex_lock(&parent->d_inode->i_mutex);
 590        __debugfs_remove(dentry, parent);
 591        mutex_unlock(&parent->d_inode->i_mutex);
 592        simple_release_fs(&debugfs_mount, &debugfs_mount_count);
 593}
 594EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
 595
 596/**
 597 * debugfs_rename - rename a file/directory in the debugfs filesystem
 598 * @old_dir: a pointer to the parent dentry for the renamed object. This
 599 *          should be a directory dentry.
 600 * @old_dentry: dentry of an object to be renamed.
 601 * @new_dir: a pointer to the parent dentry where the object should be
 602 *          moved. This should be a directory dentry.
 603 * @new_name: a pointer to a string containing the target name.
 604 *
 605 * This function renames a file/directory in debugfs.  The target must not
 606 * exist for rename to succeed.
 607 *
 608 * This function will return a pointer to old_dentry (which is updated to
 609 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
 610 * returned.
 611 *
 612 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 613 * returned.
 614 */
 615struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
 616                struct dentry *new_dir, const char *new_name)
 617{
 618        int error;
 619        struct dentry *dentry = NULL, *trap;
 620        const char *old_name;
 621
 622        trap = lock_rename(new_dir, old_dir);
 623        /* Source or destination directories don't exist? */
 624        if (!old_dir->d_inode || !new_dir->d_inode)
 625                goto exit;
 626        /* Source does not exist, cyclic rename, or mountpoint? */
 627        if (!old_dentry->d_inode || old_dentry == trap ||
 628            d_mountpoint(old_dentry))
 629                goto exit;
 630        dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
 631        /* Lookup failed, cyclic rename or target exists? */
 632        if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
 633                goto exit;
 634
 635        old_name = fsnotify_oldname_init(old_dentry->d_name.name);
 636
 637        error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
 638                dentry);
 639        if (error) {
 640                fsnotify_oldname_free(old_name);
 641                goto exit;
 642        }
 643        d_move(old_dentry, dentry);
 644        fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
 645                S_ISDIR(old_dentry->d_inode->i_mode),
 646                NULL, old_dentry);
 647        fsnotify_oldname_free(old_name);
 648        unlock_rename(new_dir, old_dir);
 649        dput(dentry);
 650        return old_dentry;
 651exit:
 652        if (dentry && !IS_ERR(dentry))
 653                dput(dentry);
 654        unlock_rename(new_dir, old_dir);
 655        return NULL;
 656}
 657EXPORT_SYMBOL_GPL(debugfs_rename);
 658
 659/**
 660 * debugfs_initialized - Tells whether debugfs has been registered
 661 */
 662bool debugfs_initialized(void)
 663{
 664        return debugfs_registered;
 665}
 666EXPORT_SYMBOL_GPL(debugfs_initialized);
 667
 668
 669static struct kobject *debug_kobj;
 670
 671static int __init debugfs_init(void)
 672{
 673        int retval;
 674
 675        debug_kobj = kobject_create_and_add("debug", kernel_kobj);
 676        if (!debug_kobj)
 677                return -EINVAL;
 678
 679        retval = register_filesystem(&debug_fs_type);
 680        if (retval)
 681                kobject_put(debug_kobj);
 682        else
 683                debugfs_registered = true;
 684
 685        return retval;
 686}
 687core_initcall(debugfs_init);
 688
 689
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.