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/*

 *  file.c - part of debugfs, a tiny little debug file system

 *

 *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>

 *  Copyright (C) 2004 IBM Inc.

 *

 *      This program is free software; you can redistribute it and/or

 *      modify it under the terms of the GNU General Public License version

 *      2 as published by the Free Software Foundation.

 *

 *  debugfs is for people to use instead of /proc or /sys.

 *  See Documentation/DocBook/kernel-api for more details.

 *

 */

/* uncomment to get debug messages from the debug filesystem, ah the irony. */

/* #define DEBUG */

#include <linux/module.h>

#include <linux/fs.h>

#include <linux/mount.h>

#include <linux/pagemap.h>

#include <linux/init.h>

#include <linux/kobject.h>

#include <linux/namei.h>

#include <linux/debugfs.h>

#include <linux/fsnotify.h>

#include <linux/string.h>

#define DEBUGFS_MAGIC   0x64626720

/* declared over in file.c */

extern struct file_operations debugfs_file_operations;

extern struct inode_operations debugfs_link_operations;

static struct vfsmount *debugfs_mount;

static int debugfs_mount_count;

static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev)

{

        struct inode *inode = new_inode(sb);

        if (inode) {

                inode->i_mode = mode;

                inode->i_uid = 0;

                inode->i_gid = 0;

                inode->i_blocks = 0;

                inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;

                switch (mode & S_IFMT) {

                default:

                        init_special_inode(inode, mode, dev);

                        break;

                case S_IFREG:

                        inode->i_fop = &debugfs_file_operations;

                        break;

                case S_IFLNK:

                        inode->i_op = &debugfs_link_operations;

                        break;

                case S_IFDIR:

                        inode->i_op = &simple_dir_inode_operations;

                        inode->i_fop = &simple_dir_operations;

                        /* directory inodes start off with i_nlink == 2

                         * (for "." entry) */

                        inc_nlink(inode);

                        break;

                }

        }

        return inode;

}

/* SMP-safe */

static int debugfs_mknod(struct inode *dir, struct dentry *dentry,

                         int mode, dev_t dev)

{

        struct inode *inode;

        int error = -EPERM;

        if (dentry->d_inode)

                return -EEXIST;

        inode = debugfs_get_inode(dir->i_sb, mode, dev);

        if (inode) {

                d_instantiate(dentry, inode);

                dget(dentry);

                error = 0;

        }

        return error;

}

static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)

{

        int res;

        mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;

        res = debugfs_mknod(dir, dentry, mode, 0);

        if (!res) {

                inc_nlink(dir);

                fsnotify_mkdir(dir, dentry);

        }

        return res;

}

static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode)

{

        mode = (mode & S_IALLUGO) | S_IFLNK;

        return debugfs_mknod(dir, dentry, mode, 0);

}

static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode)

{

        int res;

        mode = (mode & S_IALLUGO) | S_IFREG;

        res = debugfs_mknod(dir, dentry, mode, 0);

        if (!res)

                fsnotify_create(dir, dentry);

        return res;

}

static inline int debugfs_positive(struct dentry *dentry)

{

        return dentry->d_inode && !d_unhashed(dentry);

}

static int debug_fill_super(struct super_block *sb, void *data, int silent)

{

        static struct tree_descr debug_files[] = {{""}};

        return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);

}

static int debug_get_sb(struct file_system_type *fs_type,

                        int flags, const char *dev_name,

                        void *data, struct vfsmount *mnt)

{

        return get_sb_single(fs_type, flags, data, debug_fill_super, mnt);

}

static struct file_system_type debug_fs_type = {

        .owner =        THIS_MODULE,

        .name =         "debugfs",

        .get_sb =       debug_get_sb,

        .kill_sb =      kill_litter_super,

};

static int debugfs_create_by_name(const char *name, mode_t mode,

                                  struct dentry *parent,

                                  struct dentry **dentry)

{

        int error = 0;

        /* If the parent is not specified, we create it in the root.

         * We need the root dentry to do this, which is in the super

         * block. A pointer to that is in the struct vfsmount that we

         * have around.

         */

        if (!parent) {

                if (debugfs_mount && debugfs_mount->mnt_sb) {

                        parent = debugfs_mount->mnt_sb->s_root;

                }

        }

        if (!parent) {

                pr_debug("debugfs: Ah! can not find a parent!\n");

                return -EFAULT;

        }

        *dentry = NULL;

        mutex_lock(&parent->d_inode->i_mutex);

        *dentry = lookup_one_len(name, parent, strlen(name));

        if (!IS_ERR(*dentry)) {

                switch (mode & S_IFMT) {

                case S_IFDIR:

                        error = debugfs_mkdir(parent->d_inode, *dentry, mode);

                        break;

                case S_IFLNK:

                        error = debugfs_link(parent->d_inode, *dentry, mode);

                        break;

                default:

                        error = debugfs_create(parent->d_inode, *dentry, mode);

                        break;

                }

                dput(*dentry);

        } else

                error = PTR_ERR(*dentry);

        mutex_unlock(&parent->d_inode->i_mutex);

        return error;

}

/**

 * debugfs_create_file - create a file in the debugfs filesystem

 * @name: a pointer to a string containing the name of the file to create.

 * @mode: the permission that the file should have

 * @parent: a pointer to the parent dentry for this file.  This should be a

 *          directory dentry if set.  If this paramater is NULL, then the

 *          file will be created in the root of the debugfs filesystem.

 * @data: a pointer to something that the caller will want to get to later

 *        on.  The inode.i_private pointer will point to this value on

 *        the open() call.

 * @fops: a pointer to a struct file_operations that should be used for

 *        this file.

 *

 * This is the basic "create a file" function for debugfs.  It allows for a

 * wide range of flexibility in createing a file, or a directory (if you

 * want to create a directory, the debugfs_create_dir() function is

 * recommended to be used instead.)

 *

 * This function will return a pointer to a dentry if it succeeds.  This

 * pointer must be passed to the debugfs_remove() function when the file is

 * to be removed (no automatic cleanup happens if your module is unloaded,

 * you are responsible here.)  If an error occurs, %NULL will be returned.

 *

 * If debugfs is not enabled in the kernel, the value -%ENODEV will be

 * returned.

 */

struct dentry *debugfs_create_file(const char *name, mode_t mode,

                                   struct dentry *parent, void *data,

                                   const struct file_operations *fops)

{

        struct dentry *dentry = NULL;

        int error;

        pr_debug("debugfs: creating file '%s'\n",name);

        error = simple_pin_fs(&debug_fs_type, &debugfs_mount,

                              &debugfs_mount_count);

        if (error)

                goto exit;

        error = debugfs_create_by_name(name, mode, parent, &dentry);

        if (error) {

                dentry = NULL;

                simple_release_fs(&debugfs_mount, &debugfs_mount_count);

                goto exit;

        }

        if (dentry->d_inode) {

                if (data)

                        dentry->d_inode->i_private = data;

                if (fops)

                        dentry->d_inode->i_fop = fops;

        }

exit:

        return dentry;

}

EXPORT_SYMBOL_GPL(debugfs_create_file);

/**

 * debugfs_create_dir - create a directory in the debugfs filesystem

 * @name: a pointer to a string containing the name of the directory to

 *        create.

 * @parent: a pointer to the parent dentry for this file.  This should be a

 *          directory dentry if set.  If this paramater is NULL, then the

 *          directory will be created in the root of the debugfs filesystem.

 *

 * This function creates a directory in debugfs with the given name.

 *

 * This function will return a pointer to a dentry if it succeeds.  This

 * pointer must be passed to the debugfs_remove() function when the file is

 * to be removed (no automatic cleanup happens if your module is unloaded,

 * you are responsible here.)  If an error occurs, %NULL will be returned.

 *

 * If debugfs is not enabled in the kernel, the value -%ENODEV will be

 * returned.

 */

struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)

{

        return debugfs_create_file(name,

                                   S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,

                                   parent, NULL, NULL);

}

EXPORT_SYMBOL_GPL(debugfs_create_dir);

/**

 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem

 * @name: a pointer to a string containing the name of the symbolic link to

 *        create.

 * @parent: a pointer to the parent dentry for this symbolic link.  This

 *          should be a directory dentry if set.  If this paramater is NULL,

 *          then the symbolic link will be created in the root of the debugfs

 *          filesystem.

 * @target: a pointer to a string containing the path to the target of the

 *          symbolic link.

 *

 * This function creates a symbolic link with the given name in debugfs that

 * links to the given target path.

 *

 * This function will return a pointer to a dentry if it succeeds.  This

 * pointer must be passed to the debugfs_remove() function when the symbolic

 * link is to be removed (no automatic cleanup happens if your module is

 * unloaded, you are responsible here.)  If an error occurs, %NULL will be

 * returned.

 *

 * If debugfs is not enabled in the kernel, the value -%ENODEV will be

 * returned.

 */

struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,

                                      const char *target)

{

        struct dentry *result;

        char *link;

        link = kstrdup(target, GFP_KERNEL);

        if (!link)

                return NULL;

        result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link,

                                     NULL);

        if (!result)

                kfree(link);

        return result;

}

EXPORT_SYMBOL_GPL(debugfs_create_symlink);

/**

 * debugfs_remove - removes a file or directory from the debugfs filesystem

 * @dentry: a pointer to a the dentry of the file or directory to be

 *          removed.

 *

 * This function removes a file or directory in debugfs that was previously

 * created with a call to another debugfs function (like

 * debugfs_create_file() or variants thereof.)

 *

 * This function is required to be called in order for the file to be

 * removed, no automatic cleanup of files will happen when a module is

 * removed, you are responsible here.

 */

void debugfs_remove(struct dentry *dentry)

{

        struct dentry *parent;

        int ret = 0;

        if (!dentry)

                return;

        parent = dentry->d_parent;

        if (!parent || !parent->d_inode)

                return;

        mutex_lock(&parent->d_inode->i_mutex);

        if (debugfs_positive(dentry)) {

                if (dentry->d_inode) {

                        dget(dentry);

                        switch (dentry->d_inode->i_mode & S_IFMT) {

                        case S_IFDIR:

                                ret = simple_rmdir(parent->d_inode, dentry);

                                break;

                        case S_IFLNK:

                                kfree(dentry->d_inode->i_private);

                                /* fall through */

                        default:

                                simple_unlink(parent->d_inode, dentry);

                                break;

                        }

                        if (!ret)

                                d_delete(dentry);

                        dput(dentry);

                }

        }

        mutex_unlock(&parent->d_inode->i_mutex);

        simple_release_fs(&debugfs_mount, &debugfs_mount_count);

}

EXPORT_SYMBOL_GPL(debugfs_remove);

/**

 * debugfs_rename - rename a file/directory in the debugfs filesystem

 * @old_dir: a pointer to the parent dentry for the renamed object. This

 *          should be a directory dentry.

 * @old_dentry: dentry of an object to be renamed.

 * @new_dir: a pointer to the parent dentry where the object should be

 *          moved. This should be a directory dentry.

 * @new_name: a pointer to a string containing the target name.

 *

 * This function renames a file/directory in debugfs.  The target must not

 * exist for rename to succeed.

 *

 * This function will return a pointer to old_dentry (which is updated to

 * reflect renaming) if it succeeds. If an error occurs, %NULL will be

 * returned.

 *

 * If debugfs is not enabled in the kernel, the value -%ENODEV will be

 * returned.

 */

struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,

                struct dentry *new_dir, const char *new_name)

{

        int error;

        struct dentry *dentry = NULL, *trap;

        const char *old_name;

        trap = lock_rename(new_dir, old_dir);

        /* Source or destination directories don't exist? */

        if (!old_dir->d_inode || !new_dir->d_inode)

                goto exit;

        /* Source does not exist, cyclic rename, or mountpoint? */

        if (!old_dentry->d_inode || old_dentry == trap ||

            d_mountpoint(old_dentry))

                goto exit;

        dentry = lookup_one_len(new_name, new_dir, strlen(new_name));

        /* Lookup failed, cyclic rename or target exists? */

        if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)

                goto exit;

        old_name = fsnotify_oldname_init(old_dentry->d_name.name);

        error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,

                dentry);

        if (error) {

                fsnotify_oldname_free(old_name);

                goto exit;

        }

        d_move(old_dentry, dentry);

        fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,

                old_dentry->d_name.name, S_ISDIR(old_dentry->d_inode->i_mode),

                NULL, old_dentry);

        fsnotify_oldname_free(old_name);

        unlock_rename(new_dir, old_dir);

        dput(dentry);

        return old_dentry;

exit:

        if (dentry && !IS_ERR(dentry))

                dput(dentry);

        unlock_rename(new_dir, old_dir);

        return NULL;

}

EXPORT_SYMBOL_GPL(debugfs_rename);

static decl_subsys(debug, NULL, NULL);

static int __init debugfs_init(void)

{

        int retval;

        kobj_set_kset_s(&debug_subsys, kernel_subsys);

        retval = subsystem_register(&debug_subsys);

        if (retval)

                return retval;

        retval = register_filesystem(&debug_fs_type);

        if (retval)

                subsystem_unregister(&debug_subsys);

        return retval;

}

static void __exit debugfs_exit(void)

{

        simple_release_fs(&debugfs_mount, &debugfs_mount_count);

        unregister_filesystem(&debug_fs_type);

        subsystem_unregister(&debug_subsys);

}

core_initcall(debugfs_init);

module_exit(debugfs_exit);

MODULE_LICENSE("GPL");