fs/debugfs/inode.c - maze/linux - Git at Google

 /*
  *  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/namei.h>
 #include <linux/debugfs.h>

 #define DEBUGFS_MAGIC	0x64626720

 /* declared over in file.c */
 extern struct file_operations debugfs_file_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_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);
 	return res;
 }

 static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode)
 {
 	mode = (mode & S_IALLUGO) | S_IFREG;
 	return debugfs_mknod(dir, dentry, mode, 0);
 }

 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)) {
 		if ((mode & S_IFMT) == S_IFDIR)
 			error = debugfs_mkdir(parent->d_inode, *dentry, mode);
 		else
 			error = debugfs_create(parent->d_inode, *dentry, mode);
 	} 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.  It is not wise to check for this value, but rather, check for
  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
  * code.
  */
 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;
 		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.  It is not wise to check for this value, but rather, check for
  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
  * code.
  */
 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_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;

 	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) {
 			if (S_ISDIR(dentry->d_inode->i_mode))
 				simple_rmdir(parent->d_inode, dentry);
 			else
 				simple_unlink(parent->d_inode, dentry);
 		dput(dentry);
 		}
 	}
 	mutex_unlock(&parent->d_inode->i_mutex);
 	simple_release_fs(&debugfs_mount, &debugfs_mount_count);
 }
 EXPORT_SYMBOL_GPL(debugfs_remove);

 static decl_subsys(debug, NULL, NULL);

 static int __init debugfs_init(void)
 {
 	int retval;

 	kset_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");
	/*
	* 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/namei.h>
	#include <linux/debugfs.h>

	#define DEBUGFS_MAGIC 0x64626720

	/* declared over in file.c */
	extern struct file_operations debugfs_file_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_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);
	return res;
	}

	static int debugfs_create(struct inode dir, struct dentry dentry, int mode)
	{
	mode = (mode & S_IALLUGO) \| S_IFREG;
	return debugfs_mknod(dir, dentry, mode, 0);
	}

	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)) {
	if ((mode & S_IFMT) == S_IFDIR)
	error = debugfs_mkdir(parent->d_inode, *dentry, mode);
	else
	error = debugfs_create(parent->d_inode, *dentry, mode);
	} 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. It is not wise to check for this value, but rather, check for
	* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
	* code.
	*/
	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;
	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. It is not wise to check for this value, but rather, check for
	* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
	* code.
	*/
	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_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;

	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) {
	if (S_ISDIR(dentry->d_inode->i_mode))
	simple_rmdir(parent->d_inode, dentry);
	else
	simple_unlink(parent->d_inode, dentry);
	dput(dentry);
	}
	}
	mutex_unlock(&parent->d_inode->i_mutex);
	simple_release_fs(&debugfs_mount, &debugfs_mount_count);
	}
	EXPORT_SYMBOL_GPL(debugfs_remove);

	static decl_subsys(debug, NULL, NULL);

	static int __init debugfs_init(void)
	{
	int retval;

	kset_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");