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Commit 87d2846f authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

sysfs: Add support for permanently empty directories to serve as mount points. 



Add two functions sysfs_create_mount_point and
sysfs_remove_mount_point that hang a permanently empty directory off
of a kobject or remove a permanently emptpy directory hanging from a
kobject.  Export these new functions so modular filesystems can use
them.

Cc: stable@vger.kernel.org
Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent ea015218

fs/sysfs/dir.c

+34 −0
Original line number Diff line number Diff line
@@ -121,3 +121,37 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj, 


	return kernfs_rename_ns(kn, new_parent, kn->name, new_ns);

}



/**

 * sysfs_create_mount_point - create an always empty directory

 * @parent_kobj:  kobject that will contain this always empty directory

 * @name: The name of the always empty directory to add

 */

int sysfs_create_mount_point(struct kobject *parent_kobj, const char *name)

{

	struct kernfs_node *kn, *parent = parent_kobj->sd;



	kn = kernfs_create_empty_dir(parent, name);

	if (IS_ERR(kn)) {

		if (PTR_ERR(kn) == -EEXIST)

			sysfs_warn_dup(parent, name);

		return PTR_ERR(kn);

	}



	return 0;

}

EXPORT_SYMBOL_GPL(sysfs_create_mount_point);



/**

 *	sysfs_remove_mount_point - remove an always empty directory.

 *	@parent_kobj: kobject that will contain this always empty directory

 *	@name: The name of the always empty directory to remove

 *

 */

void sysfs_remove_mount_point(struct kobject *parent_kobj, const char *name)

{

	struct kernfs_node *parent = parent_kobj->sd;



	kernfs_remove_by_name_ns(parent, name, NULL);

}

EXPORT_SYMBOL_GPL(sysfs_remove_mount_point);

include/linux/sysfs.h

+15 −0
Original line number Diff line number Diff line
@@ -210,6 +210,10 @@ int __must_check sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name, 
int __must_check sysfs_move_dir_ns(struct kobject *kobj,

				   struct kobject *new_parent_kobj,

				   const void *new_ns);

int __must_check sysfs_create_mount_point(struct kobject *parent_kobj,

					  const char *name);

void sysfs_remove_mount_point(struct kobject *parent_kobj,

			      const char *name);



int __must_check sysfs_create_file_ns(struct kobject *kobj,

				      const struct attribute *attr,
@@ -298,6 +302,17 @@ static inline int sysfs_move_dir_ns(struct kobject *kobj, 
	return 0;

}



static inline int sysfs_create_mount_point(struct kobject *parent_kobj,

					   const char *name)

{

	return 0;

}



static inline void sysfs_remove_mount_point(struct kobject *parent_kobj,

					    const char *name)

{

}



static inline int sysfs_create_file_ns(struct kobject *kobj,

				       const struct attribute *attr,

				       const void *ns)