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

commit 87d2846fcf88113fae2341da1ca9a71f0d916f2c upstream.

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.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 99382c0df17e..9f65758311a4 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -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)