static int do_new_mount(struct path *path, const char *fstype, int flags,
			int mnt_flags, const char *name, void *data)
{
	struct file_system_type *type;
	struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;
	struct vfsmount *mnt;
	int err;

	if (!fstype)
		return -EINVAL;

	type = get_fs_type(fstype);
	if (!type)
		return -ENODEV;

	if (user_ns != &init_user_ns) {
		if (!(type->fs_flags & FS_USERNS_MOUNT)) {
			put_filesystem(type);
			return -EPERM;
		}
		/* Only in special cases allow devices from mounts
		 * created outside the initial user namespace.
		 */
		if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) {
			flags |= MS_NODEV;
			mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV;
		}
	}

	mnt = vfs_kern_mount(type, flags, name, data);
	if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
	    !mnt->mnt_sb->s_subtype)
		mnt = fs_set_subtype(mnt, fstype);

	put_filesystem(type);
	if (IS_ERR(mnt))
		return PTR_ERR(mnt);

	err = do_add_mount(real_mount(mnt), path, mnt_flags);
	if (err)
		mntput(mnt);
	return err;
}

Unknown