sysfs: allow creating symlinks from untagged to tagged directories

Supporting symlinks from untagged to tagged directories is reasonable,
and needed to support CONFIG_SYSFS_DEPRECATED.  So don't fail a prior
allowing that case to work.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

fs/sysfs/symlink.c

@@ -67,7 +67,8 @@ static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
 
 	sysfs_addrm_start(&acxt, parent_sd);
 	/* Symlinks must be between directories with the same ns_type */
-	if (ns_type == sysfs_ns_type(sd->s_symlink.target_sd->s_parent)) {
+	if (!ns_type ||
+	    (ns_type == sysfs_ns_type(sd->s_symlink.target_sd->s_parent))) {
 		if (warn)
 			error = sysfs_add_one(&acxt, sd);
 		else