ovl: rearrange ovl_can_list()

ovl_can_list() should return false for overlay private xattrs.  Since
currently these use the "trusted.overlay." prefix, they will always match
the "trusted." prefix as well, hence the test for being non-trusted will
not trigger.

Prepare for using the "user.overlay." namespace by moving the test for
private xattr before the test for non-trusted.

This patch doesn't change behavior.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/inode.c

@@ -393,13 +393,16 @@ int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
 
 static bool ovl_can_list(struct super_block *sb, const char *s)
 {
+	/* Never list private (.overlay) */
+	if (ovl_is_private_xattr(sb, s))
+		return false;
+
 	/* List all non-trusted xatts */
 	if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0)
 		return true;
 
-	/* Never list trusted.overlay, list other trusted for superuser only */
-	return !ovl_is_private_xattr(sb, s) &&
-	       ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN);
+	/* list other trusted for superuser only */
+	return ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN);
 }
 
 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)