ovl: separate detection of remote upper layer from stacked overlay

Following patch will allow remote as upper layer, but not overlay stacked
on upper layer.  Separate the two concepts.

This patch is doesn't change behavior.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/namei.c

@@ -845,7 +845,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		if (err)
 			goto out;
 
-		if (upperdentry && unlikely(ovl_dentry_remote(upperdentry))) {
+		if (upperdentry && (upperdentry->d_flags & DCACHE_OP_REAL ||
+				    unlikely(ovl_dentry_remote(upperdentry)))) {
 			dput(upperdentry);
 			err = -EREMOTE;
 			goto out;