ovl: Pass ovl_get_nlink() parameters in right order

Right now we seem to be passing index as "lowerdentry" and origin.dentry
as "upperdentry". IIUC, we should pass these parameters in reversed order
and this looks like a bug.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Acked-by: NAmir Goldstein <amir73il@gmail.com>
Fixes: caf70cb2 ("ovl: cleanup orphan index entries")
Cc: <stable@vger.kernel.org> #v4.13
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/namei.c

@@ -435,7 +435,7 @@ int ovl_verify_index(struct dentry *index, struct ovl_path *lower,
 
 	/* Check if index is orphan and don't warn before cleaning it */
 	if (d_inode(index)->i_nlink == 1 &&
-	    ovl_get_nlink(index, origin.dentry, 0) == 0)
+	    ovl_get_nlink(origin.dentry, index, 0) == 0)
 		err = -ENOENT;
 
 	dput(origin.dentry);