path: corretly implement path to snapshots

PVE/Storage/GlusterfsPlugin.pm

@@ -191,9 +191,15 @@ my $find_free_diskname = sub {
 };
 
 sub path {
-    my ($class, $scfg, $volname, $storeid) = @_;
+    my ($class, $scfg, $volname, $storeid, $snapname) = @_;
 
-    my ($vtype, $name, $vmid) = $class->parse_volname($volname);
+    my ($vtype, $name, $vmid, undef, undef, $isBase, $format) =
+	$class->parse_volname($volname);
+
+    # Note: qcow2/qed has internal snapshot, so path is always
+    # the same (with or without snapshot => same file).
+    die "can't snapshot this image format\n" 
+	if defined($snapname) && $format !~ m/^(qcow2|qed)$/;
 
     my $path = undef;
     if ($vtype eq 'images') {