Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754014Ab2HaPYe (ORCPT ); Fri, 31 Aug 2012 11:24:34 -0400 Received: from mail-qa0-f53.google.com ([209.85.216.53]:47013 "EHLO mail-qa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753666Ab2HaPYc (ORCPT ); Fri, 31 Aug 2012 11:24:32 -0400 MIME-Version: 1.0 In-Reply-To: <20120830150348.287bfa2f.akpm@linux-foundation.org> References: <503e0dde.ssYktQsJ5nYlhlQB%paul.clements@steeleye.com> <20120830150348.287bfa2f.akpm@linux-foundation.org> Date: Fri, 31 Aug 2012 11:24:31 -0400 Message-ID: Subject: Re: [PATCH 2/2] [RESEND] add discard support to nbd From: Paul Clements To: Andrew Morton Cc: linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1226 Lines: 39 On Thu, Aug 30, 2012 at 6:03 PM, Andrew Morton wrote: > On Wed, 29 Aug 2012 08:41:02 -0400 > paul.clements@steeleye.com wrote: > >> Description: This patch adds discard support to nbd. When the nbd client >> system receives a discard request, this will be passed along to the nbd >> server system, where the nbd-server will respond by performing: >> fallocate(.. FALLOC_FL_PUNCH_HOLE ..) >> >> To punch a hole in the backend storage, which is no longer needed. >> > > What happens if the user is running an older server? In that case, the older server will not have set NBD_SEND_FLAG_TRIM, so QUEUE_FLAG_DISCARD doesn't get set, so no discards will be sent to the device. > I is it possible that because the old server didn't set > NBD_FLAG_SEND_TRIM, the user's screen gets filled with WARN_ONs? No. > Anyway, please make sure this combination was tested! It was. Thanks for the feedback. I will resend v2 of the patches shortly. -- Paul -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/