From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755598Ab0GAM2v (ORCPT ); Thu, 1 Jul 2010 08:28:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59650 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754966Ab0GAM2t (ORCPT ); Thu, 1 Jul 2010 08:28:49 -0400 Date: Thu, 1 Jul 2010 08:28:02 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@hs20-bc2-1.build.redhat.com To: James Bottomley cc: device-mapper development , Mike Snitzer , axboe@kernel.dk, linux-scsi@vger.kernel.org, martin.petersen@oracle.com, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Christoph Hellwig Subject: Re: [dm-devel] [PATCH 1/2] block: fix leaks associated with discard request payload In-Reply-To: <1277907738.2839.9.camel@mulgrave.site> Message-ID: References: <20100622180029.GA15950@redhat.com> <1277582211-10725-1-git-send-email-snitzer@redhat.com> <1277652576.4366.19.camel@mulgrave.site> <1277852600.4379.211.camel@mulgrave.site> <1277907738.2839.9.camel@mulgrave.site> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > It is either/or choice. If the interface isn't fixed NOW, the existing > > flawed zeroed-page-allocation interface gets into RHEL > > That's a false dichotomy. You might see an either apply this hack now > or support the interface choice with RHEL, but upstream has the option > to fix stuff correctly. RHEL has never needed my blessing to apply > random crap to their kernel before ... why is this patch any different? We can't apply non-upstream patches (except few exceptions such as dm-raid45). It makes sense, non-upstream patches have smaller test coverage. > And the rest of this rubbish is based on that false premise. It might > help you to take off your SCSI antipathy and see this as a system > problem: it actually originates in block and spills out from there. > Thus it requires a system solution. > > James Imagine this: I take a FPGA PCI board, I design a storage controller on it and this controller will need 3 pages to process a discard request. Now I say: I refuse to allocate these 3 pages in the driver because the driver would look ugly --- instead, I demand that everyone in the Linux kernel who creates a discard request must attach 3 pages to the request for my driver. Do you think it is correct behavior? Would you accept such a driver? I guess you wouldn't! But this is the same thing that you are doing with SCSI. Now lets take it a bit further and I say "I may clean up the driver for my controller one day, when I do it, I remove that 3-page requirement --- and then, everyone who allocated those pages will have to change his code and remove the allocations". And this is what you are intending to do with SCSI. Mikulas