Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752034AbcCVTAU (ORCPT ); Tue, 22 Mar 2016 15:00:20 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:56471 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750899AbcCVTAR (ORCPT ); Tue, 22 Mar 2016 15:00:17 -0400 Subject: Re: [PATCH 3/6] block: add ability to flag write back caching on a device To: Christoph Hellwig References: <1458669320-6819-1-git-send-email-axboe@fb.com> <1458669320-6819-4-git-send-email-axboe@fb.com> <20160322185724.GA10113@infradead.org> CC: , , From: Jens Axboe Message-ID: <56F19621.4000909@fb.com> Date: Tue, 22 Mar 2016 12:59:45 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20160322185724.GA10113@infradead.org> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.52.123] X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-03-22_09:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 580 Lines: 16 On 03/22/2016 12:57 PM, Christoph Hellwig wrote: > On Tue, Mar 22, 2016 at 11:55:17AM -0600, Jens Axboe wrote: >> Add an internal helper and flag for setting whether a queue has >> write back caching, or write through (or none). Add a sysfs file >> to show this as well, and make it changeable from user space. > > We do this by passing the REQ_FLUSH flag to blk_queue_flush today. > While that's not a great interface, adding a second one doesn't make it > any better :) I think the newer one is cleaner, so would make more sense to put the flush part on top. -- Jens Axboe