Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751953AbcCVS53 (ORCPT ); Tue, 22 Mar 2016 14:57:29 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:48220 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750910AbcCVS5Z (ORCPT ); Tue, 22 Mar 2016 14:57:25 -0400 Date: Tue, 22 Mar 2016 11:57:24 -0700 From: Christoph Hellwig To: Jens Axboe Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org Subject: Re: [PATCH 3/6] block: add ability to flag write back caching on a device Message-ID: <20160322185724.GA10113@infradead.org> References: <1458669320-6819-1-git-send-email-axboe@fb.com> <1458669320-6819-4-git-send-email-axboe@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1458669320-6819-4-git-send-email-axboe@fb.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 411 Lines: 8 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 :)