From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [RFC][PATCH] libata: enable SATA disk fua detection on default Date: Sun, 09 Sep 2012 16:39:06 -0400 Message-ID: <504CFE6A.6020403@pobox.com> References: <1336447443-4685-1-git-send-email-wenqing.lz@taobao.com> <20120703090441.GA4804@gmail.com> <4FF351F8.1000003@msgid.tls.msk.ru> <20120704024715.GA17095@gmail.com> <4FF3E478.50609@msgid.tls.msk.ru> <20120704070604.GA17769@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-vc0-f174.google.com ([209.85.220.174]:48366 "EHLO mail-vc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754939Ab2IIUjJ (ORCPT ); Sun, 9 Sep 2012 16:39:09 -0400 In-Reply-To: Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Arvydas Sidorenko Cc: Michael Tokarev , Jeff Garzik , linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, Zheng Liu On 09/09/2012 04:34 PM, Arvydas Sidorenko wrote: >> Meanwhile there already has a number of SATA disks that have supported >> this feature. So I think maybe we can enable it. >> >> Regards, >> Zheng > > Blindly enabling FUA by default in my opinion is not a good idea at all. > I believe the focus should be on detecting FUA support on the device > instead, which the kernel at this point cannot reliably do (is it possible?). Premature assumptions. It is entirely possible that FUA is detected accurately, but the software is missing a flush somewhere that FUA requires, if disks are to be used in FUA mode. The filesystem and the block layer must properly generate and order their I/Os based on the FUA enablement bits that appear in the block layer after libata discovers the SATA FUA feature. Jeff