From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH v4] drivers/block/mtip32xx: Adding new driver mtip32xx Date: Fri, 30 Sep 2011 15:20:59 -0600 Message-ID: <4E8632BB.20700@fusionio.com> References: <22A973199D2C2F46933448F6E7990A3002C80026@ntxboimbx31.micron.com> <4E44E782.7090309@fusionio.com> <2A9BE4FF6209B644B6F8EB62DE6AEA1E07663ED4@ntxfrembx01.micron.com> <20110909085433.GA9593@infradead.org> <4E69D519.8070802@fusionio.com> <20110930133323.GA2730@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.fusionio.com ([66.114.96.31]:52943 "EHLO mx2.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755406Ab1I3VVC (ORCPT ); Fri, 30 Sep 2011 17:21:02 -0400 In-Reply-To: <20110930133323.GA2730@infradead.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Christoph Hellwig Cc: "Sam Bradshaw (sbradshaw)" , "alan@lxorguk.ukuu.org.uk" , "linux-ide@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Jeff Garzik , "jmoyer@redhat.com" , "Asai Thambi Samymuthu Pattrayasamy (asamymuthupa) [CONTRACTOR]" On 2011-09-30 07:33, Christoph Hellwig wrote: > On Fri, Sep 09, 2011 at 10:58:01AM +0200, Jens Axboe wrote: >>> - handling of REQ_FUA / REQ_FLUSH requests is completely broken. >>> There is a weird barrier flag to mtip_hw_submit_io which set the >>> hwardware FUA bit if the FLUSH bit is set on a request. >>> Please take a look at how this should be handled, the >>> Documentation/block/writeback_cache_control.txt file is the canonical >>> resource. Implementing your driver at the make_request layer >>> unfortunately means you will have to do all the hard work yourself. >> >> I noticed both of these flush/fua problems too and have fixed them up. > > I sitll can't find anything doing that in your tree while all kinds of > other patches are in. In fact I can't find a place that sends > ATA_CMD_FLUSH/ATA_CMD_FLUSH_EXT commands, not the required queue > draining for it. > > And this stuff really makes me nervous - we get a driver for a new, > expensive high end device and there seems absolutely no concern for > data integrity, or testing of it. I'm away from home, so changes have been coming in through the laptop. But don't worry about the driver, it's sort-of in a staging position at the moment. Before Micron has resolved the issues around queueing etc, it's not going to be merged into mainline. > Or does the device not even have a volatile cache at all, and we could > just remove the FUA code? In this case it should be clearly documented > in the driver. See reply from Micron folks, there's no write back cache currently. -- Jens Axboe