From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932485Ab2DTQOh (ORCPT ); Fri, 20 Apr 2012 12:14:37 -0400 Received: from acsinet15.oracle.com ([141.146.126.227]:51790 "EHLO acsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932077Ab2DTQOg (ORCPT ); Fri, 20 Apr 2012 12:14:36 -0400 Message-ID: <4F918B66.10107@oracle.com> Date: Fri, 20 Apr 2012 11:14:30 -0500 From: Dave Kleikamp User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120406 Thunderbird/11.0.1 MIME-Version: 1.0 To: Jeff Moyer CC: "Maxim V. Patlasov" , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Zach Brown Subject: Re: [RFC PATCH v2 15/21] loop: use aio to perform io on the underlying file References: <1333122228-13633-1-git-send-email-dave.kleikamp@oracle.com> <1333122228-13633-16-git-send-email-dave.kleikamp@oracle.com> <4F917751.9040600@parallels.com> <4F917C2F.4020805@oracle.com> In-Reply-To: X-Enigmail-Version: 1.4 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Source-IP: ucsinet22.oracle.com [156.151.31.94] X-CT-RefId: str=0001.0A090208.4F918B69.0094,ss=1,re=0.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/20/2012 10:20 AM, Jeff Moyer wrote: > Dave Kleikamp writes: > >> On 04/20/2012 09:48 AM, Maxim V. Patlasov wrote: >>> On 03/30/2012 07:43 PM, Dave Kleikamp wrote: >>>> From: Zach Brown >>>> >>>> This uses the new kernel aio interface to process loopback IO by >>>> submitting concurrent direct aio. Previously loop's IO was serialized >>>> by synchronous processing in a thread. >>>> >>> >>> The patch ignores REQ_FLUSH bit of bi_rw. Is it simply overlook? >> >> Good question. Since the loop device is sending only direct IO requests, >> it shouldn't be necessary to explicitly flush page cache, but REQ_FLUSH > > REQ_FLUSH isn't about the page cache, it's about flushing the volatile > disk write cache. You need to handle that. Yeah, and looking again at this code, I need to handle REQ_DISCARD as well. > > Cheers, > Jeff