From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754249AbbIWLdF (ORCPT ); Wed, 23 Sep 2015 07:33:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59701 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753795AbbIWLdC (ORCPT ); Wed, 23 Sep 2015 07:33:02 -0400 From: Vitaly Kuznetsov To: Christoph Hellwig Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, "K. Y. Srinivasan" , Haiyang Zhang , "James E.J. Bottomley" , Radim Kr??m???? Subject: Re: [PATCH] storvsc: get rid of homegrown copy_{to,from}_bounce_buffer() References: <1442939270-9651-1-git-send-email-vkuznets@redhat.com> <20150922215310.GA29802@infradead.org> Date: Wed, 23 Sep 2015 13:32:58 +0200 In-Reply-To: <20150922215310.GA29802@infradead.org> (Christoph Hellwig's message of "Tue, 22 Sep 2015 14:53:10 -0700") Message-ID: <87pp19gyl1.fsf@vitty.brq.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christoph Hellwig writes: > On Tue, Sep 22, 2015 at 06:27:50PM +0200, Vitaly Kuznetsov wrote: >> Storvsc driver needs to ensure there are no 'holes' in the presented >> sg list (all segments in the middle of the list need to be of PAGE_SIZE). > > I think it should instead set a virt_boundary. That's what we added for > the NVMe driver which has the same requirements, and Sagi recently also > switched iSER to it after we ensured that flag is handled correctly by > the SG_IO ioctl. Wow, I checked and blk_queue_virt_boundary(sdevice->request_queue, PAGE_SIZE - 1) seems to be solving the issue completely, no bounce buffer required. I'll test more and send v2 with removing the rest. -- Vitaly