From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B75F0C352A3 for ; Tue, 11 Feb 2020 15:11:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 871EE20870 for ; Tue, 11 Feb 2020 15:11:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TYHbyn27" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728809AbgBKPLc (ORCPT ); Tue, 11 Feb 2020 10:11:32 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:58124 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728643AbgBKPLb (ORCPT ); Tue, 11 Feb 2020 10:11:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581433889; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=xWrVwmVPWaQjEiPR8xrbcdO9jipuXVef6xbTXqC/E5c=; b=TYHbyn27Y9xOA0ItZjopCSWRr6zIyE9EI470NwnqAHcdkI5pGEZXtd/DYj8eP/H8eQLZHS FqS915vBrc6Fy9HlI8rIngS4TA2nmOtrPGqtmCwM2VRsmC2ajrCSgdOgauzYh9kpylp5Vz tHJLFNHnN4L/v6Wjc+3cS4wCJiCm8jk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-102-JdHOYAdvPNyeRD3JB0pOGA-1; Tue, 11 Feb 2020 10:11:22 -0500 X-MC-Unique: JdHOYAdvPNyeRD3JB0pOGA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 80F7A1005514; Tue, 11 Feb 2020 15:11:20 +0000 (UTC) Received: from horse.redhat.com (ovpn-123-66.rdu2.redhat.com [10.10.123.66]) by smtp.corp.redhat.com (Postfix) with ESMTP id 97B6C26FDB; Tue, 11 Feb 2020 15:11:14 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id 48F50220A24; Tue, 11 Feb 2020 10:11:14 -0500 (EST) Date: Tue, 11 Feb 2020 10:11:14 -0500 From: Vivek Goyal To: Gerald Schaefer Cc: linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org, hch@infradead.org, dan.j.williams@intel.com, dm-devel@redhat.com, vishal.l.verma@intel.com, linux-s390@vger.kernel.org Subject: Re: [PATCH v3 4/7] s390,dcssblk,dax: Add dax zero_page_range operation to dcssblk driver Message-ID: <20200211151114.GA8590@redhat.com> References: <20200207202652.1439-1-vgoyal@redhat.com> <20200207202652.1439-5-vgoyal@redhat.com> <20200210215315.27b7e310@thinkpad> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200210215315.27b7e310@thinkpad> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Feb 10, 2020 at 09:53:15PM +0100, Gerald Schaefer wrote: > On Fri, 7 Feb 2020 15:26:49 -0500 > Vivek Goyal wrote: > > > Add dax operation zero_page_range for dcssblk driver. > > > > CC: linux-s390@vger.kernel.org > > Suggested-by: Christoph Hellwig > > Signed-off-by: Vivek Goyal > > --- > > drivers/s390/block/dcssblk.c | 17 +++++++++++++++++ > > 1 file changed, 17 insertions(+) > > > > diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c > > index 63502ca537eb..331abab5d066 100644 > > --- a/drivers/s390/block/dcssblk.c > > +++ b/drivers/s390/block/dcssblk.c > > @@ -57,11 +57,28 @@ static size_t dcssblk_dax_copy_to_iter(struct dax_device *dax_dev, > > return copy_to_iter(addr, bytes, i); > > } > > > > +static int dcssblk_dax_zero_page_range(struct dax_device *dax_dev, u64 offset, > > + size_t len) > > +{ > > + long rc; > > + void *kaddr; > > + pgoff_t pgoff = offset >> PAGE_SHIFT; > > + unsigned page_offset = offset_in_page(offset); > > + > > + rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr, NULL); > > Why do you pass only 1 page as nr_pages argument for dax_direct_access()? > In some other patch in this series there is a comment that this will > currently only be used for one page, but support for more pages might be > added later. Wouldn't it make sense to rather use something like > PAGE_ALIGN(page_offset + len) >> PAGE_SHIFT instead of 1 here, so that > this won't have to be changed when callers will be ready to use it > with more than one page? > > Of course, I guess then we'd also need some check on the return value > from dax_direct_access(), i.e. if the returned available range is > large enough for the requested range. I left it at 1 page because that's the current limitation of this interface and there are no callers which are zeroing across page boundaries. I prefer to keep it this way and modify it when we are extending this interface to allow zeroing across page boundaries. Because even if I add that logic, I can't test it. But if you still prefer to change it, I am open to make that change. Thanks Vivek