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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 27CBFC33CAF for ; Thu, 16 Jan 2020 18:39:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 057E7208C3 for ; Thu, 16 Jan 2020 18:39:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aBGYIdVk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404237AbgAPSjP (ORCPT ); Thu, 16 Jan 2020 13:39:15 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:31480 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2390449AbgAPSjO (ORCPT ); Thu, 16 Jan 2020 13:39:14 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579199953; 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=m9QaZpo4ehb9dzb9uGDth8ZZA66JROBihleoP8BqvZ0=; b=aBGYIdVkRtFwKGt5UjY4isvPaKX1Q2LCfIlD2Nvw1gcpmqs0MMHrnINFXVFdQi1z3O5Poc uVxrDZzhy9eQ+vMbIBRumYLjWz0ztW2BnX2iAwM0wmfX5Xw7zW5op/cISksGxNhLzsenfW pl0DPvxuS0YBpJyJm7+Da3z3vLPV0PU= 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-367-1KLdtB6dNpy1BWHwcYn6Kw-1; Thu, 16 Jan 2020 13:39:08 -0500 X-MC-Unique: 1KLdtB6dNpy1BWHwcYn6Kw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 422A7800D4C; Thu, 16 Jan 2020 18:39:06 +0000 (UTC) Received: from horse.redhat.com (unknown [10.18.25.35]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5CE9480617; Thu, 16 Jan 2020 18:39:01 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id D15EA220A24; Thu, 16 Jan 2020 13:39:00 -0500 (EST) Date: Thu, 16 Jan 2020 13:39:00 -0500 From: Vivek Goyal To: Dan Williams Cc: Jeff Moyer , Jan Kara , "Darrick J. Wong" , Christoph Hellwig , Dave Chinner , Miklos Szeredi , linux-nvdimm , Linux Kernel Mailing List , "Dr. David Alan Gilbert" , virtio-fs@redhat.com, Stefan Hajnoczi , linux-fsdevel Subject: Re: [PATCH 01/19] dax: remove block device dependencies Message-ID: <20200116183900.GC25291@redhat.com> References: <20200109112447.GG27035@quack2.suse.cz> <20200114203138.GA3145@redhat.com> <20200114212805.GB3145@redhat.com> <20200115195617.GA4133@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Jan 16, 2020 at 10:09:46AM -0800, Dan Williams wrote: > On Wed, Jan 15, 2020 at 1:08 PM Jeff Moyer wrote: > > > > Hi, Dan, > > > > Dan Williams writes: > > > > > I'm going to take a look at how hard it would be to develop a kpartx > > > fallback in udev. If that can live across the driver transition then > > > maybe this can be a non-event for end users that already have that > > > udev update deployed. > > > > I just wanted to remind you that label-less dimms still exist, and are > > still being shipped. For those devices, the only way to subdivide the > > storage is via partitioning. > > True, but if kpartx + udev can make this transparent then I don't > think users lose any functionality. They just gain a device-mapper > dependency. So udev rules will trigger when a /dev/pmemX device shows up and run kpartx which in turn will create dm-linear devices and device nodes will show up in /dev/mapper/pmemXpY. IOW, /dev/pmemXpY device nodes will be gone. So if any of the scripts or systemd unit files are depenent on /dev/pmemXpY, these will still be broken out of the box and will have to be modified to use device nodes in /dev/mapper/ directory instead. Do I understand it right, Or I missed the idea completely. Vivek