From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f179.google.com (mail-pl1-f179.google.com [209.85.214.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E52842C8B for ; Thu, 4 Nov 2021 18:10:30 +0000 (UTC) Received: by mail-pl1-f179.google.com with SMTP id b13so8626674plg.2 for ; Thu, 04 Nov 2021 11:10:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=7mdrEIaynFJhMAYVbY2RCFSQ3xBs/5manpadoyeA8Jg=; b=0YEcomScst+1AzYcEtB+P3/DmeUM77501UDi4utLMr5xdKJlnd8UevBd12j9FnZ3vM pfReEE9Mys+ZVEwliSTF7urxA8Wo0+Hi1QGvdNyLT71G18SgBjzWHXiXc01F/GMcT30o 4sj59niVU83geSVU+jTxOcRmF241hREk19CsoBH8kxr2RQdc6rHN1RFVCxVTxuFK53C5 ubx4NqJpME+C1zDILd+MfHjSjbqUFn2nDpjUaVUu+wM8te1yVWJyRStj28nUJ7WDbMUk H2RDjE1nkFNI+5JNwfhWiSHo+ZLBnVukougjDJ/S9PImKe7sfLSLlzrr4uAIBYjBE48z eouQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7mdrEIaynFJhMAYVbY2RCFSQ3xBs/5manpadoyeA8Jg=; b=35W3CdZHod4IM2fUt1+c3ho57EKwwVG2f8XQn5yLZLFfb89+2FYan+UFGsvvta43Sn 5Z9u+aOMO/ifz2E3vYAobF6Y7DQAOxh5m/g4m3egJ7kSA/1mASikmhcMIwTbFkUslYc1 2b/STHs6/heEmtnlLB6o9lLns8tYZjbjIXOZHJW1akSDPpHnhMZLG9i8Qgqcp0elc9Ub CgGYtJggLY3zCiNloNqOCAm3xR/T57mkvrVyDcoSjNzJYtOkODZv5hTUfqxaa09EZ2bq XGYFQB1cZOyLiZ6UTFCWiAUUVGiZMNQ/YlMTfmshXc8E9vXnN7uNwSErmt6FJDy+SWUR 8qXg== X-Gm-Message-State: AOAM533LJc6RaEyi5iFIetOythNv65O0+XO1VshJVSI80x/pviX2CMtd o/WAP6rBxi+WvzG6StwzK9WylvFid7d5+SyJjETqXA== X-Google-Smtp-Source: ABdhPJxpE7179nYWnBAffbsem/btoh3olrocKEPy5McMuIBWtGLmZ02iwXqFLVvSNceMnE3VXVk1wLsDAvNCq2GAmrQ= X-Received: by 2002:a17:902:b697:b0:141:c7aa:e10f with SMTP id c23-20020a170902b69700b00141c7aae10fmr33445935pls.18.1636049430346; Thu, 04 Nov 2021 11:10:30 -0700 (PDT) Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20211018044054.1779424-1-hch@lst.de> <21ff4333-e567-2819-3ae0-6a2e83ec7ce6@sandeen.net> <20211104081740.GA23111@lst.de> <20211104173417.GJ2237511@magnolia> <20211104173559.GB31740@lst.de> In-Reply-To: <20211104173559.GB31740@lst.de> From: Dan Williams Date: Thu, 4 Nov 2021 11:10:19 -0700 Message-ID: Subject: Re: futher decouple DAX from block devices To: Christoph Hellwig Cc: "Darrick J. Wong" , Eric Sandeen , Mike Snitzer , Ira Weiny , device-mapper development , linux-xfs , Linux NVDIMM , linux-s390 , linux-fsdevel , linux-erofs@lists.ozlabs.org, linux-ext4 , virtualization@lists.linux-foundation.org Content-Type: text/plain; charset="UTF-8" On Thu, Nov 4, 2021 at 10:36 AM Christoph Hellwig wrote: > > On Thu, Nov 04, 2021 at 10:34:17AM -0700, Darrick J. Wong wrote: > > /me wonders, are block devices going away? Will mkfs.xfs have to learn > > how to talk to certain chardevs? I guess jffs2 and others already do > > that kind of thing... but I suppose I can wait for the real draft to > > show up to ramble further. ;) > > Right now I've mostly been looking into the kernel side. An no, I > do not expect /dev/pmem* to go away as you'll still need it for a > not DAX aware file system and/or application (such as mkfs initially). > > But yes, just pointing mkfs to the chardev should be doable with very > little work. We can point it to a regular file after all. Note that I've avoided implementing read/write fops for dax devices partly out of concern for not wanting to figure out shared-mmap vs write coherence issues, but also because of a bet with Dave Hansen that device-dax not grow features like what happened to hugetlbfs. So it would seem mkfs would need to switch to mmap I/O, or bite the bullet and implement read/write fops in the driver. 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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8DE82C433F5 for ; Thu, 4 Nov 2021 18:10:42 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 33FAD61207 for ; Thu, 4 Nov 2021 18:10:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 33FAD61207 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=tempfail smtp.mailfrom=redhat.com 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-149-6nbUv6eUM42fGS1pbdBXgA-1; Thu, 04 Nov 2021 14:10:39 -0400 X-MC-Unique: 6nbUv6eUM42fGS1pbdBXgA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D092910A8E05; Thu, 4 Nov 2021 18:10:34 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B4102A6C50; Thu, 4 Nov 2021 18:10:34 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 83F5F4A704; Thu, 4 Nov 2021 18:10:34 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 1A4IAXue009857 for ; Thu, 4 Nov 2021 14:10:33 -0400 Received: by smtp.corp.redhat.com (Postfix) id F37FD400F3C6; Thu, 4 Nov 2021 18:10:32 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast04.extmail.prod.ext.rdu2.redhat.com [10.11.55.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EF509401A993 for ; Thu, 4 Nov 2021 18:10:32 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CF97A1064E6E for ; Thu, 4 Nov 2021 18:10:32 +0000 (UTC) Received: from mail-pl1-f175.google.com (mail-pl1-f175.google.com [209.85.214.175]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-433-qzyyOctPMuG5QexIi4drfQ-1; Thu, 04 Nov 2021 14:10:31 -0400 X-MC-Unique: qzyyOctPMuG5QexIi4drfQ-1 Received: by mail-pl1-f175.google.com with SMTP id u11so8615027plf.3 for ; Thu, 04 Nov 2021 11:10:31 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7mdrEIaynFJhMAYVbY2RCFSQ3xBs/5manpadoyeA8Jg=; b=CzyS7ZS/AW801d/v7ktWHyC81D9oSEd7FksXbdF5TB2O2siTwXK/bo4w1bD8mF7yaY IoXqkkoNHgtxNeAINC7L0IPeSC4329cjtNcYH4yl9swadjO0kNbnh4++EC7RBuNkSW2Q LHQ3XeQz2oBq8/hi3SunpAF6N5oJDxSaFOFM29fDKPX5zvNWGTh74B4Pk98cZiQI6mJN s6vL9a0Dzf/XjZACouHRCNwj4JkQsEaa5l9Ljo8ggoi5eiqDEZo1NHRVNCfRxyQZpFZE 0sfNFz5/2NLiTCtTbJ44X4OhsgYTLlWqQe2aOmWz5aE33Ow/ZEanhbcO6Oc20JfSmS2R PCDw== X-Gm-Message-State: AOAM530UQIWYkZUD8e/ILBWOMlfbhJlw6dmif1Q6WG4Dh0PJYMl4ZYhE 5Ce+3PvVQmZRb8/35PJMr8VLeM1TED69rHi5NfzTyg== X-Google-Smtp-Source: ABdhPJxpE7179nYWnBAffbsem/btoh3olrocKEPy5McMuIBWtGLmZ02iwXqFLVvSNceMnE3VXVk1wLsDAvNCq2GAmrQ= X-Received: by 2002:a17:902:b697:b0:141:c7aa:e10f with SMTP id c23-20020a170902b69700b00141c7aae10fmr33445935pls.18.1636049430346; Thu, 04 Nov 2021 11:10:30 -0700 (PDT) MIME-Version: 1.0 References: <20211018044054.1779424-1-hch@lst.de> <21ff4333-e567-2819-3ae0-6a2e83ec7ce6@sandeen.net> <20211104081740.GA23111@lst.de> <20211104173417.GJ2237511@magnolia> <20211104173559.GB31740@lst.de> In-Reply-To: <20211104173559.GB31740@lst.de> From: Dan Williams Date: Thu, 4 Nov 2021 11:10:19 -0700 Message-ID: To: Christoph Hellwig X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 X-loop: dm-devel@redhat.com Cc: Linux NVDIMM , linux-erofs@lists.ozlabs.org, Mike Snitzer , linux-s390 , "Darrick J. Wong" , Eric Sandeen , virtualization@lists.linux-foundation.org, linux-xfs , device-mapper development , linux-fsdevel , linux-ext4 , Ira Weiny Subject: Re: [dm-devel] futher decouple DAX from block devices X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Thu, Nov 4, 2021 at 10:36 AM Christoph Hellwig wrote: > > On Thu, Nov 04, 2021 at 10:34:17AM -0700, Darrick J. Wong wrote: > > /me wonders, are block devices going away? Will mkfs.xfs have to learn > > how to talk to certain chardevs? I guess jffs2 and others already do > > that kind of thing... but I suppose I can wait for the real draft to > > show up to ramble further. ;) > > Right now I've mostly been looking into the kernel side. An no, I > do not expect /dev/pmem* to go away as you'll still need it for a > not DAX aware file system and/or application (such as mkfs initially). > > But yes, just pointing mkfs to the chardev should be doable with very > little work. We can point it to a regular file after all. Note that I've avoided implementing read/write fops for dax devices partly out of concern for not wanting to figure out shared-mmap vs write coherence issues, but also because of a bet with Dave Hansen that device-dax not grow features like what happened to hugetlbfs. So it would seem mkfs would need to switch to mmap I/O, or bite the bullet and implement read/write fops in the driver. -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel 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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F394DC433F5 for ; Thu, 4 Nov 2021 18:10:34 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 92D0D60EC0 for ; Thu, 4 Nov 2021 18:10:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 92D0D60EC0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 5E906405DF; Thu, 4 Nov 2021 18:10:34 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Vhn8V3cvRaEm; Thu, 4 Nov 2021 18:10:33 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp4.osuosl.org (Postfix) with ESMTPS id 05772405DE; Thu, 4 Nov 2021 18:10:32 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id CE4ECC0019; Thu, 4 Nov 2021 18:10:32 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id B2995C000E for ; Thu, 4 Nov 2021 18:10:31 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 9DA22405DF for ; Thu, 4 Nov 2021 18:10:31 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id VDv_ofQKP1_D for ; Thu, 4 Nov 2021 18:10:31 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.8.0 Received: from mail-pl1-x62d.google.com (mail-pl1-x62d.google.com [IPv6:2607:f8b0:4864:20::62d]) by smtp4.osuosl.org (Postfix) with ESMTPS id E9626405DE for ; Thu, 4 Nov 2021 18:10:30 +0000 (UTC) Received: by mail-pl1-x62d.google.com with SMTP id t21so8593050plr.6 for ; Thu, 04 Nov 2021 11:10:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=7mdrEIaynFJhMAYVbY2RCFSQ3xBs/5manpadoyeA8Jg=; b=0YEcomScst+1AzYcEtB+P3/DmeUM77501UDi4utLMr5xdKJlnd8UevBd12j9FnZ3vM pfReEE9Mys+ZVEwliSTF7urxA8Wo0+Hi1QGvdNyLT71G18SgBjzWHXiXc01F/GMcT30o 4sj59niVU83geSVU+jTxOcRmF241hREk19CsoBH8kxr2RQdc6rHN1RFVCxVTxuFK53C5 ubx4NqJpME+C1zDILd+MfHjSjbqUFn2nDpjUaVUu+wM8te1yVWJyRStj28nUJ7WDbMUk H2RDjE1nkFNI+5JNwfhWiSHo+ZLBnVukougjDJ/S9PImKe7sfLSLlzrr4uAIBYjBE48z eouQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7mdrEIaynFJhMAYVbY2RCFSQ3xBs/5manpadoyeA8Jg=; b=uj6D6xuGsq4PDxMJR/Yx/ryeVSfp7gK2cGx63kxmo+XcvEDwjzHAwK9tuYjUZ7Aq2k PajypDn+vzivO9xLYD3mgbaeIWYd5sj1UFieNDcBPN/ZQuQJioFUks/Me6DIDcg+TEqb dShaFD3DNutB8nc2iXvgXMxiyy7yd/AvPQgkMekoEM/catFUgJTVMhJOidhwfH4drd5e HOYCKFFU1c3hj3/OL20INFkdZfJb4PW8rg8xN+EQrgCqDR60jdG781uT2oRo2ZJjG5A3 ZMr1yYLa4OA6bNbp9jxWh+l/joMGQz+XxljOMGc5Uh67ruuJskaaSu2glkl7CdRjwJUC Iyvw== X-Gm-Message-State: AOAM532rETXmpBn4lIHHyZpfxannGQzsuT9RVObhV3ROgqXTB4IPWY9F WHt+Phj+POMo7bMlBMtCm7x0MGjIpfcRo+ehu6kB9w== X-Google-Smtp-Source: ABdhPJxpE7179nYWnBAffbsem/btoh3olrocKEPy5McMuIBWtGLmZ02iwXqFLVvSNceMnE3VXVk1wLsDAvNCq2GAmrQ= X-Received: by 2002:a17:902:b697:b0:141:c7aa:e10f with SMTP id c23-20020a170902b69700b00141c7aae10fmr33445935pls.18.1636049430346; Thu, 04 Nov 2021 11:10:30 -0700 (PDT) MIME-Version: 1.0 References: <20211018044054.1779424-1-hch@lst.de> <21ff4333-e567-2819-3ae0-6a2e83ec7ce6@sandeen.net> <20211104081740.GA23111@lst.de> <20211104173417.GJ2237511@magnolia> <20211104173559.GB31740@lst.de> In-Reply-To: <20211104173559.GB31740@lst.de> From: Dan Williams Date: Thu, 4 Nov 2021 11:10:19 -0700 Message-ID: Subject: Re: futher decouple DAX from block devices To: Christoph Hellwig Cc: Linux NVDIMM , linux-erofs@lists.ozlabs.org, Mike Snitzer , linux-s390 , "Darrick J. Wong" , Eric Sandeen , virtualization@lists.linux-foundation.org, linux-xfs , device-mapper development , linux-fsdevel , linux-ext4 , Ira Weiny X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On Thu, Nov 4, 2021 at 10:36 AM Christoph Hellwig wrote: > > On Thu, Nov 04, 2021 at 10:34:17AM -0700, Darrick J. Wong wrote: > > /me wonders, are block devices going away? Will mkfs.xfs have to learn > > how to talk to certain chardevs? I guess jffs2 and others already do > > that kind of thing... but I suppose I can wait for the real draft to > > show up to ramble further. ;) > > Right now I've mostly been looking into the kernel side. An no, I > do not expect /dev/pmem* to go away as you'll still need it for a > not DAX aware file system and/or application (such as mkfs initially). > > But yes, just pointing mkfs to the chardev should be doable with very > little work. We can point it to a regular file after all. Note that I've avoided implementing read/write fops for dax devices partly out of concern for not wanting to figure out shared-mmap vs write coherence issues, but also because of a bet with Dave Hansen that device-dax not grow features like what happened to hugetlbfs. So it would seem mkfs would need to switch to mmap I/O, or bite the bullet and implement read/write fops in the driver. _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization 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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8ED0BC433F5 for ; Thu, 4 Nov 2021 18:10:47 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2F2B26120F for ; Thu, 4 Nov 2021 18:10:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2F2B26120F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4HlWsK5fDyz2yPp for ; Fri, 5 Nov 2021 05:10:45 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=intel-com.20210112.gappssmtp.com header.i=@intel-com.20210112.gappssmtp.com header.a=rsa-sha256 header.s=20210112 header.b=0YEcomSc; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=intel.com (client-ip=2607:f8b0:4864:20::630; helo=mail-pl1-x630.google.com; envelope-from=dan.j.williams@intel.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=intel-com.20210112.gappssmtp.com header.i=@intel-com.20210112.gappssmtp.com header.a=rsa-sha256 header.s=20210112 header.b=0YEcomSc; dkim-atps=neutral Received: from mail-pl1-x630.google.com (mail-pl1-x630.google.com [IPv6:2607:f8b0:4864:20::630]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4HlWsD22gnz2xv2 for ; Fri, 5 Nov 2021 05:10:32 +1100 (AEDT) Received: by mail-pl1-x630.google.com with SMTP id u17so8570878plg.9 for ; Thu, 04 Nov 2021 11:10:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=7mdrEIaynFJhMAYVbY2RCFSQ3xBs/5manpadoyeA8Jg=; b=0YEcomScst+1AzYcEtB+P3/DmeUM77501UDi4utLMr5xdKJlnd8UevBd12j9FnZ3vM pfReEE9Mys+ZVEwliSTF7urxA8Wo0+Hi1QGvdNyLT71G18SgBjzWHXiXc01F/GMcT30o 4sj59niVU83geSVU+jTxOcRmF241hREk19CsoBH8kxr2RQdc6rHN1RFVCxVTxuFK53C5 ubx4NqJpME+C1zDILd+MfHjSjbqUFn2nDpjUaVUu+wM8te1yVWJyRStj28nUJ7WDbMUk H2RDjE1nkFNI+5JNwfhWiSHo+ZLBnVukougjDJ/S9PImKe7sfLSLlzrr4uAIBYjBE48z eouQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7mdrEIaynFJhMAYVbY2RCFSQ3xBs/5manpadoyeA8Jg=; b=TjmruvAh/lBKZa2e+pxvLR1RqMiKAgG8ZBOD57utO6SQ7gtupeQzGu9zvHxMyWckiA CcFgcYm5spJw1LWb8X70ZPgvXm87bfOVDlKFmkvFXeurIcp43d7tGEwIRWp3rbrx9Zff JKfoJPhEf1yve10pBkKCGaiFqB7icN0a8MS6hG8qvX+m/a9FbgAcjrhwwncnO8Ie/pIk A1Lb4+6Qre42dT1oUYTtF1jByWK/G+ebiKDngaFo/BwGx89IYx25MQ0Wv8iNtWl65bUS 7r+j6BGJOauMLWdfHA49Bv+ENy9T8rT00Ca3BV2wmu2HexXauuZnJ6R+QbCnWZPtG2k3 eixA== X-Gm-Message-State: AOAM531QeohiRFh+U8LeXr2xuEw3uonFqw/k13j833QWKqW6HX9HAn6N WxjYe/SJWGJMFuKHAx1F5ppGRE/N3znVcXK/derY7w== X-Google-Smtp-Source: ABdhPJxpE7179nYWnBAffbsem/btoh3olrocKEPy5McMuIBWtGLmZ02iwXqFLVvSNceMnE3VXVk1wLsDAvNCq2GAmrQ= X-Received: by 2002:a17:902:b697:b0:141:c7aa:e10f with SMTP id c23-20020a170902b69700b00141c7aae10fmr33445935pls.18.1636049430346; Thu, 04 Nov 2021 11:10:30 -0700 (PDT) MIME-Version: 1.0 References: <20211018044054.1779424-1-hch@lst.de> <21ff4333-e567-2819-3ae0-6a2e83ec7ce6@sandeen.net> <20211104081740.GA23111@lst.de> <20211104173417.GJ2237511@magnolia> <20211104173559.GB31740@lst.de> In-Reply-To: <20211104173559.GB31740@lst.de> From: Dan Williams Date: Thu, 4 Nov 2021 11:10:19 -0700 Message-ID: Subject: Re: futher decouple DAX from block devices To: Christoph Hellwig Content-Type: text/plain; charset="UTF-8" X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Linux NVDIMM , linux-erofs@lists.ozlabs.org, Mike Snitzer , linux-s390 , "Darrick J. Wong" , Eric Sandeen , virtualization@lists.linux-foundation.org, linux-xfs , device-mapper development , linux-fsdevel , linux-ext4 , Ira Weiny Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" On Thu, Nov 4, 2021 at 10:36 AM Christoph Hellwig wrote: > > On Thu, Nov 04, 2021 at 10:34:17AM -0700, Darrick J. Wong wrote: > > /me wonders, are block devices going away? Will mkfs.xfs have to learn > > how to talk to certain chardevs? I guess jffs2 and others already do > > that kind of thing... but I suppose I can wait for the real draft to > > show up to ramble further. ;) > > Right now I've mostly been looking into the kernel side. An no, I > do not expect /dev/pmem* to go away as you'll still need it for a > not DAX aware file system and/or application (such as mkfs initially). > > But yes, just pointing mkfs to the chardev should be doable with very > little work. We can point it to a regular file after all. Note that I've avoided implementing read/write fops for dax devices partly out of concern for not wanting to figure out shared-mmap vs write coherence issues, but also because of a bet with Dave Hansen that device-dax not grow features like what happened to hugetlbfs. So it would seem mkfs would need to switch to mmap I/O, or bite the bullet and implement read/write fops in the driver.