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=-8.7 required=3.0 tests=BAYES_00,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=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 01F53C433EF for ; Mon, 20 Sep 2021 16:33:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D41E96023D for ; Mon, 20 Sep 2021 16:33:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230099AbhITQfS (ORCPT ); Mon, 20 Sep 2021 12:35:18 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:52453 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229993AbhITQfR (ORCPT ); Mon, 20 Sep 2021 12:35:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632155630; 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=eofAwNSQHggES8FnoNdSbxlwsVv5uIPZtDIw746OjHo=; b=RE5ikbAjfJxkCve1XzNDlipsl/JONa5BluAFeHFOoEUr0tLGrfCOG5lKYRYZahYu2b3BTM eTwlNT+UxM4AZJZaVjM1JAL2V4BtEg6iC2RQmHSH2106PfBKhcbQ/cUsIlivIrEj4JSQeC qLZP6MnyalF07Lcg5CRJCIa0WwHOI+4= 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-534-lviKKn19PQC-tNZukbZv5w-1; Mon, 20 Sep 2021 12:33:48 -0400 X-MC-Unique: lviKKn19PQC-tNZukbZv5w-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E3AD1100D68E; Mon, 20 Sep 2021 16:33:27 +0000 (UTC) Received: from localhost (unknown [10.39.194.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8F2D46B545; Mon, 20 Sep 2021 16:33:27 +0000 (UTC) Date: Mon, 20 Sep 2021 17:33:26 +0100 From: "Richard W.M. Jones" To: Andreas Dilger Cc: Theodore Ts'o , Eric Blake , linux-ext4@vger.kernel.org, libguestfs@redhat.com, lersek@redhat.com Subject: Re: e2fsprogs concurrency questions Message-ID: <20210920163326.GA16016@redhat.com> References: <24A05FA3-F618-4469-BC0A-E19A425A0E36@dilger.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <24A05FA3-F618-4469-BC0A-E19A425A0E36@dilger.ca> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Sun, Sep 19, 2021 at 04:39:01AM -0600, Andreas Dilger wrote: > What I don't understand here is why not just use a network > filesystem that is explicitly designed for this task (eg. NFS or > Ganesha on to of ext4)? nbdkit-ext2-filter is very niche, but it's quite different from anything NFS can do. For example: $ nbdkit --filter=ext2 --filter=xz \ curl http://oirase.annexia.org/tmp/disk.img.xz \ ext2file=/disk/fedora-33.img $ nbdinfo nbd://localhost protocol: newstyle-fixed without TLS export="": export-size: 6442450944 content: DOS/MBR boot sector uri: nbd://localhost:10809/ contexts: base:allocation is_rotational: false is_read_only: true can_cache: true can_df: true can_fast_zero: false can_flush: true can_fua: false can_multi_conn: false can_trim: false can_zero: false $ guestfish --ro --format=raw -a nbd://localhost -i [...] Operating system: Fedora 33 (Thirty Three) /dev/sda3 mounted on / /dev/sda2 mounted on /boot What we're doing here is exporting a compressed ext4 image over HTTP and then accessing a VM image inside it. (This is a contrived example but it's similar to something called the Containerized Data Importer in Kubernetes.) Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html