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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 D5FB5C83000 for ; Thu, 30 Apr 2020 14:38:42 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 A2DB62074A for ; Thu, 30 Apr 2020 14:38:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="AzYxoFiV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A2DB62074A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:60118 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jUAKn-0004O1-QV for qemu-devel@archiver.kernel.org; Thu, 30 Apr 2020 10:38:41 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:33604) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jUAH1-0007Vg-Cp for qemu-devel@nongnu.org; Thu, 30 Apr 2020 10:34:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.90_1) (envelope-from ) id 1jUAGz-0006VJ-8h for qemu-devel@nongnu.org; Thu, 30 Apr 2020 10:34:47 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:37670 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jUAGy-0006V1-S1 for qemu-devel@nongnu.org; Thu, 30 Apr 2020 10:34:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588257283; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gr9mZHYm1mbvL06H8cfLy/QWvH+yZ284xFyWZ9hXbS4=; b=AzYxoFiVOELguQjFatXAgu4gKjPBPPoNWMKUUiB84Lv5LMC95Ff5XJ0Icegcon1udplHw3 vSOX9OgMvF270BltiGuMoI0LlmLmGZt5nnEa5KCRgmqc5O3IVLhqzoQ/gL3CvDxiRIgJrV 1NONcYa0z+NSe0vRvddx8Gh31QEjRR8= 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-176-WS6IB-f0MCW-QvhnR72ygw-1; Thu, 30 Apr 2020 10:34:37 -0400 X-MC-Unique: WS6IB-f0MCW-QvhnR72ygw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 32C6C80B70C for ; Thu, 30 Apr 2020 14:34:36 +0000 (UTC) Received: from redhat.com (unknown [10.36.110.44]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E9D4260C87; Thu, 30 Apr 2020 14:34:28 +0000 (UTC) Date: Thu, 30 Apr 2020 15:34:25 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: "Dr. David Alan Gilbert" Subject: Re: [PATCH] virtiofsd: Show submounts Message-ID: <20200430143425.GD2184629@redhat.com> References: <20200424133516.73077-1-mreitz@redhat.com> <20200427175902.GM2923@work-vm> <20200429145720.GA2835@work-vm> <8c73f374-fcc8-1684-b581-84a9ab501aa9@redhat.com> <20200430085812.GC2874@work-vm> <20200430135639.GA260081@redhat.com> <20200430142013.GI2874@work-vm> MIME-Version: 1.0 In-Reply-To: <20200430142013.GI2874@work-vm> User-Agent: Mutt/1.13.3 (2020-01-12) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.120; envelope-from=berrange@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/30 01:24:05 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: virtio-fs@redhat.com, Stefan Hajnoczi , qemu-devel@nongnu.org, Vivek Goyal , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Apr 30, 2020 at 03:20:13PM +0100, Dr. David Alan Gilbert wrote: > * Vivek Goyal (vgoyal@redhat.com) wrote: > > On Thu, Apr 30, 2020 at 09:58:12AM +0100, Dr. David Alan Gilbert wrote: > > [..] > > > > > Even without this patch, the SLAVE stuff worked so if you start t= he > > > > > daemon and *then* mount under the shared directory, the guest see= s it > > > > > with or without this patch. > > > >=20 > > > > Hm, I don=E2=80=99t. Do you really? > > >=20 > > > Yes! With your patch reverted: > > >=20 > > > Start virtiofsd, mount in the guest: > > >=20 > > > host: > > > # ./virtiofsd --socket-path=3D/tmp/vhostqemu -o source=3D/home/dgilbe= rt/virtio-fs/fs -o log_level=3Dwarn -o no_writeback > > >=20 > > > guest: > > > # mount -t virtiofs myfs /sysroot > > >=20 > > > host: > > > # findmnt -o +PROPAGATION -N 6100 > > > TARGET SOURCE = FSTYPE OPTIONS P= ROPAGATION > > > / /dev/mapper/fedora_dgilbert--t580-root[/home/dgilbert/virtio-f= s/fs] xfs rw,relatime,seclabel,attr2,inode64,logbufs=3D8,logbsize=3D32k,= no private,slave > > > # mount -t tmpfs /dev/null /home/dgilbert/virtio-fs/fs/tmp > > > # findmnt -o +PROPAGATION -N 6100 > > > TARGET SOURCE = FSTYPE OPTIONS P= ROPAGATION > > > / /dev/mapper/fedora_dgilbert--t580-root[/home/dgilbert/virtio-f= s/fs] xfs rw,relatime,seclabel,attr2,inode64,logbufs=3D8,logbsize=3D32k,= no private,slave > > > =E2=94=94=E2=94=80/tmp /dev/null = tmpfs rw,relatime,seclabel = private,slave > >=20 > > Why is it showing a mount point at "/tmp". If mount point propagated, t= hen > > inside guest we should see a mount point at /sysroot/tmp? >=20 > That findmnt is on the host. >=20 > > So there are two things. > >=20 > > A. Propagation of mount from host to virtiofsd. > > B. Visibility of that mount inside guest over fuse protocol (submount > > functionality). > >=20 > > I think A works for me without any patches. But don't think B is workin= g > > for me. I don't see the submount inside guest.=20 > >=20 > > > # touch /home/dgilbert/virtio-fs/fs/tmp/hello > > >=20 > > > guest: > > > # ls -l /sysroot/tmp > > > total 0 > > > -rw-r--r-- 1 root root 0 Apr 30 08:50 hello > >=20 > > Do a "findmnt /sysroot/tmp" inside guest and see what do you see. > >=20 > > You will be able to see "hello" as long as virtiofsd sees the new > > mount point, I think. And guest does not have to see that mount point > > for this simple test to work. >=20 > Right, the guest just sees: >=20 > `-/sysroot myfs virtiof rw,relatime That is a good thing surely ? If I'm exporting "/sysroot" from the host, I want the content in "/sysroot/some/sub/mount" to be visible to the guest, but I don't want the guest to see "/sysroot/some/sub/mount" as an actual mount point. That would be leaking information about the host storage setup into the guest. The host admin should be free to re-arrange submounts in the host OS, to bring more storage space online, and have this be transparent to the guest OS. Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberrange= :| |: https://libvirt.org -o- https://fstop138.berrange.com= :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange= :|