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=-2.2 required=3.0 tests=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 CE25EFA3728 for ; Wed, 16 Oct 2019 13:45:17 +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 A6A1421928 for ; Wed, 16 Oct 2019 13:45:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A6A1421928 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]:42846 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iKjc4-0001WY-Mm for qemu-devel@archiver.kernel.org; Wed, 16 Oct 2019 09:45:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59362) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iKjb6-00016h-Vy for qemu-devel@nongnu.org; Wed, 16 Oct 2019 09:44:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iKjb5-0001Jc-8w for qemu-devel@nongnu.org; Wed, 16 Oct 2019 09:44:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38342) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iKjb5-0001Il-0j for qemu-devel@nongnu.org; Wed, 16 Oct 2019 09:44:15 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2CC2B693CB; Wed, 16 Oct 2019 13:44:13 +0000 (UTC) Received: from work-vm (ovpn-117-133.ams2.redhat.com [10.36.117.133]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 948991048128; Wed, 16 Oct 2019 13:44:11 +0000 (UTC) Date: Wed, 16 Oct 2019 14:44:09 +0100 From: "Dr. David Alan Gilbert" To: Christian Schoenebeck Subject: Re: virtio-fs: Fix file ID collisions (was: 9p: Fix file ID collisions) Message-ID: <20191016134409.GG2978@work-vm> References: <2456208.kOTvEbKLdM@silver> <20191015112039.620997e3@bahia.lan> <4114483.KuMf1QML1b@silver> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4114483.KuMf1QML1b@silver> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 16 Oct 2019 13:44:13 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 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: , Cc: Stefan Hajnoczi , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , qemu-devel@nongnu.org, Antonios Motakis , Greg Kurz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Christian Schoenebeck (qemu_oss@crudebyte.com) wrote: > On Dienstag, 15. Oktober 2019 11:20:39 CEST Greg Kurz wrote: > > On Tue, 08 Oct 2019 14:05:28 +0200 > > > > Christian Schoenebeck wrote: > > > I wonder though whether virtio-fs suffers from the same file ID collisions > > > problem when sharing multiple file systems. > > > > I gave a try and it seems that virtio-fs might expose the inode numbers from > > different devices in the host, unvirtualized AND with the same device in > > the guest: > > > > # mkdir -p /var/tmp/virtio-fs/proc > > # mount --bind /proc /var/tmp/virtio-fs/proc > > # virtiofsd -o vhost_user_socket=/tmp/vhostqemu -o source=/var/tmp/virtio-fs > > -o cache=always > > > > and then started QEMU with: > > > > -chardev socket,id=char0,path=/tmp/vhostqemu \ > > -device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs \ > > -m 4G -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on > > \ -numa node,memdev=mem > > > > In the host: > > > > $ stat /var/tmp/virtio-fs > > File: /var/tmp/virtio-fs > > Size: 4096 Blocks: 8 IO Block: 4096 directory > > Device: fd00h/64768d Inode: 787796 Links: 4 > > Access: (0775/drwxrwxr-x) Uid: ( 1000/ greg) Gid: ( 1000/ greg) > > Context: unconfined_u:object_r:user_tmp_t:s0 > > Access: 2019-10-15 11:08:52.070080922 +0200 > > Modify: 2019-10-15 11:02:09.887404446 +0200 > > Change: 2019-10-15 11:02:09.887404446 +0200 > > Birth: 2019-10-13 19:13:04.009699354 +0200 > > [greg@bahia ~]$ stat /var/tmp/virtio-fs/FOO > > File: /var/tmp/virtio-fs/FOO > > Size: 0 Blocks: 0 IO Block: 4096 regular empty > > file Device: fd00h/64768d Inode: 790740 Links: 1 > > Access: (0664/-rw-rw-r--) Uid: ( 1000/ greg) Gid: ( 1000/ greg) > > Context: unconfined_u:object_r:user_tmp_t:s0 > > Access: 2019-10-15 11:02:09.888404448 +0200 > > Modify: 2019-10-15 11:02:09.888404448 +0200 > > Change: 2019-10-15 11:02:09.888404448 +0200 > > Birth: 2019-10-15 11:02:09.887404446 +0200 > > [greg@bahia ~]$ stat /var/tmp/virtio-fs/proc/fs > > File: /var/tmp/virtio-fs/proc/fs > > Size: 0 Blocks: 0 IO Block: 1024 directory > > Device: 4h/4d Inode: 4026531845 Links: 5 > > Access: (0555/dr-xr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root) > > Context: system_u:object_r:proc_t:s0 > > Access: 2019-10-01 14:50:09.223233901 +0200 > > Modify: 2019-10-01 14:50:09.223233901 +0200 > > Change: 2019-10-01 14:50:09.223233901 +0200 > > Birth: - > > > > In the guest: > > > > [greg@localhost ~]$ stat /mnt > > File: /mnt > > Size: 4096 Blocks: 8 IO Block: 4096 directory > > Device: 2dh/45d Inode: 787796 Links: 4 > > Access: (0775/drwxrwxr-x) Uid: ( 1000/ greg) Gid: ( 1000/ greg) > > Context: system_u:object_r:unlabeled_t:s0 > > Access: 2019-10-15 11:08:52.070080922 +0200 > > Modify: 2019-10-15 11:02:09.887404446 +0200 > > Change: 2019-10-15 11:02:09.887404446 +0200 > > Birth: - > > [greg@localhost ~]$ stat /mnt/FOO > > File: /mnt/FOO > > Size: 0 Blocks: 0 IO Block: 4096 regular empty > > file Device: 2dh/45d Inode: 790740 Links: 1 > > Access: (0664/-rw-rw-r--) Uid: ( 1000/ greg) Gid: ( 1000/ greg) > > Context: system_u:object_r:unlabeled_t:s0 > > Access: 2019-10-15 11:02:09.888404448 +0200 > > Modify: 2019-10-15 11:02:09.888404448 +0200 > > Change: 2019-10-15 11:02:09.888404448 +0200 > > Birth: - > > [greg@localhost ~]$ stat /mnt/proc/fs > > File: /mnt/proc/fs > > Size: 0 Blocks: 0 IO Block: 1024 directory > > Device: 2dh/45d Inode: 4026531845 Links: 5 > > Access: (0555/dr-xr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root) > > Context: system_u:object_r:unlabeled_t:s0 > > Access: 2019-10-01 14:50:09.223233901 +0200 > > Modify: 2019-10-01 14:50:09.223233901 +0200 > > Change: 2019-10-01 14:50:09.223233901 +0200 > > Birth: - > > > > Unless I'm missing something, it seems that "virtio-fs" has the same > > issue we had on 9pfs before Christian's patches... :-\ > > Is a fix for this desired for virtio-fs? Yes I think so; we had originally thought we were hiding the host inode numbers; but that's not true - since we pass both a device and inode number in virtiofs, unlike 9p, it seems we can probably get away with only remapping device IDs rather than inode numbers; but that requires some understanding of how multiple block device IDs are supposed to look like to the guest kernel. Dave > Greg, did you have to update kernel version on either host or guest side to > get virtio-fs running? Or were the discussed kernel changes just for optional > acceleration purposes (i.e. DAX)? > > Best regards, > Christian Schoenebeck > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK