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,URIBL_BLOCKED,USER_AGENT_SANE_2 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 A388DC10F14 for ; Tue, 8 Oct 2019 13:49:06 +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 79E30206BB for ; Tue, 8 Oct 2019 13:49:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 79E30206BB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kaod.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:55896 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iHprN-0006UR-KC for qemu-devel@archiver.kernel.org; Tue, 08 Oct 2019 09:49:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44604) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iHpqA-0005t1-MU for qemu-devel@nongnu.org; Tue, 08 Oct 2019 09:47:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iHpq9-0006fJ-5W for qemu-devel@nongnu.org; Tue, 08 Oct 2019 09:47:50 -0400 Received: from 4.mo69.mail-out.ovh.net ([46.105.42.102]:59558) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iHpq8-0006ah-VH for qemu-devel@nongnu.org; Tue, 08 Oct 2019 09:47:49 -0400 Received: from player734.ha.ovh.net (unknown [10.108.54.36]) by mo69.mail-out.ovh.net (Postfix) with ESMTP id 88B496BC0B for ; Tue, 8 Oct 2019 15:47:40 +0200 (CEST) Received: from kaod.org (deibp9eh1--blueice1n4.emea.ibm.com [195.212.29.166]) (Authenticated sender: groug@kaod.org) by player734.ha.ovh.net (Postfix) with ESMTPSA id E0ACFAA6D878; Tue, 8 Oct 2019 13:47:32 +0000 (UTC) Date: Tue, 8 Oct 2019 15:47:29 +0200 From: Greg Kurz To: Christian Schoenebeck Subject: Re: [Qemu-devel] [PATCH v7 0/3] 9p: Fix file ID collisions Message-ID: <20191008154729.5b16ef26@bahia.lan> In-Reply-To: <2456208.kOTvEbKLdM@silver> References: <1590425.yRI6RxI3rl@silver> <20191008111459.048e659f@bahia.lan> <2456208.kOTvEbKLdM@silver> X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Ovh-Tracer-Id: 10627369224858409280 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedufedrheelgdejudcutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemucehtddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 46.105.42.102 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 P. =?UTF-8?B?QmVycmFuZ8Op?=" , qemu-devel@nongnu.org, Antonios Motakis , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 08 Oct 2019 14:05:28 +0200 Christian Schoenebeck wrote: > On Dienstag, 8. Oktober 2019 11:14:59 CEST Greg Kurz wrote: > > > No, it is not a feature. It is still a fix. :) I cannot use 9p without > > > this > > > fix at all, so it is not some optional "feature" for me. > > > > I understand your need but this is still arguable. The 9p device has > > a limitation with cross-device setups. The actual bug is to silently > > cause inode number collisions in the guest. This is partly fixed by the > > "9p: Treat multiple devices on one export as an error" patch. Thinking > > again, it would even make sense to move "remap" from "9p: Added virtfs > > option 'multidevs=remap|forbid|warn'" to its own patch. We could then > > consider that the bug is fully fixed with "multidevs=forbid|warn". > > > > Then comes the "remap" feature which is expected to lift the limitation > > with cross-device setups, with a "not yet determined" performance cost > > and light reviewing of the code. > > Are these patch transfer requests addressed at me to be done? > It would certainly be appreciated :) and if it happens to be done before 2019-10-29, it can even be shipped with QEMU 4.2. > > Also, I strongly recommend you try out "virtio-fs" which is > > going to be soon the production grade way of sharing files > > between host and guest. > > > > https://www.mail-archive.com/libvir-list@redhat.com/msg182457.html > > Yes I know, I am following the development of virtio-fs already of course. > However for me it is far too early to actually use it in a production > environment. It e.g. seems to require bleeding edge kernel versions. And the > real argument for switching from 9p to virtio-fs would be a significant > performance increase. However so far (correct me if I am wrong) I have not > seen benchmarks that would show that this was already the case (yet). > > I wonder though whether virtio-fs suffers from the same file ID collisions > problem when sharing multiple file systems. > I don't know. > What is your long-term plan for 9p? Will it be dropped completely after > virtio-fs became stable? > No, 9p will survive. The local backend has an advantage despite its various limitations: it is really easy to use. No extra command needed. I also want to keep the synth backend around for testing, but I'll gladly drop the proxy backend which is clearly superseded by virtio-fs. Cheers, -- Greg > Best regards, > Christian Schoenebeck > >