From nobody Sun Feb 8 23:06:11 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=crudebyte.com ARC-Seal: i=1; a=rsa-sha256; t=1584727244; cv=none; d=zohomail.com; s=zohoarc; b=JPUkd3cQdMT2XJXzBLLarJp86GKQcwRCpDefPKrQQEYJsgw6eSCd7nPvuVK05U/2Fr63OvNopxPb8kjcIrF2ykDY/KFHvBdCVenovrEiLxLkkwkTLgnFrFl5E3MG1J8PcJH+xbGbw158ZaHztU2TU9Mxi0Xt9FX0b+EDaCiCb9E= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1584727244; h=Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:Message-ID:References:Sender:Subject:To; bh=aSFPumI060vrsGGcam3KjHjMgS6gIvm9ZtHfi26NJs8=; b=IIPWgbuO2lZju0OaOanxvV0nOmvzTriOVI57JYR5zB6sZmOZIFNRpF8VBbeFliPEf/2CuD4D6bqYOUP71M1SGQhdUs8xL8D6AVq4cglhFSlFedPMRBJMbWBWY0W3zV/oxV8XpKe7PboErPIrzQlHMfidcx2Z2wD34V5GH5zZuWI= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1584727244418886.9118004517527; Fri, 20 Mar 2020 11:00:44 -0700 (PDT) Received: from localhost ([::1]:57254 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jFLwk-0003F9-4H for importer@patchew.org; Fri, 20 Mar 2020 14:00:38 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38958) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from <680df3de98cf66c7637fec5274761b535b9f4918@lizzy.crudebyte.com>) id 1jFLw1-0002n5-Mi for qemu-devel@nongnu.org; Fri, 20 Mar 2020 13:59:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from <680df3de98cf66c7637fec5274761b535b9f4918@lizzy.crudebyte.com>) id 1jFLvz-0007Z2-Q8 for qemu-devel@nongnu.org; Fri, 20 Mar 2020 13:59:53 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:53895) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from <680df3de98cf66c7637fec5274761b535b9f4918@lizzy.crudebyte.com>) id 1jFLvz-0007FB-AW for qemu-devel@nongnu.org; Fri, 20 Mar 2020 13:59:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Cc:To:Subject:Date:From:References:In-Reply-To: Message-Id:Content-Type:Content-Transfer-Encoding:MIME-Version:Content-ID: Content-Description; bh=aSFPumI060vrsGGcam3KjHjMgS6gIvm9ZtHfi26NJs8=; b=cQXO7 vK6ab9eDWETUGmfOuQKuFBGkqN5twrZXWMNV+DxbaaLMESY0zdXzEgJDSdV4TX1JqUJ03AyxL8EZm 1b87zJXMqYe39W5+bpBEtBN6TJclv/ues21sEVyFMjEyJmKNFLJT9G8bTd9Nspsq8daYEzyRW5ii6 4VQA0ywfuOtawV/jRG8vpRq9LIhJNtB+pmkbCDK6yWLoC7Ozan/uh3U8uuYfWGzE7jZuDjPk2ytzZ HHWN6Rgg6AByIbkaP2cEAhDuO0a9cNL9JLeY8tZFRsAHUhvRM2Rh/oTdNGPRqD/YLxLuD33hwpvGb PYep29VbE+46TIyeG0uZNPnstiw0w==; Message-Id: <680df3de98cf66c7637fec5274761b535b9f4918.1584723662.git.qemu_oss@crudebyte.com> In-Reply-To: References: From: Christian Schoenebeck Date: Fri, 20 Mar 2020 17:51:35 +0100 Subject: [PATCH v2 3/4] conf: add 'multidevs' option To: libvir-list@redhat.com Cc: qemu-devel@nongnu.org, Greg Kurz X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 91.194.90.13 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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @crudebyte.com) Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Introduce new 'multidevs' option for filesystem. This option prevents misbehaviours on guest if a qemu 9pfs export contains multiple devices, due to the potential file ID collisions this otherwise may cause. Signed-off-by: Christian Schoenebeck --- docs/formatdomain.html.in | 40 ++++++++++++++++++++++++++++++++++- docs/schemas/domaincommon.rng | 10 +++++++++ src/conf/domain_conf.c | 29 +++++++++++++++++++++++++ src/conf/domain_conf.h | 13 ++++++++++++ 4 files changed, 91 insertions(+), 1 deletion(-) diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index cc2c671c14..13c506988b 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -3967,7 +3967,7 @@ <source name=3D'my-vm-template'/> <target dir=3D'/'/> </filesystem> - <filesystem type=3D'mount' accessmode=3D'passthrough'> + <filesystem type=3D'mount' accessmode=3D'passthrough' multidevs=3D're= map'> <driver type=3D'path' wrpolicy=3D'immediate'/> <source dir=3D'/export/to/guest'/> <target dir=3D'/import/from/host'/> @@ -4092,6 +4092,44 @@ for more details.

=20 +

+ The filesystem element has an optional attribute multidevs + which specifies how to deal with a filesystem export containing more= than + one device, in order to avoid file ID collisions on guest when using= 9pfs + (since 6.2.0, requires QEMU 4.2). + This attribute is not available for virtiofs. The possible values ar= e: +

+ +
+
default
+
+ Use QEMU's default setting (which currently is warn). +
+
remap
+
+ This setting allows guest to access multiple devices per export wi= thout + encountering misbehaviours. Inode numbers from host are automatica= lly + remapped on guest to actively prevent file ID collisions if guest + accesses one export containing multiple devices. +
+
forbid
+
+ Only allow to access one device per export by guest. Attempts to a= ccess + additional devices on the same export will cause the individual + filesystem access by guest to fail with an error and being logged = (once) + as error on host side. +
+
warn
+
+ This setting resembles the behaviour of 9pfs prior to QEMU 4.2, th= at is + no action is performed to prevent any potential file ID collisions= if an + export contains multiple devices, with the only exception: a warni= ng is + logged (once) on host side now. This setting may lead to misbehavi= ours + on guest side if more than one device is exported per export, due = to the + potential file ID collisions this may cause on guest side in that = case. +
+
+ =20

diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index 6805420451..9b37740e30 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -2676,6 +2676,16 @@ + + + + default + remap + forbid + warn + + + diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 71535f53f5..6a9a7dd0bb 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -501,6 +501,14 @@ VIR_ENUM_IMPL(virDomainFSModel, "virtio-non-transitional", ); =20 +VIR_ENUM_IMPL(virDomainFSMultidevs, + VIR_DOMAIN_FS_MULTIDEVS_LAST, + "default", + "remap", + "forbid", + "warn", +); + VIR_ENUM_IMPL(virDomainFSCacheMode, VIR_DOMAIN_FS_CACHE_MODE_LAST, "default", @@ -11376,6 +11384,7 @@ virDomainFSDefParseXML(virDomainXMLOptionPtr xmlopt, g_autofree char *usage =3D NULL; g_autofree char *units =3D NULL; g_autofree char *model =3D NULL; + g_autofree char *multidevs =3D NULL; =20 ctxt->node =3D node; =20 @@ -11414,6 +11423,17 @@ virDomainFSDefParseXML(virDomainXMLOptionPtr xmlop= t, } } =20 + multidevs =3D virXMLPropString(node, "multidevs"); + if (multidevs) { + if ((def->multidevs =3D virDomainFSMultidevsTypeFromString(multide= vs)) < 0) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("unknown multidevs '%s'"), multidevs); + goto error; + } + } else { + def->multidevs =3D VIR_DOMAIN_FS_MULTIDEVS_DEFAULT; + } + if (virDomainParseScaledValue("./space_hard_limit[1]", NULL, ctxt, &def->space_hard_limit, 1, ULLONG_MAX, false) < 0) @@ -25397,6 +25417,7 @@ virDomainFSDefFormat(virBufferPtr buf, const char *accessmode =3D virDomainFSAccessModeTypeToString(def->acce= ssmode); const char *fsdriver =3D virDomainFSDriverTypeToString(def->fsdriver); const char *wrpolicy =3D virDomainFSWrpolicyTypeToString(def->wrpolicy= ); + const char *multidevs =3D virDomainFSMultidevsTypeToString(def->multid= evs); const char *src =3D def->src->path; g_auto(virBuffer) driverAttrBuf =3D VIR_BUFFER_INITIALIZER; g_auto(virBuffer) driverBuf =3D VIR_BUFFER_INIT_CHILD(buf); @@ -25415,6 +25436,12 @@ virDomainFSDefFormat(virBufferPtr buf, return -1; } =20 + if (!multidevs) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("unexpected multidevs %d"), def->multidevs); + return -1; + } + virBufferAsprintf(buf, "model)); } + if (def->multidevs) + virBufferAsprintf(buf, " multidevs=3D'%s'", multidevs); virBufferAddLit(buf, ">\n"); =20 virBufferAdjustIndent(buf, 2); diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index 91b776c28a..23b7924781 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -796,6 +796,18 @@ typedef enum { VIR_DOMAIN_FS_WRPOLICY_LAST } virDomainFSWrpolicy; =20 +/* How to handle exports containing multiple devices. */ +typedef enum { + VIR_DOMAIN_FS_MULTIDEVS_DEFAULT =3D 0, /* Use QEMU's default setting */ + VIR_DOMAIN_FS_MULTIDEVS_REMAP, /* Remap inodes from host to guest */ + VIR_DOMAIN_FS_MULTIDEVS_FORBID, /* Prohibit more than one device */ + VIR_DOMAIN_FS_MULTIDEVS_WARN, /* Just log a warning if multiple device= s */ + + VIR_DOMAIN_FS_MULTIDEVS_LAST +} virDomainFSMultidevs; + +VIR_ENUM_DECL(virDomainFSMultidevs); + typedef enum { VIR_DOMAIN_FS_MODEL_DEFAULT =3D 0, VIR_DOMAIN_FS_MODEL_VIRTIO, @@ -820,6 +832,7 @@ struct _virDomainFSDef { int wrpolicy; /* enum virDomainFSWrpolicy */ int format; /* virStorageFileFormat */ int model; /* virDomainFSModel */ + int multidevs; /* virDomainFSMultidevs */ unsigned long long usage; /* in bytes */ virStorageSourcePtr src; char *dst; --=20 2.20.1