Signed-off-by: Christian Schoenebeck <qemu_oss(a)crudebyte.com&gt; --- docs/formatdomain.html.in | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index 594146009d..cc2c671c14 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -4084,13 +4084,20 @@ </dd> </dl> + <p> <span class="since">Since 5.2.0</span>, the filesystem element has an optional attribute <code>model</code> with supported values "virtio-transitional", "virtio-non-transitional", or "virtio". See <a href="#elementsVirtioTransitional">Virtio transitional devices</a> for more details. + </p> + </dd> + <p> + The <code>filesystem</code> element may contain the following subelements: + </p> + <dt><code>driver</code></dt> <dd> The optional driver element allows specifying further details -- 2.20.1

The QEMU 9pfs 'multidevs' option exists since QEMU 4.2, so just set this capability based on that QEMU version. Signed-off-by: Christian Schoenebeck <qemu_oss(a)crudebyte.com&gt; --- src/qemu/qemu_capabilities.c | 5 +++++ src/qemu/qemu_capabilities.h | 1 + tests/qemucapabilitiesdata/caps_4.2.0.x86_64.xml | 1 + tests/qemucapabilitiesdata/caps_5.0.0.aarch64.xml | 1 + tests/qemucapabilitiesdata/caps_5.0.0.x86_64.xml | 1 + 5 files changed, 9 insertions(+) diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c index a95a60c36a..68b6e166e9 100644 --- a/src/qemu/qemu_capabilities.c +++ b/src/qemu/qemu_capabilities.c @@ -567,6 +567,7 @@ VIR_ENUM_IMPL(virQEMUCaps, "query-named-block-nodes.flat", "blockdev-snapshot.allow-write-only-overlay", "blockdev-reopen", + "virtfs-multidevs", ); @@ -4837,6 +4838,10 @@ virQEMUCapsInitQMPVersionCaps(virQEMUCapsPtr qemuCaps) ARCH_IS_PPC64(qemuCaps->arch)) { virQEMUCapsSet(qemuCaps, QEMU_CAPS_MACHINE_PSERIES_MAX_CPU_COMPAT); } + + /* -virtfs multidevs option is supported since QEMU 4.2 */ + if (qemuCaps->version >= 4002000) + virQEMUCapsSet(qemuCaps, QEMU_CAPS_VIRTFS_MULTIDEVS); } diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h index f0961e273c..a6025312be 100644 --- a/src/qemu/qemu_capabilities.h +++ b/src/qemu/qemu_capabilities.h @@ -548,6 +548,7 @@ typedef enum { /* virQEMUCapsFlags grouping marker for syntax-check */ QEMU_CAPS_QMP_QUERY_NAMED_BLOCK_NODES_FLAT, /* query-named-block-nodes supports the 'flat' option */ QEMU_CAPS_BLOCKDEV_SNAPSHOT_ALLOW_WRITE_ONLY, /* blockdev-snapshot has the 'allow-write-only-overlay' feature */ QEMU_CAPS_BLOCKDEV_REOPEN, /* 'blockdev-reopen' qmp command is supported */ + QEMU_CAPS_VIRTFS_MULTIDEVS, /* -virtfs multidevs supported by virtio-9p */ QEMU_CAPS_LAST /* this must always be the last item */ } virQEMUCapsFlags; diff --git a/tests/qemucapabilitiesdata/caps_4.2.0.x86_64.xml b/tests/qemucapabilitiesdata/caps_4.2.0.x86_64.xml index 83e804ea36..d8b0de46cd 100644 --- a/tests/qemucapabilitiesdata/caps_4.2.0.x86_64.xml +++ b/tests/qemucapabilitiesdata/caps_4.2.0.x86_64.xml @@ -223,6 +223,7 @@ <flag name='rng-builtin'/> <flag name='virtio-net.failover'/> <flag name='vhost-user-fs'/> + <flag name='virtfs-multidevs'/> <version>4002000</version> <kvmVersion>0</kvmVersion> <microcodeVersion>43100242</microcodeVersion> diff --git a/tests/qemucapabilitiesdata/caps_5.0.0.aarch64.xml b/tests/qemucapabilitiesdata/caps_5.0.0.aarch64.xml index e52c60607d..3a695fbe79 100644 --- a/tests/qemucapabilitiesdata/caps_5.0.0.aarch64.xml +++ b/tests/qemucapabilitiesdata/caps_5.0.0.aarch64.xml @@ -181,6 +181,7 @@ <flag name='virtio-net.failover'/> <flag name='cpu.kvm-no-adjvtime'/> <flag name='vhost-user-fs'/> + <flag name='virtfs-multidevs'/> <version>4002050</version> <kvmVersion>0</kvmVersion> <microcodeVersion>61700241</microcodeVersion> diff --git a/tests/qemucapabilitiesdata/caps_5.0.0.x86_64.xml b/tests/qemucapabilitiesdata/caps_5.0.0.x86_64.xml index d773f7e356..95fa0813dd 100644 --- a/tests/qemucapabilitiesdata/caps_5.0.0.x86_64.xml +++ b/tests/qemucapabilitiesdata/caps_5.0.0.x86_64.xml @@ -226,6 +226,7 @@ <flag name='vhost-user-fs'/> <flag name='query-named-block-nodes.flat'/> <flag name='blockdev-snapshot.allow-write-only-overlay'/> + <flag name='virtfs-multidevs'/> <version>4002050</version> <kvmVersion>0</kvmVersion> <microcodeVersion>43100241</microcodeVersion> -- 2.20.1

Introduce new 'multidevs' option for filesystem. <filesystem type='mount' accessmode='mapped' multidevs='remap'> <source dir='/path'/> <target dir='mount_tag'> </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 <qemu_oss(a)crudebyte.com&gt; --- 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 @@ &lt;source name='my-vm-template'/&gt; &lt;target dir='/'/&gt; &lt;/filesystem&gt; - &lt;filesystem type='mount' accessmode='passthrough'&gt; + &lt;filesystem type='mount' accessmode='passthrough' multidevs='remap'&gt; &lt;driver type='path' wrpolicy='immediate'/&gt; &lt;source dir='/export/to/guest'/&gt; &lt;target dir='/import/from/host'/&gt; @@ -4092,6 +4092,44 @@ for more details. </p> + <p> + The filesystem element has an optional attribute <code>multidevs</code> + 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 + (<span class="since">since 6.2.0, requires QEMU 4.2</span>). + This attribute is not available for virtiofs. The possible values are: + </p> + + <dl> + <dt><code>default</code></dt> + <dd> + Use QEMU's default setting (which currently is <code>warn</code>). + </dd> + <dt><code>remap</code></dt> + <dd> + This setting allows guest to access multiple devices per export without + encountering misbehaviours. Inode numbers from host are automatically + remapped on guest to actively prevent file ID collisions if guest + accesses one export containing multiple devices. + </dd> + <dt><code>forbid</code></dt> + <dd> + Only allow to access one device per export by guest. Attempts to access + 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. + </dd> + <dt><code>warn</code></dt> + <dd> + This setting resembles the behaviour of 9pfs prior to QEMU 4.2, that is + no action is performed to prevent any potential file ID collisions if an + export contains multiple devices, with the only exception: a warning is + logged (once) on host side now. This setting may lead to misbehaviours + 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. + </dd> + </dl> + </dd> <p> 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 @@ </choice> </attribute> </optional> + <optional> + <attribute name="multidevs"> + <choice> + <value>default</value> + <value>remap</value> + <value>forbid</value> + <value>warn</value> + </choice> + </attribute> + </optional> <optional> <element name='readonly'> <empty/> 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", ); +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 = NULL; g_autofree char *units = NULL; g_autofree char *model = NULL; + g_autofree char *multidevs = NULL; ctxt->node = node; @@ -11414,6 +11423,17 @@ virDomainFSDefParseXML(virDomainXMLOptionPtr xmlopt, } } + multidevs = virXMLPropString(node, "multidevs"); + if (multidevs) { + if ((def->multidevs = virDomainFSMultidevsTypeFromString(multidevs)) < 0) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("unknown multidevs '%s'"), multidevs); + goto error; + } + } else { + def->multidevs = 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 = virDomainFSAccessModeTypeToString(def->accessmode); const char *fsdriver = virDomainFSDriverTypeToString(def->fsdriver); const char *wrpolicy = virDomainFSWrpolicyTypeToString(def->wrpolicy); + const char *multidevs = virDomainFSMultidevsTypeToString(def->multidevs); const char *src = def->src->path; g_auto(virBuffer) driverAttrBuf = VIR_BUFFER_INITIALIZER; g_auto(virBuffer) driverBuf = VIR_BUFFER_INIT_CHILD(buf); @@ -25415,6 +25436,12 @@ virDomainFSDefFormat(virBufferPtr buf, return -1; } + if (!multidevs) { + virReportError(VIR_ERR_INTERNAL_ERROR, + _("unexpected multidevs %d"), def->multidevs); + return -1; + } + virBufferAsprintf(buf, "<filesystem type='%s' accessmode='%s'", type, accessmode); @@ -25422,6 +25449,8 @@ virDomainFSDefFormat(virBufferPtr buf, virBufferAsprintf(buf, " model='%s'", virDomainFSModelTypeToString(def->model)); } + if (def->multidevs) + virBufferAsprintf(buf, " multidevs='%s'", multidevs); virBufferAddLit(buf, ">\n"); 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; +/* How to handle exports containing multiple devices. */ +typedef enum { + VIR_DOMAIN_FS_MULTIDEVS_DEFAULT = 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 devices */ + + VIR_DOMAIN_FS_MULTIDEVS_LAST +} virDomainFSMultidevs; + +VIR_ENUM_DECL(virDomainFSMultidevs); + typedef enum { VIR_DOMAIN_FS_MODEL_DEFAULT = 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; -- 2.20.1

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 <qemu_oss(a)crudebyte.com&gt; --- src/qemu/qemu_command.c | 7 +++++++ src/qemu/qemu_domain.c | 12 ++++++++++++ 2 files changed, 19 insertions(+) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 9790c92cf8..7020e5448c 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -2632,6 +2632,13 @@ qemuBuildFSStr(virDomainFSDefPtr fs) } else if (fs->accessmode == VIR_DOMAIN_FS_ACCESSMODE_SQUASH) { virBufferAddLit(&opt, ",security_model=none"); } + if (fs->multidevs == VIR_DOMAIN_FS_MULTIDEVS_REMAP) { + virBufferAddLit(&opt, ",multidevs=remap"); + } else if (fs->multidevs == VIR_DOMAIN_FS_MULTIDEVS_FORBID) { + virBufferAddLit(&opt, ",multidevs=forbid"); + } else if (fs->multidevs == VIR_DOMAIN_FS_MULTIDEVS_WARN) { + virBufferAddLit(&opt, ",multidevs=warn"); + } } else if (fs->fsdriver == VIR_DOMAIN_FS_DRIVER_TYPE_HANDLE) { /* removed since qemu 4.0.0 see v3.1.0-29-g93aee84f57 */ virBufferAddLit(&opt, "handle"); diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index edc8ba2ddb..c54c64fadb 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -8529,6 +8529,13 @@ qemuDomainDeviceDefValidateFS(virDomainFSDefPtr fs, _("only supports mount filesystem type")); return -1; } + if (fs->multidevs != VIR_DOMAIN_FS_MODEL_DEFAULT && + !virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTFS_MULTIDEVS)) + { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("multidevs is not supported with this QEMU binary")); + return -1; + } switch ((virDomainFSDriverType) fs->fsdriver) { case VIR_DOMAIN_FS_DRIVER_TYPE_DEFAULT: @@ -8581,6 +8588,11 @@ qemuDomainDeviceDefValidateFS(virDomainFSDefPtr fs, _("virtiofs is not supported with this QEMU binary")); return -1; } + if (fs->multidevs != VIR_DOMAIN_FS_MULTIDEVS_DEFAULT) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("virtiofs does not support multidevs")); + return -1; + } if (qemuDomainDefValidateVirtioFSSharedMemory(def) < 0) return -1; break; -- 2.20.1

On Freitag, 27. März 2020 18:16:37 CEST Ján Tomko wrote: Looking at the existing test cases, it probably makes sense to extend qemuxml2argvdata/virtio-options.xml instead of adding a separate XML file, that is: diff --git a/tests/qemuxml2argvdata/virtio-options.xml b/tests/ qemuxml2argvdata/virtio-options.xml index dd9a4f4a01..7ea624dfad 100644 --- a/tests/qemuxml2argvdata/virtio-options.xml +++ b/tests/qemuxml2argvdata/virtio-options.xml @@ -47,6 +47,21 @@ <target dir='fs2'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/> </filesystem> + <filesystem type='mount' accessmode='mapped' multidevs='remap'> + <source dir='/export/fs3'/> + <target dir='fs3'/> + <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> + </filesystem> + <filesystem type='mount' accessmode='mapped' multidevs='forbid'> + <source dir='/export/fs4'/> + <target dir='fs4'/> + <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/> + </filesystem> + <filesystem type='mount' accessmode='mapped' multidevs='warn'> + <source dir='/export/fs5'/> + <target dir='fs5'/> + <address type='pci' domain='0x0000' bus='0x00' slot='0x13' function='0x0'/> + </filesystem> <interface type='user'> <mac address='52:54:56:58:5a:5c'/> <model type='virtio'/> Ah, that's the one! :) I was already wondering whether other people are auto generating the files I manually changed so far. I'll post a rebased v3 with the things discussed so far. Thanks Ján! Best regards, Christian Schoenebeck