* [PATCH v2 2/4] qemu: capabilities: add QEMU_CAPS_VIRTFS_MULTIDEVS
2020-03-20 17:01 [PATCH v2 0/4] add support for QEMU 9pfs 'multidevs' option Christian Schoenebeck
2020-03-20 16:46 ` [PATCH v2 1/4] docs: virtfs: add section separators Christian Schoenebeck
@ 2020-03-20 16:48 ` Christian Schoenebeck
2020-03-20 16:51 ` [PATCH v2 3/4] conf: add 'multidevs' option Christian Schoenebeck
2020-03-20 16:54 ` [PATCH v2 4/4] qemu: add support for " Christian Schoenebeck
3 siblings, 0 replies; 5+ messages in thread
From: Christian Schoenebeck @ 2020-03-20 16:48 UTC (permalink / raw)
To: libvir-list; +Cc: qemu-devel, Greg Kurz
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@crudebyte.com>
---
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
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v2 3/4] conf: add 'multidevs' option
2020-03-20 17:01 [PATCH v2 0/4] add support for QEMU 9pfs 'multidevs' option Christian Schoenebeck
2020-03-20 16:46 ` [PATCH v2 1/4] docs: virtfs: add section separators Christian Schoenebeck
2020-03-20 16:48 ` [PATCH v2 2/4] qemu: capabilities: add QEMU_CAPS_VIRTFS_MULTIDEVS Christian Schoenebeck
@ 2020-03-20 16:51 ` Christian Schoenebeck
2020-03-20 16:54 ` [PATCH v2 4/4] qemu: add support for " Christian Schoenebeck
3 siblings, 0 replies; 5+ messages in thread
From: Christian Schoenebeck @ 2020-03-20 16:51 UTC (permalink / raw)
To: libvir-list; +Cc: qemu-devel, Greg Kurz
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@crudebyte.com>
---
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='my-vm-template'/>
<target dir='/'/>
</filesystem>
- <filesystem type='mount' accessmode='passthrough'>
+ <filesystem type='mount' accessmode='passthrough' multidevs='remap'>
<driver type='path' wrpolicy='immediate'/>
<source dir='/export/to/guest'/>
<target dir='/import/from/host'/>
@@ -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
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v2 4/4] qemu: add support for 'multidevs' option
2020-03-20 17:01 [PATCH v2 0/4] add support for QEMU 9pfs 'multidevs' option Christian Schoenebeck
` (2 preceding siblings ...)
2020-03-20 16:51 ` [PATCH v2 3/4] conf: add 'multidevs' option Christian Schoenebeck
@ 2020-03-20 16:54 ` Christian Schoenebeck
3 siblings, 0 replies; 5+ messages in thread
From: Christian Schoenebeck @ 2020-03-20 16:54 UTC (permalink / raw)
To: libvir-list; +Cc: qemu-devel, Greg Kurz
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@crudebyte.com>
---
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
^ permalink raw reply related [flat|nested] 5+ messages in thread