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@xxxxxxxxxxxxx>
---
docs/formatdomain.html.in | 40 ++++++++++++-
docs/schemas/domaincommon.rng | 10 ++++
src/conf/domain_conf.c | 29 ++++++++++
src/conf/domain_conf.h | 13 +++++
.../qemuxml2argvdata/virtio-9p-multidevs.xml | 53 ++++++++++++++++++
.../virtio-9p-multidevs.x86_64-latest.xml | 56 +++++++++++++++++++
tests/qemuxml2xmltest.c | 2 +
7 files changed, 202 insertions(+), 1 deletion(-)
create mode 100644 tests/qemuxml2argvdata/virtio-9p-multidevs.xml
create mode 100644 tests/qemuxml2xmloutdata/virtio-9p-multidevs.x86_64-latest.xml
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 28e779b90a..43e8a557c0 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 5de17593c1..6bfb8e8d27 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -2700,6 +2700,16 @@
</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 27bc5a797b..011d244ed6 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -502,6 +502,14 @@ 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",
@@ -11385,6 +11393,7 @@ 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;
@@ -11423,6 +11432,17 @@ 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)
@@ -25380,6 +25400,7 @@ 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);
@@ -25398,6 +25419,12 @@ 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);
@@ -25405,6 +25432,8 @@ 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 33875d942f..2038b54c32 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;
diff --git a/tests/qemuxml2argvdata/virtio-9p-multidevs.xml b/tests/qemuxml2argvdata/virtio-9p-multidevs.xml
new file mode 100644
index 0000000000..7a3b865415
--- /dev/null
+++ b/tests/qemuxml2argvdata/virtio-9p-multidevs.xml
@@ -0,0 +1,53 @@
+<domain type='qemu'>
+ <name>QEMUGuest1</name>
+ <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+ <memory unit='KiB'>219136</memory>
+ <currentMemory unit='KiB'>219136</currentMemory>
+ <vcpu placement='static'>1</vcpu>
+ <os>
+ <type arch='x86_64' machine='pc'>hvm</type>
+ <boot dev='hd'/>
+ </os>
+ <clock offset='utc'/>
+ <on_poweroff>destroy</on_poweroff>
+ <on_reboot>restart</on_reboot>
+ <on_crash>destroy</on_crash>
+ <devices>
+ <emulator>/usr/bin/qemu-system-x86_64</emulator>
+ <controller type='usb' index='0'>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+ </controller>
+ <controller type='ide' index='0'>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
+ </controller>
+ <controller type='pci' index='0' model='pci-root'/>
+ <filesystem type='mount' accessmode='mapped' multidevs='remap'>
+ <source dir='/export/fs0'/>
+ <target dir='fs0'/>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
+ </filesystem>
+ <filesystem type='mount' accessmode='mapped' multidevs='forbid'>
+ <source dir='/export/fs1'/>
+ <target dir='fs1'/>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+ </filesystem>
+ <filesystem type='mount' accessmode='mapped' multidevs='warn'>
+ <source dir='/export/fs2'/>
+ <target dir='fs2'/>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
+ </filesystem>
+ <serial type='pty'>
+ <target type='isa-serial' port='0'>
+ <model name='isa-serial'/>
+ </target>
+ </serial>
+ <console type='pty'>
+ <target type='serial' port='0'/>
+ </console>
+ <input type='mouse' bus='ps2'/>
+ <input type='keyboard' bus='ps2'/>
+ <memballoon model='virtio'>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' function='0x0'/>
+ </memballoon>
+ </devices>
+</domain>
diff --git a/tests/qemuxml2xmloutdata/virtio-9p-multidevs.x86_64-latest.xml b/tests/qemuxml2xmloutdata/virtio-9p-multidevs.x86_64-latest.xml
new file mode 100644
index 0000000000..4ea75ff8e3
--- /dev/null
+++ b/tests/qemuxml2xmloutdata/virtio-9p-multidevs.x86_64-latest.xml
@@ -0,0 +1,56 @@
+<domain type='qemu'>
+ <name>QEMUGuest1</name>
+ <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+ <memory unit='KiB'>219136</memory>
+ <currentMemory unit='KiB'>219136</currentMemory>
+ <vcpu placement='static'>1</vcpu>
+ <os>
+ <type arch='x86_64' machine='pc'>hvm</type>
+ <boot dev='hd'/>
+ </os>
+ <cpu mode='custom' match='exact' check='none'>
+ <model fallback='forbid'>qemu64</model>
+ </cpu>
+ <clock offset='utc'/>
+ <on_poweroff>destroy</on_poweroff>
+ <on_reboot>restart</on_reboot>
+ <on_crash>destroy</on_crash>
+ <devices>
+ <emulator>/usr/bin/qemu-system-x86_64</emulator>
+ <controller type='usb' index='0' model='piix3-uhci'>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+ </controller>
+ <controller type='ide' index='0'>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
+ </controller>
+ <controller type='pci' index='0' model='pci-root'/>
+ <filesystem type='mount' accessmode='mapped' multidevs='remap'>
+ <source dir='/export/fs0'/>
+ <target dir='fs0'/>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
+ </filesystem>
+ <filesystem type='mount' accessmode='mapped' multidevs='forbid'>
+ <source dir='/export/fs1'/>
+ <target dir='fs1'/>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+ </filesystem>
+ <filesystem type='mount' accessmode='mapped' multidevs='warn'>
+ <source dir='/export/fs2'/>
+ <target dir='fs2'/>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
+ </filesystem>
+ <serial type='pty'>
+ <target type='isa-serial' port='0'>
+ <model name='isa-serial'/>
+ </target>
+ </serial>
+ <console type='pty'>
+ <target type='serial' port='0'/>
+ </console>
+ <input type='mouse' bus='ps2'/>
+ <input type='keyboard' bus='ps2'/>
+ <memballoon model='virtio'>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' function='0x0'/>
+ </memballoon>
+ </devices>
+</domain>
diff --git a/tests/qemuxml2xmltest.c b/tests/qemuxml2xmltest.c
index a0d27fdcf8..b4c83fccca 100644
--- a/tests/qemuxml2xmltest.c
+++ b/tests/qemuxml2xmltest.c
@@ -1485,6 +1485,8 @@ mymain(void)
DO_TEST_CAPS_ARCH_LATEST("x86_64-default-cpu-kvm-q35-4.2", "x86_64");
DO_TEST_CAPS_ARCH_LATEST("x86_64-default-cpu-tcg-q35-4.2", "x86_64");
+ DO_TEST_CAPS_LATEST("virtio-9p-multidevs");
+
if (getenv("LIBVIRT_SKIP_CLEANUP") == NULL)
virFileDeleteTree(fakerootdir);
--
2.20.1
