[libvirt] [PATCH v2 1/2] qemu: make attaching disk partition to VM illegal

[Pavel Mores]

The way in which the qemu driver generates aliases for disks involves
ignoring the partition number part of a target dev name.  This means that
all partitions of a block device and the device itself all end up with the
same alias.  If multiple such disks are specified in XML, the resulting
name clash makes qemu invocation fail.

Since attaching partitions to qemu VMs doesn't seem to make much sense
anyway, disallow partitions in target specifications altogether.

https://bugzilla.redhat.com/show_bug.cgi?id=1346265

Signed-off-by: Pavel Mores <pmores at redhat.com>
---
 src/qemu/qemu_domain.c                        | 15 +++++++++++
 .../disk-attaching-partition-nosupport.xml    | 27 +++++++++++++++++++
 tests/qemuxml2argvtest.c                      |  1 +
 3 files changed, 43 insertions(+)
 create mode 100644 tests/qemuxml2argvdata/disk-attaching-partition-nosupport.xml

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index e8e895d9aa..545c985f40 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -5880,6 +5880,8 @@ qemuDomainDeviceDefValidateDisk(const virDomainDiskDef *disk,
 {
     const char *driverName = virDomainDiskGetDriver(disk);
     virStorageSourcePtr n;
+    int idx;
+    int partition;
 
     if (disk->src->shared && !disk->src->readonly &&
         !qemuBlockStorageSourceSupportsConcurrentAccess(disk->src)) {
@@ -5948,6 +5950,19 @@ qemuDomainDeviceDefValidateDisk(const virDomainDiskDef *disk,
         return -1;
     }
 
+    if (virDiskNameParse(disk->dst, &idx, &partition) < 0) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("invalid disk target '%s'"), disk->dst);
+        return -1;
+    }
+
+    if (partition != 0) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("can't attach disk partition '%s', please attach whole disk instead"),
+                       disk->dst);
+        return -1;
+    }
+
     for (n = disk->src; virStorageSourceIsBacking(n); n = n->backingStore) {
         if (qemuDomainValidateStorageSource(n, qemuCaps) < 0)
             return -1;
diff --git a/tests/qemuxml2argvdata/disk-attaching-partition-nosupport.xml b/tests/qemuxml2argvdata/disk-attaching-partition-nosupport.xml
new file mode 100644
index 0000000000..591819fbb6
--- /dev/null
+++ b/tests/qemuxml2argvdata/disk-attaching-partition-nosupport.xml
@@ -0,0 +1,27 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' 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-i686</emulator>
+    <disk type='file' device='disk'>
+      <driver name='qemu' type='raw'/>
+      <source file='/export/vmimages/1.raw'/>
+      <target dev='vdb1' bus='virtio'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='ide' index='0'/>
+    <controller type='pci' index='0' model='pci-root'/>
+    <memballoon model='virtio'/>
+  </devices>
+</domain>
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index 5bbac1c8b8..058eee998f 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -1097,6 +1097,7 @@ mymain(void)
     DO_TEST("disk-no-boot", NONE);
     DO_TEST_PARSE_ERROR("disk-device-lun-type-invalid",
                         QEMU_CAPS_VIRTIO_SCSI);
+    DO_TEST_CAPS_LATEST_PARSE_ERROR("disk-attaching-partition-nosupport");
     DO_TEST_FAILURE("disk-usb-nosupport", NONE);
     DO_TEST("disk-usb-device",
             QEMU_CAPS_DEVICE_USB_STORAGE);
-- 
2.21.0