[libvirt] [PATCH 07/11] qemu: domain: Reject shared disk access if backing format does not support it

[Peter Krempa]

Certain disk format drivers in qemu don't allow concurrent acces at the
level of the format driver since it would corrupt the metadata. Reject
shared access for a disk if the format does not support it. Currently
only RAW format supports it since it does not have any metadata.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1511480
---
 src/qemu/qemu_domain.c                             | 19 +++++++++++++++
 .../qemuxml2argv-disk-drive-shared-qcow.xml        | 28 ++++++++++++++++++++++
 .../qemuxml2argv-disk-drive-shared.args            |  2 +-
 .../qemuxml2argv-disk-drive-shared.xml             |  2 +-
 tests/qemuxml2argvtest.c                           |  1 +
 5 files changed, 50 insertions(+), 2 deletions(-)
 create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared-qcow.xml

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 29fdb49d1..fdbe6a4e3 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -25,6 +25,7 @@

 #include "qemu_domain.h"
 #include "qemu_alias.h"
+#include "qemu_block.h"
 #include "qemu_cgroup.h"
 #include "qemu_command.h"
 #include "qemu_process.h"
@@ -3724,6 +3725,21 @@ qemuDomainDeviceDefValidateVideo(const virDomainVideoDef *video)
 }


+static int
+qemuDomainDeviceDefValidateDisk(const virDomainDiskDef *disk)
+{
+    if (disk->src->shared && !disk->src->readonly &&
+        !qemuBlockStorageSourceSupportsConcurrentAccess(disk->src)) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("shared access for disk '%s' requires use of "
+                         "supported storage format"), disk->dst);
+        return -1;
+    }
+
+    return 0;
+}
+
+
 static int
 qemuDomainDeviceDefValidate(const virDomainDeviceDef *dev,
                             const virDomainDef *def,
@@ -3765,6 +3781,9 @@ qemuDomainDeviceDefValidate(const virDomainDeviceDef *dev,
         break;

     case VIR_DOMAIN_DEVICE_DISK:
+        ret = qemuDomainDeviceDefValidateDisk(dev->data.disk);
+        break;
+
     case VIR_DOMAIN_DEVICE_LEASE:
     case VIR_DOMAIN_DEVICE_FS:
     case VIR_DOMAIN_DEVICE_INPUT:
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared-qcow.xml b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared-qcow.xml
new file mode 100644
index 000000000..ca88a944b
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared-qcow.xml
@@ -0,0 +1,28 @@
+<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='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='block' device='disk'>
+      <driver name='qemu' type='qcow2'/>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <shareable/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='ide' index='0'/>
+    <memballoon model='virtio'/>
+  </devices>
+</domain>
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.args b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.args
index 502157bf8..326fde1b3 100644
--- a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.args
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.args
@@ -19,7 +19,7 @@ server,nowait \
 -no-acpi \
 -boot c \
 -usb \
--drive file=/dev/HostVG/QEMUGuest1,format=qcow2,if=none,id=drive-ide0-0-0,\
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-ide0-0-0,\
 serial=XYZXYZXYZYXXYZYZYXYZY,cache=none \
 -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 \
 -drive file=/dev/HostVG/QEMUGuest2,format=raw,if=none,media=cdrom,\
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.xml b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.xml
index 9f7472378..677c2b0b7 100644
--- a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.xml
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-shared.xml
@@ -15,7 +15,7 @@
   <devices>
     <emulator>/usr/bin/qemu-system-i686</emulator>
     <disk type='block' device='disk'>
-      <driver name='qemu' type='qcow2'/>
+      <driver name='qemu' type='raw'/>
       <source dev='/dev/HostVG/QEMUGuest1'/>
       <target dev='hda' bus='ide'/>
       <shareable/>
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index 1bedc6874..bfced6dda 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -908,6 +908,7 @@ mymain(void)
             QEMU_CAPS_DRIVE_BOOT);
     DO_TEST("disk-drive-shared",
             QEMU_CAPS_DRIVE_SERIAL);
+    DO_TEST_PARSE_ERROR("disk-drive-shared-qcow", NONE);
     DO_TEST("disk-drive-error-policy-stop",
             QEMU_CAPS_MONITOR_JSON);
     DO_TEST("disk-drive-error-policy-enospace",
-- 
2.14.3