qemu: hotplug: Disallow media change while blockjob is active

Until the block job completes we can't change the disk chain. Removal
would fail as the block job still has reference to the chain.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/qemu/qemu_hotplug.c

@@ -852,10 +852,17 @@ qemuDomainChangeEjectableMedia(virQEMUDriverPtr driver,
     VIR_AUTOUNREF(virQEMUDriverConfigPtr) cfg = virQEMUDriverGetConfig(driver);
     qemuDomainObjPrivatePtr priv = vm->privateData;
     virStorageSourcePtr oldsrc = disk->src;
+    qemuDomainDiskPrivatePtr diskPriv = QEMU_DOMAIN_DISK_PRIVATE(disk);
     bool sharedAdded = false;
     int ret = -1;
     int rc;
 
+    if (diskPriv->blockjob && qemuBlockJobIsRunning(diskPriv->blockjob)) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("can't change media while a block job is running on the device"));
+        return -1;
+    }
+
     disk->src = newsrc;
 
     if (virDomainDiskTranslateSourcePool(disk) < 0)