Allow growing a running KVM VM's ROOT volume through a new disk offering

A size-only resizeVolume of a ROOT volume already works on a running KVM
VM: orchestrateResizeVolume checks that the host is Up and Enabled, and
the agent grows the disk in place with virsh blockresize.

Growing the same volume by giving it a larger disk offering is refused,
through resizeVolume with diskofferingid, through changeOfferingForVolume,
and so through scaleVirtualMachine when
allow.diskoffering.change.during.scale.vm is on:

    Cannot resize ROOT volume [...] when VM is not on Stopped State

checkIfVolumeIsRootAndVmIsRunning, which the size-only path does not
call, refuses any size change of a ROOT volume unless the VM is Stopped,
on every hypervisor. Where the ROOT volume's offering fixes its size, the
size-only path is refused too, so stopping the VM was the only way to
grow its root disk.

Let the check through when the volume belongs to a Running KVM user VM
and the new size is larger than the current one. Shrinking, other
hypervisors, system VMs and other VM states are refused as before. The
resize then follows the same path as a size-only resize of a running VM.

Signed-off-by: Brad House <bhouse@nexthop.ai>

Author: bhouse-nexthop

server/src/main/java/com/cloud/storage/VolumeApiServiceImpl.java

@@ -1524,13 +1524,26 @@ protected boolean isNotPossibleToResize(VolumeVO volume, DiskOfferingVO diskOffe
         return isOfferingEnforcingRootDiskSize && isRoot && isNotIso;
     }
 
-    private void checkIfVolumeIsRootAndVmIsRunning(Long newSize, VolumeVO volume, VMInstanceVO vmInstanceVO) {
-        if (!volume.getSize().equals(newSize) && volume.getVolumeType().equals(Volume.Type.ROOT) && !State.Stopped.equals(vmInstanceVO.getState())) {
-            throw new InvalidParameterValueException(String.format("Cannot resize ROOT volume [%s] when VM is not on Stopped State. VM %s is in state %s", volume.getName(), vmInstanceVO
+    protected void checkIfVolumeIsRootAndVmIsRunning(Long newSize, VolumeVO volume, VMInstanceVO vmInstanceVO) {
+        if (!volume.getSize().equals(newSize) && volume.getVolumeType().equals(Volume.Type.ROOT) && !State.Stopped.equals(vmInstanceVO.getState())
+                && !isGrowOfVolumeOnRunningKvmVm(newSize, volume, vmInstanceVO)) {
+            throw new InvalidParameterValueException(String.format("Cannot resize ROOT volume [%s] when VM is not on Stopped State. VM %s is in state %s. "
+                    + "Only growing the ROOT volume of a Running KVM user VM is allowed without stopping it.", volume.getName(), vmInstanceVO
                     .getInstanceName(), vmInstanceVO.getState()));
         }
     }
 
+    /**
+     * KVM grows the disk of a running user VM in place (virsh blockresize), and a size-only resizeVolume of a
+     * ROOT volume already does so. Growing it through a new disk offering is the same operation.
+     * Shrinking still requires the VM to be stopped. Only user VMs are let through, since the resize orchestration
+     * (orchestrateResizeVolume) only looks up the running VM and its host for user VMs.
+     */
+    private boolean isGrowOfVolumeOnRunningKvmVm(Long newSize, VolumeVO volume, VMInstanceVO vmInstanceVO) {
+        return HypervisorType.KVM.equals(vmInstanceVO.getHypervisorType()) && VirtualMachine.Type.User.equals(vmInstanceVO.getType())
+                && State.Running.equals(vmInstanceVO.getState()) && newSize != null && newSize > volume.getSize();
+    }
+
     private void validateIops(Long minIops, Long maxIops, Storage.StoragePoolType poolType) {
         if (poolType == Storage.StoragePoolType.PowerFlex) {
             // PowerFlex takes iopsLimit as input, skip minIops validation

server/src/test/java/com/cloud/storage/VolumeApiServiceImplTest.java

@@ -139,6 +139,7 @@
 import com.cloud.vm.DiskProfile;
 import com.cloud.vm.UserVmManager;
 import com.cloud.vm.UserVmVO;
+import com.cloud.vm.VMInstanceVO;
 import com.cloud.vm.VirtualMachine;
 import com.cloud.vm.VirtualMachine.State;
 import com.cloud.vm.VirtualMachineManager;
@@ -2504,4 +2505,59 @@ public void testResizeVolumeInternal_VMware_VMRunning_ShouldThrowStateGuardError
                     e.getMessage() != null && e.getMessage().contains("VM should be in"));
         }
     }
+
+    private VolumeVO mockRootVolumeOfSize(long size) {
+        VolumeVO volume = Mockito.mock(VolumeVO.class);
+        Mockito.when(volume.getSize()).thenReturn(size);
+        Mockito.when(volume.getVolumeType()).thenReturn(Volume.Type.ROOT);
+        return volume;
+    }
+
+    private VMInstanceVO mockVm(HypervisorType hypervisorType, State state) {
+        VMInstanceVO vm = Mockito.mock(VMInstanceVO.class);
+        Mockito.lenient().when(vm.getHypervisorType()).thenReturn(hypervisorType);
+        Mockito.lenient().when(vm.getType()).thenReturn(VirtualMachine.Type.User);
+        Mockito.when(vm.getState()).thenReturn(state);
+        return vm;
+    }
+
+    @Test
+    public void checkIfVolumeIsRootAndVmIsRunningAllowsGrowOnRunningKvmVm() {
+        volumeApiServiceImpl.checkIfVolumeIsRootAndVmIsRunning(20L << 30, mockRootVolumeOfSize(10L << 30), mockVm(HypervisorType.KVM, State.Running));
+    }
+
+    @Test(expected = InvalidParameterValueException.class)
+    public void checkIfVolumeIsRootAndVmIsRunningRefusesShrinkOnRunningKvmVm() {
+        volumeApiServiceImpl.checkIfVolumeIsRootAndVmIsRunning(5L << 30, mockRootVolumeOfSize(10L << 30), mockVm(HypervisorType.KVM, State.Running));
+    }
+
+    @Test(expected = InvalidParameterValueException.class)
+    public void checkIfVolumeIsRootAndVmIsRunningRefusesGrowOnRunningNonKvmVm() {
+        volumeApiServiceImpl.checkIfVolumeIsRootAndVmIsRunning(20L << 30, mockRootVolumeOfSize(10L << 30), mockVm(HypervisorType.VMware, State.Running));
+    }
+
+    @Test(expected = InvalidParameterValueException.class)
+    public void checkIfVolumeIsRootAndVmIsRunningRefusesGrowOnRunningKvmSystemVm() {
+        VMInstanceVO vm = mockVm(HypervisorType.KVM, State.Running);
+        Mockito.when(vm.getType()).thenReturn(VirtualMachine.Type.DomainRouter);
+        volumeApiServiceImpl.checkIfVolumeIsRootAndVmIsRunning(20L << 30, mockRootVolumeOfSize(10L << 30), vm);
+    }
+
+    @Test(expected = InvalidParameterValueException.class)
+    public void checkIfVolumeIsRootAndVmIsRunningRefusesGrowOnKvmVmNotRunning() {
+        volumeApiServiceImpl.checkIfVolumeIsRootAndVmIsRunning(20L << 30, mockRootVolumeOfSize(10L << 30), mockVm(HypervisorType.KVM, State.Migrating));
+    }
+
+    @Test
+    public void checkIfVolumeIsRootAndVmIsRunningAllowsResizeOnStoppedVm() {
+        volumeApiServiceImpl.checkIfVolumeIsRootAndVmIsRunning(5L << 30, mockRootVolumeOfSize(10L << 30), mockVm(HypervisorType.VMware, State.Stopped));
+    }
+
+    @Test
+    public void checkIfVolumeIsRootAndVmIsRunningIgnoresDataDisk() {
+        VolumeVO volume = Mockito.mock(VolumeVO.class);
+        Mockito.when(volume.getSize()).thenReturn(10L << 30);
+        Mockito.when(volume.getVolumeType()).thenReturn(Volume.Type.DATADISK);
+        volumeApiServiceImpl.checkIfVolumeIsRootAndVmIsRunning(5L << 30, volume, Mockito.mock(VMInstanceVO.class));
+    }
 }