skip a queued volume detach when the volume is no longer on that vm

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

@@ -3559,6 +3559,12 @@ private Volume orchestrateDetachVolumeFromVM(long vmId, long volumeId) {
         Volume volume = _volsDao.findById(volumeId);
         VMInstanceVO vm = _vmInstanceDao.findById(vmId);
 
+        // A queued detach can run after the volume was already detached and attached elsewhere; leave that attachment alone
+        if (volume.getInstanceId() == null || volume.getInstanceId() != vmId) {
+            logger.warn("Volume {} is no longer attached to VM {}, skipping detach", volume, vm);
+            return volume;
+        }
+
         String errorMsg = "Failed to detach volume " + volume.getName() + " from VM " + vm.getHostName();
         boolean sendCommand = vm.getState() == State.Running;
 

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

@@ -619,6 +619,30 @@ public void testDetachVolumeFromStoppedXenVm() throws NoSuchFieldException, Ille
         volumeApiServiceImpl.detachVolumeFromVM(detachCmd);
     }
 
+    @Test
+    public void testDetachVolumeSkippedWhenAttachedToAnotherVm() {
+        VolumeVO volume = Mockito.mock(VolumeVO.class);
+        Mockito.when(volume.getInstanceId()).thenReturn(200L);
+        Mockito.when(volumeDaoMock.findById(100L)).thenReturn(volume);
+
+        Volume result = volumeApiServiceImpl.detachVolumeViaDestroyVM(300L, 100L);
+
+        Assert.assertEquals(volume, result);
+        Mockito.verify(volumeDaoMock, Mockito.never()).detachVolume(Mockito.anyLong());
+    }
+
+    @Test
+    public void testDetachVolumeSkippedWhenAlreadyDetached() {
+        VolumeVO volume = Mockito.mock(VolumeVO.class);
+        Mockito.when(volume.getInstanceId()).thenReturn(null);
+        Mockito.when(volumeDaoMock.findById(100L)).thenReturn(volume);
+
+        Volume result = volumeApiServiceImpl.detachVolumeViaDestroyVM(300L, 100L);
+
+        Assert.assertEquals(volume, result);
+        Mockito.verify(volumeDaoMock, Mockito.never()).detachVolume(Mockito.anyLong());
+    }
+
     /**
      * TESTS FOR ATTACH ROOT VOLUME, COUNT=7
      */