Index: /trunk/src/VBox/Devices/Storage/DrvSCSI.cpp
===================================================================
--- /trunk/src/VBox/Devices/Storage/DrvSCSI.cpp	(revision 43692)
+++ /trunk/src/VBox/Devices/Storage/DrvSCSI.cpp	(revision 43693)
@@ -246,4 +246,16 @@
 }
 
+static DECLCALLBACK(int) drvscsiSetLock(VSCSILUN hVScsiLun, void *pvScsiLunUser, bool fLocked)
+{
+    PDRVSCSI pThis = (PDRVSCSI)pvScsiLunUser;
+
+    if (fLocked)
+        pThis->pDrvMount->pfnLock(pThis->pDrvMount);
+    else
+        pThis->pDrvMount->pfnUnlock(pThis->pDrvMount);
+
+    return VINF_SUCCESS;
+}
+
 static int drvscsiTransferCompleteNotify(PPDMIBLOCKASYNCPORT pInterface, void *pvUser, int rc)
 {
@@ -961,4 +973,5 @@
     pThis->VScsiIoCallbacks.pfnVScsiLunReqTransferEnqueue = drvscsiReqTransferEnqueue;
     pThis->VScsiIoCallbacks.pfnVScsiLunGetFeatureFlags    = drvscsiGetFeatureFlags;
+    pThis->VScsiIoCallbacks.pfnVScsiLunMediumSetLock      = drvscsiSetLock;
 
     rc = VSCSIDeviceCreate(&pThis->hVScsiDevice, drvscsiVScsiReqCompleted, pThis);
Index: /trunk/src/VBox/Devices/Storage/VSCSI/VSCSIInternal.h
===================================================================
--- /trunk/src/VBox/Devices/Storage/VSCSI/VSCSIInternal.h	(revision 43692)
+++ /trunk/src/VBox/Devices/Storage/VSCSI/VSCSIInternal.h	(revision 43693)
@@ -364,4 +364,18 @@
 
 /**
+ * Wrapper for the get medium lock/unlock I/O callback.
+ *
+ * @returns VBox status code.
+ * @param   pVScsiLun   The LUN.
+ * @param   bool        The new medium lock state.
+ */
+DECLINLINE(int) vscsiLunMediumSetLock(PVSCSILUNINT pVScsiLun, bool fLocked)
+{
+    return pVScsiLun->pVScsiLunIoCallbacks->pfnVScsiLunMediumSetLock(pVScsiLun,
+                                                                     pVScsiLun->pvVScsiLunUser,
+                                                                     fLocked);
+}
+
+/**
  * Wrapper for the I/O request enqueue I/O callback.
  *
Index: /trunk/src/VBox/Devices/Storage/VSCSI/VSCSILunMmc.cpp
===================================================================
--- /trunk/src/VBox/Devices/Storage/VSCSI/VSCSILunMmc.cpp	(revision 43692)
+++ /trunk/src/VBox/Devices/Storage/VSCSI/VSCSILunMmc.cpp	(revision 43693)
@@ -409,4 +409,5 @@
         {
             pVScsiLunMmc->fLocked = pVScsiReq->pbCDB[4] & 1;
+            vscsiLunMediumSetLock(pVScsiLun, pVScsiLunMmc->fLocked);
             rcReq = vscsiLunReqSenseOkSet(pVScsiLun, pVScsiReq);
             break;