Index: /trunk/src/VBox/Storage/VD.cpp
===================================================================
--- /trunk/src/VBox/Storage/VD.cpp	(revision 66664)
+++ /trunk/src/VBox/Storage/VD.cpp	(revision 66665)
@@ -1452,6 +1452,10 @@
             LogFlowFunc(("Waiting I/O context completed pTmp=%#p\n", pTmp));
             vdThreadFinishWrite(pDisk);
+
+            bool fFreeCtx = RT_BOOL(!(pTmp->fFlags & VDIOCTX_FLAGS_DONT_FREE));
             vdIoCtxRootComplete(pDisk, pTmp);
-            vdIoCtxFree(pDisk, pTmp);
+
+            if (fFreeCtx)
+                vdIoCtxFree(pDisk, pTmp);
         }
     }
@@ -1507,6 +1511,9 @@
             LogFlowFunc(("Waiting I/O context completed pTmp=%#p\n", pTmp));
             vdThreadFinishWrite(pDisk);
+
+            bool fFreeCtx = RT_BOOL(!(pTmp->fFlags & VDIOCTX_FLAGS_DONT_FREE));
             vdIoCtxRootComplete(pDisk, pTmp);
-            vdIoCtxFree(pDisk, pTmp);
+            if (fFreeCtx)
+                vdIoCtxFree(pDisk, pTmp);
         }
     }
@@ -3352,4 +3359,5 @@
         {
             LogFlowFunc(("I/O context completed pIoCtx=%#p\n", pIoCtx));
+            bool fFreeCtx = RT_BOOL(!(pIoCtx->fFlags & VDIOCTX_FLAGS_DONT_FREE));
             if (pIoCtx->pIoCtxParent)
             {
@@ -3389,7 +3397,10 @@
                 {
                     LogFlowFunc(("Parent I/O context completed pIoCtxParent=%#p rcReq=%Rrc\n", pIoCtxParent, pIoCtxParent->rcReq));
+                    bool fFreeParentCtx = RT_BOOL(!(pIoCtxParent->fFlags & VDIOCTX_FLAGS_DONT_FREE));
                     vdIoCtxRootComplete(pDisk, pIoCtxParent);
                     vdThreadFinishWrite(pDisk);
-                    vdIoCtxFree(pDisk, pIoCtxParent);
+
+                    if (fFreeParentCtx)
+                        vdIoCtxFree(pDisk, pIoCtxParent);
                     vdDiskProcessBlockedIoCtx(pDisk);
                 }
@@ -3420,5 +3431,6 @@
             }
 
-            vdIoCtxFree(pDisk, pIoCtx);
+            if (fFreeCtx)
+                vdIoCtxFree(pDisk, pIoCtx);
         }
     }