sys: QueryDirectory stability:

- FspMetaCacheAddItem now handles exceptions during copy from fs buffer
- FspFsvolQueryDirectoryLengthMax is correct max length for QueryDirectory

src/sys/driver.h

@@ -837,6 +837,10 @@ PIRP FspIoqNextCompleteIrp(FSP_IOQ *Ioq, PIRP BoundaryIrp);
 ULONG FspIoqRetriedIrpCount(FSP_IOQ *Ioq);
 
 /* meta cache */
+enum
+{
+    FspMetaCacheItemHeaderSize = MEMORY_ALLOCATION_ALIGNMENT,
+};
 typedef struct
 {
     KSPIN_LOCK SpinLock;