文件关闭时，无法将文件删除，为什么？

文件关闭时，无法将文件删除，为什么？

HANDLE openLogfile()
{

  UNICODE_STRING     uniName;
  OBJECT_ATTRIBUTES  objAttr;

  HANDLE   handle;
  NTSTATUS ntstatus;
  FILE_DISPOSITION_INFORMATION Dispose;
  IO_STATUS_BLOCK   IoStatus;

  RtlInitUnicodeString(&uniName, LOG_FILE);  // or L"\\SystemRoot\\example.txt"
  InitializeObjectAttributes(&objAttr, &uniName,
    OBJ_CASE_INSENSITIVE | OBJ_KERNEL_HANDLE,
    NULL, NULL);

  // Do not try to perform any file operations at higher IRQL levels.
  // Instead, you may use a work item or a system worker thread to perform file operations.

  if(KeGetCurrentIrql() != PASSIVE_LEVEL)
    return NULL;

  ntstatus = ZwCreateFile(&handle,
    FILE_APPEND_DATA,
    &objAttr, &log_file_ioStatusBlock, NULL,
    FILE_ATTRIBUTE_NORMAL,
    FILE_SHARE_READ | FILE_SHARE_WRITE,
    FILE_OPEN_IF,
    FILE_SYNCHRONOUS_IO_NONALERT,
    NULL, 0);

  if(NT_SUCCESS(ntstatus)) {
 Dispose.DeleteFile = TRUE;
 ntstatus = ZwSetInformationFile(handle,&IoStatus,&Dispose,sizeof(FILE_DISPOSITION_INFORMATION),
                                 FileDispositionInformation);

 if( NT_SUCCESS(ntstatus) )
  return handle;
 }

return NULL;

}


但是调用ZwClose关闭文件后，文件没有删除？不知道为什么，是哪里设置不正确？谢谢

How Are Files Deleted In Windows
http://www.osronline.com/article.cfm?article=245