If Close command is interrupted before sending a request
to the server the client ends up leaking an open file
handle. This wastes server resources and can potentially
block applications that try to remove the file or any
directory containing this file.

Fix this by putting the close command into a worker queue,
so another thread retries it later.

Cc: Stable <stable@vger.kernel.org>
Tested-by: NFrank Sorenson <sorenson@redhat.com>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NPavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>