Currently we get MTU credits before we check an open file if
it needs to be reopened. Reopening the file in such conditions
leads to a possibility of being stuck waiting indefinitely
for credits in the transport layer. Fix this by reopening the
file first if needed and then getting MTU credits for async IO.
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>