If the z/VM reader is already open, it can happen that after opening the
Linux reader device, not the topmost file is processed. According the
semantics of the Linux z/VM unit record device driver, always the topmost
file has to be processed. With this fix an error is returned if that is
not the case.
Signed-off-by: NMichael Holzheu <holzheu@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>