The Scsi_Host structure max_lun field is the maximum allowed LUN plus 1. So
a LUN value is invalid if >= max_lun.
Signed-off-by: Mark Knibbs <markk@clara.co.uk>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>