cciss: make rebuild_lun_table behave better

This patch makes the rebuild_lun_table smart enough to not rip a logical
volume out from under the OS. Without this fix if a customer is running
hpacucli to monitor their storage the driver will blindly remove and re-add
the disks whenever the utility calls the CCISS_REGNEWD ioctl. Unfortunately,
both hpacucli and ACUXE call the ioctl repeatedly. Customers have reported
IO coming to a standstill. Calling the ioctl is the problem, this patch is
the fix.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cca.cpqcorp.net>
Signed-off-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

drivers/block/cciss.h

@@ -39,6 +39,8 @@ typedef struct _drive_info_struct
 				   *to prevent it from being opened or it's queue
 				   *from being started.
 				  */
+	__u8 serial_no[16]; /* from inquiry page 0x83, */
+			    /* not necc. null terminated. */
 } drive_info_struct;
 
 #ifdef CONFIG_CISS_SCSI_TAPE