Previous logic was not differentiating disconnected LUNs and absent targets.
That made it to stop scan if LUN 0 was not found for any reason. That made
problematic, for example, using iSCSI targets declaring SPC-2 compliance and
having no LUN 0 configured.
The new logic continues sequential LUN scan if:
-- we have more configured LUNs that need recheck;
-- this LUN is connected and its SCSI version allows more LUNs;
-- this LUN is disconnected, its SCSI version allows more LUNs and we
guess they may be connected (we haven't scanned first 8 LUNs yet or
kern.cam.cam_srch_hi sysctl is set to scan more).
Reported by: trasz
MFC after: 1 month
1d4bc8bce6