[case 1] nVidia meta stripe_sectors=0, array_width=2 -> rounddown(total_sectors=1000000, 0*2)
    BUG: integer divide-by-zero -> SIGFPE 8 (kernel equivalent: #DE trap -> panic in ata_raid_attach at ata-raid.c:157-158)
[case 2] Intel meta stripe_sectors=64, array_width=0 -> rounddown(total_sectors=1000000, 64*0)
    BUG: integer divide-by-zero -> SIGFPE 8 (kernel equivalent: #DE trap -> panic in ata_raid_attach at ata-raid.c:157-158)
[case 3] ITE meta stripe_sectors=0, array_width=0 -> rounddown(total_sectors=1000000, 0*0)
    BUG: integer divide-by-zero -> SIGFPE 8 (kernel equivalent: #DE trap -> panic in ata_raid_attach at ata-raid.c:157-158)

[case 4] IOCATARAIDSTATUS: total_sectors=0 (crafted metadata)
    BUG: integer divide-by-zero -> SIGFPE 8 (kernel equivalent: #DE trap -> panic in ata_raid_status at ata-raid.c:1028)

DF-1174 harness: all div-by-zero cases demonstrated.
EXIT=0