Comment # 2 on bug 1003103 from Jan Kara

OK, it looks like a bug in the ramdisk driver. The problem is that rd_size
argument is stored in 'int' and furthermore multiplied by 2 to get number of
sectors the device should have. With rd_size == 1<<30 this overflows resulting
in the device having absurdly large size which then confuses mkfs.ext4.

I'll send a patch to fix this in brd driver and also add a defensive check to
mkfs.ext4.