I don't today... but I am writing this software as a utility for an open software project where people may have much larger filesystems. Since one can have 1 inode per 4K block, I was assuming that one might need to go beyond longs when drives/filesystems hit 16TB... but if inodes are type long, then I imagine that mkfs.ext4 (and its ilk) will just enforce a larger minimum bytes-per-inode size.

Anyway, good to know that I can for now get by with using 'V' and not 'Q'. Thanks!