block size in XFS = hard coded constant?

["L A Walsh" <law@xxxxxxxxx>]

I wanted to use an alternate block size on my SCSI hard disk.

I did a low-level reformat to use 4096 and got an additional 10.3% in hard
disk space.  (17783MB -> 19627).

I can't think of a reason why I'd want to have a 512 byte block when the
smallest allocation unit on a disk is 4K.

However -- I ran into a hard coded reason with XFS -- it's hard coded to use
 512 byte blocks.

Is there a reason for this?  Am I missing something?  Is it a bug, or is there
some reason why xfs can't handle different sized blocks?

-l