The return of SEEK_HOLE

I think I'm missing something. I'll repeat what I already said and you can tell me where I go wrong. The "large blocks" is a consequence of an implementation that doesn't care about the size of blocks. It just reports holes.

Perhaps you're talking about the holes feature in general, and saying that users or applications should be able to configure when a seek while writing will create a hole? Then I would understand a little better.