In talking with Nikolay about the data reservation patches it became clear that there's way more about the space reservation system that exists soley in my head than I thought. I've written three big comments on the different sections of the space reservation system to hopefully help people understand how the system works generally. Again this is from my point of view, and since I'm the one who wrote it I'm not sure where the gaps in peoples understanding is, so if there's something that is not clear here now is the time to bring it up. Hopefully this will make reviewing patches I submit to this system less scary for reviewers. Thanks, Josef
