Should the Lustre preparation patches go in?

Should the Lustre preparation patches go in?

it can turn out that an API looks fine until you look at the code which uses it, at which point it becomes clear that the code that uses it has to work around annoying aspects of the API.

Remember that the Lustre people are already using these interfaces, and have plenty of experience with them. It couldn't be any more clear to someone else if they are working around annoying aspects of the API they designed.

So really the only evaluation to be done in this area is whether the API is good for some hypothetical future user. And considering the hypothetical future user is exactly contrary to the mindset that says leave out the Lustre APIs because Lustre isn't in-tree now.

A good interface stands on its own. An interface designed for a particular present user, or many particular users, is usually pretty bad.

The "don't have interfaces for out-of-tree modules" philosophy has nothing to do with making good interfaces. It has to do with having the flexibility to change the interfaces later. If you can't modify all the users of an interface, then you're either stuck with never changing it, or you regularly break things.

Linux developers have always abhorred the leave it alone -- you might break something philosophy, so interfaces for out-of-tree modules are anathema to their development style.