Re: [rfc][patch 3/5] afs: new aops

[David Howells <dhowells@redhat.com>]

Nick Piggin <npiggin@suse.de> wrote:

> > So you're saying a struct page controls an area of PAGE_CACHE_SIZE, not an
> > area of PAGE_SIZE?
> 
> No, a pagecache page is PAGE_CACHE_SIZE.

That doesn't answer my question.  I didn't ask about 'pagecache pages' per se.

Are you saying then that a page struct always represents an area of PAGE_SIZE
to, say, the page allocator and PAGE_CACHE_SIZE to a filesystem's address
operations?

How about I state it this way: Please define what the coverage of a
(non-compound) struct page is, and how this relates to PAGE_SIZE and
PAGE_CACHE_SIZE.  If it's well-defined then this cannot be hard, right?

> And not all struct pages control the same amount of data anyway, with
> compound pages.

Compound pages are irrelevant to my question.  A compound page is actually a
regulated by a series of page structs, each of which represents a 'page' of
real memory.

Do you say, then, that all, say, readpage() and readpages() methods must
handle a compound page if that is given to them?

David