From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Subject: Re: [rfc][patch 3/5] afs: new aops Date: Thu, 15 Nov 2007 12:15:41 +0000 Message-ID: <335.1195128941@redhat.com> References: <20071114213210.GB31048@wotan.suse.de> <20071114042420.GF557@wotan.suse.de> <20071113004459.GE30650@wotan.suse.de> <20071113001548.GA30650@wotan.suse.de> <20071112071448.GE22953@wotan.suse.de> <20071112071245.GB22953@wotan.suse.de> <6161.1194881354@redhat.com> <17445.1194913805@redhat.com> <18637.1194951385@redhat.com> <30440.1195042723@redhat.com> <22543.1195055866@redhat.com> Cc: dhowells@redhat.com, Andrew Morton , linux-fsdevel@vger.kernel.org, mhalcrow@us.ibm.com, phillip@hellewell.homeip.net, sfrench@samba.org To: Nick Piggin Return-path: Received: from mx1.redhat.com ([66.187.233.31]:53192 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752480AbXKOMQC (ORCPT ); Thu, 15 Nov 2007 07:16:02 -0500 In-Reply-To: <20071114213210.GB31048@wotan.suse.de> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Nick Piggin 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