Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754037AbcCUIue (ORCPT ); Mon, 21 Mar 2016 04:50:34 -0400 Received: from mx2.suse.de ([195.135.220.15]:53550 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753967AbcCUIuU (ORCPT ); Mon, 21 Mar 2016 04:50:20 -0400 Date: Mon, 21 Mar 2016 09:50:47 +0100 From: Jan Kara To: "Kirill A. Shutemov" Cc: Andrew Morton , Alexander Viro , Linus Torvalds , Christoph Lameter , Matthew Wilcox , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Jan Kara Subject: Re: [PATCH 32/71] ext2: get rid of PAGE_CACHE_* and page_cache_{get,release} macros Message-ID: <20160321085047.GD30819@quack.suse.cz> References: <1458499278-1516-1-git-send-email-kirill.shutemov@linux.intel.com> <1458499278-1516-33-git-send-email-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1458499278-1516-33-git-send-email-kirill.shutemov@linux.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1185 Lines: 36 On Sun 20-03-16 21:40:39, Kirill A. Shutemov wrote: > PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago > with promise that one day it will be possible to implement page cache with > bigger chunks than PAGE_SIZE. > > This promise never materialized. And unlikely will. > > We have many places where PAGE_CACHE_SIZE assumed to be equal to > PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* > or PAGE_* constant should be used in a particular case, especially on the > border between fs and mm. > > Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much > breakage to be doable. > > Let's stop pretending that pages in page cache are special. They are not. > > The changes are pretty straight-forward: > > - << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> ; > > - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; > > - page_cache_get() -> get_page(); > > - page_cache_release() -> put_page(); > > Signed-off-by: Kirill A. Shutemov > Cc: Jan Kara Reviewed-by: Jan Kara Honza -- Jan Kara SUSE Labs, CR