From: Nitin Gupta Subject: Re: [PATCH V3 0/8] Cleancache: overview Date: Fri, 23 Jul 2010 20:26:35 +0530 Message-ID: <4C49ADA3.9060501@vflare.org> References: <20100621231809.GA11111@ca-server1.us.oracle.com> <4C49468B.40307@vflare.org> Reply-To: ngupta@vflare.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Dan Magenheimer , chris.mason@oracle.com, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, adilger@sun.com, tytso@mit.edu, mfasheh@suse.com, joel.becker@oracle.com, matthew@wil.cx, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, ocfs2-devel@oss.oracle.com, linux-mm@kvack.org, jeremy@goop.org, JBeulich@novell.com, kurt.hackel@oracle.com, npiggin@suse.de, dave.mccracken@oracle.com, riel@redhat.com, avi@redhat.com, konrad.wilk@oracle.com To: Minchan Kim Return-path: Received: from mail-pv0-f174.google.com ([74.125.83.174]:44474 "EHLO mail-pv0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755589Ab0GWO4K (ORCPT ); Fri, 23 Jul 2010 10:56:10 -0400 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On 07/23/2010 01:46 PM, Minchan Kim wrote: > On Fri, Jul 23, 2010 at 4:36 PM, Nitin Gupta wrote: >> >> 2. I think change in btrfs can be avoided by moving cleancache_get_page() >> from do_mpage_reapage() to filemap_fault() and this should work for all >> filesystems. See: >> >> handle_pte_fault() -> do_(non)linear_fault() -> __do_fault() >> -> vma->vm_ops->fault() >> >> which is defined as filemap_fault() for all filesystems. If some future >> filesystem uses its own custom function (why?) then it will have to arrange for >> call to cleancache_get_page(), if it wants this feature. > > > filemap fault works only in case of file-backed page which is mapped > but don't work not-mapped cache page. So we could miss cache page by > read system call if we move it into filemap_fault. > > Oh, yes. Then we need cleancache_get_page() call in do_generic_file_read() too. So, if I am missing anything now, we should now be able to get rid of per-fs changes. Thanks, Nitin