Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757170Ab0GWRjD (ORCPT ); Fri, 23 Jul 2010 13:39:03 -0400 Received: from rcsinet10.oracle.com ([148.87.113.121]:38517 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756647Ab0GWRjA convert rfc822-to-8bit (ORCPT ); Fri, 23 Jul 2010 13:39:00 -0400 MIME-Version: 1.0 Message-ID: Date: Fri, 23 Jul 2010 10:37:51 -0700 (PDT) From: Dan Magenheimer To: Christoph Hellwig , ngupta@vflare.org Cc: akpm@linux-foundation.org, Chris Mason , viro@zeniv.linux.org.uk, adilger@sun.com, tytso@mit.edu, mfasheh@suse.com, Joel Becker , 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 , npiggin@suse.de, Dave Mccracken , riel@redhat.com, avi@redhat.com, Konrad Wilk Subject: RE: [PATCH V3 0/8] Cleancache: overview References: <20100621231809.GA11111@ca-server1.us.oracle.com4C49468B.40307@vflare.org> <840b32ff-a303-468e-9d4e-30fc92f629f8@default 20100723140440.GA12423@infradead.org 364c83bd-ccb2-48cc-920d-ffcf9ca7df19@default> In-Reply-To: <364c83bd-ccb2-48cc-920d-ffcf9ca7df19@default> X-Priority: 3 X-Mailer: Oracle Beehive Extensions for Outlook 2.0.1.2.1.2 (406224) [OL 12.0.6535.5005] Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT X-Source-IP: acsmt355.oracle.com [141.146.40.155] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090205.4C49D395.006F:SCFMA4539814,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1885 Lines: 49 > From: Dan Magenheimer > Subject: RE: [PATCH V3 0/8] Cleancache: overview > > > From: Christoph Hellwig [mailto:hch@infradead.org] > > Subject: Re: [PATCH V3 0/8] Cleancache: overview > > > > On Fri, Jul 23, 2010 at 06:58:03AM -0700, Dan Magenheimer wrote: > > > CHRISTOPH AND ANDREW, if you disagree and your concerns have > > > not been resolved, please speak up. > > Hi Christoph -- > > Thanks very much for the quick (instantaneous?) reply! > > > Anything that need modification of a normal non-shared fs is utterly > > broken and you'll get a clear NAK, so the propsal before is a good > > one. > > Unless/until all filesystems are 100% built on top of VFS, > I have to disagree. Abstractions (e.g. VFS) are never perfect. After thinking about this some more, I can see a way to enforce "opt-in" in the cleancache backend without any changes to non-generic fs code. I think it's a horrible hack and we can try it, but I expect fs maintainers would prefer the explicit one-line-patch opt-in. 1) Cleancache backend maintains a list of "known working" filesystems (those that have been tested). 2) Nitin's proposed changes pass the *sb as a parameter. The string name of the filesystem type is available via sb->s_type->name. This can be compared against the "known working" list. Using the sb pointer as a "handle" requires an extra table search on every cleancache get/put/flush, and fs/super.c changes are required for fs unmount notification anyway (e.g. to call cleancache_flush_fs) so I'd prefer to keep the cleancache_poolid addition to the sb. I'll assume this is OK since this is in generic fs code. Dan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/