From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759167AbYEENIV (ORCPT ); Mon, 5 May 2008 09:08:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755516AbYEENIK (ORCPT ); Mon, 5 May 2008 09:08:10 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:56355 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752181AbYEENII (ORCPT ); Mon, 5 May 2008 09:08:08 -0400 Date: Mon, 5 May 2008 09:08:04 -0400 From: Christoph Hellwig To: Miklos Szeredi Cc: hch@infradead.org, akpm@linux-foundation.org, viro@ZenIV.linux.org.uk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, menage@google.com Subject: Re: [patch 03/15] cgroup: dont call vfs_mkdir Message-ID: <20080505130804.GA1809@infradead.org> References: <20080505095440.820370974@szeredi.hu> <20080505095511.217634550@szeredi.hu> <20080505110016.GC20910@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 05, 2008 at 02:32:22PM +0200, Miklos Szeredi wrote: > > Looks correct but I don't think it's a good idea. Spreading more logic > > into filesystems without a good reason is rarely a good idea. > > (Thanks for the review, Christoph) > > Agreed completely, but vfs_* aren't for filesystems to call, rather > for entities calling _into_ filesystems from the outside. This is > actually a very rare thing, so adding some extra logic for the sake of > cleanliness should be OK. > > Now it can be argued, that cgroup_clone() is calling into the > filesystem from the outside. But it's not really doing that, rather > it's making an internal modification to a specific filesystem, > triggered by some external action. I don't think that matters. We're not about overly strict layering, and especialy this kind where you call into a higher layer to get back into the lower one is not harmful at all. For cgroup it's only a small duplication, but e.g. I don't really like all the duplications in the reiserfs case. Unless we have a very good reason why the useage of the vfs_ function should go away from the filesystem code I don't think we want this.