Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756037AbYGPFus (ORCPT ); Wed, 16 Jul 2008 01:50:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751823AbYGPFuh (ORCPT ); Wed, 16 Jul 2008 01:50:37 -0400 Received: from ti-out-0910.google.com ([209.85.142.186]:26449 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751210AbYGPFug (ORCPT ); Wed, 16 Jul 2008 01:50:36 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:x-enigmail-version:content-type :content-transfer-encoding; b=bFTPBtv3HYvRzP1Dh5n5j5EGd3dOwN3I4WtjLlqTSHFj+XG98Ln1+d3lK4xCaFrx0B /vrzeM9zDkuVkUpnUlVrI2qeF+UbK80WN+/f3L24BmLDeNH2el/m1ivJLPEaJFkuoi/M AJIt/iUE69tvB/kI7Tb4kQDeWVUqdIIsILZ+U= Message-ID: <487D8C0A.9060100@gmail.com> Date: Wed, 16 Jul 2008 14:50:02 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.12 (X11/20071114) MIME-Version: 1.0 To: "Eric W. Biederman" CC: Greg KH , Andrew Morton , Daniel Lezcano , linux-kernel@vger.kernel.org, Al Viro , Linux Containers , Benjamin Thery , netdev@vger.kernel.org Subject: Re: [PATCH 12/15] driver core: Implement tagged directory support for device classes. References: <486DD650.3000804@gmail.com> <486E2C3B.6020603@gmail.com> <20080704161200.GA1440@suse.de> <487D6A24.9070001@gmail.com> In-Reply-To: X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1161 Lines: 29 Hello, Eric W. Biederman wrote: >> Eric, with the multiple superblocks, sysfs now uses inode from the >> default sysfs_sb with dentries from other sb's. Is this okay? Are >> there any other filesystems which do this? > > I don't know of any other filesystems where this unique challenge arises. > /proc almost qualifies but it never needs to be modified. > > It is certainly ok to go from multiple dentries to a single inode. > I'm trying to remember why I choose to do that. I think both because it simplifies > the locking and keeps us more efficient in the icache. It's a bit scary tho. Working inode->i_dentry or dentry->d_alias crosses multiple sb's. sysfs isn't too greedy about dcache/icache. Only open files and directories hold them and only single copy of sysfs_dirent is there for most nodes. Wouldn't it be better to stay on the safer side and use separate inode hierarchy? Thanks. -- tejun -- 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/