Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762069AbXEWPha (ORCPT ); Wed, 23 May 2007 11:37:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757005AbXEWPhV (ORCPT ); Wed, 23 May 2007 11:37:21 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:49989 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754564AbXEWPhT (ORCPT ); Wed, 23 May 2007 11:37:19 -0400 Date: Wed, 23 May 2007 16:37:18 +0100 From: Al Viro To: Miklos Szeredi Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, torvalds@linux-foundation.org Subject: Re: [RFC PATCH] file as directory Message-ID: <20070523153718.GB4095@ftp.linux.org.uk> References: <20070523102437.GS4095@ftp.linux.org.uk> <20070523113925.GT4095@ftp.linux.org.uk> <20070523121620.GU4095@ftp.linux.org.uk> <20070523135140.GW4095@ftp.linux.org.uk> <20070523150602.GZ4095@ftp.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1352 Lines: 28 On Wed, May 23, 2007 at 05:25:49PM +0200, Miklos Szeredi wrote: > > > How will this work with copy_tree() and namespace duplication, which > > > currently walk the tree with only namespace_sem held? > > > > Easy - grab namespace_sem, grab vfsmount_lock, walk the subtree and bump > > mnt_busy on everything (by 1 + number of non-busy children). Then drop > > vfsmount_lock and do as usual, dropping references in tree being copied > > as you go. Nothing will get attached or detached due to namespace_sem, > > nothing will get evicted by anybody other than you since you've got all > > that stuff pinned down. End of story... > > Right. > > Do you have some code? > > Should I try to code something up? I hope to get some breathing space next week, then I'll get back to VFS work. I'd rather do that one myself, since it'll be a long series of equivalent transformations - debugging such rewrite of refcounting done as a single patch is going to be hell. And yes, refcounting rewrite is near the top of the list (another thing is wading through several threads from hell and reviewing unionfs ;-/) - 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/