Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752526Ab3COFJV (ORCPT ); Fri, 15 Mar 2013 01:09:21 -0400 Received: from mail02-md.ns.itscom.net ([175.177.155.112]:49663 "EHLO mail02-md.ns.itscom.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752061Ab3COFJT (ORCPT ); Fri, 15 Mar 2013 01:09:19 -0400 From: "J. R. Okajima" Subject: Re: [PATCH 0/9] overlay filesystem: request for inclusion (v17) To: Al Viro Cc: Miklos Szeredi , Andrew Morton , torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, hch@infradead.org, apw@canonical.com, nbd@openwrt.org, neilb@suse.de, jordipujolp@gmail.com, ezk@fsl.cs.sunysb.edu, dhowells@redhat.com, sedat.dilek@googlemail.com, mszeredi@suse.cz In-Reply-To: <20130315044411.GW21522@ZenIV.linux.org.uk> References: <1363184193-1796-1-git-send-email-miklos@szeredi.hu> <20130313160854.54ac0491044371b4db214698@linux-foundation.org> <20130315012541.GU21522@ZenIV.linux.org.uk> <19058.1363320936@jrobl> <20130315044411.GW21522@ZenIV.linux.org.uk> Date: Fri, 15 Mar 2013 14:09:14 +0900 Message-ID: <20079.1363324154@jrobl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1393 Lines: 37 Al Viro: > > +- whiteout is hardlinked in order to reduce the consumption of inodes > > + on branch > > *blink* Whiteouts have no inodes at all. Filesystem has an additional > kind of directory entries, recognizable as whiteouts. How they are > done is up to filesystem in question. "no inodes at all"? Are you assuming the implementation in dcache only (with a new d_type flag)? And it is up to the real fs (layer or branch) whether it consumes inode or not? If so, it has a big disadvantage for the layer-fs (or branch-fs) to have to implement a new method for whiteout. Overlayfs implements whiteout as symlink+xattr which consumes an inode. And you don't like it, right? What I showed is another generic approach without xattr where the new method to whiteout is unnecessary. > > +The whiteout in aufs is very similar to Unionfs's. That is represented > > +by its filename. UnionMount takes an approach of a file mode, but I am > > +afraid several utilities (find(1) or something) will have to support it. > > Why the devil should find(1) even see them? It is the case when find(1) for the layer-fs/branch-fs directly. J. R. Okajima -- 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/