From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shaya Potter Subject: Re: [PATCH 05/24] Unionfs: Copyup Functionality Date: Mon, 08 Jan 2007 17:00:15 -0500 Message-ID: <1168293615.9853.10.camel@localhost.localdomain> References: <1168229596580-git-send-email-jsipek@cs.sunysb.edu> <11682295971184-git-send-email-jsipek@cs.sunysb.edu> <20070108132947.6a8f9cf4.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: "Josef 'Jeff' Sipek" , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, hch@infradead.org, viro@ftp.linux.org.uk, torvalds@osdl.org, mhalcrow@us.ibm.com, David Quigley , Erez Zadok Return-path: Received: from cs.columbia.edu ([128.59.16.20]:49818 "EHLO cs.columbia.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030247AbXAHWKk (ORCPT ); Mon, 8 Jan 2007 17:10:40 -0500 To: Andrew Morton In-Reply-To: <20070108132947.6a8f9cf4.akpm@osdl.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Mon, 2007-01-08 at 13:29 -0800, Andrew Morton wrote: > On Sun, 7 Jan 2007 23:12:57 -0500 > "Josef 'Jeff' Sipek" wrote: > > > From: Josef "Jeff" Sipek > > > > This patch contains the functions used to perform copyup operations in unionfs. > > What is a copyup operation and why does it exist? > > It seems to be copying the entire contents of certain files. That's not a > thing I'd have expected to see in a union filesystem. Explain it all, > please? (Somewhere where the info will be retained for posterity - a > random email is good, but not sufficient...) to do the random e-mail, it's because it just doesn't union "directories", but lets you assign read-write, read-only properties to them. If you try to modify a file on a read-only layer, it will be copied to the top most layer (has to be read-write) and then modified. It can be slow though (imagine modifying a 1GB file).