From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932311AbWGEEID (ORCPT ); Wed, 5 Jul 2006 00:08:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932386AbWGEEID (ORCPT ); Wed, 5 Jul 2006 00:08:03 -0400 Received: from mail.tmr.com ([64.65.253.246]:52615 "EHLO pixels.tmr.com") by vger.kernel.org with ESMTP id S932311AbWGEEIB (ORCPT ); Wed, 5 Jul 2006 00:08:01 -0400 Message-ID: <44AB3BC9.2020602@tmr.com> Date: Wed, 05 Jul 2006 00:10:49 -0400 From: Bill Davidsen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.4) Gecko/20060516 SeaMonkey/1.0.2 MIME-Version: 1.0 To: Peter Zijlstra CC: Diego Calleja , linux-kernel@vger.kernel.org Subject: Re: ext4 features References: <20060701163301.GB24570@cip.informatik.uni-erlangen.de> <20060701170729.GB8763@irc.pl> <20060701174716.GC24570@cip.informatik.uni-erlangen.de> <20060701181702.GC8763@irc.pl> <20060703202219.GA9707@aitel.hist.no> <20060703205523.GA17122@irc.pl> <1151960503.3108.55.camel@laptopd505.fenrus.org> <44A9904F.7060207@wolfmountaingroup.com> <20060703232547.2d54ab9b.diegocg@gmail.com> <1152004929.3374.13.camel@elijah.suse.cz> <1152012907.23628.20.camel@lappy> In-Reply-To: <1152012907.23628.20.camel@lappy> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Peter Zijlstra wrote: > On Tue, 2006-07-04 at 11:22 +0200, Petr Tesarik wrote: >> On Mon, 2006-07-03 at 23:25 +0200, Diego Calleja wrote: >>> El Mon, 03 Jul 2006 15:46:55 -0600, >>> "Jeff V. Merkey" escribió: >>> >>>> Add a salvagable file system to ext4, i.e. when a file is deleted, you >>>> just rename it and move it to a directory called DELETED.SAV and recycle >>>> the files as people allocate new ones. Easy to do (internal "mv" of >>> >>> Easily doable in userspace, why bother with kernel programming >> Yes and no. A simple mv is better done in userspace, but what I'd >> _really_ appreciate would be a true kernel salvage (similar to the way >> NetWare does things). That means marking the file as deleted in the >> directory, marking its blocks as deleted but avoiding the use of those >> blocks. The kernel would then prefer allocating new blocks from >> elsewhere but once the filesystem runs out of space, it would start >> allocating from the deleted files area and marking the blocks as well as >> the corresponding files purged. >> >> Salvaging files would be done with a separate tool. Of course, if you >> delete more files with the same name in the same directory, you'd need >> to tell that tool which one of them you want to salvage. Yes, I really >> mean you'd have more than one deleted file with the same name in the >> directory. >> >> Anyway, I doubt we want such feature for ext4, because to make things >> efficient, you'd need to provide some kind of pointer from the deleted >> (but not yet purged) blocks to the corresponding file. Hard links are >> also problematic and there is a whole lot of other troubles I haven't >> even thought of. > > Wouldn't such a scheme interfere with the block allocator algorithms, > and hence increase the risk of fragmentation? Schemes like this realy > put my hairs on end, > > 1) if you don't want to lose your data, make backups; > 2) if I mean to delete a file, I want it gone proper. Silently keeping > it about is not unix like; > 3) don't aid third parties in recovering your removed data. If I want > them to have it I'll give it to them. > > Peter > If you wanted to add a feature which would overwrite the file when removed or truncated I'd be happy. Yes I know about attributes and dban, and I have a version of rm which does that if people use it, but would be nice to have it on the whole filesystem. It's not proof against a TLA, but nice for casual snooping. -- Bill Davidsen Obscure bug of 2004: BASH BUFFER OVERFLOW - if bash is being run by a normal user and is setuid root, with the "vi" line edit mode selected, and the character set is "big5," an off-by-one errors occurs during wildcard (glob) expansion.