From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Albert Cahalan" Subject: Re: [ANNOUNCE] Btrfs: a copy on write, snapshotting FS Date: Thu, 14 Jun 2007 02:59:23 -0400 Message-ID: <787b0d920706132359h17531f57gdc4ed01724e53361@mail.gmail.com> References: <787b0d920706122245j3a2ff7e8ja611ecf41cc67a4c@mail.gmail.com> <20070613120037.GA28279@think.oraclecorp.com> <787b0d920706130914l676a24cau62525e90a90b5839@mail.gmail.com> <20070613165706.GF28279@think.oraclecorp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, hch@infradead.org, snitzer@gmail.com To: "Chris Mason" Return-path: Received: from wa-out-1112.google.com ([209.85.146.180]:26080 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751172AbXFNG7X (ORCPT ); Thu, 14 Jun 2007 02:59:23 -0400 Received: by wa-out-1112.google.com with SMTP id v27so562573wah for ; Wed, 13 Jun 2007 23:59:23 -0700 (PDT) In-Reply-To: <20070613165706.GF28279@think.oraclecorp.com> Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On 6/13/07, Chris Mason wrote: > On Wed, Jun 13, 2007 at 12:14:40PM -0400, Albert Cahalan wrote: > > On 6/13/07, Chris Mason wrote: > > >On Wed, Jun 13, 2007 at 01:45:28AM -0400, Albert Cahalan wrote: > > >> * secure delete via destruction of per-file or per-block random crypto > > >keys > > > > > >I'd rather keep secure delete as a userland problem (or a layered FS > > >problem). When you take backups and other copies of the file into > > >account, it's a bigger problem than btrfs wants to tackle right now. > > > > It can't be a userland problem if you allow disk blocks to move. > > Volume resizing, logging/journalling, etc. -- they combine to make > > the userland solution essentially impossible. (one could wipe the > > whole partition, or maybe fill ALL space on the volume) > > Right about here is where I would insert a long story about ecryptfs, or > encryption solutions that happen all in userland. At any rate, it is > outside the scope of v1.0, even though I definitely agree it is an > important problem for some people. I'm sure you do have a nice long story, and I'm sure it seems correct, but there is something not quite right about the add-on hacks. BTW, I'm suggesting that this be about deletion, not protection of data you wish to keep. It covers more than just file bodies. It covers inode data, block allocations, etc. > > >> * atomic creation of copy-on-write directory trees > > > > > >Do you mean something more fine grained than the current snapshotting > > >system? > > > > I believe so. Example: I have a linux-2.6 directory. It's not > > a mount point or anything special like that. I want to copy > > it to a new directory called wip, without actually copying > > all the blocks. To all the normal POSIX API stuff, this copy > > should look like the result of "cp -a", not hard links. > > This would be a snapshot, which has to be done on a subvolume right now. > It is not as nice as being able to pick a random directory, but I've > only been able to get this far by limiting the feature scope > significantly. What I did do was make subvolumes very cheap...just make > a bunch of them. Can a regular user create and use a subvolume? If not, then this doesn't work. (if so, then I have other concerns...)