From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from meiko.romanrm.net ([195.154.97.166]:51911 "EHLO meiko.romanrm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752869AbaK0AUY (ORCPT ); Wed, 26 Nov 2014 19:20:24 -0500 Date: Thu, 27 Nov 2014 05:20:21 +0500 From: Roman Mamedov To: Robert White Cc: linux-btrfs@vger.kernel.org Subject: Re: Can't cp --reflink files on a Ext4-converted FS w/o checksums Message-ID: <20141127052021.47734be0@natsu> In-Reply-To: <54766997.1040101@pobox.com> References: <20141127005527.42a7fe59@natsu> <54765FC2.2050309@pobox.com> <20141127043337.198d6084@natsu> <54766997.1040101@pobox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Wed, 26 Nov 2014 16:00:23 -0800 Robert White wrote: > Uh... you may _still_ have no checksums on any of those data extents. > They are not going to come back until you write them to a normal file > with a normal copy. So you may be lacking most of the data validation > features of this filesystem. Well, this FS is coming from being Ext4 for years, so it's not worse off now than it was before. And anyways the main feature that I wanted were snapshots. > You might want to go experiment. Make another new subvol (or at least a > directory in a directory/root/subvol that never had the +C attribute > set) and see if you can cp --reflink any of these files into that > subdirectory without repeating the +C trick. Ha, indeed I can't. Maybe there should be a way to generate checksums without rewriting files, just via reading them, then calculating and writing checksum to metadata. > Clearing NODATACOW does _not_ clear NODATASUM (at least not on a > non-empty file) as near as I can tell, so that directory hierarchy and > its subsequent snapshots is likely "less safe" than you think. The nodatasum flag also isn't accessible via chattr, is it? -- With respect, Roman