From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from james.kirk.hungrycats.org ([174.142.39.145]:43180 "EHLO james.kirk.hungrycats.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752021AbcISWbh (ORCPT ); Mon, 19 Sep 2016 18:31:37 -0400 Date: Mon, 19 Sep 2016 18:31:22 -0400 From: Zygo Blaxell To: Chris Murphy Cc: Alex Elsayed , Btrfs BTRFS Subject: Re: [RFC] Preliminary BTRFS Encryption Message-ID: <20160919223119.GK21290@hungrycats.org> References: <1473773990-3071-1-git-send-email-anand.jain@oracle.com> <20160916011213.GV22388@dastard> <20160917043829.GC21290@hungrycats.org> <20160919180805.GG21290@hungrycats.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="yr6OvWOSyJed8q4v" In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-ID: --yr6OvWOSyJed8q4v Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Sep 19, 2016 at 04:25:55PM -0600, Chris Murphy wrote: > >> Files are modified by creating new extents (using parameters inherited > >> from the inode to fill in the extent attributes) and updating the inode > >> to refer to the new extent instead of the old one at the modified > >> offset. Cloned extents are references to existing extents associated > >> with a different inode or at a different place within the same inode (= if > >> the extent is not compatible with the destination inode, clone fails > >> with an error). A snapshot is an efficient way to clone an entire > >> subvol tree at once, including all inodes and attributes. > > > > There is the caveat of chattr +C, which would need hard-disabled for > > extent-level encryption (vs block level). >=20 > What about raid56 partial stripe writes? Aren't these effectively nocow? Those are a straight-up bug that should be fixed. They are mixing committed data with uncommitted data from two different transactions, and the stripe temporarily contains garbage. Combine that with unclean shutdown in degrad= ed mode and the data is gone. --yr6OvWOSyJed8q4v Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlfgZzcACgkQgfmLGlazG5zlRQCgu/Jcm/4DoVbrNfyp1Fo3dwhh 3/sAoLmps7+5tzx3nZpGXuwu5z8yhAeH =+Lc1 -----END PGP SIGNATURE----- --yr6OvWOSyJed8q4v--