From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1RUKpZ-0004M5-8b for garchives@archives.gentoo.org; Sat, 26 Nov 2011 16:10:21 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id DD71821C1C8; Sat, 26 Nov 2011 16:09:47 +0000 (UTC) Received: from smtp.gentoo.org (smtp.gentoo.org [140.211.166.183]) by pigeon.gentoo.org (Postfix) with ESMTP id 4161521C15B for ; Sat, 26 Nov 2011 16:08:08 +0000 (UTC) Received: from pomiocik.lan (77-255-21-18.adsl.inetia.pl [77.255.21.18]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) (Authenticated sender: mgorny) by smtp.gentoo.org (Postfix) with ESMTPSA id 70D951B402E; Sat, 26 Nov 2011 16:08:05 +0000 (UTC) Date: Sat, 26 Nov 2011 17:08:31 +0100 From: =?UTF-8?B?TWljaGHFgiBHw7Nybnk=?= To: gentoo-dev@lists.gentoo.org Cc: nirbheek@gentoo.org, rich0@gentoo.org Subject: Re: [gentoo-dev] Re: proj/portage:master commit in: pym/portage/dbapi/ Message-ID: <20111126170831.16d9d656@pomiocik.lan> In-Reply-To: References: <1d4ac47c28706094230cb2c4e6ee1c1c71629aa0.arfrever@gentoo> <20111126105822.GA37825@gentoo.org> <20111126113830.GC37825@gentoo.org> <20111126125915.428cb31a@googlemail.com> <20111126160936.64eeee1c@pomiocik.lan> Organization: Gentoo X-Mailer: Claws Mail 3.7.10 (GTK+ 2.24.8; x86_64-pc-linux-gnu) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-dev@lists.gentoo.org Reply-to: gentoo-dev@lists.gentoo.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA256; boundary="Sig_/.Tj/+4kM5QTPPz+f9yxU3VB"; protocol="application/pgp-signature" X-Archives-Salt: 257d8388-4a00-4ace-b6c6-948b94d943ee X-Archives-Hash: f8cc2c3a8a06d82fdf11f415b93a93f9 --Sig_/.Tj/+4kM5QTPPz+f9yxU3VB Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Sat, 26 Nov 2011 21:28:51 +0530 Nirbheek Chauhan wrote: > On Sat, Nov 26, 2011 at 8:39 PM, Micha=C5=82 G=C3=B3rny > wrote: > > But in this particular case, I don't think COW is particularly > > useful. If it works only on filesystem bounds, we could move the > > file directly anyway. > > >=20 > There are still a few specific cases in which CoW would indeed be > useful. IIRC, reflinking of files works across btrfs *subvolumes*, and > such a copy would normally be detected as a cross-device move. For such a thing, shouldn't rename() work neat anyway? > Another use would be an patch-merge which makes use of *ranged > reflinks* to only CoW copy those parts of the file that were > changed[1]. rsync has support for this, but only while appending to > files (--append-verify --no-whole-file). So, it'd be like: 1) CoW-dup old file, 2) patch-merge into the duped old file, 3) replace. Am I understanding correctly? --=20 Best regards, Micha=C5=82 G=C3=B3rny --Sig_/.Tj/+4kM5QTPPz+f9yxU3VB Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iJwEAQEIAAYFAk7RDwAACgkQfXuS5UK5QB2XWgQArOQ5Wz8ueEH20W3rA42vLT2X 1T46ZMNqvD3yNzEDndlHKCZQAy4Y39wH3Hk8iDAYSnFlHFrZmZjCjPW9oBQcwSau heT2vzzWRwX5y1vGqaQVucpEZQi36nh79+VrcOJwY6eQOKFa5lM38sbI5Vokh5bT qIynmvtdvLQSvCXmKUg= =gs21 -----END PGP SIGNATURE----- --Sig_/.Tj/+4kM5QTPPz+f9yxU3VB--