From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from len.romanrm.net ([195.154.117.182]:46566 "EHLO len.romanrm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754918AbcIXMkS (ORCPT ); Sat, 24 Sep 2016 08:40:18 -0400 Date: Sat, 24 Sep 2016 17:40:12 +0500 From: Roman Mamedov To: Alexander Tomokhov Cc: "linux-btrfs@vger.kernel.org" Subject: Re: Does data checksumming remain for files with No_COW file attribute? Message-ID: <20160924174012.51d44caa@natsu> In-Reply-To: <767591474719974@web21o.yandex.ru> References: <767591474719974@web21o.yandex.ru> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/IJt7Q5ZrWRjOOMC_WycJ/QN"; protocol="application/pgp-signature" Sender: linux-btrfs-owner@vger.kernel.org List-ID: --Sig_/IJt7Q5ZrWRjOOMC_WycJ/QN Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Sat, 24 Sep 2016 15:26:14 +0300 Alexander Tomokhov wrote: > does setting No_COW on a file (chattr +C) imply disabling data checksummi= ng on it? Yes. IIRC the reasoning was that it's more difficult to track checksums of data which is being overwritten in-place (as opposed to CoW). > may it disable checksumming only for newly written extents and keep for r= eading existing ones? You can't apply chattr +C to any files of non-zero length, so by definition there won't be any pre-existing checksummed extents in that file. --=20 With respect, Roman --Sig_/IJt7Q5ZrWRjOOMC_WycJ/QN Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEARECAAYFAlfmdC4ACgkQTLKSvz+PZwjbBwCfd9EbRCcgQYDYkcxL1XmbN7/+ CTEAoI+AWTJGiC1Hf7v3BadtpDnkFWLD =DrZQ -----END PGP SIGNATURE----- --Sig_/IJt7Q5ZrWRjOOMC_WycJ/QN--