From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from outgoing.tormail.org ([82.221.96.22]:39618 "EHLO outgoing.tormail.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754959Ab3AHAhp (ORCPT ); Mon, 7 Jan 2013 19:37:45 -0500 Received: from localhost ([127.0.0.1] helo=internal.tormail.org) by outgoing.tormail.org with esmtp (Exim 4.72) (envelope-from ) id 1TsNCJ-0004cH-5b for linux-btrfs@vger.kernel.org; Tue, 08 Jan 2013 03:37:44 +0300 Received: from junlion by internal.tormail.org with local (Exim 4.63) (envelope-from ) id 1TsN9p-000FDf-SX for linux-btrfs@vger.kernel.org; Tue, 08 Jan 2013 00:35:12 +0000 Date: Tue, 8 Jan 2013 00:37:11 +0000 From: Jun Lion To: linux-btrfs@vger.kernel.org Subject: chattr +C vs. btrfs subvolume snapshot MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Message-Id: <1TsN9p-000FDf-SX@internal.tormail.org> Sender: linux-btrfs-owner@vger.kernel.org List-ID: What happens if you set an individual file inside a subvolume as nocow (chattr +C) and then take a snapshot of that subvolume and modify the file in both? Will btrfs now ignore the nocow attribute completely or will it do "as few copies as possible"? (I'd love to know if it's possible to visualize the fragmentation of a single file.)