From patchwork Tue Jun 6 13:00:58 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hans van Kranenburg X-Patchwork-Id: 9768867 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 724D16034B for ; Tue, 6 Jun 2017 13:01:05 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 667622847C for ; Tue, 6 Jun 2017 13:01:05 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5B4E22847E; Tue, 6 Jun 2017 13:01:05 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 25C85209D8 for ; Tue, 6 Jun 2017 13:01:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751390AbdFFNBB (ORCPT ); Tue, 6 Jun 2017 09:01:01 -0400 Received: from smtp.dpl.mendix.net ([83.96.177.10]:45575 "EHLO smtp.dpl.mendix.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751305AbdFFNBA (ORCPT ); Tue, 6 Jun 2017 09:01:00 -0400 Received: from blackbox.mgt.dpl.mendix.net (blackbox.bofh.hq.mendix.net [IPv6:2001:828:13c8:10b::c]) by smtp.dpl.mendix.net (Postfix) with ESMTP id 15F14201B7 for ; Tue, 6 Jun 2017 15:00:59 +0200 (CEST) From: Hans van Kranenburg To: linux-btrfs@vger.kernel.org Subject: [PATCH v2] btrfs-progs: send operates on ro snapshots only Date: Tue, 6 Jun 2017 15:00:58 +0200 Message-Id: <20170606130058.11619-1-hans.van.kranenburg@mendix.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170605233218.12421-1-hans.van.kranenburg@mendix.com> References: <20170605233218.12421-1-hans.van.kranenburg@mendix.com> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP While talking to another btrfs user on IRC today, it became clear that a major point of confusion in the btrfs send manual is that it's not telling the user soon enough that send/receive solely operates on subvolume snapshots instead of the original (read/write) subvolumes. So, change the first few lines to explicitly mention snapshots instead. Technically, snapshots are also just subvolumes, but requiring this level of technical detailed knowledge doesn't help the user who is just trying out things. Signed-off-by: Hans van Kranenburg --- Changes since v1: - spelling / grammer corrections in the commit message Documentation/btrfs-send.asciidoc | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/Documentation/btrfs-send.asciidoc b/Documentation/btrfs-send.asciidoc index 1c5ccbe6..ef345f68 100644 --- a/Documentation/btrfs-send.asciidoc +++ b/Documentation/btrfs-send.asciidoc @@ -3,7 +3,7 @@ btrfs-send(8) NAME ---- -btrfs-send - generate a stream of changes between two subvolumes +btrfs-send - generate a stream of changes between two subvolume snapshots SYNOPSIS -------- @@ -13,20 +13,21 @@ DESCRIPTION ----------- This command will generate a stream of instructions that describe changes -between two subvolumes. The stream can be consumed by the *btrfs receive* -command to replicate the sent subvolume on a different filesystem. +between two subvolume snapshots. The stream can be consumed by the *btrfs +receive* command to replicate the sent snapshot on a different filesystem. The command operates in two modes: full and incremental. -All subvolumes involved in one send command must be read-only (ie. the -read-only snapshots and this status cannot be changed if there's a running send -operation that uses the subvolume). +All snapshots involved in one send command must be read-only, and this status +cannot be changed as long as there's a running send operation that uses the +snapshot. -In the full mode, the entire subvolume data and metadata will end up in the +In the full mode, the entire snapshot data and metadata will end up in the stream. -In the incremental mode (options '-p' and '-c'), there can be one or more -parent subvolumes that will establish the base for determining the changes. -The final stream will be smaller compared to the full mode. +In the incremental mode (options '-p' and '-c'), previously sent snapshots that +are available on both the sending and receiving side can be used to reduce the +amount of information that has to be sent to reconstruct the sent snapshot on a +different filesystem. It is allowed to omit the '-p ' option when '-c ' options are given, in which case *btrfs send* will determine a suitable parent among the