From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from magic.merlins.org ([209.81.13.136]:37601 "EHLO mail1.merlins.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754472AbaEGI4U (ORCPT ); Wed, 7 May 2014 04:56:20 -0400 Date: Wed, 7 May 2014 01:56:12 -0700 From: Marc MERLIN To: Duncan <1i5t5.duncan@cox.net> Cc: linux-btrfs@vger.kernel.org Subject: Re: How does Suse do live filesystem revert with btrfs? Message-ID: <20140507085612.GB19238@merlins.org> References: <20140504005257.GF9061@merlins.org> <20140504232645.GQ9061@merlins.org> <20140505003639.GO24298@carfax.org.uk> <20140505050459.GF10159@merlins.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Tue, May 06, 2014 at 04:26:48PM +0000, Duncan wrote: > Marc MERLIN posted on Sun, 04 May 2014 22:04:59 -0700 as excerpted: > > > On Mon, May 05, 2014 at 01:36:39AM +0100, Hugo Mills wrote: > >> I'm guessing it involves reflink copies of files from the snapshot > >> back to the "original", and then restarting affected services. That's > >> about the only other thing that I can think of, but it's got load of > >> race conditions in it (albeit difficult to hit in most cases, I > >> suspect). > > > > Aaah, right, you can use a script to see the file differences between > > two snapshots, and then restore that with reflink if you can truly get a > > list of all changed files. > > However, that is indeed not atomic at all, even if faster than rsync. > > Would send/receive help in such a script? Not really, you still end up with a new snapshot that you can't live switch to. It's really either 1) reboot 2) use cp --reflink to copy a list of changed files (as well as rm to delete the ones that were removed). I'm currently using btrfs-diff (below) which shows changed files but it doesn't show files deleted. Is there something better that would show me which files changed and how between 2 snapshots? btrfs-diff: ------------------------------------------------------------- #!/bin/bash usage() { echo $@ >2; echo "Usage: $0 " >2; exit 1; } [ $# -eq 2 ] || usage "Incorrect invocation"; SNAPSHOT_OLD=$1; SNAPSHOT_NEW=$2; [ -d $SNAPSHOT_OLD ] || usage "$SNAPSHOT_OLD does not exist"; [ -d $SNAPSHOT_NEW ] || usage "$SNAPSHOT_NEW does not exist"; OLD_TRANSID=`btrfs subvolume find-new "$SNAPSHOT_OLD" 9999999` OLD_TRANSID=${OLD_TRANSID#transid marker was } [ -n "$OLD_TRANSID" -a "$OLD_TRANSID" -gt 0 ] || usage "Failed to find generation for $SNAPSHOT_NEW" btrfs subvolume find-new "$SNAPSHOT_NEW" $OLD_TRANSID | sed '$d' | cut -f17- -d' ' | sort | uniq ------------------------------------------------------------- Thanks, Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/ | PGP 1024R/763BE901