From mboxrd@z Thu Jan 1 00:00:00 1970 From: C Anthony Risinger Subject: Re: Replacing the top-level root Date: Wed, 27 Oct 2010 11:52:44 -0500 Message-ID: References: <20101027055311.GA8550@davidb.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Chris Mason , Sage Weil , linux-btrfs@vger.kernel.org To: David Brown Return-path: In-Reply-To: <20101027055311.GA8550@davidb.org> List-ID: On Wed, Oct 27, 2010 at 12:53 AM, David Brown wrote: > On Mon, Oct 25, 2010 at 03:20:58PM -0500, C Anthony Risinger wrote: > >> For example, right now extlinux support booting btrfs, but _only_ fr= om >> the top-level root. =A0if i just had a way to "swap" the top-level r= oot >> with a different subvol, i could overcome several problems i have wi= th >> users all at once: >> >> ) users install their system to the top-level root, which means it i= s >> no longer manageable by snapshot scripts [currently] >> ) if the top-level root could be swapped, extlinux could then boot m= y >> snapshot? (i'm probably wrong here) > > I don't think this is a solution to the extlinux problem, but I've > moved roots into new subvolumes, basically something like this. > > Root is mounted as /, I've also mounted the volume on /mounted in thi= s > example. > > =A0# btrfs subvolume snapshot /mounted /mounted/newrootname > > Now reboot, adding the subvol option to use the newrootname. > Go into /mounted and make sure files touced there don't show up in '/= ' > (we really are mounting the submount). > > Then just use rm -rf to remove everything that isn't a subvol. =A0I > don't know of an easy way to do that, and be careful. yeah, this is precisely what i do currently... the problem is i have to tell the user to do this themselves, as there isn't a way to safely accomplish it automatically. i expect this will become a more common problem, esp. for those trying to integrate advanced btrfs handlers into their distro; like myself. basically, i have ultimate control over all subvols, except top-level, and i want to why/how to address this. imo, if there really is not a proper solution to this issue because of some technical reason, i think mkfs.btrfs should automatically create a subvol, and mark it default... because from the feedback i'm getting or lack thereof, the top-level subvol is dangerous because it's not manageable. this should be done immediately imo, but at the very least, once grub2/extlinux support booting from subvols. thoughts? C Anthony -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html