On Fri, Jul 8, 2016 at 3:39 PM, Chris Murphy <li...@colorremedies.com> wrote: > On Fri, Jul 8, 2016 at 2:08 PM, Kai Herlemann <nesa...@freenet.de> wrote: > >> If here any developers read along: I'd like to suggest that there's >> automatically made a subvolume "@" by default, which is set as default >> subvolume, or a tip to the distribution, that it would made sense to do that >> with the installation. It would protect other users against confusion and >> work like I had it. > > I think that upstream won't do that or recommend it. There is already > a subvolume created at mkfs time, that's subvolid=5 (a.k.a. 0) and it > is set as the default subvolume. I don't see the point in having two > of them. If you want it, make it. If your distro wants it, it should > be done in the installer, not mkfs. > > Further I think it's inappropriate to take 'btrfs sub set-default' > away from the user. That is a user owned setting. It is not OK for > some utility to assert domain over that setting, and depend on it for > proper booting. It makes the entire boot process undiscoverable, > breaks self-describing boot process which are simpler to understand > and troubleshoot, in favor of secret decoder ring booting that now > requires even more esoteric knowledge on the part of users. So I think > it's a bad design. > > Instead those utilities should employ rootflags=subvol or subvolid to > explicitly use a particular fs tree for rootfs, rather that hide this > fact by using subvolume set-default.
The only distro installer I know that works this way out of the box is Fedora/Red Hat's Anaconda. It leaves the default subvolume as 5, but does not install the OS there. Instead each mountpoint is created as a subvolume in that top level, and rootflags kernel parameter and fstab are used to assemble those subvolumes per the FHS virtually. It's completely discoverable, you can follow each step along the way, it's not obscured. The additional benefit is no nested subvolumes. A possible improvement for those distros that will likely continue doing things the way they are, would be if the kernel code stated what fs tree ID was being mounted when the default subvolume is not 5, and neither subvol nor subvolid mount options were used. *shrug* -- Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
