hi,

i'm working on an initrd hook [http://aur.archlinux.org/packages.php?ID=33376] to support non-volatile system rollbacks (promoting a temporary rollback snapshot to the new active/default). when the system is installed to the default/"." subvolume (as many users probably initially do), it is more difficult/messier to manage system state; there are empty folders in each "child" snapshot where a subvolume used to exist (this seems like BUG to me, dir should not exist?) in the default subvolume. these grow/vary with time. to work around this and for cleaner implementation, i'll intend to permanently boot a named subvolume [__active] (though its contents may be swapped out). ultimately, i have to tell the user to manually remove the old junk (/usr, /etc, /var, etc...) from the default subvolume (since its really in the /__active subvolume)

moving along to a question... can the default subvolume be swapped/removed/renamed/popped/shifted?

what would have been useful, would be the ability to generate an empty, parent subvolume to _contain_ the current one, and rename it to __active. btrfs gives rise to a "subroot" structure; the structure beneath the root.

is something like this possible or can be added?

an alternative idea i had was "promoting" a subvolume to be the new root, and anything "above" the new root is lost/forgotten. then i could create the subroot structure in a subvol, snapshot the default subvol to where i want it, and promote the subvol to be the new root. like a permanent pivot_root/chroot.

great stuff,

C Anthony