Re: btrfs-progs: New utility to swap subvolumes

[Goffredo Baroncelli <kreijack@gmail.com>]

Hi Taruisi,

On Monday 28 December 2009, TARUISI Hiroaki wrote:
[...]
 
> We can swap subvolumes regardless of mounted-subvolume. (only
> when we mount other subvolume than fs tree)
I resolved this kind of problem as described in my previous email ([RFC] 
proposal for a btrfs filesystem layout - 20/Nov/2009): I used a sub-volume as 
root of my system, but I mounted also the root of the btrfs filesystem for 
handling the sub-volumes under "/var/btrfs". It work quiet well:
1) I can swap the sub-volumes only with the mv commands
2) I can switch to an old snapshot of the root at boot time, because my 
scripts update the grub entries with the list of the valid snapshots
3) I can switch permanently two sub-volumes exchanging their names
4) I can remove a sub-volume quite easily

> And, because we can identify snapshot (its date or target subvol)
> with subvolume ID, it is suitable to swap with ID.
Why you want to to identify a sub-volume with its id ? 
I like the idea to identify a sub-volumes with an identifier which is not 
file-system related. To me the fact that a sub-volume is identified with its 
"mount point" seems to me a limit instead that an advantage. But it seems that 
I am alone to thinking that :-(
So I am curious about your reasons.

BR
Goffredo

-- 
gpg key@ keyserver.linux.it: Goffredo Baroncelli (ghigo) <kreijackATinwind.it>
Key fingerprint = 4769 7E51 5293 D36C 814E  C054 BF04 F161 3DC5 0512