[Btrfs-devel] Selective Compression/Encryption

[Christian Hesse]

On Tuesday 09 December 2008, Miguel Figueiredo Mascarenhas Sousa Filipe wrote:
> Hi there,
>
> On Tue, Dec 9, 2008 at 2:59 PM, Lee Trager <lt73 at cs.drexel.edu> wrote:
> > Currently compression and I assume if encryption is implemented it is
> > turned on or off during mount. There are however many times when a user
> > may want to select which files/directories they want to compress or
> > encrypt. This will also be helpful when implementing btrfs support in
> > grub for example. We can say the disk can be compressed/encrypted except
> > for /boot so compression/encryption doesn't have to be implemented in
> > grub.

You could just use an additional partition for /boot that has compression an 
encryption disabled...

> > I was thinking of adding this functionality to the userspace application
> > btrfstune. The way I was thinking of doing this is when btrfstune +c is
> > applied to a directory or file the directory(and all its contents) or
> > file will always be compressed reguardless of how the filesystem is
> > mounted. The opposite would happen when btrfstune -c is used.
> >
> > Would this be a reasonable thing to implement? Any suggestions before I
> > start doing this?
>
> Things like compression or encription should be used at the "volume" level.

That was what I said some time ago when I asked why encryption support for 
btrfs is planned. On a volume level you can use dm-crypt and the fs can 
ignore that part completely.

The answer was that different users on a home partition could use their own 
encryption key. That sounds like volume level is out of bet. ;)

> So.. if a user wants a specific set of files or dirs ..they should
> create a mount-point/volume like:
>
> private_vol
> bigarchives_vol
>
> and set those volumes as compressed or encripted volumes
>
> Regarding usability, the best would be for the sub-volume creation
> tool to optionally allow passing encription/compression arguments.
>
>
> and then:
>  should mount those volumes somewhere like: ~/Confidential or ~/Archives.
>
> Basically, do it at the directory level (which in btrfs is at the
> sub-volume level).
> File-level granularity is totally unmanageable in the long term.
>
> Kind regards,

-- 
Regards,
Chris