Re: Selective Compression/Encryption

Joshua J. Berry
2008-12-09T19:26:03Z

On Tuesday 09 December 2008 08:35:16 Chris Mason wrote:
> On Tue, 2008-12-09 at 09:59 -0500, Lee Trager 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.
> >
> > 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.
>
> This was my plan, but btrfstune probably isn't the best program to do it
> (the ext2 tune program is mostly aimed at the super block level things).
>
> I think it would be better to make a setattr style program to call the
> ioctls. There is already a per file compression flag, and the code
> should already be checking it.

Is there some reason this can't be done with the existing extended attribute
facilities?

It seems like xattrs would be preferable to some btrfs-specific tunable, as
programs like rsync or backup tools would be able to preserve (and restore)
these bits with no extra work required.

-- Josh

--
Joshua J. Berry

"I haven't lost my mind -- it's backed up on tape somewhere."
-- /usr/games/fortune