Re: [ANNOUNCE] Btrfs: a copy on write, snapshotting FS

From: Chris Mason
Date: Thu Jun 14 2007 - 08:34:23 EST

On Thu, Jun 14, 2007 at 02:59:23AM -0400, Albert Cahalan wrote:
> On 6/13/07, Chris Mason <chris.mason@xxxxxxxxxx> wrote:

[ secure deletion in btrfs ]

> >
> >Right about here is where I would insert a long story about ecryptfs, or
> >encryption solutions that happen all in userland. At any rate, it is
> >outside the scope of v1.0, even though I definitely agree it is an
> >important problem for some people.
> I'm sure you do have a nice long story, and I'm sure it seems
> correct, but there is something not quite right about the add-on
> hacks.
> BTW, I'm suggesting that this be about deletion, not protection
> of data you wish to keep. It covers more than just file bodies.
> It covers inode data, block allocations, etc.

Sorry, it's still way outside the scope of v1.0.

> >> >> * atomic creation of copy-on-write directory trees
> >> >
> >> >Do you mean something more fine grained than the current snapshotting
> >> >system?
> >>
> >> I believe so. Example: I have a linux-2.6 directory. It's not
> >> a mount point or anything special like that. I want to copy
> >> it to a new directory called wip, without actually copying
> >> all the blocks. To all the normal POSIX API stuff, this copy
> >> should look like the result of "cp -a", not hard links.
> >
> >This would be a snapshot, which has to be done on a subvolume right now.
> >It is not as nice as being able to pick a random directory, but I've
> >only been able to get this far by limiting the feature scope
> >significantly. What I did do was make subvolumes very cheap...just make
> >a bunch of them.
> Can a regular user create and use a subvolume? If not, then
> this doesn't work. (if so, then I have other concerns...)

That's the long term goal, but I'll have to reorganize things such that
subvolumes created by a user can all fall under sane accounting.


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