very simple datastore reimplementation

C. Scott Ananian cscott at
Thu May 8 15:28:11 EDT 2008

On Thu, May 8, 2008 at 3:11 PM, Marco Pesenti Gritti <mpgritti at> wrote:
> On Thu, May 8, 2008 at 8:43 PM, C. Scott Ananian <cscott at> wrote:
>  >  Again, in the olpcfs design we provide a vfat-like metadata structure
>  >  (mounted via FUSE) so that the filesystem on the USB key appears to
>  >  the journal code just like the flash does.  No FUSE is necessary to
>  >  see the files on the Windows box, although if you want to see all the
>  >  metadata then you need some tool.  If you're transferring the file to
>  >  another XO, then the metadata comes along with you.
>  These are all very good points in favor of olpcfs to me.
>  Personally I'm pretty much sold on the design. And I'm all for
>  experimenting with it on a branch (try to port journal and a few
>  activities), even if it's not a priority for August. Are you aware of
>  any showstopper in this regard? Feature wise it seem to be pretty much
>  there already.

The current implementation of indexes is incomplete, and there are
some design questions regarding how search results for certain key
types ought to be presented using the POSIX API.  These are not
showstoppers, but I/we should finish the implementation before Journal
search would be expected to work. I also haven't implement version
tagging or version gc, but these wouldn't be required to start playing
with things.  There are some journal integration questions, for
example w.r.t. grouping objects by action -- if a number of files have
'action_id' set to (say) 1, is there a file named '1' with mime-type
'text/sugar-action' somewhere with more details about the action?
That sort of thing is best figured out by actually hacking up some
code and figuring out what extra information needs to be stored.

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