Ceph » rbd

Work on this really started in November 2012.

In October there were a number of cleanup tasks we agreed
should get done first, and the the first "real" task was
to implement fetching information about an image's parent
if present. That work was completed (but from what I can
tell had no issue assigned to it).

After several false starts in November attempting to
implement the read path (redirecting read requests with
ENOENT responses to the parent image) I found the existing
code and data structures would not very easily support
this different source of I/O requests to OSD's. After
some discussion, we agreed that doing a sort of
reimplementation was a reasonable course forward.

That work was nearly complete in November, but numerous
other things have preempted further progress. Specifically,
I have been working on expanding xfstests coverage over rbd,
setting up, running, and recovering from the failures hit
when network connection failures are in injected.

I'll return to this task as soon as possible. I had hoped
to have this completed in November, now I'm hopeful for
the end of December.