rbd: ignore zero-overlap parent
authorAlex Elder <elder@inktank.com>
Mon, 6 May 2013 22:40:33 +0000 (17:40 -0500)
committerAlex Elder <elder@inktank.com>
Mon, 13 May 2013 19:12:41 +0000 (14:12 -0500)
commit70cf49cfc7a4d1eb4aeea6cd128b88230be9d0b1
treeecc02aa809064607d872cf4c433cf0489b2f5604
parentb91f09f17b2a302f07022e2f766969e2536d71b3
rbd: ignore zero-overlap parent

An rbd clone image that has an overlap with its parent of 0 is
effectively not a layered image at all.  Detect this case and treat
such an image as non-layered.  Issue a warning to be sure the user
knows what's going on.

This resolves:
    http://tracker.ceph.com/issues/5028

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
drivers/block/rbd.c