When a snapshot context update occurs, rbd_update_mapping_size() is
called to set the capacity of the disk to record the updated
size of the image in case it has changed.
There's a bug though. The mapping size is in units of *bytes*. The
code that updates the mapping size field is assigning a value that
has been scaled down to *sectors*.
Fix that. Also, check to see if the size has actually changed, and
don't bother updating things (specifically, calling set_capacity())
if it has not.
This resolves:
http://tracker.ceph.com/issues/4833
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
e28626a08b