gfs2_convert: exits with success without doing anything
    
    A recent gfs2-utils patch  added a sanity check (gfs2_check_range())
    to the codepath of gfs1_ri_update() that's used by gfs2_convert.
    This new check requires the value of sbp->fssize to be initialized
    to a valid non-zero size, which gfs2_convert does not do. The check
    fails and gfs2_convert bails out. This patch initializes sbp->fssize
    to the device size and the check is successful and gfs2_convert runs
    to completion as expected.
    
    Resolves: rhbz#688734
    Signed-off-by: Abhi Das <adas@redhat.com>