Return 0 rather than BUG() if __rdev_sectors() fails and catch invalid
rdev size in the constructor.
Reported-by: Hannes Reinecke <hare@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>