When we're reading a btree block, make sure that what we retrieved
matches the owner and level; and has a plausible number of records.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>