We need to check items in a node to make sure that we're reading
a valid one, otherwise we could get various crashes while processing
delayed_refs.
Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>