The old code was
		sector_div(stride, fc);
the new code was
		sector_dir(size, conf->near_copies);
'size' is right (the stride various wasn't really needed), but
'fc' means 'far_copies', and that is an important difference.
Signed-off-by: NeilBrown <neilb@suse.de>
        if (conf->far_offset)
                conf->stride = 1 << conf->chunk_shift;
        else {
-               sector_div(size, conf->near_copies);
+               sector_div(size, conf->far_copies);
                conf->stride = size << conf->chunk_shift;
        }
 }