A small bitmap-chunksize hurts performance without helping resync speed much - particularly on internal bitmaps. So set the default to at least 64Meg. Signed-off-by: NeilBrown <neilb@suse.de>
A number of odd bugs here, but now we have a regression test as well.
Previously it onl worked when one missing device. Also split the "force" update_super method into two and it is really serving two functions.