Big One.  Flushing/rereading partition tables is taken from
->revalidate() for partitioned devices; now it's done in the
caller (check_disk_change()).  BLKRRPART handling also moved
out of drivers - they are still allowed to override it (DAC960
and i2o are the only remaining ones), but common case is handled
in fs/block_dev.c.

Note: we are still only shifting stuff - bd_sem deadlocks in
check_disk_change() are still there.  However, now we have all
relevant code outside of drivers and that will allow to fix the
thing (see next patches).