Merge branch 'rhashtable-bitlocks'

NeilBrown says:

====================
Convert rhashtable to use bitlocks

This series converts rhashtable to use a per-bucket bitlock
rather than a separate array of spinlocks.
This:
  reduces memory usage
  results in slightly fewer memory accesses
  slightly improves parallelism
  makes a configuration option unnecessary

The main change from previous version is to use a distinct type for
the pointer in the bucket which has a bit-lock in it.  This
helped find two places where rht_ptr() was missed, one
in  rhashtable_free_and_destroy() in print_ht in the test code.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>