Merge remote-tracking branch 'bonzini/nbd-next' into staging

# By Stefan Hajnoczi
# Via Paolo Bonzini
* bonzini/nbd-next:
  nbd: set TCP_NODELAY
  nbd: use TCP_CORK in nbd_co_send_request()
  nbd: unlock mutex in nbd_co_send_request() error path

Message-id: 1366381830-11267-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>