---
features:
  - |
    A new quota driver is added: ``DbQuotaNoLockDriver``. This driver, unlike
    ``DbQuotaDriver``, does not create a unique lock per (resource,
    project_id). That may lead to a database deadlock state if the number of
    server requests exceeds the number of resolved resource creations, as
    described in `LP#1926787 <https://bugs.launchpad.net/neutron/+bug/1926787>`_.
    This driver relays on the database transactionality isolation and counts
    the number of used and reserved resources and, if available, creates the
    new resource reservations in one single database transaction.
