From 245a488c36003764e3550c2c95fa4bef6119e0ea Mon Sep 17 00:00:00 2001
From: Jon Bernard <jobernar@redhat.com>
Date: Thu, 22 Mar 2018 08:09:35 -0700
Subject: [PATCH] RBD: add support for active/active replication

This patch breaks failover_host into the two requisite parts (failover
and failover_completed) to support both single-backend and multiple
backends configured as active/active.

Change-Id: Ie59ba9ad538b2e607dd7ccabc0fbb035a6acf3b0
---
 cinder/tests/unit/volume/drivers/test_rbd.py  |  2 +-
 cinder/volume/drivers/rbd.py                  | 30 ++++++++++++++++---
 ...e-active-replication-b230367912fe4a23.yaml |  5 ++++
 3 files changed, 32 insertions(+), 5 deletions(-)
 create mode 100644 releasenotes/notes/rbd-active-active-replication-b230367912fe4a23.yaml

diff --git a/cinder/tests/unit/volume/drivers/test_rbd.py b/cinder/tests/unit/volume/drivers/test_rbd.py
index 8c63bc019f4..c6e2ee8e7eb 100644
--- a/cinder/tests/unit/volume/drivers/test_rbd.py
+++ b/cinder/tests/unit/volume/drivers/test_rbd.py
@@ -1804,7 +1804,7 @@ class RBDTestCase(test.TestCase):
             [mock.call(mock.ANY, v, remote, False,
                        fields.ReplicationStatus.FAILED_OVER)
              for v in volumes])
-        mock_get_cfg.assert_called_once_with(secondary_id)
+        mock_get_cfg.assert_called_with(secondary_id)
 
     @mock.patch.object(driver.RBDDriver, '_failover_volume', autospec=True)
     def test_failover_host_failback(self, mock_failover_vol):
diff --git a/cinder/volume/drivers/rbd.py b/cinder/volume/drivers/rbd.py
index 4c64976e24b..0d9187af40f 100644
--- a/cinder/volume/drivers/rbd.py
+++ b/cinder/volume/drivers/rbd.py
@@ -200,6 +200,8 @@ class RBDDriver(driver.CloneableImageVD, driver.MigrateVD,
     # ThirdPartySystems wiki page
     CI_WIKI_NAME = "Cinder_Jenkins"
 
+    SUPPORTS_ACTIVE_ACTIVE = True
+
     SYSCONFDIR = '/etc/ceph/'
 
     def __init__(self, active_backend_id=None, *args, **kwargs):
@@ -1185,8 +1187,8 @@ class RBDDriver(driver.CloneableImageVD, driver.MigrateVD,
             secondary_id = candidates.pop()
         return secondary_id, self._get_target_config(secondary_id)
 
-    def failover_host(self, context, volumes, secondary_id=None, groups=None):
-        """Failover to replication target."""
+    def failover(self, context, volumes, secondary_id=None, groups=None):
+        """Failover replicated volumes."""
         LOG.info('RBD driver failover started.')
         if not self._is_replication_enabled:
             raise exception.UnableToFailOver(
@@ -1201,15 +1203,35 @@ class RBDDriver(driver.CloneableImageVD, driver.MigrateVD,
 
         # Try to demote the volumes first
         demotion_results = self._demote_volumes(volumes)
+
         # Do the failover taking into consideration if they have been demoted
         updates = [self._failover_volume(volume, remote, is_demoted,
                                          replication_status)
                    for volume, is_demoted in zip(volumes, demotion_results)]
-        self._active_backend_id = secondary_id
-        self._active_config = remote
+
         LOG.info('RBD driver failover completed.')
         return secondary_id, updates, []
 
+    def failover_completed(self, context, secondary_id=None):
+        """Failover to replication target."""
+        LOG.info('RBD driver failover completion started.')
+        secondary_id, remote = self._get_failover_target_config(secondary_id)
+
+        self._active_backend_id = secondary_id
+        self._active_config = remote
+        LOG.info('RBD driver failover completion completed.')
+
+    def failover_host(self, context, volumes, secondary_id=None, groups=None):
+        """Failover to replication target.
+
+        This function combines calls to failover() and failover_completed() to
+        perform failover when Active/Active is not enabled.
+        """
+        active_backend_id, volume_update_list, group_update_list = (
+            self.failover(context, volumes, secondary_id, groups))
+        self.failover_completed(context, secondary_id)
+        return active_backend_id, volume_update_list, group_update_list
+
     def ensure_export(self, context, volume):
         """Synchronously recreates an export for a logical volume."""
         pass
diff --git a/releasenotes/notes/rbd-active-active-replication-b230367912fe4a23.yaml b/releasenotes/notes/rbd-active-active-replication-b230367912fe4a23.yaml
new file mode 100644
index 00000000000..fa7f236a37f
--- /dev/null
+++ b/releasenotes/notes/rbd-active-active-replication-b230367912fe4a23.yaml
@@ -0,0 +1,5 @@
+---
+features:
+  - Added support for active-active replication to the RBD driver.  This allows
+    users to configure multiple volume backends that are all a member of the
+    same cluster participating in replication.