controller: Allow DR volume activation if the latest backup is empty

Longhorn 7997

Signed-off-by: Shuo Wu <shuo.wu@suse.com>

controller/volume_controller.go

@@ -3120,15 +3120,19 @@ func (c *VolumeController) checkAndFinishVolumeRestore(v *longhorn.Volume, e *lo
 			return err
 		}
 		if bv != nil {
-			if !bv.Status.LastSyncedAt.IsZero() &&
-				bv.Spec.SyncRequestedAt.After(bv.Status.LastSyncedAt.Time) {
-				log.Infof("Restore/DR volume needs to wait for backup volume %s update", bvName)
-				return nil
-			}
-			if bv.Status.LastBackupName != e.Status.LastRestoredBackup {
-				log.Infof("Restore/DR volume needs to restore the latest backup %s, and the current restored backup is %s", bv.Status.LastBackupName, e.Status.LastRestoredBackup)
-				c.enqueueVolume(v)
-				return nil
+			if bv.Status.LastBackupName != "" {
+				// If the backup CR does not exist, the Longhorn system may be still syncing up the info with the remote backup target.
+				// If the backup is removed already, the backup volume should receive the notification and update bv.Status.LastBackupName.
+				// Hence we cannot continue the activation when the backup get call returns error IsNotFound.
+				b, err := c.ds.GetBackup(bv.Status.LastBackupName)
+				if err != nil {
+					return err
+				}
+				if b.Name != e.Status.LastRestoredBackup {
+					log.Infof("Restore/DR volume needs to restore the latest backup %s, and the current restored backup is %s", b.Name, e.Status.LastRestoredBackup)
+					c.enqueueVolume(v)
+					return nil
+				}
 			}
 		}
 	}