Don't update pvc.status.capacity if pvc is already Bound

pkg/controller/volume/persistentvolume/pv_controller.go

@@ -625,6 +625,10 @@ func (ctrl *PersistentVolumeController) updateClaimStatus(claim *v1.PersistentVo
 			dirty = true
 		}
 
+		// Update Capacity if the claim is becoming Bound, not if it was already.
+		// A discrepancy can be intentional to mean that the PVC filesystem size
+		// doesn't match the PV block device size, so don't clobber it
+		if claim.Status.Phase != phase {
 			volumeCap, ok := volume.Spec.Capacity[v1.ResourceStorage]
 			if !ok {
 				return nil, fmt.Errorf("PersistentVolume %q is without a storage capacity", volume.Name)
@@ -635,6 +639,7 @@ func (ctrl *PersistentVolumeController) updateClaimStatus(claim *v1.PersistentVo
 				dirty = true
 			}
 		}
+	}
 
 	if !dirty {
 		// Nothing to do.