Fix issue 64119.

pkg/volume/rbd/rbd_test.go

@@ -329,6 +329,7 @@ func TestPlugin(t *testing.T) {
 					RBDPool:      "pool1",
 					RBDImage:     "image1",
 					FSType:       "ext4",
+					ReadOnly:	  true,
 				},
 			},
 		}),

pkg/volume/rbd/rbd_util.go

@@ -399,6 +399,10 @@ func (util *RBDUtil) AttachDisk(b rbdMounter) (string, error) {
 					break
 				}
 			}
+		} else {
+			// ReadOnly rbd volume should not check rbd status of being used to
+			// support mounted as read-only by multiple consumers simultaneously.
+			needValidUsed = !b.rbd.ReadOnly
 		}
 		err := wait.ExponentialBackoff(backoff, func() (bool, error) {
 			used, rbdOutput, err := util.rbdStatus(&b)