fix race condition between list and remove volume

This was done by making List not populate the cache.

fixes #21403

Signed-off-by: Viktor Stanchev <me@viktorstanchev.com>

volume/store/store.go

@@ -127,9 +127,8 @@ func (s *VolumeStore) List() ([]volume.Volume, []string, error) {
 
 		s.locks.Lock(name)
 		storedV, exists := s.getNamed(name)
-		if !exists {
-			s.setNamed(v, "")
-		}
+		// Note: it's not safe to populate the cache here because the volume may have been
+		// deleted before we acquire a lock on its name
 		if exists && storedV.DriverName() != v.DriverName() {
 			logrus.Warnf("Volume name %s already exists for driver %s, not including volume returned by %s", v.Name(), storedV.DriverName(), v.DriverName())
 			s.locks.Unlock(v.Name())

volume/testutils/testutils.go

@@ -26,19 +26,20 @@ func (NoopVolume) Unmount() error { return nil }
 
 // FakeVolume is a fake volume with a random name
 type FakeVolume struct {
-	name string
+	name       string
+	driverName string
 }
 
 // NewFakeVolume creates a new fake volume for testing
-func NewFakeVolume(name string) volume.Volume {
-	return FakeVolume{name: name}
+func NewFakeVolume(name string, driverName string) volume.Volume {
+	return FakeVolume{name: name, driverName: driverName}
 }
 
 // Name is the name of the volume
 func (f FakeVolume) Name() string { return f.name }
 
 // DriverName is the name of the driver
-func (FakeVolume) DriverName() string { return "fake" }
+func (f FakeVolume) DriverName() string { return f.driverName }
 
 // Path is the filesystem path to the volume
 func (FakeVolume) Path() string { return "fake" }
@@ -72,7 +73,7 @@ func (d *FakeDriver) Create(name string, opts map[string]string) (volume.Volume,
 	if opts != nil && opts["error"] != "" {
 		return nil, fmt.Errorf(opts["error"])
 	}
-	v := NewFakeVolume(name)
+	v := NewFakeVolume(name, d.name)
 	d.vols[name] = v
 	return v, nil
 }