libn/d/o/ovmanager: assign vxlans using bitmap pkg

The idm package wraps bitseq.Handle to provide an offset and
synchronization. bitseq.Handle wraps bitmap.Bitmap to provide
persistence in a datastore. As no datastore is passed and the offset is
zero, the idm.Idm instance is nothing more than a concurrency-safe
wrapper around a bitmap.Bitmap with differently-named methods. Switch
over to using bitmap.Bitmap directly, using the ovmanager driver's mutex
for concurrency control.

Hold the driver mutex for the entire duration that VXLANs are being
assigned to the new network. This makes allocating VXLANs for a network
an atomic operation.

Signed-off-by: Cory Snider <csnider@mirantis.com>

libnetwork/drivers/overlay/ovmanager/ovmanager.go

@@ -9,10 +9,10 @@ import (
 	"sync"
 
 	"github.com/containerd/containerd/log"
+	"github.com/docker/docker/libnetwork/bitmap"
 	"github.com/docker/docker/libnetwork/datastore"
 	"github.com/docker/docker/libnetwork/discoverapi"
 	"github.com/docker/docker/libnetwork/driverapi"
-	"github.com/docker/docker/libnetwork/idm"
 	"github.com/docker/docker/libnetwork/netlabel"
 	"github.com/docker/docker/libnetwork/types"
 )
@@ -31,7 +31,7 @@ type networkTable map[string]*network
 type driver struct {
 	mu       sync.Mutex
 	networks networkTable
-	vxlanIdm *idm.Idm
+	vxlanIdm *bitmap.Bitmap
 }
 
 type subnet struct {
@@ -55,22 +55,19 @@ func Init(dc driverapi.DriverCallback, _ map[string]interface{}) error {
 
 // Register registers a new instance of the overlay driver.
 func Register(r driverapi.Registerer, _ map[string]interface{}) error {
-	var err error
-	d := &driver{
-		networks: networkTable{},
-	}
-
-	d.vxlanIdm, err = idm.New(nil, "vxlan-id", 0, vxlanIDEnd)
-	if err != nil {
-		return fmt.Errorf("failed to initialize vxlan id manager: %v", err)
-	}
-
-	return r.RegisterDriver(networkType, d, driverapi.Capability{
+	return r.RegisterDriver(networkType, newDriver(), driverapi.Capability{
 		DataScope:         datastore.GlobalScope,
 		ConnectivityScope: datastore.GlobalScope,
 	})
 }
 
+func newDriver() *driver {
+	return &driver{
+		networks: networkTable{},
+		vxlanIdm: bitmap.New(vxlanIDEnd + 1), // The full range of valid vxlan IDs: [0, 2^24).
+	}
+}
+
 func (d *driver) NetworkAllocate(id string, option map[string]string, ipV4Data, ipV6Data []driverapi.IPAMData) (map[string]string, error) {
 	if id == "" {
 		return nil, fmt.Errorf("invalid network id for overlay network")
@@ -105,6 +102,8 @@ func (d *driver) NetworkAllocate(id string, option map[string]string, ipV4Data,
 		}
 	}
 
+	d.mu.Lock()
+	defer d.mu.Unlock()
 	for i, ipd := range ipV4Data {
 		s := &subnet{
 			subnetIP: ipd.Pool,
@@ -113,7 +112,7 @@ func (d *driver) NetworkAllocate(id string, option map[string]string, ipV4Data,
 
 		if len(vxlanIDList) > i { // The VNI for this subnet was specified in the network options.
 			s.vni = vxlanIDList[i]
-			err := d.vxlanIdm.GetSpecificID(uint64(s.vni)) // Mark VNI as in-use.
+			err := d.vxlanIdm.Set(uint64(s.vni)) // Mark VNI as in-use.
 			if err != nil {
 				// The VNI is already in use by another subnet/network.
 				n.releaseVxlanID()
@@ -121,7 +120,7 @@ func (d *driver) NetworkAllocate(id string, option map[string]string, ipV4Data,
 			}
 		} else {
 			// Allocate an available VNI for the subnet, outside the range of 802.1Q VLAN IDs.
-			vni, err := d.vxlanIdm.GetIDInRange(vxlanIDStart, vxlanIDEnd, true)
+			vni, err := d.vxlanIdm.SetAnyInRange(vxlanIDStart, vxlanIDEnd, true)
 			if err != nil {
 				n.releaseVxlanID()
 				return nil, fmt.Errorf("could not obtain vxlan id for pool %s: %v", s.subnetIP, err)
@@ -138,8 +137,6 @@ func (d *driver) NetworkAllocate(id string, option map[string]string, ipV4Data,
 	}
 	opts[netlabel.OverlayVxlanIDList] = val
 
-	d.mu.Lock()
-	defer d.mu.Unlock()
 	if _, ok := d.networks[id]; ok {
 		n.releaseVxlanID()
 		return nil, fmt.Errorf("network %s already exists", id)
@@ -172,7 +169,7 @@ func (d *driver) NetworkFree(id string) error {
 
 func (n *network) releaseVxlanID() {
 	for _, s := range n.subnets {
-		n.driver.vxlanIdm.Release(uint64(s.vni))
+		n.driver.vxlanIdm.Unset(uint64(s.vni))
 		s.vni = 0
 	}
 }

libnetwork/drivers/overlay/ovmanager/ovmanager_test.go

@@ -7,25 +7,12 @@ import (
 	"testing"
 
 	"github.com/docker/docker/libnetwork/driverapi"
-	"github.com/docker/docker/libnetwork/idm"
 	"github.com/docker/docker/libnetwork/netlabel"
 	"github.com/docker/docker/libnetwork/types"
 	"gotest.tools/v3/assert"
 	is "gotest.tools/v3/assert/cmp"
 )
 
-func newDriver(t *testing.T) *driver {
-	d := &driver{
-		networks: networkTable{},
-	}
-
-	vxlanIdm, err := idm.New(nil, "vxlan-id", vxlanIDStart, vxlanIDEnd)
-	assert.NilError(t, err)
-
-	d.vxlanIdm = vxlanIdm
-	return d
-}
-
 func parseCIDR(t *testing.T, ipnet string) *net.IPNet {
 	subnet, err := types.ParseCIDR(ipnet)
 	assert.NilError(t, err)
@@ -33,7 +20,7 @@ func parseCIDR(t *testing.T, ipnet string) *net.IPNet {
 }
 
 func TestNetworkAllocateFree(t *testing.T) {
-	d := newDriver(t)
+	d := newDriver()
 
 	ipamData := []driverapi.IPAMData{
 		{
@@ -56,7 +43,7 @@ func TestNetworkAllocateFree(t *testing.T) {
 }
 
 func TestNetworkAllocateUserDefinedVNIs(t *testing.T) {
-	d := newDriver(t)
+	d := newDriver()
 
 	ipamData := []driverapi.IPAMData{
 		{