disable backfill if the checkpoint sync origin slot is in fulu (#15987)

Co-authored-by: Kasey Kirkham <kasey@users.noreply.github.com>

beacon-chain/sync/backfill/BUILD.bazel

@@ -81,6 +81,7 @@ go_test(
         "//runtime/interop:go_default_library",
         "//testing/require:go_default_library",
         "//testing/util:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
         "@com_github_libp2p_go_libp2p//core/peer:go_default_library",
         "@com_github_pkg_errors//:go_default_library",

beacon-chain/sync/backfill/service.go

@@ -249,6 +249,18 @@ func (s *Service) scheduleTodos() {
 	}
 }
 
+// fuluOrigin checks whether the origin block (ie the checkpoint sync block from which backfill
+// syncs backwards) is in an unsupported fork, enabling the backfill service to shut down rather than
+// run with buggy behavior.
+// This will be removed once DataColumnSidecar support is released.
+func fuluOrigin(cfg *params.BeaconChainConfig, status *dbval.BackfillStatus) bool {
+	originEpoch := slots.ToEpoch(primitives.Slot(status.OriginSlot))
+	if originEpoch < cfg.FuluForkEpoch {
+		return false
+	}
+	return true
+}
+
 // Start begins the runloop of backfill.Service in the current goroutine.
 func (s *Service) Start() {
 	if !s.enabled {
@@ -281,6 +293,12 @@ func (s *Service) Start() {
 		return
 	}
 	status := s.store.status()
+	if fuluOrigin(params.BeaconConfig(), status) {
+		log.WithField("originSlot", s.store.status().OriginSlot).
+			Warn("backfill disabled; DataColumnSidecar currently unsupported, for updates follow https://github.com/OffchainLabs/prysm/issues/15982")
+		s.markComplete()
+		return
+	}
 	// Exit early if there aren't going to be any batches to backfill.
 	if primitives.Slot(status.LowSlot) <= s.ms(s.clock.CurrentSlot()) {
 		log.WithField("minimumRequiredSlot", s.ms(s.clock.CurrentSlot())).
@@ -289,6 +307,7 @@ func (s *Service) Start() {
 		s.markComplete()
 		return
 	}
+
 	s.verifier, s.ctxMap, err = s.initVerifier(ctx)
 	if err != nil {
 		log.WithError(err).Error("Unable to initialize backfill verifier")

beacon-chain/sync/backfill/service_test.go

@@ -15,6 +15,7 @@ import (
 	"github.com/OffchainLabs/prysm/v6/proto/dbval"
 	"github.com/OffchainLabs/prysm/v6/testing/require"
 	"github.com/OffchainLabs/prysm/v6/testing/util"
+	"github.com/OffchainLabs/prysm/v6/time/slots"
 )
 
 type mockMinimumSlotter struct {
@@ -131,3 +132,41 @@ func TestBackfillMinSlotDefault(t *testing.T) {
 		require.Equal(t, specMin, s.ms(current))
 	})
 }
+
+func TestFuluOrigin(t *testing.T) {
+	cfg := params.BeaconConfig()
+	fuluEpoch := cfg.FuluForkEpoch
+	fuluSlot, err := slots.EpochStart(fuluEpoch)
+	require.NoError(t, err)
+	cases := []struct {
+		name   string
+		origin primitives.Slot
+		isFulu bool
+	}{
+		{
+			name:   "before fulu",
+			origin: fuluSlot - 1,
+			isFulu: false,
+		},
+		{
+			name:   "at fulu",
+			origin: fuluSlot,
+			isFulu: true,
+		},
+		{
+			name:   "after fulu",
+			origin: fuluSlot + 1,
+			isFulu: true,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			status := &dbval.BackfillStatus{
+				OriginSlot: uint64(tc.origin),
+			}
+			result := fuluOrigin(cfg, status)
+			require.Equal(t, tc.isFulu, result)
+		})
+	}
+}

changelog/kasey_disable-backfill-if-fulu.md

@@ -0,0 +1,2 @@
+### Fixed
+- Backfill disabled if checkpoint sync origin is after fulu fork due to lack of DataColumnSidecar support in backfill. To track the availability of fulu-compatible backfill please watch https://github.com/OffchainLabs/prysm/issues/15982