core/txpool: add blobTxForPool migration in limbo (#35209)

This PR adds blobTxForPool migration support in limbo. Previously, there
was no conversion path from limbo entries containing types.Transaction.
Now that we have the new blobTxForPool type, this PR adds migration
logic between both types. New test code (limbo_test.go) to test this
conversion is added.

---------

Co-authored-by: Felix Lange <fjl@twurst.com>

core/txpool/blobpool/limbo.go

@@ -65,11 +65,18 @@ func newLimbo(config *params.ChainConfig, datadir string) (*limbo, error) {
 	}
 
 	// Index all limboed blobs on disk and delete anything unprocessable
-	var fails []uint64
+	var (
+		fails   []uint64
+		convert []uint64
+	)
 	index := func(id uint64, size uint32, data []byte) {
-		if l.parseBlob(id, data) != nil {
+		err := l.parseBlob(id, data)
+		if err != nil {
 			fails = append(fails, id)
 		}
+		if errors.Is(err, errLegacyTx) {
+			convert = append(convert, id)
+		}
 	}
 	store, err := billy.Open(billy.Options{Path: datadir, Repair: true}, slotter, index)
 	if err != nil {
@@ -77,6 +84,39 @@ func newLimbo(config *params.ChainConfig, datadir string) (*limbo, error) {
 	}
 	l.store = store
 
+	// Migrate legacy limbo entries to blobTxForPool. Note all ids in `converted` are also
+	// in `fails`, and the converted entries will be deleted by the loop that handles
+	// `fails`.
+	for _, id := range convert {
+		data, err := l.store.Get(id)
+		if err != nil {
+			continue
+		}
+		var legacy struct {
+			TxHash common.Hash
+			Block  uint64
+			Tx     *types.Transaction
+		}
+		if err := rlp.DecodeBytes(data, &legacy); err != nil {
+			continue
+		}
+		blob, err := rlp.EncodeToBytes(&limboBlob{
+			TxHash: legacy.TxHash,
+			Block:  legacy.Block,
+			Ptx:    newBlobTxForPool(legacy.Tx),
+		})
+		if err != nil {
+			continue
+		}
+		newID, err := l.store.Put(blob)
+		if err != nil {
+			continue
+		}
+		if err := l.parseBlob(newID, blob); err != nil {
+			fails = append(fails, newID)
+		}
+	}
+
 	if len(fails) > 0 {
 		log.Warn("Dropping invalidated limboed blobs", "ids", fails)
 		for _, id := range fails {
@@ -99,6 +139,10 @@ func (l *limbo) Close() error {
 func (l *limbo) parseBlob(id uint64, data []byte) error {
 	item := new(limboBlob)
 	if err := rlp.DecodeBytes(data, item); err != nil {
+		// This entry may have been stored with the legacy limboBlob type
+		if isLegacy(data) {
+			return errLegacyTx
+		}
 		// This path is impossible unless the disk data representation changes
 		// across restarts. For that ever improbable case, recover gracefully
 		// by ignoring this data entry.
@@ -122,6 +166,17 @@ func (l *limbo) parseBlob(id uint64, data []byte) error {
 	return nil
 }
 
+// isLegacy reports whether data is a limbo entry with the legacy limboBlob
+// {TxHash, Block, Tx *types.Transaction} type.
+func isLegacy(data []byte) bool {
+	elems, err := rlp.SplitListValues(data)
+	if err != nil || len(elems) < 3 {
+		return false
+	}
+	kind, content, _, err := rlp.Split(elems[2])
+	return err == nil && kind == rlp.String && len(content) > 1 && content[0] == types.BlobTxType
+}
+
 // finalize evicts all blobs belonging to a recently finalized block or older.
 func (l *limbo) finalize(final *types.Header) {
 	// Just in case there's no final block yet (network not yet merged, weird

core/txpool/blobpool/limbo_test.go

@@ -0,0 +1,72 @@
+// Copyright 2026 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package blobpool
+
+import (
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/holiman/billy"
+)
+
+// TestLimboLegacyMigration checks whether limbo entries in the legacy limboBlob type
+// are migrated to the blobTxForPool layout on startup instead of being dropped.
+func TestLimboLegacyMigration(t *testing.T) {
+	key, _ := crypto.GenerateKey()
+	tx := makeMultiBlobTx(0, 10, 100, 100, 2, 0, key)
+
+	dir := t.TempDir()
+
+	// Write a single entry using the legacy on-disk layout.
+	store, err := billy.Open(billy.Options{Path: dir}, newSlotterEIP7594(params.BlobTxMaxBlobs), nil)
+	if err != nil {
+		t.Fatalf("failed to open store: %v", err)
+	}
+	legacy := struct {
+		TxHash common.Hash
+		Block  uint64
+		Tx     *types.Transaction
+	}{tx.Hash(), 42, tx}
+	data, err := rlp.EncodeToBytes(&legacy)
+	if err != nil {
+		t.Fatalf("failed to encode legacy entry: %v", err)
+	}
+	if _, err := store.Put(data); err != nil {
+		t.Fatalf("failed to store legacy entry: %v", err)
+	}
+	store.Close()
+
+	// Open the limbo, which should migrate the legacy entry.
+	l, err := newLimbo(new(params.ChainConfig), dir)
+	if err != nil {
+		t.Fatalf("failed to open limbo: %v", err)
+	}
+	defer l.Close()
+
+	// The migrated transaction must be tracked and reconstruct the original.
+	ptx, err := l.pull(tx.Hash())
+	if err != nil {
+		t.Fatalf("failed to pull migrated tx: %v", err)
+	}
+	if got := ptx.ToTx().Hash(); got != tx.Hash() {
+		t.Fatalf("migrated tx hash mismatch: got %x, want %x", got, tx.Hash())
+	}
+}