From f30179d62e239521290690ac0688da8648ddebc6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A9ter=20Szil=C3=A1gyi?= <peterke@gmail.com>
Date: Wed, 6 Sep 2017 15:02:44 +0300
Subject: [PATCH] eth: disable fast sync after pivot is committed

---
 eth/downloader/downloader.go |  3 +--
 eth/sync.go                  | 20 +++++++++++---------
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/eth/downloader/downloader.go b/eth/downloader/downloader.go
index 6ac58140a3..f2dbf0f88a 100644
--- a/eth/downloader/downloader.go
+++ b/eth/downloader/downloader.go
@@ -1170,7 +1170,7 @@ func (d *Downloader) processHeaders(origin uint64, td *big.Int) error {
 
 			// If we're already past the pivot point, this could be an attack, thread carefully
 			if rollback[len(rollback)-1].Number.Uint64() > pivot {
-				// If we didn't ever fail, lock in te pivot header (must! not! change!)
+				// If we didn't ever fail, lock in the pivot header (must! not! change!)
 				if atomic.LoadUint32(&d.fsPivotFails) == 0 {
 					for _, header := range rollback {
 						if header.Number.Uint64() == pivot {
@@ -1392,7 +1392,6 @@ func (d *Downloader) processFastSyncContent(latest *types.Header) error {
 			stateSync.Cancel()
 			if err := d.commitPivotBlock(P); err != nil {
 				return err
-
 			}
 		}
 		if err := d.importBlockResults(afterP); err != nil {
diff --git a/eth/sync.go b/eth/sync.go
index 7442f912c7..a8ae646170 100644
--- a/eth/sync.go
+++ b/eth/sync.go
@@ -188,7 +188,17 @@ func (pm *ProtocolManager) synchronise(peer *peer) {
 		atomic.StoreUint32(&pm.fastSync, 1)
 		mode = downloader.FastSync
 	}
-	if err := pm.downloader.Synchronise(peer.id, pHead, pTd, mode); err != nil {
+	// Run the sync cycle, and disable fast sync if we've went past the pivot block
+	err := pm.downloader.Synchronise(peer.id, pHead, pTd, mode)
+
+	if atomic.LoadUint32(&pm.fastSync) == 1 {
+		// Disable fast sync if we indeed have something in our chain
+		if pm.blockchain.CurrentBlock().NumberU64() > 0 {
+			log.Info("Fast sync complete, auto disabling")
+			atomic.StoreUint32(&pm.fastSync, 0)
+		}
+	}
+	if err != nil {
 		return
 	}
 	atomic.StoreUint32(&pm.acceptTxs, 1) // Mark initial sync done
@@ -201,12 +211,4 @@ func (pm *ProtocolManager) synchronise(peer *peer) {
 		// more reliably update peers or the local TD state.
 		go pm.BroadcastBlock(head, false)
 	}
-	// If fast sync was enabled, and we synced up, disable it
-	if atomic.LoadUint32(&pm.fastSync) == 1 {
-		// Disable fast sync if we indeed have something in our chain
-		if pm.blockchain.CurrentBlock().NumberU64() > 0 {
-			log.Info("Fast sync complete, auto disabling")
-			atomic.StoreUint32(&pm.fastSync, 0)
-		}
-	}
 }