fix: if configured pivot <= origin, start at origin. fix comment

Author: wgr523

consensus/XDPoS/engines/engine_v2/epochSwitch.go

@@ -11,7 +11,7 @@ import (
 )
 
 // Given header and its hash, get epoch switch info from the epoch switch block of that epoch,
-// headers is allow to be nil. headers contain header (as last item) and it parents if any, which can be used to avoid
+// headers is allow to be nil. if not nil, headers contain header (as last item) and its parents if any, which can be used to avoid
 // fetching from the database during recursive lookups (useful during VerifyHeaders).
 func (x *XDPoS_v2) getEpochSwitchInfo(chain consensus.ChainReader, headers []*types.Header, hash common.Hash) (*types.EpochSwitchInfo, error) {
 	epochSwitchInfo, ok := x.epochSwitches.Get(hash)

eth/downloader/downloader.go

@@ -511,11 +511,8 @@ func (d *Downloader) syncWithPeer(p *peerConnection, hash common.Hash, td *big.I
 	if mode == FastSync {
 		if d.pivotNumber != 0 {
 			// Use configured pivot block
-			log.Info("Using configured pivot block", "number", d.pivotNumber)
+			log.Info("Using configured pivot block", "number", d.pivotNumber, "origin", origin)
 			pivot = d.pivotNumber
-			if pivot <= origin {
-				origin = pivot - 1
-			}
 		} else if height <= uint64(fsMinFullBlocks) {
 			origin = 0
 		} else {
@@ -529,6 +526,9 @@ func (d *Downloader) syncWithPeer(p *peerConnection, hash common.Hash, td *big.I
 	if mode == FastSync && pivot != 0 {
 		d.committed = 0
 	}
+	if mode == FastSync && d.pivotNumber != 0 && pivot <= origin {
+		d.committed = 1
+	}
 	// Initiate the sync using a concurrent header and content retrieval algorithm
 	d.queue.Prepare(origin+1, mode)
 	if d.syncInitHook != nil {