From a18f62bbe7e5e477fd891849b44ec5a25d8988d2 Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Mon, 23 Dec 2019 18:06:13 -0800
Subject: [PATCH] only copy required shards

---
 weed/shell/command_ec_decode.go               | 2 +-
 weed/storage/erasure_coding/ec_volume_info.go | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/weed/shell/command_ec_decode.go b/weed/shell/command_ec_decode.go
index 5ea359b2b..4ec1a7e8f 100644
--- a/weed/shell/command_ec_decode.go
+++ b/weed/shell/command_ec_decode.go
@@ -164,7 +164,7 @@ func collectEcShards(ctx context.Context, commandEnv *CommandEnv, nodeToEcIndexB
 			continue
 		}
 
-		needToCopyEcIndexBits := ecIndexBits.Minus(exisitngEcIndexBits)
+		needToCopyEcIndexBits := ecIndexBits.Minus(exisitngEcIndexBits).MinusParityShards()
 		if needToCopyEcIndexBits.ShardIdCount() == 0 {
 			continue
 		}
diff --git a/weed/storage/erasure_coding/ec_volume_info.go b/weed/storage/erasure_coding/ec_volume_info.go
index bb1fd0bf8..8ff65bb0f 100644
--- a/weed/storage/erasure_coding/ec_volume_info.go
+++ b/weed/storage/erasure_coding/ec_volume_info.go
@@ -104,3 +104,10 @@ func (b ShardBits) Minus(other ShardBits) ShardBits {
 func (b ShardBits) Plus(other ShardBits) ShardBits {
 	return b | other
 }
+
+func (b ShardBits) MinusParityShards() ShardBits {
+	for i := DataShardsCount; i < TotalShardsCount; i++ {
+		b = b.RemoveShardId(ShardId(i))
+	}
+	return b
+}