fix ec related bugs

weed/storage/disk_location.go

@@ -223,8 +223,8 @@ func (l *DiskLocation) Close() {
 	l.Unlock()
 
 	l.ecVolumesLock.Lock()
-	for _, shards := range l.ecVolumes {
-		shards.Close()
+	for _, ecVolume := range l.ecVolumes {
+		ecVolume.Close()
 	}
 	l.ecVolumesLock.Unlock()
 

weed/storage/disk_location_ec.go

@@ -87,8 +87,8 @@ func (l *DiskLocation) UnloadEcShard(vid needle.VolumeId, shardId erasure_coding
 	if _, deleted := ecVolume.DeleteEcVolumeShard(shardId); deleted {
 		if len(ecVolume.Shards) == 0 {
 			delete(l.ecVolumes, vid)
+			ecVolume.Close()
 		}
-		ecVolume.Close()
 		return true
 	}
 

weed/storage/erasure_coding/ec_volume.go

@@ -155,7 +155,7 @@ func (ev *EcVolume) LocateEcShardNeedle(n *needle.Needle, version needle.Version
 	// find the needle from ecx file
 	offset, size, err = ev.findNeedleFromEcx(n.Id)
 	if err != nil {
-		return types.Offset{}, 0, nil, err
+		return types.Offset{}, 0, nil, fmt.Errorf("findNeedleFromEcx: %v", err)
 	}
 
 	shard := ev.Shards[0]
@@ -173,7 +173,7 @@ func (ev *EcVolume) findNeedleFromEcx(needleId types.NeedleId) (offset types.Off
 	for l < h {
 		m := (l + h) / 2
 		if _, err := ev.ecxFile.ReadAt(buf, m*types.NeedleMapEntrySize); err != nil {
-			return types.Offset{}, 0, err
+			return types.Offset{}, 0, fmt.Errorf("ecx file %d read at %d: %v", ev.ecxFileSize, m*types.NeedleMapEntrySize, err)
 		}
 		key, offset, size = idx.IdxFileEntry(buf)
 		if key == needleId {

weed/storage/store_ec.go

@@ -118,7 +118,7 @@ func (s *Store) ReadEcShardNeedle(ctx context.Context, vid needle.VolumeId, n *n
 
 			offset, size, intervals, err := localEcVolume.LocateEcShardNeedle(n, version)
 			if err != nil {
-				return 0, err
+				return 0, fmt.Errorf("locate in local ec volume: %v", err)
 			}
 
 			glog.V(4).Infof("read ec volume %d offset %d size %d intervals:%+v", vid, offset.ToAcutalOffset(), size, intervals)