From 630f72f8c577fba9ca11fee7694e0748af03fadf Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Mon, 20 Jan 2020 00:00:08 -0800
Subject: [PATCH] mount: able to trim a file

---
 weed/filesys/file.go | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/weed/filesys/file.go b/weed/filesys/file.go
index 7e562eabc..622ba6f57 100644
--- a/weed/filesys/file.go
+++ b/weed/filesys/file.go
@@ -102,9 +102,18 @@ func (file *File) Setattr(ctx context.Context, req *fuse.SetattrRequest, resp *f
 	if req.Valid.Size() {
 
 		glog.V(3).Infof("%v file setattr set size=%v", file.fullpath(), req.Size)
-		if req.Size == 0 {
+		if req.Size < filer2.TotalSize(file.entry.Chunks) {
 			// fmt.Printf("truncate %v \n", fullPath)
-			file.entry.Chunks = nil
+			var chunks []*filer_pb.FileChunk
+			for _, chunk := range file.entry.Chunks {
+				if uint64(chunk.Offset)+chunk.Size > req.Size {
+					chunk.Size = req.Size - uint64(chunk.Offset)
+				}
+				if chunk.Size > 0 {
+					chunks = append(chunks, chunk)
+				}
+			}
+			file.entry.Chunks = chunks
 			file.entryViewCache = nil
 		}
 		file.entry.Attributes.FileSize = req.Size