Actually inspect canSplice setting.

fuse/mountstate_linux.go

@@ -9,16 +9,19 @@ func (ms *MountState) systemWrite(req *request, header []byte) Status {
 	}
 
 	if req.fdData != nil {
-		if err := ms.trySplice(header, req, req.fdData); err == nil {
-			req.readResult.Done()
-			return OK
-		} else {
+		if ms.canSplice {
+			err := ms.trySplice(header, req, req.fdData)
+			if err == nil {
+				req.readResult.Done()
+				return OK
+			}
 			log.Println("trySplice:", err)
-			sz := req.flatDataSize()
-			buf := ms.AllocOut(req, uint32(sz))
-			req.flatData, req.status = req.fdData.Bytes(buf)
-			header = req.serializeHeader(len(req.flatData))
 		}
+
+		sz := req.flatDataSize()
+		buf := ms.AllocOut(req, uint32(sz))
+		req.flatData, req.status = req.fdData.Bytes(buf)
+		header = req.serializeHeader(len(req.flatData))
 	}
 
 	_, err := Writev(int(ms.mountFile.Fd()), [][]byte{header, req.flatData})

fuse/request.go

@@ -116,7 +116,7 @@ func (r *request) OutputDebug() string {
 		} else {
 			spl := ""
 			if r.fdData != nil {
-				spl = " (splice)"
+				spl = " (fd data)"
 			}
 			flatStr = fmt.Sprintf(" %d bytes data%s\n", r.flatDataSize(), spl)
 		}

splice/splice.go

@@ -32,8 +32,9 @@ func init() {
 	content, err := ioutil.ReadFile("/proc/sys/fs/pipe-max-size")
 	if err != nil {
 		maxPipeSize = DefaultPipeSize
+	} else {
+		fmt.Sscan(string(content), &maxPipeSize)
 	}
-	fmt.Sscan(string(content), &maxPipeSize)
 
 	r, w, err := os.Pipe()
 	if err != nil {