Add Done() method to ReadResult, so splicing code manage resources.

fuse/api.go

@@ -195,6 +195,9 @@ type ReadResult interface {
 
 	// Size returns how many bytes this return value takes at most.
 	Size() int
+
+	// Done() is called after sending the data to the kernel.
+	Done()
 }
 
 // Wrap a File return in this to set FUSE flags.  Also used internally

fuse/mountstate.go

@@ -382,6 +382,7 @@ func (ms *MountState) write(req *request) Status {
 
 	if req.fdData != nil {
 		if err := ms.trySplice(header, req, req.fdData); err == nil {
+			req.readResult.Done()
 			return OK
 		} else {
 			log.Println("trySplice:", err)
@@ -393,6 +394,9 @@ func (ms *MountState) write(req *request) Status {
 	}
 
 	_, err := Writev(int(ms.mountFile.Fd()), [][]byte{header, req.flatData})
+	if req.readResult != nil {
+		req.readResult.Done()
+	}
 	return ToStatus(err)
 }
 

fuse/opcode.go

@@ -279,13 +279,12 @@ func doRead(state *MountState, req *request) {
 	in := (*raw.ReadIn)(req.inData)
 	buf := state.AllocOut(req, in.Size)
 
-	var r ReadResult
-	r, req.status = state.fileSystem.Read(&req.context, in, buf)
-	if fd, ok := r.(*ReadResultFd); ok {
+	req.readResult, req.status = state.fileSystem.Read(&req.context, in, buf)
+	if fd, ok := req.readResult.(*ReadResultFd); ok {
 		req.fdData = fd
 		req.flatData = nil
-	} else if r != nil {
-		req.flatData, req.status = r.Bytes(buf)
+	} else if req.readResult != nil {
+		req.flatData, req.status = req.readResult.Bytes(buf)
 	}
 }
 

fuse/read.go

@@ -15,6 +15,9 @@ func (r *ReadResultData) Size() int {
 	return len(r.Data)
 }
 
+func (r *ReadResultData) Done() {
+}
+
 func (r *ReadResultData) Bytes(buf []byte) ([]byte, Status) {
 	return r.Data, OK
 }
@@ -55,3 +58,6 @@ func (r *ReadResultFd) Bytes(buf []byte) ([]byte, Status) {
 func (r *ReadResultFd) Size() int {
 	return r.Sz
 }
+
+func (r *ReadResultFd) Done() {
+}

fuse/request.go

@@ -29,6 +29,10 @@ type request struct {
 	flatData []byte
 	fdData   *ReadResultFd
 
+	// In case of read, keep read result here so we can call
+	// Done() on it.
+	readResult ReadResult
+
 	// Start timestamp for timing info.
 	startNs    int64
 	preWriteNs int64
@@ -66,6 +70,7 @@ func (r *request) clear() {
 	r.preWriteNs = 0
 	r.startNs = 0
 	r.handler = nil
+	r.readResult = nil
 }
 
 func (r *request) InputDebug() string {