Fixed a panic.

fuseops/common_op.go

@@ -34,6 +34,9 @@ type internalOp interface {
 
 	// Create a response message for the kernel, with leading pading for a
 	// fusekernel.OutHeader struct.
+	//
+	// Special case: a return value of nil means that the kernel is not expecting
+	// a response.
 	kernelResponse() []byte
 }
 
@@ -147,17 +150,19 @@ func (o *commonOp) Respond(err error) {
 		msg = fuseshim.NewBuffer(0)
 	}
 
-	// Fill in the header.
-	h := (*fusekernel.OutHeader)(unsafe.Pointer(&msg[0]))
-	h.Unique = o.fuseID
-	h.Len = uint32(len(msg))
-	if err != nil {
-		errno := fuseshim.EIO
-		if ferr, ok := err.(fuseshim.ErrorNumber); ok {
-			errno = ferr.Errno()
+	// Fill in the header if a reply is needed.
+	if msg != nil {
+		h := (*fusekernel.OutHeader)(unsafe.Pointer(&msg[0]))
+		h.Unique = o.fuseID
+		h.Len = uint32(len(msg))
+		if err != nil {
+			errno := fuseshim.EIO
+			if ferr, ok := err.(fuseshim.ErrorNumber); ok {
+				errno = ferr.Errno()
+			}
+
+			h.Error = -int32(errno)
 		}
-
-		h.Error = -int32(errno)
 	}
 
 	// Reply.

fuseops/ops.go

@@ -217,7 +217,8 @@ type ForgetInodeOp struct {
 }
 
 func (o *ForgetInodeOp) kernelResponse() (msg []byte) {
-	panic("TODO: Signal that no response should happen here.")
+	// No response.
+	return
 }
 
 ////////////////////////////////////////////////////////////////////////

internal/fuseshim/fuse.go

@@ -1061,10 +1061,13 @@ func errorString(err error) string {
 	return err.Error()
 }
 
-func (c *Conn) WriteToKernel(msg []byte) error {
+func (c *Conn) writeToKernel(msg []byte) error {
 	out := (*fusekernel.OutHeader)(unsafe.Pointer(&msg[0]))
 	out.Len = uint32(len(msg))
+	return c.WriteToKernel(msg)
+}
 
+func (c *Conn) WriteToKernel(msg []byte) error {
 	c.wio.RLock()
 	defer c.wio.RUnlock()
 	_, err := syscall.Write(c.fd(), msg)