fuse: maybe handle opFsyncdir.

Change-Id: I899a2bd07aa60be38e10f062f3607fa9c07ac3c9

third_party/code.google.com/p/rsc/fuse/fuse.go

@@ -674,7 +674,21 @@ func (c *Conn) ReadRequest() (Request, error) {
 		}
 
 	case opFsyncdir:
-		panic("opFsyncdir")
+		// TODO(bradfitz): not really tested. I see this rarely on OS X,
+		// generally when a Finder window is open showing a directory
+		// and then the filesystem is unmounted. But I should write proper
+		// tests for it before I remove this comment.
+		in := (*fsyncIn)(m.data())
+		if m.len() < unsafe.Sizeof(*in) {
+			goto corrupt
+		}
+		req = &FsyncRequest{
+			Dir:    true,
+			Header: m.Header(),
+			Handle: HandleID(in.Fh),
+			Flags:  in.FsyncFlags,
+		}
+
 	case opGetlk:
 		panic("opGetlk")
 	case opSetlk:
@@ -1611,6 +1625,7 @@ type FsyncRequest struct {
 	Header
 	Handle HandleID
 	Flags  uint32
+	Dir    bool // if opFsyncDir
 }
 
 func (r *FsyncRequest) String() string {