fuse: MountDirect: always pass max_read

Commit 265a3926 missed
adding max_read to the DirectMount path.

Add it, which fixes the TestDirectMount failures.

Change-Id: Ie934944d8f0a08fb65e2b6f675c8032f404d50df

fuse/mount_linux.go

@@ -59,6 +59,8 @@ func mountDirect(mountPoint string, opts *MountOptions, ready chan<- error) (fd
 		fmt.Sprintf("rootmode=%o", st.Mode&syscall.S_IFMT),
 		fmt.Sprintf("user_id=%d", os.Geteuid()),
 		fmt.Sprintf("group_id=%d", os.Getegid()),
+		// match what we do with fusermount
+		fmt.Sprintf("max_read=%d", opts.MaxWrite),
 	}
 	r = append(r, opts.Options...)