Fix various issues with invalid file operations:

- Add invfo_rdwr() (for read and write), invfo_ioctl(), invfo_poll(),
  and invfo_kqfilter() for use by file types that do not support the
  respective operations.  Home-grown versions of invfo_poll() were
  universally broken (they returned an errno value, invfo_poll()
  uses poll_no_poll() to return an appropriate event mask).  Home-grown
  ioctl routines also tended to return an incorrect errno (invfo_ioctl
  returns ENOTTY).
- Use the invfo_*() functions instead of local versions for
  unsupported file operations.
- Reorder fileops members to match the order in the structure definition
  to make it easier to spot missing members.
- Add several missing methods to linuxfileops used by the OFED shim
  layer: fo_write(), fo_truncate(), fo_kqfilter(), and fo_stat().  Most
  of these used invfo_*(), but a dummy fo_stat() implementation was
  added.

sys/kern/uipc_mqueue.c

@@ -2417,35 +2417,6 @@ mq_proc_exit(void *arg __unused, struct proc *p)
 	KASSERT(LIST_EMPTY(&p->p_mqnotifier), ("mq notifiers left"));
 }
 
-static int
-mqf_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
-	int flags, struct thread *td)
-{
-	return (EOPNOTSUPP);
-}
-
-static int
-mqf_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
-	int flags, struct thread *td)
-{
-	return (EOPNOTSUPP);
-}
-
-static int
-mqf_truncate(struct file *fp, off_t length, struct ucred *active_cred,
-    struct thread *td)
-{
-
-	return (EINVAL);
-}
-
-static int
-mqf_ioctl(struct file *fp, u_long cmd, void *data,
-	struct ucred *active_cred, struct thread *td)
-{
-	return (ENOTTY);
-}
-
 static int
 mqf_poll(struct file *fp, int events, struct ucred *active_cred,
 	struct thread *td)
@@ -2601,16 +2572,16 @@ filt_mqwrite(struct knote *kn, long hint)
 }
 
 static struct fileops mqueueops = {
-	.fo_read		= mqf_read,
-	.fo_write		= mqf_write,
-	.fo_truncate		= mqf_truncate,
-	.fo_ioctl		= mqf_ioctl,
+	.fo_read		= invfo_rdwr,
+	.fo_write		= invfo_rdwr,
+	.fo_truncate		= invfo_truncate,
+	.fo_ioctl		= invfo_ioctl,
 	.fo_poll		= mqf_poll,
 	.fo_kqfilter		= mqf_kqfilter,
 	.fo_stat		= mqf_stat,
+	.fo_close		= mqf_close,
 	.fo_chmod		= mqf_chmod,
 	.fo_chown		= mqf_chown,
-	.fo_close		= mqf_close,
 	.fo_sendfile		= invfo_sendfile,
 };