Index: sys/kern/vfs_vnops.c
===================================================================
--- sys/kern/vfs_vnops.c
+++ sys/kern/vfs_vnops.c
@@ -806,9 +806,12 @@
 
 	flagsp = &fp->f_vflags;
 	state = atomic_load_16(flagsp);
-	if ((state & lock_bit) == 0 &&
-	    atomic_cmpset_acq_16(flagsp, state, state | lock_bit))
-		return;
+	for (;;) {
+		if ((state & lock_bit) != 0)
+			break;
+		if (atomic_fcmpset_acq_16(flagsp, &state, state | lock_bit))
+			return;
+	}
 
 	sleepq_lock(flagsp);
 	state = atomic_load_16(flagsp);
@@ -842,9 +845,12 @@
 
 	flagsp = &fp->f_vflags;
 	state = atomic_load_16(flagsp);
-	if ((state & lock_wait_bit) == 0 &&
-	    atomic_cmpset_rel_16(flagsp, state, state & ~lock_bit))
-		return;
+	for (;;) {
+		if ((state & lock_wait_bit) != 0)
+			break;
+		if (atomic_fcmpset_rel_16(flagsp, &state, state & ~lock_bit))
+			return;
+	}
 
 	sleepq_lock(flagsp);
 	MPASS((*flagsp & lock_bit) != 0);
@@ -864,10 +870,6 @@
 		    FILE_V_FOFFSET_LOCK_WAITING);
 	}
 
-	/*
-	 * According to McKusick the vn lock was protecting f_offset here.
-	 * It is now protected by the FOFFSET_LOCKED flag.
-	 */
 	return (atomic_load_long(&fp->f_offset));
 }