Changes to msync(2)

- Return EBUSY if the region was wired by mlock(2) and MS_INVALIDATE
   is specified to msync(2).  This is required by the Open Group Base
   Specifications Issue 6.
 - vm_map_sync() doesn't return KERN_FAILURE.  Thus, msync(2) can't
   possibly return EIO.
 - The second major loop in vm_map_sync() handles sub maps.  Thus,
   failing on sub maps in the first major loop isn't necessary.

sys/vm/vm_map.c

@@ -1985,10 +1985,10 @@ vm_map_sync(
 		end = entry->end;
 	}
 	/*
-	 * Make a first pass to check for holes.
+	 * Make a first pass to check for user-wired memory and holes.
 	 */
 	for (current = entry; current->start < end; current = current->next) {
-		if (current->eflags & MAP_ENTRY_IS_SUB_MAP) {
+		if (invalidate && (current->eflags & MAP_ENTRY_USER_WIRED)) {
 			vm_map_unlock_read(map);
 			return (KERN_INVALID_ARGUMENT);
 		}

sys/vm/vm_mmap.c

@@ -558,8 +558,8 @@ msync(td, uap)
 		return (0);
 	case KERN_INVALID_ADDRESS:
 		return (EINVAL);	/* Sun returns ENOMEM? */
-	case KERN_FAILURE:
-		return (EIO);
+	case KERN_INVALID_ARGUMENT:
+		return (EBUSY);
 	default:
 		return (EINVAL);
 	}