Index: kern_descrip.c
===================================================================
--- kern_descrip.c	(wersja 236851)
+++ kern_descrip.c	(kopia robocza)
@@ -886,14 +886,23 @@
 	}
 	KASSERT(old != new, ("new fd is same as old"));
 
+	delfp = fdp->fd_ofiles[new];
 	/*
+	 * Duplicate the source descriptor.
+	 */
+	fdp->fd_ofiles[new] = fp;
+	fdp->fd_ofileflags[new] = fdp->fd_ofileflags[old] &~ UF_EXCLOSE;
+	if (new > fdp->fd_lastfile)
+		fdp->fd_lastfile = new;
+	*retval = new;
+
+	/*
 	 * Save info on the descriptor being overwritten.  We cannot close
 	 * it without introducing an ownership race for the slot, since we
 	 * need to drop the filedesc lock to call closef().
 	 *
 	 * XXX this duplicates parts of close().
 	 */
-	delfp = fdp->fd_ofiles[new];
 	holdleaders = 0;
 	if (delfp != NULL && td->td_proc->p_fdtol != NULL) {
 		/*
@@ -905,15 +914,6 @@
 	}
 
 	/*
-	 * Duplicate the source descriptor.
-	 */
-	fdp->fd_ofiles[new] = fp;
-	fdp->fd_ofileflags[new] = fdp->fd_ofileflags[old] &~ UF_EXCLOSE;
-	if (new > fdp->fd_lastfile)
-		fdp->fd_lastfile = new;
-	*retval = new;
-
-	/*
 	 * If we dup'd over a valid file, we now own the reference to it
 	 * and must dispose of it using closef() semantics (as if a
 	 * close() were performed on it).