dirty workaround for #650667
http://www.freebsd.org/cgi/query-pr.cgi?pr=163076

--- a/sys/fs/pseudofs/pseudofs_vnops.c
+++ b/sys/fs/pseudofs/pseudofs_vnops.c
@@ -640,7 +640,7 @@
 	if (buflen > MAXPHYS + 1)
 		buflen = MAXPHYS + 1;
 
-	sb = sbuf_new(sb, NULL, buflen, 0);
+	sb = sbuf_new(sb, NULL, MAXPHYS + 1, 0);
 	if (sb == NULL) {
 		error = EIO;
 		goto ret;
@@ -654,7 +654,12 @@
 	}
 
 	sbuf_finish(sb);
-	error = uiomove_frombuf(sbuf_data(sb), sbuf_len(sb), uio);
+	
+	if (buflen > sbuf_len(sb))
+	    buflen = sbuf_len(sb);
+	else
+	    buflen--;    
+	error = uiomove_frombuf(sbuf_data(sb), buflen, uio);
 	sbuf_delete(sb);
 ret:
 	vn_lock(vn, locked | LK_RETRY);