Correct nbtree page split lock coupling comment.
There is no reason to distinguish between readers and writers here.
@@ -1861,11 +1861,9 @@ _bt_split(Relation rel, BTScanInsert itup_key, Buffer buf, Buffer cbuf,
}
/*
- * We have to grab the right sibling (if any) and fix the prev pointer
- * there. We are guaranteed that this is deadlock-free since no other
- * writer will be holding a lock on that page and trying to move left, and
- * all readers release locks on a page before trying to fetch its
- * neighbors.
+ * We have to grab the original right sibling (if any) and update its prev
+ * link. We are guaranteed that this is deadlock-free, since we couple
+ * the locks in the standard order: left to right.
*/
if (!isrightmost)
{
