---

yaml
---
r: 318876
b: refs/heads/master
c: 709c048
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 416ac51da90e98daaac17e1f359a6c5591f7f5bd
+refs/heads/master: 709c0486b9fe9586736b108b7233bbce0300cfa5

trunk/fs/btrfs/extent-tree.c

@@ -34,6 +34,8 @@
 #include "locking.h"
 #include "free-space-cache.h"
 
+#undef SCRAMBLE_DELAYED_REFS
+
 /*
  * control flags for do_chunk_alloc's force field
  * CHUNK_ALLOC_NO_FORCE means to only allocate a chunk
@@ -2364,6 +2366,49 @@ static void wait_for_more_refs(struct btrfs_fs_info *fs_info,
 	spin_lock(&delayed_refs->lock);
 }
 
+#ifdef SCRAMBLE_DELAYED_REFS
+/*
+ * Normally delayed refs get processed in ascending bytenr order. This
+ * correlates in most cases to the order added. To expose dependencies on this
+ * order, we start to process the tree in the middle instead of the beginning
+ */
+static u64 find_middle(struct rb_root *root)
+{
+	struct rb_node *n = root->rb_node;
+	struct btrfs_delayed_ref_node *entry;
+	int alt = 1;
+	u64 middle;
+	u64 first = 0, last = 0;
+
+	n = rb_first(root);
+	if (n) {
+		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
+		first = entry->bytenr;
+	}
+	n = rb_last(root);
+	if (n) {
+		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
+		last = entry->bytenr;
+	}
+	n = root->rb_node;
+
+	while (n) {
+		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
+		WARN_ON(!entry->in_tree);
+
+		middle = entry->bytenr;
+
+		if (alt)
+			n = n->rb_left;
+		else
+			n = n->rb_right;
+
+		alt = 1 - alt;
+	}
+	return middle;
+}
+#endif
+
 /*
  * this starts processing the delayed reference count updates and
  * extent insertions we have queued up so far.  count can be
@@ -2406,6 +2451,10 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
 	consider_waiting = 0;
 	spin_lock(&delayed_refs->lock);
 
+#ifdef SCRAMBLE_DELAYED_REFS
+	delayed_refs->run_delayed_start = find_middle(&delayed_refs->root);
+#endif
+
 	if (count == 0) {
 		count = delayed_refs->num_entries * 2;
 		run_most = 1;