From 309ce6768b29f72815ab8301b3670c7d8f7af307 Mon Sep 17 00:00:00 2001
From: Chris Mason <chris.mason@oracle.com>
Date: Thu, 24 Apr 2008 14:46:15 -0400
Subject: [PATCH] Fix balance_level to free the middle block if there is room
 in the left one

balance level starts by trying to empty the middle block, and then
pushes from the right to the middle.  This might empty the right block
and leave a small number of pointers in the middle.
---
 ctree.c       | 35 ++++++++++++++++++++++++++++-------
 extent-tree.c |  4 ++--
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/ctree.c b/ctree.c
index eb645da..5608bb4 100644
--- a/ctree.c
+++ b/ctree.c
@@ -745,7 +745,7 @@ static int balance_level(struct btrfs_trans_handle *trans,
 	/* first, try to make some room in the middle buffer */
 	if (left) {
 		orig_slot += btrfs_header_nritems(left);
-		wret = push_node_left(trans, root, left, mid, 0);
+		wret = push_node_left(trans, root, left, mid, 1);
 		if (wret < 0)
 			ret = wret;
 		if (btrfs_header_nritems(mid) < 2)
@@ -801,6 +801,11 @@ static int balance_level(struct btrfs_trans_handle *trans,
 			ret = wret;
 			goto enospc;
 		}
+		if (wret == 1) {
+			wret = push_node_left(trans, root, left, mid, 1);
+			if (wret < 0)
+				ret = wret;
+		}
 		BUG_ON(wret == 1);
 	}
 	if (btrfs_header_nritems(mid) == 0) {
@@ -1213,17 +1218,27 @@ static int push_node_left(struct btrfs_trans_handle *trans,
 	WARN_ON(btrfs_header_generation(src) != trans->transid);
 	WARN_ON(btrfs_header_generation(dst) != trans->transid);
 
-	if (!empty && src_nritems <= 2)
+	if (!empty && src_nritems <= 8)
 		return 1;
 
 	if (push_items <= 0) {
 		return 1;
 	}
 
-	if (empty)
+	if (empty) {
 		push_items = min(src_nritems, push_items);
-	else
-		push_items = min(src_nritems - 2, push_items);
+		if (push_items < src_nritems) {
+			/* leave at least 8 pointers in the node if
+			 * we aren't going to empty it
+			 */
+			if (src_nritems - push_items < 8) {
+				if (push_items <= 8)
+					return 1;
+				push_items -= 8;
+			}
+		}
+	} else
+		push_items = min(src_nritems - 8, push_items);
 
 	copy_extent_buffer(dst, src,
 			   btrfs_node_key_ptr_offset(dst_nritems),
@@ -1269,13 +1284,19 @@ static int balance_node_right(struct btrfs_trans_handle *trans,
 	src_nritems = btrfs_header_nritems(src);
 	dst_nritems = btrfs_header_nritems(dst);
 	push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
-	if (push_items <= 0)
+	if (push_items <= 0) {
 		return 1;
+	}
+
+	if (src_nritems < 4) {
+		return 1;
+	}
 
 	max_push = src_nritems / 2 + 1;
 	/* don't try to empty the node */
-	if (max_push >= src_nritems)
+	if (max_push >= src_nritems) {
 		return 1;
+	}
 
 	if (max_push < push_items)
 		push_items = max_push;
diff --git a/extent-tree.c b/extent-tree.c
index a13b12e..6687d2e 100644
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -293,12 +293,12 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 	int bit;
 	int ret;
 	int full_search = 0;
-	int factor = 8;
+	int factor = 10;
 
 	block_group_cache = &info->block_group_cache;
 
 	if (!owner)
-		factor = 8;
+		factor = 10;
 
 	bit = block_group_state_bits(data);
 
-- 
2.7.4