From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Tue, 25 Feb 2020 16:45:28 +0000 (-0500)
Subject: Revert "maple_tree: Rework node split calculation for better non-leaf node split"
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=bd7dbfdb4af61da39a1d275b460a6378c8e04d48;p=users%2Fjedix%2Flinux-maple.git

Revert "maple_tree: Rework node split calculation for better non-leaf node split"

Efficient splitting is causing issues in certain scenarios with regards
to allocation trees.  Revisit later.

This reverts commit 4a0a2dd623fae22f2823a0711193aafef3479e71.
---

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 12838071355a6..3c68ad94d0acb 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1364,21 +1364,10 @@ static inline unsigned char mas_append_calc_split(struct ma_state *mas,
 	unsigned long range = mas->max - mas->min;
 	unsigned long half;
 	unsigned long piv = 0;
-	unsigned long min_range = 8;
 	enum maple_type mas_type = mte_node_type(mas->node);
 
-	if (mas_type == maple_arange_64) {
+	if (mas_type == maple_arange_64)
 		max = 5;
-		ret = 5;
-	}
-
-	if (!ma_is_leaf(mas_type)) {
-		min_range *= max;
-		if (mas->max == ULONG_MAX) {
-			max--;
-			ret--;
-		}
-	}
 
 	if (!active) {
 		if (ma_is_leaf(mas_type))
@@ -1386,27 +1375,34 @@ static inline unsigned char mas_append_calc_split(struct ma_state *mas,
 		return max - 2;
 	}
 
+	//if (mas->min == 0)
+	//	max = 7;
+
 	half = max / 2;
-	if (range <= min_range)
-		return ret;
+	if (ma_is_leaf(mas_type)) {
+		if (range <= 8UL)
+			return ret;
 
-	for (slot = 0; slot <= mt_pivots[mas_type]; slot++) {
-		piv = mas_get_safe_pivot(mas, slot);
+		for (slot = 0; slot <= mt_pivots[mas_type]; slot++) {
+			piv = mas_get_safe_pivot(mas, slot);
 
-		if (!piv && slot)
-			return ret;
+			if (!piv && slot)
+				return ret;
 
-		range = piv - mas->min;
-		if (range >= min_range) {
-			if (slot > half)
-				ret = (max > slot ? slot : max);
-			else
-				ret = half;
-			goto done;
-		}
+			range = piv - mas->min;
+			if (range >= 8) {
+				if (slot > half)
+					ret = slot;
+				else
+					ret = half;
+				goto done;
+			}
 
+		}
 	}
 
+	return half;
+
 done:
 	if (ret < max && (piv == ULONG_MAX))
 		ret++;