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From:   Peng Zhang <zhangpeng.00@bytedance.com>
To:     Liam.Howlett@oracle.com
Cc:     akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org,
        Peng Zhang <zhangpeng.00@bytedance.com>
Subject: [RESEND PATCH 2/8] maple_tree: don't use MAPLE_ARANGE64_META_MAX to indicate no gap
Date:   Fri,  7 Jul 2023 18:10:51 +0800
Message-Id: <20230707101057.29326-3-zhangpeng.00@bytedance.com>
In-Reply-To: <20230707101057.29326-1-zhangpeng.00@bytedance.com>
References: <20230707101057.29326-1-zhangpeng.00@bytedance.com>
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Do not use a special offset to indicate that there is no gap. When there
is no gap, offset can point to any valid slots because its gap is 0.

Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
---
 include/linux/maple_tree.h |  2 --
 lib/maple_tree.c           | 13 ++-----------
 2 files changed, 2 insertions(+), 13 deletions(-)

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index e18ecbefc7f7..4e004d86c780 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -29,14 +29,12 @@
 #define MAPLE_NODE_SLOTS	31	/* 256 bytes including ->parent */
 #define MAPLE_RANGE64_SLOTS	16	/* 256 bytes */
 #define MAPLE_ARANGE64_SLOTS	10	/* 240 bytes */
-#define MAPLE_ARANGE64_META_MAX	15	/* Out of range for metadata */
 #define MAPLE_ALLOC_SLOTS	(MAPLE_NODE_SLOTS - 1)
 #else
 /* 32bit sizes */
 #define MAPLE_NODE_SLOTS	63	/* 256 bytes including ->parent */
 #define MAPLE_RANGE64_SLOTS	32	/* 256 bytes */
 #define MAPLE_ARANGE64_SLOTS	21	/* 240 bytes */
-#define MAPLE_ARANGE64_META_MAX	31	/* Out of range for metadata */
 #define MAPLE_ALLOC_SLOTS	(MAPLE_NODE_SLOTS - 2)
 #endif /* defined(CONFIG_64BIT) || defined(BUILD_VDSO32_64) */
 
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index f55e59bd9122..6a8982146338 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1610,8 +1610,6 @@ ma_max_gap(struct maple_node *node, unsigned long *gaps, enum maple_type mt,
  * mas_max_gap() - find the largest gap in a non-leaf node and set the slot.
  * @mas: The maple state.
  *
- * If the metadata gap is set to MAPLE_ARANGE64_META_MAX, there is no gap.
- *
  * Return: The gap value.
  */
 static inline unsigned long mas_max_gap(struct ma_state *mas)
@@ -1628,9 +1626,6 @@ static inline unsigned long mas_max_gap(struct ma_state *mas)
 	node = mas_mn(mas);
 	MAS_BUG_ON(mas, mt != maple_arange_64);
 	offset = ma_meta_gap(node, mt);
-	if (offset == MAPLE_ARANGE64_META_MAX)
-		return 0;
-
 	gaps = ma_gaps(node, mt);
 	return gaps[offset];
 }
@@ -1662,10 +1657,7 @@ static inline void mas_parent_gap(struct ma_state *mas, unsigned char offset,
 ascend:
 	MAS_BUG_ON(mas, pmt != maple_arange_64);
 	meta_offset = ma_meta_gap(pnode, pmt);
-	if (meta_offset == MAPLE_ARANGE64_META_MAX)
-		meta_gap = 0;
-	else
-		meta_gap = pgaps[meta_offset];
+	meta_gap = pgaps[meta_offset];
 
 	pgaps[offset] = new;
 
@@ -1678,7 +1670,6 @@ static inline void mas_parent_gap(struct ma_state *mas, unsigned char offset,
 
 		ma_set_meta_gap(pnode, pmt, offset);
 	} else if (new < meta_gap) {
-		meta_offset = 15;
 		new = ma_max_gap(pnode, pgaps, pmt, &meta_offset);
 		ma_set_meta_gap(pnode, pmt, meta_offset);
 	}
@@ -2076,7 +2067,7 @@ static inline void mab_mas_cp(struct maple_big_node *b_node,
 	end = j - 1;
 	if (likely(!ma_is_leaf(mt) && mt_is_alloc(mas->tree))) {
 		unsigned long max_gap = 0;
-		unsigned char offset = 15;
+		unsigned char offset = 0;
 
 		gaps = ma_gaps(node, mt);
 		do {
-- 
2.20.1