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Message-Id: <20230515131757.60035-9-zhangpeng.00@bytedance.com>
Date: Mon, 15 May 2023 21:17:55 +0800
From: Peng Zhang <zhangpeng.00@...edance.com>
To: Liam.Howlett@...cle.com
Cc: akpm@...ux-foundation.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, maple-tree@...ts.infradead.org,
Peng Zhang <zhangpeng.00@...edance.com>
Subject: [PATCH 08/10] maple_tree: Add comments and some minor cleanups to mas_wr_append()
Add comment for mas_wr_append(), move mas_update_gap() into
mas_wr_append(), and other cleanups to make mas_wr_modify() cleaner.
Signed-off-by: Peng Zhang <zhangpeng.00@...edance.com>
---
lib/maple_tree.c | 52 ++++++++++++++++++++++++++++++++++++------------
1 file changed, 39 insertions(+), 13 deletions(-)
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 20082ef8c396c..538e49feafbe4 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -4315,6 +4315,31 @@ static inline unsigned char mas_wr_new_end(struct ma_wr_state *wr_mas)
return new_end;
}
+/*
+ * mas_wr_append: Attempt to append
+ * @wr_mas: the maple write state
+ *
+ * Return: True if appended, false otherwise
+ *
+ * Case 1:
+ * r_min r_max/end_piv
+ * +-------+-------+
+ * original range: | |offset |
+ * +-------+-------+
+ * +---+
+ * overwrite: | |
+ * +---+
+ * index last
+ * Case 2:
+ * r_min r_max/end_piv
+ * +-------+-------+
+ * original range: | |offset |
+ * +-------+-------+
+ * +---+
+ * overwrite: | |
+ * +---+
+ * index last
+ */
static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
{
unsigned char end = wr_mas->node_end;
@@ -4322,7 +4347,11 @@ static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
struct ma_state *mas = wr_mas->mas;
unsigned char node_pivots = mt_pivots[wr_mas->type];
+ if (!(mas->offset == wr_mas->node_end))
+ return false;
+
if ((mas->index != wr_mas->r_min) && (mas->last == wr_mas->r_max)) {
+ /* Case 1 */
if (new_end < node_pivots)
wr_mas->pivots[new_end] = wr_mas->pivots[end];
@@ -4330,13 +4359,10 @@ static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
ma_set_meta(wr_mas->node, maple_leaf_64, 0, new_end);
rcu_assign_pointer(wr_mas->slots[new_end], wr_mas->entry);
- mas->offset = new_end;
wr_mas->pivots[end] = mas->index - 1;
-
- return true;
- }
-
- if ((mas->index == wr_mas->r_min) && (mas->last < wr_mas->r_max)) {
+ mas->offset = new_end;
+ } else if ((mas->index == wr_mas->r_min) && (mas->last < wr_mas->r_max)) {
+ /* Case 2 */
if (new_end < node_pivots)
wr_mas->pivots[new_end] = wr_mas->pivots[end];
@@ -4346,10 +4372,13 @@ static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
wr_mas->pivots[end] = mas->last;
rcu_assign_pointer(wr_mas->slots[end], wr_mas->entry);
- return true;
+ } else {
+ return false;
}
- return false;
+ if (!wr_mas->content || !wr_mas->entry)
+ mas_update_gap(mas);
+ return true;
}
/*
@@ -4385,12 +4414,9 @@ static inline void mas_wr_modify(struct ma_wr_state *wr_mas)
if (new_end >= mt_slots[wr_mas->type])
goto slow_path;
- if (wr_mas->entry && (wr_mas->node_end < mt_slots[wr_mas->type] - 1) &&
- (mas->offset == wr_mas->node_end) && mas_wr_append(wr_mas)) {
- if (!wr_mas->content || !wr_mas->entry)
- mas_update_gap(mas);
+ /* Attempt to append */
+ if (new_end == wr_mas->node_end + 1 && mas_wr_append(wr_mas))
return;
- }
if ((wr_mas->offset_end - mas->offset <= 1) && mas_wr_slot_store(wr_mas))
return;
--
2.20.1
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