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Subject[PATCH v4 07/10] maple_tree: Add comments and some minor cleanups to mas_wr_append()
Date
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@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
lib/maple_tree.c | 47 +++++++++++++++++++++++------------------------
1 file changed, 23 insertions(+), 24 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 07c5c7afd415..676976a005e5 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -4311,6 +4311,12 @@ 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
+ */
static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
{
unsigned char end = wr_mas->node_end;
@@ -4318,34 +4324,30 @@ 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->index != wr_mas->r_min) && (mas->last == wr_mas->r_max)) {
- if (new_end < node_pivots)
- wr_mas->pivots[new_end] = wr_mas->pivots[end];
+ if (mas->offset != wr_mas->node_end)
+ return false;

- if (new_end < node_pivots)
- ma_set_meta(wr_mas->node, maple_leaf_64, 0, new_end);
+ if (new_end < node_pivots) {
+ wr_mas->pivots[new_end] = wr_mas->pivots[end];
+ ma_set_meta(wr_mas->node, maple_leaf_64, 0, new_end);
+ }

+ if (mas->last == wr_mas->r_max) {
+ /* Append to end of range */
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)) {
- if (new_end < node_pivots)
- wr_mas->pivots[new_end] = wr_mas->pivots[end];
-
+ mas->offset = new_end;
+ } else {
+ /* Append to start of range */
rcu_assign_pointer(wr_mas->slots[new_end], wr_mas->content);
- if (new_end < node_pivots)
- ma_set_meta(wr_mas->node, maple_leaf_64, 0, new_end);
-
wr_mas->pivots[end] = mas->last;
rcu_assign_pointer(wr_mas->slots[end], wr_mas->entry);
- return true;
}

- return false;
+ if (!wr_mas->content || !wr_mas->entry)
+ mas_update_gap(mas);
+
+ return true;
}

/*
@@ -4385,12 +4387,9 @@ 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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