[PATCH v2 04/10] maple_tree: Simplify mas_is_span_wr()

From: Peng Zhang
Date: Wed May 17 2023 - 04:59:40 EST


Make the code for detecting spanning writes more concise.

Signed-off-by: Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx>
---
lib/maple_tree.c | 42 ++++++++++++++----------------------------
1 file changed, 14 insertions(+), 28 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index bec9906b0c8c..82dccc660889 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -3728,43 +3728,29 @@ static inline void mas_store_root(struct ma_state *mas, void *entry)
*/
static bool mas_is_span_wr(struct ma_wr_state *wr_mas)
{
- unsigned long max;
+ unsigned long max = wr_mas->r_max;
unsigned long last = wr_mas->mas->last;
- unsigned long piv = wr_mas->r_max;
enum maple_type type = wr_mas->type;
void *entry = wr_mas->entry;

- /* Contained in this pivot */
- if (piv > last)
+ /* Contained in this pivot, fast path */
+ if (last < max)
return false;
-
- max = wr_mas->mas->max;
- if (unlikely(ma_is_leaf(type))) {
- /* Fits in the node, but may span slots. */
- if (last < max)
- return false;
-
- /* Writes to the end of the node but not null. */
- if ((last == max) && entry)
- return false;
-
+ if (ma_is_leaf(type))
+ max = wr_mas->mas->max;
+ if (last < max) {
+ /* Contained in this pivot or this leaf node */
+ return false;
+ } else if (last == max) {
/*
- * Writing ULONG_MAX is not a spanning write regardless of the
- * value being written as long as the range fits in the node.
+ * The last entry of leaf node cannot be NULL unless it is the
+ * rightmost node (writing ULONG_MAX), otherwise it spans slots.
+ * If this is not leaf node, detect spanning store wr walk.
*/
- if ((last == ULONG_MAX) && (last == max))
- return false;
- } else if (piv == last) {
- if (entry)
- return false;
-
- /* Detect spanning store wr walk */
- if (last == ULONG_MAX)
+ if (entry || last == ULONG_MAX)
return false;
}
-
- trace_ma_write(__func__, wr_mas->mas, piv, entry);
-
+ trace_ma_write(__func__, wr_mas->mas, wr_mas->r_max, entry);
return true;
}

--
2.20.1