From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Tue, 25 Aug 2020 17:56:13 +0000 (-0400)
Subject: maple_tree: Alloc at most 1 page of nodes during fork.
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=1020374d187ba2f0dfb5e7f2f5de09c2f464c5a7;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Alloc at most 1 page of nodes during fork.

Also fix a corner case of root + children being 17 and thus failing out during a fork

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index 105731e081e34..20cb7c6cf4d7a 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -37,6 +37,7 @@
 #define MAPLE_SPARSE16_SLOTS	24	/* 248 bytes */
 #define MAPLE_SPARSE9_SLOTS	27	/* 256 bytes */
 #define MAPLE_SPARSE6_SLOTS	30	/* 256 bytes */
+#define MA_NODE_PER_PAGE        16
 #else
 #define MAPLE_NODE_SLOTS       15      /* 128 bytes including ->parent */
 #define MAPLE_RANGE64_SLOTS    8       /* 128 bytes */
@@ -49,6 +50,7 @@
 #define MAPLE_SPARSE16_SLOTS   12      /* 128 bytes */
 #define MAPLE_SPARSE9_SLOTS    13      /* 127 bytes */
 #define MAPLE_SPARSE6_SLOTS    14      /* 128 bytes */
+#define MA_NODE_PER_PAGE       32
 #endif // End NODE256
 
 #else
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 0d15a5cc99fa6..6733ab06e13f9 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -22,9 +22,6 @@
 #define ma_parent_ptr(x) ((struct maple_pnode *)(x))
 #define ma_mnode_ptr(x) ((struct maple_node *)(x))
 #define ma_enode_ptr(x) ((struct maple_enode *)(x))
-#undef XA_RETRY_ENTRY
-#undef XA_SKIP_ENTRY
-#undef XA_DELETED_ENTRY
 
 static struct kmem_cache *maple_node_cache;
 
@@ -572,6 +569,7 @@ static inline struct maple_enode *ma_get_rcu_slot(
 		const struct maple_node *mn, unsigned char slot,
 		enum maple_type type, struct maple_tree *mtree)
 {
+
 	switch (type) {
 	case maple_range_64:
 	case maple_leaf_64:
@@ -4357,7 +4355,7 @@ static inline struct maple_enode *mas_dup_node(struct ma_state *oldmas,
 static inline void mas_dup_alloc(struct ma_state *mas, int *node_cnt)
 {
 
-	int alloc_cnt = min(*node_cnt, 127);
+	int alloc_cnt = min(*node_cnt, MA_NODE_PER_PAGE);
 	/* Allocate nodes for new tree.  Maximum will be 16 ** height */
 	*node_cnt -= alloc_cnt;
 	mas_node_cnt(mas, alloc_cnt);
@@ -4411,6 +4409,9 @@ static inline void mas_dup_tree_start(struct ma_state *oldmas,
 				      struct ma_state *mas,
 				      int *node_cnt)
 {
+	if (xa_is_node(mas->tree->ma_root))
+		goto dup_children;
+
 	if (mas->alloc)
 		goto allocated;
 
@@ -4435,8 +4436,12 @@ allocated:
 	mte_to_node(mas->node)->parent = ma_parent_ptr(
 				((unsigned long)mas->tree | MA_ROOT_PARENT));
 	rcu_assign_pointer(mas->tree->ma_root, mte_mk_root(mas->node));
+
+dup_children:
 	if (!mte_is_leaf(oldmas->node)) {
 		mas_dup_children(mas, node_cnt);
+		if (mas_is_err(mas))
+			return;
 		mas_adopt_children(mas, mas->node);
 	}
 }