maple_tree: Convert forking to use the sheaf interface

Use the generic interface which should result in less bulk allocations
during a forking.

A part of this is to abstract the freeing of the sheaf or maple state
allocations into its own function so mas_destroy() and the tree
duplication code can use the same functionality to return any unused
resources.

[[email protected]: remove unused mt_alloc_bulk()]
Signed-off-by: Liam R. Howlett <[email protected]>
Reviewed-by: Suren Baghdasaryan <[email protected]>
Signed-off-by: Vlastimil Babka <[email protected]>

Author: howlett

lib/maple_tree.c

@@ -172,11 +172,6 @@ static inline struct maple_node *mt_alloc_one(gfp_t gfp)
 	return kmem_cache_alloc(maple_node_cache, gfp);
 }
 
-static inline int mt_alloc_bulk(gfp_t gfp, size_t size, void **nodes)
-{
-	return kmem_cache_alloc_bulk(maple_node_cache, gfp, size, nodes);
-}
-
 static inline void mt_free_bulk(size_t size, void __rcu **nodes)
 {
 	kmem_cache_free_bulk(maple_node_cache, size, (void **)nodes);
@@ -1150,6 +1145,19 @@ static inline void mas_alloc_nodes(struct ma_state *mas, gfp_t gfp)
 	mas_set_err(mas, -ENOMEM);
 }
 
+static inline void mas_empty_nodes(struct ma_state *mas)
+{
+	mas->node_request = 0;
+	if (mas->sheaf) {
+		mt_return_sheaf(mas->sheaf);
+		mas->sheaf = NULL;
+	}
+
+	if (mas->alloc) {
+		kfree(mas->alloc);
+		mas->alloc = NULL;
+	}
+}
 
 /*
  * mas_free() - Free an encoded maple node
@@ -5208,15 +5216,7 @@ EXPORT_SYMBOL_GPL(mas_preallocate);
 void mas_destroy(struct ma_state *mas)
 {
 	mas->mas_flags &= ~MA_STATE_PREALLOC;
-
-	mas->node_request = 0;
-	if (mas->sheaf)
-		mt_return_sheaf(mas->sheaf);
-	mas->sheaf = NULL;
-
-	if (mas->alloc)
-		kfree(mas->alloc);
-	mas->alloc = NULL;
+	mas_empty_nodes(mas);
 }
 EXPORT_SYMBOL_GPL(mas_destroy);
 
@@ -6241,28 +6241,25 @@ static inline void mas_dup_alloc(struct ma_state *mas, struct ma_state *new_mas,
 	struct maple_node *node = mte_to_node(mas->node);
 	struct maple_node *new_node = mte_to_node(new_mas->node);
 	enum maple_type type;
-	unsigned char request, count, i;
+	unsigned char count, i;
 	void __rcu **slots;
 	void __rcu **new_slots;
 	unsigned long val;
 
 	/* Allocate memory for child nodes. */
 	type = mte_node_type(mas->node);
 	new_slots = ma_slots(new_node, type);
-	request = mas_data_end(mas) + 1;
-	count = mt_alloc_bulk(gfp, request, (void **)new_slots);
-	if (unlikely(count < request)) {
-		memset(new_slots, 0, request * sizeof(void *));
-		mas_set_err(mas, -ENOMEM);
+	count = mas->node_request = mas_data_end(mas) + 1;
+	mas_alloc_nodes(mas, gfp);
+	if (unlikely(mas_is_err(mas)))
 		return;
-	}
 
-	/* Restore node type information in slots. */
 	slots = ma_slots(node, type);
 	for (i = 0; i < count; i++) {
 		val = (unsigned long)mt_slot_locked(mas->tree, slots, i);
 		val &= MAPLE_NODE_MASK;
-		((unsigned long *)new_slots)[i] |= val;
+		new_slots[i] = ma_mnode_ptr((unsigned long)mas_pop_node(mas) |
+					    val);
 	}
 }
 
@@ -6316,7 +6313,7 @@ static inline void mas_dup_build(struct ma_state *mas, struct ma_state *new_mas,
 			/* Only allocate child nodes for non-leaf nodes. */
 			mas_dup_alloc(mas, new_mas, gfp);
 			if (unlikely(mas_is_err(mas)))
-				return;
+				goto empty_mas;
 		} else {
 			/*
 			 * This is the last leaf node and duplication is
@@ -6349,6 +6346,8 @@ static inline void mas_dup_build(struct ma_state *mas, struct ma_state *new_mas,
 	/* Make them the same height */
 	new_mas->tree->ma_flags = mas->tree->ma_flags;
 	rcu_assign_pointer(new_mas->tree->ma_root, root);
+empty_mas:
+	mas_empty_nodes(mas);
 }
 
 /**