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.

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

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 5b8f4ac791d764019402afe906f0a713d66ac3eb..6277c3b117a954d17fac44d8993a1e0b91af4421 100644 (file)
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1179,6 +1179,19 @@ error:
        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) {
+               mt_free_one(mas->alloc);
+               mas->alloc = NULL;
+       }
+}
 /*
  * mas_free() - Free an encoded maple node
  * @mas: The maple state
@@ -5420,15 +5433,7 @@ void mas_destroy(struct ma_state *mas)
                mas->mas_flags &= ~MA_STATE_REBALANCE;
        }
        mas->mas_flags &= ~(MA_STATE_BULK|MA_STATE_PREALLOC);
-
-       mas->node_request = 0;
-       if (mas->sheaf)
-               mt_return_sheaf(mas->sheaf);
-       mas->sheaf = NULL;
-
-       if (mas->alloc)
-               mt_free_one(mas->alloc);
-       mas->alloc = NULL;
+       mas_empty_nodes(mas);
 }
 EXPORT_SYMBOL_GPL(mas_destroy);
 
@@ -6504,7 +6509,7 @@ 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;
@@ -6512,20 +6517,17 @@ static inline void mas_dup_alloc(struct ma_state *mas, struct ma_state *new_mas,
        /* 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);
        }
 }
 
@@ -6579,7 +6581,7 @@ 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
@@ -6612,6 +6614,8 @@ set_new_tree:
        /* 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);
 }
 
 /**