Introduce helpers for can_rebalance directions

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

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 88467f48b68eb0fc58b9e145d3fa3feba31f71f8..158b6a67678794b98bf104be564ee40311cfe852 100644 (file)
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -3947,6 +3947,48 @@ static void mt_wr_split_data(struct ma_node_info *src,
        } while (node_off <= src->end);
 }
 
+
+static inline
+bool can_rebalance_right(struct ma_state *tmp_mas, struct ma_node_info *parent,
+               struct ma_node_info *src2, struct split_data *sd)
+{
+       if (parent->insert_off >= parent->end) /* No right node */
+               return false;
+
+       tmp_mas->offset++;
+       mas_descend(tmp_mas);
+       mni_mas_init(src2, tmp_mas);
+       mni_set_end(src2);
+       sd->split = mas_wr_rebalance_calc(src2->end + sd->new_end, src2->type);
+       if (!sd->split) {
+               mas_ascend(tmp_mas);
+               tmp_mas->offset--;
+               return false;
+       }
+       return true;
+}
+
+static inline
+bool can_rebalance_left(struct ma_state *tmp_mas, struct ma_node_info *parent,
+               struct ma_node_info *src2, struct split_data *sd)
+{
+       if (!parent->insert_off) /* No left node */
+               return false;
+
+       tmp_mas->offset--;
+       mas_descend(tmp_mas);
+       mni_mas_init(src2, tmp_mas);
+       mni_set_end(src2);
+       sd->split = mas_wr_rebalance_calc(src2->end + sd->new_end, src2->type);
+       if (!sd->split) {
+               mas_ascend(tmp_mas);
+               tmp_mas->offset++;
+               return false;
+       }
+
+       parent->insert_off--;
+       return true;
+}
 /*
  * mas_wr_try_rebalance() - Try to rebalance two nodes, this may not work out.
  * @src: The source node state
@@ -3976,39 +4018,17 @@ bool mas_wr_try_rebalance(struct ma_state *mas, struct ma_node_info *src,
        mas_wr_ascend_init(&tmp_mas, &parent);
 
        src->end = mas->end;
-       if (!parent.insert_off) /* No left sibling */
-               goto try_right; /* There must be a right sibling */
-
-       /* Check for space in left sibling */
-       tmp_mas.offset--;
-       mas_descend(&tmp_mas);
-       mni_mas_init(&src2, &tmp_mas);
-       sd->split = mas_wr_rebalance_calc(src2.end + sd->new_end, src2.type);
-
-       if (sd->split) {
-               parent.insert_off--;
-               /* Left will be src2, right will be src */
+       if (can_rebalance_left(&tmp_mas, &parent, &src2, sd)) {
                left->min = src2.min;
                right->max = src->max;
-       } else {
-               if (parent.end <= parent.insert_off)
-                       return false;
-
-               mas_ascend(&tmp_mas);
-try_right:
-               tmp_mas.offset = parent.insert_off + 1;
-               mas_descend(&tmp_mas);
-               mni_mas_init(&src2, &tmp_mas);
-               mni_set_end(&src2);
-               sd->split = mas_wr_rebalance_calc(src2.end + sd->new_end, src2.type);
-               if (!sd->split)
-                       return false;
-
+       } else if (can_rebalance_right(&tmp_mas, &parent, &src2, sd)) {
                sd->split = src2.end + sd->new_end - sd->split;
                left_store = true;
                /* Left will be src, right will be src2 */
                left->min = src->min;
                right->max = src2.max;
+       } else {
+               return false;
        }
 
        /* The rebalance operation will succeed. */
@@ -4054,7 +4074,7 @@ try_right:
        return true;
 }
 
-#if 1
+#if 0
 static void mas_wr_rebalance(struct ma_wr_state *wr_mas)
 {
        struct ma_state *mas;
@@ -4080,6 +4100,24 @@ static void mas_wr_rebalance(struct ma_wr_state *wr_mas)
        height = mas_mt_height(mas);
        mas->depth = height;
 
+       mni_mas_init(&src, mas);
+       src.end = mas->end;
+
+       mni_node_init(&left, mas_pop_node(mas), wr_mas->type);
+       if (mt_is_alloc(mas->tree))
+               left.is_alloc = true;
+
+       tmp_mas = *mas;
+       mas_wr_ascend_init(&tmp_mas, &parent);
+       if (mas_wr_try_right(&tmp_mas, &parent, &src2)) {
+               sd.insert = mas->offset;
+       } else {
+               /* Won't fail here */
+               MAS_BUG_ON(try_rebalance_left(&tmp_mas, &parent, &src2));
+               sd.insert = mas->offset + src2.end + 1;
+       }
+
+
        /*
         * allocate left
         * set alloc in left
@@ -4113,8 +4151,6 @@ static void mas_wr_rebalance(struct ma_wr_state *wr_mas)
         *
         */
 
-       mni_mas_init(&src, mas);
-       tmp_mas = *mas;
        while (height--) {
                printk("height %d\n", height);
                mas_wr_ascend_init(&tmp_mas, &parent);
@@ -5198,8 +5234,8 @@ static inline void mas_wr_store_entry(struct ma_wr_state *wr_mas)
                mas_wr_split(wr_mas);
                break;
        case wr_rebalance:
-               //mas_wr_bnode(wr_mas);
-               mas_wr_rebalance(wr_mas);
+               mas_wr_bnode(wr_mas);
+               //mas_wr_rebalance(wr_mas);
                break;
        case wr_exact_fit:
                rcu_assign_pointer(wr_mas->slots[mas->offset], wr_mas->entry);