maple_tree: wip, fix underrun on root expand when range starts at zero but ends elsewhere

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

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 1ee6dc35196537e4b6363f94e63b67c0ceea96b5..a8ae9c4374df183f47741684b7b565e26b64927c 100644 (file)
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1571,24 +1571,23 @@ static inline bool mab_middle_node(struct maple_big_node *b_node, int size,
        return false;
 }
 static inline int mab_calc_split(struct maple_big_node *b_node, int size,
-                                    unsigned char slot_cnt, unsigned long min)
+                                    unsigned char slot_cnt, unsigned long min,
+                                    enum maple_type type)
 {
        int split = (size - 1) / 2; // Assume equal split.
-       printk("orig split %u\n", split);
 
        if (mab_middle_node(b_node, size, slot_cnt)) {
                split = (size + 1) / 3;
-               printk("3 split %u\n", split);
        } else {
-               /* Avoid ending a node in NULL and avoid having a range less
-                * than the slot count
-                */
+               /* Avoid having a range less than the slot count unless it
+                * causes one node to be deficient. */
                while (((b_node->pivot[split] - min) < slot_cnt - 1) &&
-                      (split < slot_cnt))
+                      (split < slot_cnt) &&
+                      (size - split > mt_min_slots[type]))
                        split++;
        }
 
-       printk("adjusted split %u\n", split);
+       /* Avoid ending a node on a NULL entry */
        if (!b_node->slot[split]) {
                printk("%u is null\n", split);
                if (split < slot_cnt - 1)
@@ -1596,7 +1595,7 @@ static inline int mab_calc_split(struct maple_big_node *b_node, int size,
                else
                        split--;
        }
-       //printk("Setting split (leaf split) to %u\n", split);
+
        return split;
 }
 
@@ -1863,7 +1862,8 @@ static inline int mas_combine_separate(struct ma_state *mas,
                        split = b_end;
                } else {
                        split = mab_calc_split(b_node, b_end, slot_cnt,
-                                              orig_l_mas->min);
+                                              orig_l_mas->min,
+                                              mte_node_type(orig_l_mas->node));
                        r = mt_mk_node(ma_mnode_ptr(mas_next_alloc(mas)),
                                       mte_node_type(orig_l_mas->node));
                }
@@ -2299,7 +2299,7 @@ static inline int mas_split(struct ma_state *mas,
                if (mte_is_leaf(mas->node)) {
                        printk("Splitting leaf %p\n", mas_mn(mas));
                        split = mab_calc_split(b_node, new_end, slot_cnt,
-                                               mas->min);
+                                               mas->min, type);
                        printk("Splitting at %u\n", split);
                        if (split < slot_cnt)
                                i = mab_mas_cp(b_node, 0, split, &l_mas, 0);
@@ -2480,12 +2480,11 @@ static inline int mas_root_expand(struct ma_state *mas, void *entry)
        if (contents)
                mte_set_rcu_slot(mas->node, slot++, contents);
 
-       if (!mas->index)
+       if (!mas->index && slot)
                slot--;
        else if (mas->index > 1)
                mte_set_pivot(mas->node, slot++, mas->index - 1);
 
-
        mte_set_rcu_slot(mas->node, slot, entry);
        mte_set_pivot(mas->node, slot++, mas->last);
 

diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c
index bf6564d0d3e5ddc4df694c38ddb67033fcadba7e..c6adf2419a15cfb33d6d11660efa372cbfa00ff3 100644 (file)
--- a/lib/test_maple_tree.c
+++ b/lib/test_maple_tree.c
@@ -30367,7 +30367,6 @@ static noinline void check_ranges(struct maple_tree *mt)
        mtree_destroy(mt);
 
        check_seq(mt, 50, false);
-       return;
        mt_set_non_kernel(4);
        check_store_range(mt, 5, 47,  xa_mk_value(47), 0);
        mtree_destroy(mt);