radix-tree: fix replacement for multiorder entries

When replacing an entry with NULL, we need to delete any sibling
entries.  Also account deleting exceptional entries properly.  Also fix
a bug with radix_tree_iter_replace() where we would fail to remove
entirely freed nodes.  Also fix accounting bug when switching between
normal and exceptional entries with replace_slot.  Also add testcases
for all these bugs.

Link: http://lkml.kernel.org/r/1480369871-5271-61-git-send-email-mawilcox@linuxonhyperv.com
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index be1183e62590fd8cd739224dcebc06f2dc6fd102..d09c17dd60ae048f68ba0317d73c67e86847891a 100644 (file)
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -977,6 +977,24 @@ void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
 }
 EXPORT_SYMBOL(radix_tree_lookup);
 
+static inline int slot_count(struct radix_tree_node *node,
+                                               void **slot)
+{
+       int n = 1;
+#ifdef CONFIG_RADIX_TREE_MULTIORDER
+       void *ptr = node_to_entry(slot);
+       unsigned offset = get_slot_offset(node, slot);
+       int i;
+
+       for (i = 1; offset + i < RADIX_TREE_MAP_SIZE; i++) {
+               if (node->slots[offset + i] != ptr)
+                       break;
+               n++;
+       }
+#endif
+       return n;
+}
+
 static void replace_slot(struct radix_tree_root *root,
                         struct radix_tree_node *node,
                         void **slot, void *item,
@@ -995,12 +1013,35 @@ static void replace_slot(struct radix_tree_root *root,
 
        if (node) {
                node->count += count;
-               node->exceptional += exceptional;
+               if (exceptional) {
+                       exceptional *= slot_count(node, slot);
+                       node->exceptional += exceptional;
+               }
        }
 
        rcu_assign_pointer(*slot, item);
 }
 
+static inline void delete_sibling_entries(struct radix_tree_node *node,
+                                               void **slot)
+{
+#ifdef CONFIG_RADIX_TREE_MULTIORDER
+       bool exceptional = radix_tree_exceptional_entry(*slot);
+       void *ptr = node_to_entry(slot);
+       unsigned offset = get_slot_offset(node, slot);
+       int i;
+
+       for (i = 1; offset + i < RADIX_TREE_MAP_SIZE; i++) {
+               if (node->slots[offset + i] != ptr)
+                       break;
+               node->slots[offset + i] = NULL;
+               node->count--;
+               if (exceptional)
+                       node->exceptional--;
+       }
+#endif
+}
+
 /**
  * __radix_tree_replace                - replace item in a slot
  * @root:              radix tree root
@@ -1018,6 +1059,8 @@ void __radix_tree_replace(struct radix_tree_root *root,
                          void **slot, void *item,
                          radix_tree_update_node_t update_node, void *private)
 {
+       if (!item)
+               delete_sibling_entries(node, slot);
        /*
         * This function supports replacing exceptional entries and
         * deleting entries, but that needs accounting against the
@@ -1794,20 +1837,6 @@ void __radix_tree_delete_node(struct radix_tree_root *root,
        delete_node(root, node, NULL, NULL);
 }
 
-static inline void delete_sibling_entries(struct radix_tree_node *node,
-                                       void *ptr, unsigned offset)
-{
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
-       int i;
-       for (i = 1; offset + i < RADIX_TREE_MAP_SIZE; i++) {
-               if (node->slots[offset + i] != ptr)
-                       break;
-               node->slots[offset + i] = NULL;
-               node->count--;
-       }
-#endif
-}
-
 /**
  *     radix_tree_delete_item    -    delete an item from a radix tree
  *     @root:          radix tree root
@@ -1847,7 +1876,6 @@ void *radix_tree_delete_item(struct radix_tree_root *root,
        for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
                node_tag_clear(root, node, tag, offset);
 
-       delete_sibling_entries(node, node_to_entry(slot), offset);
        __radix_tree_replace(root, node, slot, NULL, NULL, NULL);
 
        return entry;

diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
index 5421f015f46c0bd4dce6f7b14c508a1d324a4570..9757b8928bd499b7662ad64d8fd1591c1e6e291b 100644 (file)
--- a/tools/testing/radix-tree/multiorder.c
+++ b/tools/testing/radix-tree/multiorder.c
@@ -410,8 +410,6 @@ static void __multiorder_split(int old_order, int new_order)
        RADIX_TREE(tree, GFP_ATOMIC);
        void **slot;
        struct radix_tree_iter iter;
-       struct radix_tree_node *node;
-       void *item;
        unsigned alloc;
 
        radix_tree_preload(GFP_KERNEL);
@@ -434,58 +432,122 @@ static void __multiorder_split(int old_order, int new_order)
        radix_tree_preload_end();
 
        item_kill_tree(&tree);
+}
+
+static void __multiorder_split2(int old_order, int new_order)
+{
+       RADIX_TREE(tree, GFP_KERNEL);
+       void **slot;
+       struct radix_tree_iter iter;
+       struct radix_tree_node *node;
+       void *item;
 
-       radix_tree_preload(GFP_KERNEL);
        __radix_tree_insert(&tree, 0, old_order, (void *)0x12);
-       radix_tree_preload_end();
 
        item = __radix_tree_lookup(&tree, 0, &node, NULL);
        assert(item == (void *)0x12);
        assert(node->exceptional > 0);
 
-       radix_tree_split_preload(old_order, new_order, GFP_KERNEL);
        radix_tree_split(&tree, 0, new_order);
        radix_tree_for_each_slot(slot, &tree, &iter, 0) {
                radix_tree_iter_replace(&tree, &iter, slot,
                                        item_create(iter.index, new_order));
        }
-       radix_tree_preload_end();
 
        item = __radix_tree_lookup(&tree, 0, &node, NULL);
        assert(item != (void *)0x12);
        assert(node->exceptional == 0);
 
        item_kill_tree(&tree);
+}
+
+static void __multiorder_split3(int old_order, int new_order)
+{
+       RADIX_TREE(tree, GFP_KERNEL);
+       void **slot;
+       struct radix_tree_iter iter;
+       struct radix_tree_node *node;
+       void *item;
 
-       radix_tree_preload(GFP_KERNEL);
        __radix_tree_insert(&tree, 0, old_order, (void *)0x12);
-       radix_tree_preload_end();
 
        item = __radix_tree_lookup(&tree, 0, &node, NULL);
        assert(item == (void *)0x12);
        assert(node->exceptional > 0);
 
-       radix_tree_split_preload(old_order, new_order, GFP_KERNEL);
        radix_tree_split(&tree, 0, new_order);
        radix_tree_for_each_slot(slot, &tree, &iter, 0) {
                radix_tree_iter_replace(&tree, &iter, slot, (void *)0x16);
        }
-       radix_tree_preload_end();
 
        item = __radix_tree_lookup(&tree, 0, &node, NULL);
        assert(item == (void *)0x16);
        assert(node->exceptional > 0);
 
        item_kill_tree(&tree);
+
+       __radix_tree_insert(&tree, 0, old_order, (void *)0x12);
+
+       item = __radix_tree_lookup(&tree, 0, &node, NULL);
+       assert(item == (void *)0x12);
+       assert(node->exceptional > 0);
+
+       radix_tree_split(&tree, 0, new_order);
+       radix_tree_for_each_slot(slot, &tree, &iter, 0) {
+               if (iter.index == (1 << new_order))
+                       radix_tree_iter_replace(&tree, &iter, slot,
+                                               (void *)0x16);
+               else
+                       radix_tree_iter_replace(&tree, &iter, slot, NULL);
+       }
+
+       item = __radix_tree_lookup(&tree, 1 << new_order, &node, NULL);
+       assert(item == (void *)0x16);
+       assert(node->count == node->exceptional);
+       do {
+               node = node->parent;
+               if (!node)
+                       break;
+               assert(node->count == 1);
+               assert(node->exceptional == 0);
+       } while (1);
+
+       item_kill_tree(&tree);
 }
 
 static void multiorder_split(void)
 {
        int i, j;
 
-       for (i = 9; i < 19; i++)
-               for (j = 0; j < i; j++)
+       for (i = 3; i < 11; i++)
+               for (j = 0; j < i; j++) {
                        __multiorder_split(i, j);
+                       __multiorder_split2(i, j);
+                       __multiorder_split3(i, j);
+               }
+}
+
+static void multiorder_account(void)
+{
+       RADIX_TREE(tree, GFP_KERNEL);
+       struct radix_tree_node *node;
+       void **slot;
+
+       item_insert_order(&tree, 0, 5);
+
+       __radix_tree_insert(&tree, 1 << 5, 5, (void *)0x12);
+       __radix_tree_lookup(&tree, 0, &node, NULL);
+       assert(node->count == node->exceptional * 2);
+       radix_tree_delete(&tree, 1 << 5);
+       assert(node->exceptional == 0);
+
+       __radix_tree_insert(&tree, 1 << 5, 5, (void *)0x12);
+       __radix_tree_lookup(&tree, 1 << 5, &node, &slot);
+       assert(node->count == node->exceptional * 2);
+       __radix_tree_replace(&tree, node, slot, NULL, NULL, NULL);
+       assert(node->exceptional == 0);
+
+       item_kill_tree(&tree);
 }
 
 void multiorder_checks(void)
@@ -507,6 +569,7 @@ void multiorder_checks(void)
        multiorder_tagged_iteration();
        multiorder_join();
        multiorder_split();
+       multiorder_account();
 
        radix_tree_cpu_dead(0);
 }