radix-tree: Fix bug in remove_prefix()

Accidental decrement of the nr entries when a n256 didn't have the
entry in the first place.

base/data-struct/radix-tree.c

@@ -907,6 +907,9 @@ static bool _remove_subtree(struct radix_tree *rt, struct value *root, uint8_t *
 
  case NODE256:
  n256 = root->value.ptr;
+ if (n256->values[*kb].type == UNSET)
+ return true; // No entries
+
  r = _remove_subtree(rt, n256->values + (*kb), kb + 1, ke, count);
  if (r && n256->values[*kb].type == UNSET) {
  n256->nr_entries--;

test/unit/radix_tree_t.c

@@ -635,6 +635,121 @@ static void test_bcache_scenario(void *fixture)
 
 //----------------------------------------------------------------
 
+static void _bcs2_step1(struct radix_tree *rt)
+{
+ unsigned i;
+ uint8_t k[12];
+ union radix_value v;
+
+ memset(k, 0, sizeof(k));
+ for (i = 0x6; i < 0x69; i++) {
+ k[0] = i;
+ v.n = i;
+ T_ASSERT(radix_tree_insert(rt, k, k + sizeof(k), v));
+ }
+ T_ASSERT(radix_tree_is_well_formed(rt));
+}
+
+static void _bcs2_step2(struct radix_tree *rt)
+{
+ unsigned i;
+ uint8_t k[12];
+
+ memset(k, 0, sizeof(k));
+ for (i = 0x6; i < 0x69; i++) {
+ k[0] = i;
+ radix_tree_remove_prefix(rt, k, k + 4);
+ }
+ T_ASSERT(radix_tree_is_well_formed(rt));
+}
+
+static void test_bcache_scenario2(void *fixture)
+{
+ unsigned i;
+ struct radix_tree *rt = fixture;
+ uint8_t k[12];
+ union radix_value v;
+
+ _bcs2_step1(rt);
+ _bcs2_step2(rt);
+
+ memset(k, 0, sizeof(k));
+ for (i = 0; i < 50; i++) {
+ k[0] = 0x6;
+ v.n = 0x6;
+ T_ASSERT(radix_tree_insert(rt, k, k + sizeof(k), v));
+ radix_tree_remove_prefix(rt, k, k + 4);
+ }
+ T_ASSERT(radix_tree_is_well_formed(rt));
+
+ _bcs2_step1(rt);
+ _bcs2_step2(rt);
+ _bcs2_step1(rt);
+ _bcs2_step2(rt);
+
+ memset(k, 0, sizeof(k));
+ for(i = 0x6; i < 0x37; i++) {
+ k[0] = i;
+ k[4] = 0xf;
+ k[5] = 0x1;
+ T_ASSERT(radix_tree_insert(rt, k, k + sizeof(k), v));
+ k[4] = 0;
+ k[5] = 0;
+ T_ASSERT(radix_tree_insert(rt, k, k + sizeof(k), v));
+ }
+ T_ASSERT(radix_tree_is_well_formed(rt));
+
+ memset(k, 0, sizeof(k));
+ for (i = 0x38; i < 0x69; i++) {
+ k[0] = i - 0x32;
+ k[4] = 0xf;
+ k[5] = 1;
+ T_ASSERT(radix_tree_remove(rt, k, k + sizeof(k)));
+
+ k[0] = i;
+ T_ASSERT(radix_tree_insert(rt, k, k + sizeof(k), v));
+
+ k[0] = i - 0x32;
+ k[4] = 0;
+ k[5] = 0;
+ T_ASSERT(radix_tree_remove(rt, k, k + sizeof(k)));
+
+ k[0] = i;
+ T_ASSERT(radix_tree_insert(rt, k, k + sizeof(k), v));
+ }
+ T_ASSERT(radix_tree_is_well_formed(rt));
+
+ memset(k, 0, sizeof(k));
+ k[0] = 0x6;
+ radix_tree_remove_prefix(rt, k, k + 4);
+ T_ASSERT(radix_tree_is_well_formed(rt));
+
+ k[0] = 0x38;
+ k[4] = 0xf;
+ k[5] = 0x1;
+ T_ASSERT(radix_tree_remove(rt, k, k + sizeof(k)));
+ T_ASSERT(radix_tree_is_well_formed(rt));
+
+ memset(k, 0, sizeof(k));
+ k[0] = 0x6;
+ T_ASSERT(radix_tree_insert(rt, k, k + sizeof(k), v));
+ T_ASSERT(radix_tree_is_well_formed(rt));
+
+ k[0] = 0x7;
+ radix_tree_remove_prefix(rt, k, k + 4);
+ T_ASSERT(radix_tree_is_well_formed(rt));
+
+ k[0] = 0x38;
+ T_ASSERT(radix_tree_remove(rt, k, k + sizeof(k)));
+ T_ASSERT(radix_tree_is_well_formed(rt));
+
+ k[0] = 7;
+ T_ASSERT(radix_tree_insert(rt, k, k + sizeof(k), v));
+ T_ASSERT(radix_tree_is_well_formed(rt));
+}
+
+//----------------------------------------------------------------
+
 #define T(path, desc, fn) register_test(ts, "/base/data-struct/radix-tree/" path, desc, fn)
 
 void radix_tree_tests(struct dm_list *all_tests)
@@ -668,6 +783,7 @@ void radix_tree_tests(struct dm_list *all_tests)
  T("remove-calls-dtr", "remove should call the dtr for the value", test_remove_calls_dtr);
  T("destroy-calls-dtr", "destroy should call the dtr for all values", test_destroy_calls_dtr);
  T("bcache-scenario", "A specific series of keys from a bcache scenario", test_bcache_scenario);
+ T("bcache-scenario-2", "A second series of keys from a bcache scenario", test_bcache_scenario2);
 
  dm_list_add(all_tests, &ts->list);
 }