dsdb: Wait until a transaction starts to call dsdb_schema_set_indices_and_attributes()

This avoids starting a transaction in schema_load_init() and allows it
to operate with a read lock held, which will avoid locking issues
(deadlock detected due to lock odering if we do not have a global
read lock).

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13379

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>

diff --git a/selftest/knownfail.d/dsdb_schema_attributes b/selftest/knownfail.d/dsdb_schema_attributes
new file mode 100644 (file)
index 0000000..4e9e7a0
--- /dev/null
+++ b/selftest/knownfail.d/dsdb_schema_attributes
@@ -0,0 +1,2 @@
+^samba.tests.dsdb_schema_attributes.samba.tests.dsdb_schema_attributes.SchemaAttributesTestCase.test_modify_at_attributes
+^samba.tests.dsdb_schema_attributes.samba.tests.dsdb_schema_attributes.SchemaAttributesTestCase.test_modify_at_indexlist

diff --git a/source4/dsdb/samdb/ldb_modules/schema_load.c b/source4/dsdb/samdb/ldb_modules/schema_load.c
index 2099fac1159ed59104bef185a4417e61db635473..55fb63a0f30f78669014bcdddc1c649463e89c30 100644 (file)
--- a/source4/dsdb/samdb/ldb_modules/schema_load.c
+++ b/source4/dsdb/samdb/ldb_modules/schema_load.c
@@ -42,6 +42,12 @@ struct schema_load_private_data {
        uint64_t schema_seq_num_read_lock;
        uint64_t schema_seq_num_cache;
        int tdb_seqnum;
+
+       /*
+        * Please write out the updated schema on the next transaction
+        * start
+        */
+       bool need_write;
 };
 
 static int dsdb_schema_from_db(struct ldb_module *module,
@@ -495,7 +501,6 @@ static int schema_load_init(struct ldb_module *module)
        struct ldb_context *ldb = ldb_module_get_ctx(module);
        struct schema_load_private_data *private_data;
        int ret;
-       bool need_write = false;
 
        private_data = talloc_zero(module, struct schema_load_private_data);
        if (private_data == NULL) {
@@ -510,50 +515,7 @@ static int schema_load_init(struct ldb_module *module)
                return ret;
        }
 
-       ret = schema_load(ldb, module, &need_write);
-
-       if (ret == LDB_SUCCESS && need_write) {
-               TALLOC_CTX *frame = talloc_stackframe();
-               struct dsdb_schema *schema = NULL;
-
-               ret = ldb_transaction_start(ldb);
-               if (ret != LDB_SUCCESS) {
-                       ldb_debug_set(ldb, LDB_DEBUG_FATAL,
-                                     "schema_load_init: transaction start failed");
-                       return LDB_ERR_OPERATIONS_ERROR;
-               }
-
-               schema = dsdb_get_schema(ldb, frame);
-               if (schema == NULL) {
-                       ldb_debug_set(ldb, LDB_DEBUG_FATAL,
-                                     "schema_load_init: dsdb_get_schema failed");
-                       ldb_transaction_cancel(ldb);
-                       return LDB_ERR_OPERATIONS_ERROR;
-               }
-               ret = dsdb_schema_set_indices_and_attributes(ldb, schema,
-                                                            SCHEMA_WRITE);
-
-               TALLOC_FREE(frame);
-
-               if (ret != LDB_SUCCESS) {
-                       ldb_asprintf_errstring(ldb, "Failed to write new "
-                                              "@INDEXLIST and @ATTRIBUTES "
-                                              "records for updated schema: %s",
-                                              ldb_errstring(ldb));
-                       ldb_transaction_cancel(ldb);
-                       return ret;
-               }
-
-               ret = ldb_transaction_commit(ldb);
-               if (ret != LDB_SUCCESS) {
-                       ldb_debug_set(ldb, LDB_DEBUG_FATAL,
-                                     "schema_load_init: transaction commit failed");
-                       return LDB_ERR_OPERATIONS_ERROR;
-               }
-       }
-
-
-       return ret;
+       return schema_load(ldb, module, &private_data->need_write);
 }
 
 static int schema_search(struct ldb_module *module, struct ldb_request *req)
@@ -586,6 +548,14 @@ static int schema_load_start_transaction(struct ldb_module *module)
                              "schema_load_init: dsdb_get_schema failed");
                return LDB_ERR_OPERATIONS_ERROR;
        }
+
+       if (private_data->need_write) {
+               ret = dsdb_schema_set_indices_and_attributes(ldb,
+                                                            schema,
+                                                            SCHEMA_WRITE);
+               private_data->need_write = false;
+       }
+
        private_data->in_transaction++;
 
        return ret;