ovsdb: Check for ephemeral columns before writing a new schema.

Clustered databases do not support ephemeral columns, but ovsdb-server
checks for them after the conversion result is read from the storage.
It's much easier to recover if this constraint is checked before writing
to the storage instead.

It's not a big problem, because the check is always performed by the
native ovsdb clients before sending a conversion request.  But the
server, in general, should not trust clients to do the right thing.

Check in the update_schema() remains, because we shouldn't blindly
trust the storage.

Reviewed-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Dumitru Ceara <dceara@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

5 files changed, 23 insertions, 12 deletions

diff --git a/ovsdb/storage.c b/ovsdb/storage.c
index d4984be25..6069c4f10 100644
--- a/ovsdb/storage.c
+++ b/ovsdb/storage.c
@@ -622,7 +622,7 @@ ovsdb_storage_store_snapshot(struct ovsdb_storage *storage,
 
 struct ovsdb_write * OVS_WARN_UNUSED_RESULT
 ovsdb_storage_write_schema_change(struct ovsdb_storage *storage,
-                                  const struct json *schema,
+                                  const struct ovsdb_schema *schema,
                                   const struct json *data,
                                   const struct uuid *prereq,
                                   struct uuid *resultp)
@@ -632,13 +632,22 @@ ovsdb_storage_write_schema_change(struct ovsdb_storage *storage,
     if (storage->error) {
         w->error = ovsdb_error_clone(storage->error);
     } else if (storage->raft) {
-        struct json *txn_json = json_array_create_2(json_clone(schema),
-                                                    json_clone(data));
-        w->command = raft_command_execute(storage->raft, txn_json,
-                                          prereq, &result);
-        json_destroy(txn_json);
+        /* Clustered storage doesn't support ephemeral columns. */
+        w->error = ovsdb_schema_check_for_ephemeral_columns(schema);
+        if (!w->error) {
+            struct json *schema_json, *txn_json;
+
+            schema_json = ovsdb_schema_to_json(schema);
+            txn_json = json_array_create_2(schema_json, json_clone(data));
+            w->command = raft_command_execute(storage->raft, txn_json,
+                                              prereq, &result);
+            json_destroy(txn_json);
+        }
     } else if (storage->log) {
-        w->error = ovsdb_storage_store_snapshot__(storage, schema, data);
+        struct json *schema_json = ovsdb_schema_to_json(schema);
+
+        w->error = ovsdb_storage_store_snapshot__(storage, schema_json, data);
+        json_destroy(schema_json);
     } else {
         /* When 'error' and 'command' are both null, it indicates that the
          * command is complete.  This is fine since this unbacked storage drops
diff --git a/ovsdb/storage.h b/ovsdb/storage.h
index ff026b77f..6c69e5313 100644
--- a/ovsdb/storage.h
+++ b/ovsdb/storage.h
@@ -84,7 +84,7 @@ struct ovsdb_error *ovsdb_storage_store_snapshot(struct ovsdb_storage *storage,
 
 struct ovsdb_write *ovsdb_storage_write_schema_change(
     struct ovsdb_storage *,
-    const struct json *schema, const struct json *data,
+    const struct ovsdb_schema *, const struct json *data,
     const struct uuid *prereq, struct uuid *result)
     OVS_WARN_UNUSED_RESULT;
 
diff --git a/ovsdb/transaction.c b/ovsdb/transaction.c
index 9adbabf80..8eafefa4b 100644
--- a/ovsdb/transaction.c
+++ b/ovsdb/transaction.c
@@ -1191,7 +1191,7 @@ ovsdb_txn_precheck_prereq(const struct ovsdb *db)
 
 struct ovsdb_txn_progress *
 ovsdb_txn_propose_schema_change(struct ovsdb *db,
-                                const struct json *schema,
+                                const struct ovsdb_schema *schema,
                                 const struct json *data)
 {
     struct ovsdb_txn_progress *progress = xzalloc(sizeof *progress);
diff --git a/ovsdb/transaction.h b/ovsdb/transaction.h
index 6b5bb7f24..9991f34d2 100644
--- a/ovsdb/transaction.h
+++ b/ovsdb/transaction.h
@@ -21,6 +21,7 @@
 
 struct json;
 struct ovsdb;
+struct ovsdb_schema;
 struct ovsdb_table;
 struct uuid;
 
@@ -41,7 +42,7 @@ struct ovsdb_error *ovsdb_txn_propose_commit_block(struct ovsdb_txn *,
 void ovsdb_txn_complete(struct ovsdb_txn *);
 
 struct ovsdb_txn_progress *ovsdb_txn_propose_schema_change(
-    struct ovsdb *, const struct json *schema, const struct json *data);
+    struct ovsdb *, const struct ovsdb_schema *, const struct json *data);
 
 bool ovsdb_txn_progress_is_complete(const struct ovsdb_txn_progress *);
 const struct ovsdb_error *ovsdb_txn_progress_get_error(
diff --git a/ovsdb/trigger.c b/ovsdb/trigger.c
index 7d3003bca..3a693855b 100644
--- a/ovsdb/trigger.c
+++ b/ovsdb/trigger.c
@@ -274,8 +274,8 @@ ovsdb_trigger_try(struct ovsdb_trigger *t, long long int now)
             if (!error) {
                 error = ovsdb_convert(t->db, new_schema, &newdb);
             }
-            ovsdb_schema_destroy(new_schema);
             if (error) {
+                ovsdb_schema_destroy(new_schema);
                 trigger_convert_error(t, error);
                 return false;
             }
@@ -286,7 +286,8 @@ ovsdb_trigger_try(struct ovsdb_trigger *t, long long int now)
 
             /* Propose the change. */
             t->progress = ovsdb_txn_propose_schema_change(
-                t->db, new_schema_json, txn_json);
+                t->db, new_schema, txn_json);
+            ovsdb_schema_destroy(new_schema);
             json_destroy(txn_json);
             t->reply = jsonrpc_create_reply(json_object_create(),
                                             t->request->id);