PXB-3227 Dropped table is still in the backup

How to reproduce :
1 . Create table t1.ibd before the backup
2. Start backup with --lock-ddl=REDUCED
3. Pause at debug_sync_point("xtrabackup_suspend_at_start");
4. RENAME t1.ibd -> t2.ibd
5. DROP t2.ibd
6. Run prepare
7. we end up with t1.ibd in the backup which should have been dropped

PXB-3229 Can't create/write to file 't2.ibd.del' (OS errno 17 - File exists)
How to reproduce :
1.Create tables t1.ibd t3.ibd before the backup
2.Start backup with --lock-ddl=REDUCED
3.Pause atdebug_sync_point("xtrabackup_suspend_at_start");
4.RENAME t1.ibd -> t2.ibd
5.DROP t2.ibd
6.RENAME t3.ibd -> t2.ibd
7.DROP t2.ibd
8.Can't create/write to file 't2.ibd.del' (OS errno 17 - File exists)

Fix:
if dropped table was renamed from another table and original_table was created before backup started and have been copied then we should create `.del` file for original_table and skip creating `.del` file for renamed_table

storage/innobase/xtrabackup/src/ddl_tracker.cc

@@ -195,11 +195,19 @@ void ddl_tracker_t::handle_ddl_operations() {
 
   /* Some tables might get to the new list if the DDL happen in between
    * redo_mgr.start and xb_load_tablespaces. This causes we ending up with two
-   * tablespaces with the same spaceID. Remove them from new tables */
+   * tablespaces with the same spaceID. Remove them from new tables
+   *
+   * Rename DDL can happen in between redo_mgr.start and xb_load_tablespaces
+   * as well. In this case we should erase rename DDL cause we already scanned
+   * the table with new name */
   for (auto &table : tables_in_backup) {
     if (new_tables.find(table.first) != new_tables.end()) {
       new_tables.erase(table.first);
     }
+    if (renames.find(table.first) != renames.end() &&
+        renames[table.first].second == table.second) {
+      renames.erase(table.first);
+    }
   }
 
   /* recopy_tables will be handled as follow:
@@ -223,15 +231,36 @@ void ddl_tracker_t::handle_ddl_operations() {
     if (check_if_skip_table(table.second.c_str())) {
       continue;
     }
-    /* Remove from rename */
-    renames.erase(table.first);
 
-    /* Remove from new tables and skip drop*/
+    /* Remove from new tables and skip drop */
     if (new_tables.find(table.first) != new_tables.end()) {
       new_tables.erase(table.first);
+
+      /* Remove from rename */
+      renames.erase(table.first);
+      continue;
+    }
+
+    /* If table_space_id does not exist in new_tables nor in tables_in_backup
+      then this drop ddl happened between redo_mgr.start and xb_tablespace_load.
+      We skip drop.
+    */
+    if (new_tables.find(table.first) == new_tables.end() &&
+        tables_in_backup.find(table.first) == tables_in_backup.end()) {
       continue;
     }
-    backup_file_printf((table.second + ".del").c_str(), "%s", "");
+
+    if (renames.find(table.first) != renames.end()) {
+      /* If original table was there before backup start and have been copied
+        then we should delete it */
+      backup_file_printf((renames[table.first].first + ".del").c_str(), "%s",
+                         "");
+
+      /* Remove from rename */
+      renames.erase(table.first);
+    } else {
+      backup_file_printf((table.second + ".del").c_str(), "%s", "");
+    }
   }
 
   for (auto &table : renames) {

storage/innobase/xtrabackup/src/xtrabackup.cc

@@ -4254,6 +4254,9 @@ void xtrabackup_backup_func(void) {
 
   Tablespace_map::instance().scan(mysql_connection);
 
+  debug_sync_point(
+      "xtrabackup_suspend_between_redo_mgr_start_and_xb_load_tablespaces");
+
   /* Populate fil_system with tablespaces to copy */
   dberr_t err = xb_load_tablespaces();
   if (err != DB_SUCCESS) {

storage/innobase/xtrabackup/test/suites/lockless/rename_then_drop_table.sh

@@ -0,0 +1,99 @@
+#########################################################################################
+# PXB-3227: Rename table and then drop table, make sure that original table was deleted 
+#########################################################################################
+
+. inc/common.sh
+
+require_debug_pxb_version
+start_server
+
+$MYSQL $MYSQL_ARGS -Ns -e "CREATE TABLE test.original_table (id INT PRIMARY KEY AUTO_INCREMENT); INSERT INTO test.original_table VALUES(1);" test
+innodb_wait_for_flush_all
+
+xtrabackup --backup --target-dir=$topdir/backup \
+  --debug-sync="xtrabackup_suspend_at_start" --lock-ddl=REDUCED \
+  2> >( tee $topdir/backup.log)&
+
+job_pid=$!
+pid_file=$topdir/backup/xtrabackup_debug_sync
+wait_for_xb_to_suspend $pid_file
+xb_pid=`cat $pid_file`
+echo "backup pid is $job_pid"
+
+# Rename table and generate redo
+$MYSQL $MYSQL_ARGS -Ns -e "RENAME TABLE test.original_table TO test.renamed_table; INSERT INTO test.renamed_table VALUES (2);" test
+# Drop table
+$MYSQL $MYSQL_ARGS -Ns -e "DROP TABLE test.renamed_table;" test
+
+# Resume the xtrabackup process
+vlog "Resuming xtrabackup"
+kill -SIGCONT $xb_pid
+run_cmd wait $job_pid
+
+if ! egrep -q "Done: Writing file $topdir/backup/test/original_table.ibd.del" $topdir/backup.log ; then
+    die "xtrabackup did not create .del file for original_table"
+fi
+
+xtrabackup --prepare --target-dir=$topdir/backup
+record_db_state test
+stop_server
+rm -rf $mysql_datadir/*
+xtrabackup --copy-back --target-dir=$topdir/backup
+start_server
+verify_db_state test
+
+if [ -f $mysql_datadir/test/original_table.ibd ] ; then
+    die 'dropped original_table.ibd file has been copied to the datadir'
+fi
+
+stop_server
+rm -rf $topdir/backup
+
+#########################################################################################################
+# PXB-3229: Make sure backup does not fail with `File exists` error trying to create .del file twice 
+#########################################################################################################
+
+start_server
+
+$MYSQL $MYSQL_ARGS -Ns -e "CREATE TABLE test.t1 (id INT PRIMARY KEY AUTO_INCREMENT); INSERT INTO test.t1 VALUES(1);" test
+$MYSQL $MYSQL_ARGS -Ns -e "CREATE TABLE test.t2 (id INT PRIMARY KEY AUTO_INCREMENT); INSERT INTO test.t2 VALUES(1);" test
+innodb_wait_for_flush_all
+
+xtrabackup --backup --target-dir=$topdir/backup \
+  --debug-sync="xtrabackup_suspend_at_start" --lock-ddl=REDUCED \
+  2> >( tee $topdir/backup.log)&
+
+job_pid=$!
+pid_file=$topdir/backup/xtrabackup_debug_sync
+wait_for_xb_to_suspend $pid_file
+xb_pid=`cat $pid_file`
+echo "backup pid is $job_pid"
+
+# Rename table and generate redo
+$MYSQL $MYSQL_ARGS -Ns -e "RENAME TABLE test.t1 TO test.t3; INSERT INTO test.t3 VALUES (2);" test
+# Drop table
+$MYSQL $MYSQL_ARGS -Ns -e "DROP TABLE test.t3;" test
+# Rename table and generate redo
+$MYSQL $MYSQL_ARGS -Ns -e "RENAME TABLE test.t2 TO test.t3; INSERT INTO test.t3 VALUES (2);" test
+# Drop table
+$MYSQL $MYSQL_ARGS -Ns -e "DROP TABLE test.t3;" test
+
+# Resume the xtrabackup process
+vlog "Resuming xtrabackup"
+kill -SIGCONT $xb_pid
+run_cmd wait $job_pid
+
+xtrabackup --prepare --target-dir=$topdir/backup
+record_db_state test
+stop_server
+rm -rf $mysql_datadir/*
+xtrabackup --copy-back --target-dir=$topdir/backup
+start_server
+verify_db_state test
+stop_server
+rm -rf $mysql_datadir $topdir/backup
+
+
+
+
+