wsrep_dump_rbr_buf in wsrep_apply_cb should be avoided for (ignored) TOI errors

[Raghavendra D Prabhu]

Testing with fk grammar

perl runall-new.pl --basedir=/pxc56 --vardir=/tmp/node1 --galera=ms --grammar=conf/galera/galera_stress-fk.yy --gendata=conf/galera/galera_stress-56.zz --mysqld=--innodb_buffer_pool_size=500M --mysqld=--query_cache_type=0 --mysqld=--wsrep_slave_threads=8 --mysqld=--query_cache_size=0 --mysqld=--innodb_flush_log_at_trx_commit=0 --reporter=Shutdown,Backtrace,ErrorLog,ErrorLogAlarm,Deadlock --threads=16 --queries=30000 --mysqld=--wsrep-provider=/pxc56/lib/libgalera_smm.so --seed=time --mysqld=--innodb_flush_method=O_DIRECT

overwhelmed the filesystem with hundreds of GRA files containing DDLs.

They were on applier end and from ignored TOI errors.

wsrep_apply_cb:

  if (WSREP_CB_SUCCESS != rcode)
  {
    wsrep_dump_rbr_buf(thd, buf, buf_len);
  }

It would be best to not dump in case of ignored errors or use wsrep-debug with them. (or both)

[Raghavendra D Prabhu (raghavendra-prabhu)]

This is severe for TOI errors since they are passed first without evaluation on the master node and then error is returned.

This makes it easy to DOS other nodes by creating spurious DDLs on one
node and filling the filesystem on other nodes with GRA* files. Note,
that even a user without DDL credentials can do this.

[Raghavendra D Prabhu (raghavendra-prabhu)]

Actually, credentials checking is done before, so that shouldn't be a problem here. (test database is an exception).

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PXC-1622