This makes it possible to do safe multi volume snapshots as long as one snapshots the volume with the transaction logs last.


include/mysql_com.h:
  Added REFRESH_CHECKPOINT
mysql-test/r/flush.result:
  Added test of new FLUSH TABLES syntax + calls to checkpoint_status handler calls
mysql-test/t/flush.test:
  Added test of new FLUSH TABLES syntax + calls to checkpoint_status handler calls
sql/handler.cc:
  Added code to call checkpoint_state for all handlertons that supports it
sql/handler.h:
  Added new checkpoint_state() handlerton call to temporarly disable checkpoints.
sql/lex.h:
  Added CHECKPOINT keyword
sql/sql_yacc.yy:
  Added support for FLUSH TABLES WITH READ LOCK AND DISABLE CHECKPOINT
storage/maria/ha_maria.cc:
  Added handlerton call to disable checkpoints.
storage/maria/ma_checkpoint.c:
  Don't do checkpoint if checkpoints are disabled.
storage/maria/ma_static.c:
  Added maria_checkpoint_disabled
storage/maria/maria_def.h:
  Added maria_checkpoint_disabled
storage/xtradb/handler/ha_innodb.cc:
  Added handlerton call to disable checkpoints.
storage/xtradb/include/log0log.h:
  Added option to log_checkpoint() to allow one to ignore not critical checkpoints during the time checkpoints are disabled.
storage/xtradb/log/log0log.c:
  Added code to allow one to disable checkpoints during a FLUSH TABLES ... DISABLE CHECKPOINT
  This was done by adding a new argument to log_checkpoint() which tells us when the checkpoint is called by srv_master_thread (which are safe to ignore)
storage/xtradb/srv/srv0srv.c:
  Tell log_checkpoint() that checkpoints from srv_master_thread() are safe to ignore (will just delay recovery time a bit).