in file buf0mtflu.cc line 439
Analysis: At shutdown multi-threaded flush sends a exit work
items to all mtflush threads. We wait until the work queue is
empty. However, as we did not hold the mutex, some other thread
could also put work-items to work queue.
Fix: Take mutex before adding exit work items to work queue and
wait until all work-items are really processed. Release
mutex after we have marked that multi-threaded flush is not
anymore active.
Fix test failure on innodb_bug12902967 caused by unnecessary
info output on xtradb/buf/buf0mtflush.cc.
Do not try to enable atomic writes if the file type
is not OS_DATA_FILE. Atomic writes are unnecessary
for log files. If we try to enable atomic writes
to log writes that are stored to media supporting
atomic writes we will end up problems later.