trans_logger: fix possible endless loop on termination
lib_log: change misleading wording of error message
infra: add tracing of max region to mapfree
aio: fix race on file length (workaround)

It appears that concurrent reads and writes on AIO seem to
result in inconsistent reads in some very rare cases, due to
races. Sometimes, the inode claims that the file has been already
appended by a write operation, but the data has not actually hit
the page cache, such that a concurrent read gets NULL blocks.

This is a workaround by "misusing" the mapfree infrastructure.
It depends on uniqueness of file names, which is not the right thing
to do.

Best fix would be in the kernel.
infra: remove obsolete black interface

The backing file should not be exposed from the brick blackbox.
infra: initialize IO transfer metadata correctly
trans_logger: report replay errors separately