Merging r4077, r4101, r4102:

Merging r4077, r4101, r4102:

open_file_cache related fixes:

*) Bugfix: open_file_cache lost is_directio flag.

On file retest open_file_cache lost is_directio if file wasn't changed.
This caused unaligned operations under Linux to fail with EINVAL.
It wasn't noticeable with AIO though, as errors wasn't properly logged.

*) Bugfix: open_file_cache did not update file info on retest.

If file inode was not changed, cached file information was not updated
on retest.  As a result stale information might be cached forever if file
attributes was changed and/or file was extended.