Add test which spawns two processes both writing one file via mmap.
Then to the test when processes first prefault the file by reading it
via mmap. This is mainly interesting to uncover races in DAX fault
handling.
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Jan Kara