Test if direct write invalidates pagecache correctly, so that
subsequent buffer read reads the correct data from disk.
This test is inspired by LTP tests dio29, and serves as a regression
test for the bug found by it, see kernel commit c771c14baa33
("iomap: invalidate page caches should be after iomap_dio_complete()
in direct write").
The test can be easily expanded to other write/read combinations,
e.g. buffer write + direct read and direct write + direct read, so
they are also being tested.
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>
Eryu Guan