The only XFS-specific part of this test is the setup, so we can make
the rest a generic test. It's slow, though, as it needs to write 8GB
to convert a big unwritten extent to written.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>