generic: add a less thorough testing mode for fsync-err program

generic: add a less thorough testing mode for fsync-err program

Currently we just have this test run on a whitelist of filesystems,
but it would be best to be able to run it on all of them. The
problem is that a lot of filesystems basically shut down once they
hit metadata errors.

Allow the fsync-err testcase to operate in two different modes. One
mode just does basic testing to ensure that we get an error back on
all fd's when we fsync. The other does a more thorough test to
ensure that we get back 0 on subsequent fsyncs when there hasn't
been any write activity.

For now, we just opt-in to the more thorough testing on certain
filesystems: xfs, ext3 and ext4 on the generic test. All other
filesystems will run in simple mode.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>