If I start a default test run with runltp, all of the diotest runs except diotest1 will fail with an error that mkdtemp hit no such file or directory. It appears that the tmp directory is getting removed somehow after the first test and then all the subsequent tests fail. I can get around the problem by not specifying a tmp dir option to runltp and instead setting an environment variable for TDIRECTORY which according to tst_tmpdir code is not removed.
Forgot to add; I'm using version ltp-full-20090831