This patchset tries to add new IO_URING test into fsstress [1/3]. And then do some changes and bug fix by the way [2/3 and 3/3]. fsstress is an important tool in xfstests to do random filesystem I/Os test, lots of test cases use it. So add IO_URING operation into fsstress will help to make lots of test cases cover IO_URING test naturally. I'm not an IO_URING expert, so cc io-uring@ list, please feel free to tell me if you find something wrong or have any suggestions to improve the test. Thanks, Zorro
