whint_mode=%s          Control which write hints are passed down to block
                       layer. This supports "off", "user-based", and
                       "fs-based".  In "off" mode (default), f2fs does not pass
                       down hints. In "user-based" mode, f2fs tries to pass
                       down hints given by users. And in "fs-based" mode, f2fs
                       passes down hints with its policy.