With recent advancement in NVM technologies, non-volatile main memory(NVMM) has been highlighted as promising systems for large scale data centers. By utilizing memory-mapped IO, researchers have attempted to provide fast IOs without kernel mode switches and complex kernel IO layers. Even though they improve the performance by taking advantage of NVMM characteristics, memory-mapped IOs still require additional user-level logging techniques to guarantee write atomicity and file system integrity. We propose a user-level library file system, Libpubl, which is designed to minimize the write amplification overhead of traditional logging by exploiting persistent user buffers as logs. Libpubl ensures atomic updates of data and improves the performance and the scalability. Compared to the state-of-the-art NVM file systems, Libpubl increases the performance by 50~120% in Fio benchmark.