Storage-class memory based method for improving performance of log file system

The invention discloses an SCM (storage-class memory) based method for improving the performance of a log file system. An SCM serves as a memory device for storing metadata and logs of the file system, so that the reading and writing of the metadata are optimized; coverage writing and additional writing are distinguished, only coverage writing data are written in the logs, additional writing data are directly written in the file system, and an update sequence is controlled to ensure the consistency of the file system, reduce the log overhead, and improve the performance of the file system; and the characteristic of modification by byte for the SCM is utilized, and the difference between new and old log blocks is computed, so that the update of log byte granularity is realized, and log data streams are reduced. The method mainly comprises five operations of storage system construction, log writing, garbage collection, data back-writing and system recovery, can be used for various log file systems, is suitable for constructing high-performance, high-capacity and high-reliability large-sized storage systems, and solves the problems of high extra overhead, high metadata back-writing frequency, low recovery speed after downtime and the like of a log technology in an existing log file system.