A low-latency file system file address space management method and system, and a medium. The method of the present invention comprises: generating a superblock and a block group allocation table from an address space of a storage device, wherein the superblock stores file system information and the allocation situation of block groups on a liner address space of the storage device, and the block group allocation table is used for marking the allocation situation of data blocks in the corresponding block group; when a file is created, dynamically creating or selecting a corresponding block group according to the size of a specified data block and allocating the data block; and writing file data into the allocated data block, and updating the block group allocation table and information of the superblock.