A file data access method and a computer system, where the method includes accessing a page global directory (PGD) of the process using PGD space when accessing first file data by a process, determining, based on access to the PGD and according to a first virtual address of the first file data in file system space, a first PGD entry in the PGD, linking a file page table of the process to the first PGD entry, where the file page table points to a physical address of the file data such that a processor retrieves a first physical address of the first file data in a memory according to the first virtual address using the PGD and the file page table, and accessing the first file data according to the first physical address.