Lab 07

NCTU OSDI Lab 7: Virtual File System

Documentation: Lab 7

Lab 7 Demo Release

Required

• Required 1
  • Set up tmpfs as the root file system.
• Requried 2
  • implement struct file* vfs_open(const char *pathname, int flags)
  • implement int vfs_close(struct file* file)
• Required 3
  • Implement int vfs_write(struct file* file, const void* buf, size_t len)
  • Implement int vfs_read(struct file* file, void* buf, size_t len)

Elective

• Elective 1
  • Implement an API for users to get the directory entries information from a directory.
• Elective 2
  • Implement file descriptor table for tasks.
  • Implement VFS system calls.
• Elective 3
  • Implement a VFS interface and a tmpfs method for int mkdir(const char* pathname).
  • Implement int chdir(const char* pathname)
  • Implement VFS interfaces and tmpfs methods for int mount(const char* device, const char* mountpoint, const char* filesystem) and int umount(const char* mountpoint).
    Implement pathname lookup.
• Elective 4
  • The procfs creates switch and hello file in its root directory. Users can access them by open, read, and write.
  • The procfs lazily updates the task-related directory and file. Users can read task’s status by reading <task id>/status
• Elective 5
  • Implement initramfs to populate the root file system.

Questions

• Is it possible that a file exists in a file system, but there is no vnode object of it?
• Is EOF pass to the reader by a special character in the reader’s buffer?
• Should each task owns its current working directory and the root directory?