Anatomy of fstatfs system call

sys_fstatfs(fd, buf) { /* for things like “df” */

file = fget(fd);

if ( file == NULL ) return -EBADF;

superb = file->f_dentry->d_inode->i_super;

rc = superb->sb_op->sb_statfs(sb, buf);

return rc;

}

Call into superblock layer of filesystem

Translate fd to VFS data structure