ext2_iget
extern struct inode *ext2_iget (struct super_block *, unsigned long);
inode = ext2_iget(dir->i_sb, ino);
return d_obtain_alias(ext2_iget(child->d_sb, ino));
root = ext2_iget(sb, EXT2_ROOT_INO);
inode = ext2_iget(sb, ino);