d_lookup in real-lookup?

[krushnaal pai <krisonearth@xxxxxxxxx>]

in kernel 2.6.11
> to retrieve a particular file the kernel calls d_lookup to check cache but
> if  it is not found in dcache ,kernel calls real_lookup to search the hard
> disk.
> however inside real_lookup the kernel again calls d_lookup . can someone plz
> explain why?
>