On Tue 05-02-13 13:27:41, Andrew Morton wrote:
[...]
> > +static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
> > + unsigned long address)
> > +{
> > if (unlikely(is_vm_hugetlb_page(vma)))
> > return linear_hugepage_index(vma, address);
> > - pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
> > - pgoff += vma->vm_pgoff;
> > - return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
> > + return __linear_page_index(vma, address) >>
> > + (PAGE_CACHE_SHIFT - PAGE_SHIFT);
> > }
>
> I don't think we need bother creating both linear_page_index() and
> __linear_page_index(). Realistically, we won't be supporting
> PAGE_SHIFT!=PAGE_CACHE_SHIFT. And most (or all?) of the sites which
> you changed should have been using PAGE_CACHE_SHIFT anyway!
Except for hugetlb (huge_pmd_share, unmap_ref_private) which uses
PAGE_SHIFT to get an index into mapping. History proves there was
some confusion about those in the past (36e4f20a fixing 0c176d52). So
__linear_page_index makes some sense here.
--
Michal Hocko
SUSE Labs
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