On (19/02/07 22:29), Christoph Hellwig didst pronounce:
> On Mon, Feb 19, 2007 at 10:31:34AM -0800, Adam Litke wrote:
> > Signed-off-by: Adam Litke <[EMAIL PROTECTED]>
> > ---
> >
> > include/linux/mm.h | 25 +++++++++++++++++++++++++
> > 1 files changed, 25 insertions(+), 0 deletions(-)
> >
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index 2d2c08d..a2fa66d 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -98,6 +98,7 @@ struct vm_area_struct {
> >
> > /* Function pointers to deal with this struct. */
> > struct vm_operations_struct * vm_ops;
> > + struct pagetable_operations_struct * pagetable_ops;
> >
> > /* Information about our backing store: */
> > unsigned long vm_pgoff; /* Offset (within vm_file) in PAGE_SIZE
> > @@ -218,6 +219,30 @@ struct vm_operations_struct {
> > };
> >
> > struct mmu_gather;
> > +
> > +struct pagetable_operations_struct {
> > + int (*fault)(struct mm_struct *mm,
> > + struct vm_area_struct *vma,
> > + unsigned long address, int write_access);
> > + int (*copy_vma)(struct mm_struct *dst, struct mm_struct *src,
> > + struct vm_area_struct *vma);
> > + int (*pin_pages)(struct mm_struct *mm, struct vm_area_struct *vma,
> > + struct page **pages, struct vm_area_struct **vmas,
> > + unsigned long *position, int *length, int i);
> > + void (*change_protection)(struct vm_area_struct *vma,
> > + unsigned long address, unsigned long end, pgprot_t newprot);
> > + unsigned long (*unmap_page_range)(struct vm_area_struct *vma,
> > + unsigned long address, unsigned long end, long *zap_work);
> > + void (*free_pgtable_range)(struct mmu_gather **tlb,
> > + unsigned long addr, unsigned long end,
> > + unsigned long floor, unsigned long ceiling);
> > +};
>
> I don't think adding another operation vector is a good idea. But I'd
> rather extend the vma operations vector to deal with all nessecary
> buts ubstead if addubg a second one.
Well, there are a lot of users of vm_operations_struct that have no interest in
the operations in pagetable_operations_struct. Expanding vm_operations_struct
would increase the size of all VMAs by more than is necessary.
Also, having the pagetable ops in vm_operations_struct might lead device
drivers to believe they should be doing something entertaining there. In
reality, we would only want drivers playing with pagetable_operations when
they really know what they are doing and why. Having the pagetable_ops
set is similar to VM_HUGETLB set as a strong sign that something unusual is
going on that is fairly easy to check for.
I prefer the additional struct to extending VMAs anyway.
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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