+
+int hugetlb_prefault(struct address_space *mapping, struct vm_area_struct *vma)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long addr;
+ int ret = 0;
+
+ WARN_ON(!is_vm_hugetlb_page(vma));
+ BUG_ON(vma->vm_start & ~HPAGE_MASK);
+ BUG_ON(vma->vm_end & ~HPAGE_MASK);
+
+ hugetlb_prefault_arch_hook(mm);
+
+ spin_lock(&mm->page_table_lock);
+ for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
+ unsigned long idx;
+ pte_t *pte = huge_pte_alloc(mm, addr);
+ struct page *page;
+
+ if (!pte) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ if (! pte_none(*pte))
+ hugetlb_clean_stale_pgtable(pte);
+
+ idx = ((addr - vma->vm_start) >> HPAGE_SHIFT)
+ + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
+ page = find_get_page(mapping, idx);
+ if (!page) {
+ /* charge the fs quota first */
+ if (hugetlb_get_quota(mapping)) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ page = alloc_huge_page();
+ if (!page) {
+ hugetlb_put_quota(mapping);
+ ret = -ENOMEM;
+ goto out;
+ }
+ ret = add_to_page_cache(page, mapping, idx, GFP_ATOMIC);
+ if (! ret) {
+ unlock_page(page);
+ } else {
+ hugetlb_put_quota(mapping);
+ free_huge_page(page);
+ goto out;
+ }
+ }
+ add_mm_counter(mm, rss, HPAGE_SIZE / PAGE_SIZE);
+ set_huge_pte_at(mm, addr, pte, make_huge_pte(vma, page));
+ }
+out:
+ spin_unlock(&mm->page_table_lock);
+ return ret;
+}
+
+int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
+ struct page **pages, struct vm_area_struct **vmas,
+ unsigned long *position, int *length, int i)
+{
+ unsigned long vpfn, vaddr = *position;
+ int remainder = *length;
+
+ BUG_ON(!is_vm_hugetlb_page(vma));
+
+ vpfn = vaddr/PAGE_SIZE;
+ while (vaddr < vma->vm_end && remainder) {
+
+ if (pages) {
+ pte_t *pte;
+ struct page *page;
+
+ /* Some archs (sparc64, sh*) have multiple
+ * pte_ts to each hugepage. We have to make
+ * sure we get the first, for the page
+ * indexing below to work. */
+ pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
+
+ /* hugetlb should be locked, and hence, prefaulted */
+ WARN_ON(!pte || pte_none(*pte));
+
+ page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
+
+ WARN_ON(!PageCompound(page));
+
+ get_page(page);
+ pages[i] = page;
+ }
+
+ if (vmas)
+ vmas[i] = vma;
+
+ vaddr += PAGE_SIZE;
+ ++vpfn;
+ --remainder;
+ ++i;
+ }
+
+ *length = remainder;
+ *position = vaddr;
+
+ return i;
+}