[PATCH] mm: mincore anon

#include <linux/mm.h>

#include <linux/mman.h>

#include <linux/syscalls.h>

#include <linux/swap.h>

#include <linux/swapops.h>

#include <asm/uaccess.h>

#include <asm/pgtable.h>

 * and is up to date; i.e. that no page-in operation would be required

 * at this time if an application were to map and access this page.

 */

static unsigned char mincore_page(struct vm_area_struct * vma,

	unsigned long pgoff)

static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)

{

	unsigned char present = 0;

	struct address_space * as = vma->vm_file->f_mapping;

	struct page *page;

	page = find_get_page(as, pgoff);

	/*

	 * When tmpfs swaps out a page from a file, any process mapping that

	 * file will not get a swp_entry_t in its pte, but rather it is like

	 * any other file mapping (ie. marked !present and faulted in with

	 * tmpfs's .nopage). So swapped out tmpfs mappings are tested here.

	 *

	 * However when tmpfs moves the page from pagecache and into swapcache,

	 * it is still in core, but the find_get_page below won't find it.

	 * No big deal, but make a note of it.

	 */

	page = find_get_page(mapping, pgoff);

	if (page) {

		present = PageUptodate(page);

		page_cache_release(page);

 */

static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pages)

{

	unsigned long i, nr, pgoff;

	pgd_t *pgd;

	pud_t *pud;

	pmd_t *pmd;

	pte_t *ptep;

	spinlock_t *ptl;

	unsigned long nr;

	int i;

	pgoff_t pgoff;

	struct vm_area_struct *vma = find_vma(current->mm, addr);

	/*

		return -ENOMEM;

	/*

	 * Ok, got it. But check whether it's a segment we support

	 * mincore() on. Right now, we don't do any anonymous mappings.

	 *

	 * FIXME: This is just stupid. And returning ENOMEM is 

	 * stupid too. We should just look at the page tables. But

	 * this is what we've traditionally done, so we'll just

	 * continue doing it.

	 */

	if (!vma->vm_file)

		return -ENOMEM;

	/*

	 * Calculate how many pages there are left in the vma, and

	 * what the pgoff is for our address.

	 * Calculate how many pages there are left in the last level of the

	 * PTE array for our address.

	 */

	nr = (vma->vm_end - addr) >> PAGE_SHIFT;

	nr = PTRS_PER_PTE - ((addr >> PAGE_SHIFT) & (PTRS_PER_PTE-1));

	if (nr > pages)

		nr = pages;

	pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;

	pgoff += vma->vm_pgoff;

	pgd = pgd_offset(vma->vm_mm, addr);

	if (pgd_none_or_clear_bad(pgd))

		goto none_mapped;

	pud = pud_offset(pgd, addr);

	if (pud_none_or_clear_bad(pud))

		goto none_mapped;

	pmd = pmd_offset(pud, addr);

	if (pmd_none_or_clear_bad(pmd))

		goto none_mapped;

	ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);

	for (i = 0; i < nr; i++, ptep++, addr += PAGE_SIZE) {

		unsigned char present;

		pte_t pte = *ptep;

		if (pte_present(pte)) {

			present = 1;

		} else if (pte_none(pte)) {

			if (vma->vm_file) {

				pgoff = linear_page_index(vma, addr);

				present = mincore_page(vma->vm_file->f_mapping,

							pgoff);

			} else

				present = 0;

		} else if (pte_file(pte)) {

			pgoff = pte_to_pgoff(pte);

			present = mincore_page(vma->vm_file->f_mapping, pgoff);

		} else { /* pte is a swap entry */

			swp_entry_t entry = pte_to_swp_entry(pte);

			if (is_migration_entry(entry)) {

				/* migration entries are always uptodate */

				present = 1;

			} else {

				pgoff = entry.val;

				present = mincore_page(&swapper_space, pgoff);

			}

		}

	}

	pte_unmap_unlock(ptep-1, ptl);

	/* And then we just fill the sucker in.. */

	return nr;

none_mapped:

	if (vma->vm_file) {

		pgoff = linear_page_index(vma, addr);

		for (i = 0; i < nr; i++, pgoff++)

		vec[i] = mincore_page(vma, pgoff);

			vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);

	}

	return nr;

}