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[PATCH] mm: mincore anon 

Make mincore work for anon mappings, nonlinear, and migration entries.
Based on patch from Linus Torvalds <torvalds@linux-foundation.org>.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nick Piggin 2007-02-12 00:51:39 -08:00 committed by Linus Torvalds
parent 22cd25ed31
commit 42da9cbd3e
1 changed files with 76 additions and 26 deletions
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102
mm/mincore.c
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@ -12,6 +12,8 @@
#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>
@ -22,14 +24,22 @@
* 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;
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);
@ -45,7 +55,14 @@ static unsigned char mincore_page(struct vm_area_struct * vma,
*/
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);
/*
@ -56,31 +73,64 @@ static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pag
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.
* Calculate how many pages there are left in the last level of the
* PTE array for our address.
*/
if (!vma->vm_file)
return -ENOMEM;
/*
* Calculate how many pages there are left in the vma, and
* what the pgoff is 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;
/* And then we just fill the sucker in.. */
for (i = 0 ; i < nr; i++, pgoff++)
vec[i] = mincore_page(vma, pgoff);
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);
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->vm_file->f_mapping, pgoff);
}
return nr;
}