From: Peter Zijlstra <[email protected]>
With the tracking of dirty pages properly done now, msync doesn't need to
scan the pte's anymore to determine the dirty status.
Signed-off-by: Peter Zijlstra <[email protected]>
mm/msync.c | 145 ++++---------------------------------------------------------
1 file changed, 10 insertions(+), 135 deletions(-)
Index: linux-2.6/mm/msync.c
===================================================================
--- linux-2.6.orig/mm/msync.c 2006-05-24 18:03:15.000000000 +0200
+++ linux-2.6/mm/msync.c 2006-05-24 18:38:09.000000000 +0200
@@ -20,128 +20,20 @@
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
-static unsigned long msync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
- unsigned long addr, unsigned long end)
-{
- pte_t *pte;
- spinlock_t *ptl;
- int progress = 0;
- unsigned long ret = 0;
-
-again:
- pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
- do {
- struct page *page;
-
- if (progress >= 64) {
- progress = 0;
- if (need_resched() || need_lockbreak(ptl))
- break;
- }
- progress++;
- if (!pte_present(*pte))
- continue;
- if (!pte_maybe_dirty(*pte))
- continue;
- page = vm_normal_page(vma, addr, *pte);
- if (!page)
- continue;
- if (ptep_clear_flush_dirty(vma, addr, pte) ||
- page_test_and_clear_dirty(page))
- ret += set_page_dirty(page);
- progress += 3;
- } while (pte++, addr += PAGE_SIZE, addr != end);
- pte_unmap_unlock(pte - 1, ptl);
- cond_resched();
- if (addr != end)
- goto again;
- return ret;
-}
-
-static inline unsigned long msync_pmd_range(struct vm_area_struct *vma,
- pud_t *pud, unsigned long addr, unsigned long end)
-{
- pmd_t *pmd;
- unsigned long next;
- unsigned long ret = 0;
-
- pmd = pmd_offset(pud, addr);
- do {
- next = pmd_addr_end(addr, end);
- if (pmd_none_or_clear_bad(pmd))
- continue;
- ret += msync_pte_range(vma, pmd, addr, next);
- } while (pmd++, addr = next, addr != end);
- return ret;
-}
-
-static inline unsigned long msync_pud_range(struct vm_area_struct *vma,
- pgd_t *pgd, unsigned long addr, unsigned long end)
-{
- pud_t *pud;
- unsigned long next;
- unsigned long ret = 0;
-
- pud = pud_offset(pgd, addr);
- do {
- next = pud_addr_end(addr, end);
- if (pud_none_or_clear_bad(pud))
- continue;
- ret += msync_pmd_range(vma, pud, addr, next);
- } while (pud++, addr = next, addr != end);
- return ret;
-}
-
-static unsigned long msync_page_range(struct vm_area_struct *vma,
- unsigned long addr, unsigned long end)
-{
- pgd_t *pgd;
- unsigned long next;
- unsigned long ret = 0;
-
- /* For hugepages we can't go walking the page table normally,
- * but that's ok, hugetlbfs is memory based, so we don't need
- * to do anything more on an msync().
- */
- if (vma->vm_flags & VM_HUGETLB)
- return 0;
-
- BUG_ON(addr >= end);
- pgd = pgd_offset(vma->vm_mm, addr);
- flush_cache_range(vma, addr, end);
- do {
- next = pgd_addr_end(addr, end);
- if (pgd_none_or_clear_bad(pgd))
- continue;
- ret += msync_pud_range(vma, pgd, addr, next);
- } while (pgd++, addr = next, addr != end);
- return ret;
-}
-
/*
* MS_SYNC syncs the entire file - including mappings.
*
- * MS_ASYNC does not start I/O (it used to, up to 2.5.67). Instead, it just
- * marks the relevant pages dirty. The application may now run fsync() to
+ * MS_ASYNC does not start I/O (it used to, up to 2.5.67).
+ * Nor does it just marks the relevant pages dirty (it used to up to 2.6.17).
+ * Now it doesn't do anything, since dirty pages are properly tracked.
+ *
+ * The application may now run fsync() to
* write out the dirty pages and wait on the writeout and check the result.
* Or the application may run fadvise(FADV_DONTNEED) against the fd to start
* async writeout immediately.
* So by _not_ starting I/O in MS_ASYNC we provide complete flexibility to
* applications.
*/
-static int msync_interval(struct vm_area_struct *vma, unsigned long addr,
- unsigned long end, int flags,
- unsigned long *nr_pages_dirtied)
-{
- struct file *file = vma->vm_file;
-
- if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED))
- return -EBUSY;
-
- if (file && (vma->vm_flags & VM_SHARED))
- *nr_pages_dirtied = msync_page_range(vma, addr, end);
- return 0;
-}
asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
{
@@ -157,6 +49,10 @@ asmlinkage long sys_msync(unsigned long
goto out;
if ((flags & MS_ASYNC) && (flags & MS_SYNC))
goto out;
+ if (flags & MS_ASYNC) {
+ error = 0;
+ goto out;
+ }
error = -ENOMEM;
len = (len + ~PAGE_MASK) & PAGE_MASK;
end = start + len;
@@ -178,7 +74,6 @@ asmlinkage long sys_msync(unsigned long
goto out_unlock;
}
do {
- unsigned long nr_pages_dirtied = 0;
struct file *file;
/* Here start < vma->vm_end. */
@@ -188,32 +83,12 @@ asmlinkage long sys_msync(unsigned long
}
/* Here vma->vm_start <= start < vma->vm_end. */
if (end <= vma->vm_end) {
- if (start < end) {
- error = msync_interval(vma, start, end, flags,
- &nr_pages_dirtied);
- if (error)
- goto out_unlock;
- }
error = unmapped_error;
done = 1;
- } else {
- /* Here vma->vm_start <= start < vma->vm_end < end. */
- error = msync_interval(vma, start, vma->vm_end, flags,
- &nr_pages_dirtied);
- if (error)
- goto out_unlock;
}
file = vma->vm_file;
start = vma->vm_end;
- if ((flags & MS_ASYNC) && file && nr_pages_dirtied) {
- get_file(file);
- up_read(¤t->mm->mmap_sem);
- balance_dirty_pages_ratelimited_nr(file->f_mapping,
- nr_pages_dirtied);
- fput(file);
- down_read(¤t->mm->mmap_sem);
- vma = find_vma(current->mm, start);
- } else if ((flags & MS_SYNC) && file &&
+ if ((flags & MS_SYNC) && file &&
(vma->vm_flags & VM_SHARED)) {
get_file(file);
up_read(¤t->mm->mmap_sem);
-
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