Force file times update at the next write reference after
calling the msync() system call with the MS_ASYNC flag.
Signed-off-by: Anton Salikhmetov <salikhmetov@gmail.com>
---
mm/msync.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++------
1 files changed, 82 insertions(+), 10 deletions(-)
diff --git a/mm/msync.c b/mm/msync.c
index 60efa36..87f990e 100644
--- a/mm/msync.c
+++ b/mm/msync.c
@@ -5,6 +5,7 @@
* Copyright (C) 2008 Anton Salikhmetov <salikhmetov@gmail.com>
*/
+#include <asm/tlbflush.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/mm.h>
@@ -12,6 +13,73 @@
#include <linux/sched.h>
#include <linux/syscalls.h>
+static void vma_wrprotect_pmd_range(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long start, unsigned long end)
+{
+ while (start < end) {
+ spinlock_t *ptl;
+ pte_t *pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
+
+ if (pte_dirty(*pte) && pte_write(*pte)) {
+ pte_t entry = ptep_clear_flush(vma, start, pte);
+
+ entry = pte_wrprotect(entry);
+ set_pte_at(vma->vm_mm, start, pte, entry);
+ }
+
+ pte_unmap_unlock(pte, ptl);
+ start += PAGE_SIZE;
+ }
+}
+
+static void vma_wrprotect_pud_range(struct vm_area_struct *vma, pud_t *pud,
+ unsigned long start, unsigned long end)
+{
+ pmd_t *pmd = pmd_offset(pud, start);
+
+ while (start < end) {
+ unsigned long next = pmd_addr_end(start, end);
+
+ if (!pmd_none_or_clear_bad(pmd))
+ vma_wrprotect_pmd_range(vma, pmd, start, next);
+
+ ++pmd;
+ start = next;
+ }
+}
+
+static void vma_wrprotect_pgd_range(struct vm_area_struct *vma, pgd_t *pgd,
+ unsigned long start, unsigned long end)
+{
+ pud_t *pud = pud_offset(pgd, start);
+
+ while (start < end) {
+ unsigned long next = pud_addr_end(start, end);
+
+ if (!pud_none_or_clear_bad(pud))
+ vma_wrprotect_pud_range(vma, pud, start, next);
+
+ ++pud;
+ start = next;
+ }
+}
+
+static void vma_wrprotect(struct vm_area_struct *vma)
+{
+ unsigned long addr = vma->vm_start;
+ pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
+
+ while (addr < vma->vm_end) {
+ unsigned long next = pgd_addr_end(addr, vma->vm_end);
+
+ if (!pgd_none_or_clear_bad(pgd))
+ vma_wrprotect_pgd_range(vma, pgd, addr, next);
+
+ ++pgd;
+ addr = next;
+ }
+}
+
/*
* MS_SYNC syncs the entire file - including mappings.
*
@@ -78,16 +146,20 @@ asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
error = 0;
start = vma->vm_end;
file = vma->vm_file;
- if (file && (vma->vm_flags & VM_SHARED) && (flags & MS_SYNC)) {
- get_file(file);
- up_read(&mm->mmap_sem);
- error = do_fsync(file, 0);
- fput(file);
- if (error || start >= end)
- goto out;
- down_read(&mm->mmap_sem);
- vma = find_vma(mm, start);
- continue;
+ if (file && (vma->vm_flags & VM_SHARED)) {
+ if ((flags & MS_ASYNC))
+ vma_wrprotect(vma);
+ if (flags & MS_SYNC) {
+ get_file(file);
+ up_read(&mm->mmap_sem);
+ error = do_fsync(file, 0);
+ fput(file);
+ if (error || start >= end)
+ goto out;
+ down_read(&mm->mmap_sem);
+ vma = find_vma(mm, start);
+ continue;
+ }
}
vma = vma->vm_next;
--
1.4.4.4
--
