Updating file times at write references to memory-mapped files and forcing file times update at the next write reference after calling the msync() system call with the MS_ASYNC flag.
Signed-off-by: Anton Salikhmetov <[EMAIL PROTECTED]> --- mm/memory.c | 6 ++++++ mm/msync.c | 52 +++++++++++++++++++++++++++++++++++++++------------- 2 files changed, 45 insertions(+), 13 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 4bf0b6d..13d5bbf 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1668,6 +1668,9 @@ gotten: unlock: pte_unmap_unlock(page_table, ptl); if (dirty_page) { + if (vma->vm_file) + file_update_time(vma->vm_file); + /* * Yes, Virginia, this is actually required to prevent a race * with clear_page_dirty_for_io() from clearing the page dirty @@ -2341,6 +2344,9 @@ out_unlocked: if (anon) page_cache_release(vmf.page); else if (dirty_page) { + if (vma->vm_file) + file_update_time(vma->vm_file); + set_page_dirty_balance(dirty_page, page_mkwrite); put_page(dirty_page); } diff --git a/mm/msync.c b/mm/msync.c index a4de868..a49af28 100644 --- a/mm/msync.c +++ b/mm/msync.c @@ -13,11 +13,33 @@ #include <linux/syscalls.h> /* + * Scan the PTEs for pages belonging to the VMA and mark them read-only. + * It will force a pagefault on the next write access. + */ +static void vma_wrprotect(struct vm_area_struct *vma) +{ + unsigned long addr; + + for (addr = vma->vm_start; addr < vma->vm_end; addr += PAGE_SIZE) { + spinlock_t *ptl; + pgd_t *pgd = pgd_offset(vma->vm_mm, addr); + pud_t *pud = pud_offset(pgd, addr); + pmd_t *pmd = pmd_offset(pud, addr); + pte_t *pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + + if (pte_dirty(*pte) && pte_write(*pte)) + *pte = pte_wrprotect(*pte); + pte_unmap_unlock(pte, ptl); + } +} + +/* * MS_SYNC syncs the entire file - including mappings. * - * MS_ASYNC does not start I/O (it used to, up to 2.5.67). - * Nor does it mark the relevant pages dirty (it used to up to 2.6.17). - * Now it doesn't do anything, since dirty pages are properly tracked. + * MS_ASYNC does not start I/O. Instead, it marks the relevant pages + * read-only by calling vma_wrprotect(). This is needed to catch the next + * write reference to the mapped region and update the file times + * accordingly. * * 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 @@ -77,16 +99,20 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/