> 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); > + } > +}
What about ram based filesystems? They don't start out with read-only pte's, so I think they don't want them read-protected now either. Unless this is essential for correct mtime/ctime accounting on these filesystems (I don't think it really is). But then the mapping should start out read-only as well, otherwise the time update will only work after an msync(MS_ASYNC). > + > +/* > * 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/