Re: [patch resend v4] update ctime and mtime for mmaped write

Matt Mackall
2007-03-26T21:10:09Z

On Mon, Mar 26, 2007 at 02:00:36PM -0700, Andrew Morton wrote:
> On Sun, 25 Mar 2007 23:10:21 +0200
> Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> > This patch makes writing to shared memory mappings update st_ctime and
> > st_mtime as defined by SUSv3:
>
> Boy this is complicated.
>
> Is there a simpler way of doing all this? Say, we define a new page flag
> PG_dirtiedbywrite and we do SetPageDirtiedByWrite() inside write() and
> ClearPageDirtiedByWrite() whenever we propagate pte-dirtiness into
> page-dirtiness. Then, when performing writeback we look to see if any of
> the dirty pages are !PageDirtiedByWrite() and, if so, we update [mc]time to
> current-time.
>
> Or something like that - I'm just thinking out loud and picking holes in
> the above doesn't shut me up ;) We're adding complexity and some overhead
> and we're losing our recent msync() simplifications and this all hurts. Is
> there some other way? I think burning a page flag to avoid this additional
> complexity would be worthwhile.

Aren't we basically out of those?

--
Mathematics is the supreme nostalgia of our time.