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SubjectRe: [PATCH] write-back: fix break condition
On Mon, Feb 09, 2009 at 03:21:40PM -0800, Andrew Morton wrote:
>
> Thanks, but please do cc the people who were involved with a patch when
> you find a problem with it!
>
> On Sat, 7 Feb 2009 01:33:30 -0200
> Federico Cuello <fedux@lugmen.org.ar> wrote:
>
> > Commit 673353723e7a6550625fb719059c5f31cfaecd18 fixed nr_to_write
> > counter, but didn't set the break condition properly.
>
> It's actually commit dcf6a79dda5cc2a2bec183e50d829030c0972aaa
> ("write-back: fix nr_to_write counter").
>
> > If nr_to_write == 0 after being decremented it will loop one more time
> > before setting done = 1 and breaking the loop.
>
> We prefer that patches include the author's Signed-off-by:, as per
> Documentation/SubmittingPatches, please.
>
> >
> > diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> > index bb5fa2b..9e2ae50 100644
> > --- a/mm/page-writeback.c
> > +++ b/mm/page-writeback.c
> > @@ -981,20 +981,21 @@ continue_unlock:
> > }
> > }
> >
> > - if (nr_to_write > 0)
> > + if (nr_to_write > 0) {
> > nr_to_write--;
> > - else if (wbc->sync_mode == WB_SYNC_NONE) {
> > - /*
> > - * We stop writing back only if we are not
> > - * doing integrity sync. In case of integrity
> > - * sync we have to keep going because someone
> > - * may be concurrently dirtying pages, and we
> > - * might have synced a lot of newly appeared
> > - * dirty pages, but have not synced all of the
> > - * old dirty pages.
> > - */
> > - done = 1;
> > - break;
> > + if (nr_to_write == 0 && wbc->sync_mode == WB_SYNC_NONE) {
> > + /*
> > + * We stop writing back only if we are not
> > + * doing integrity sync. In case of integrity
> > + * sync we have to keep going because someone
> > + * may be concurrently dirtying pages, and we
> > + * might have synced a lot of newly appeared
> > + * dirty pages, but have not synced all of the
> > + * old dirty pages.
> > + */
> > + done = 1;
> > + break;
> > + }
> > }
> >
> > if (wbc->nonblocking && bdi_write_congested(bdi)) {
>
> Artem, Nick, please check?

Yes, this looks OK by me.

Acked-by: Nick Piggin <npiggin@suse.de>



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