Messages in this thread | | | Date | Tue, 10 Feb 2009 07:22:49 +0100 | From | Damien Wyart <> | Subject | Re: [PATCH] write-back: fix break condition |
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* Nick Piggin <npiggin@suse.de> [2009-02-10 01:34]: > 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>
Shouldn't this go to stable 2.6.28, too ? They have not been in Cc for now. I think the problem was at first detected in 2.6.28.X, but it is not yet sure if it is solved or if this interacts with some ext4 problems.
-- Damien Wyart
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