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SubjectRe: [PATCH] write-back: fix break condition

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?


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