> From 7b559f1cea41cdba7b39138ad1637f8000e218b9 Mon Sep 17 00:00:00 2001
> From: Jan Kara <jack@xxxxxxx>
> Date: Wed, 19 Oct 2011 11:44:41 +0200
> Subject: [PATCH] writeback: Include all dirty inodes in background writeback
>
> Current livelock avoidance code makes background work to include only inodes
> that were dirtied before background writeback has started. However background
> writeback can be running for a long time and thus excluding newly dirtied
> inodes can eventually exclude significant portion of dirty inodes making
> background writeback inefficient. Since background writeback avoids livelocking
> the flusher thread by yielding to any other work, there is no real reason why
> background work should not include all dirty inodes so change the logic in
> wb_writeback().
Looks good to me. Thanks!
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> fs/fs-writeback.c | 10 ++++++++--
> 1 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 04cf3b9..8314241 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -730,11 +730,17 @@ static long wb_writeback(struct bdi_writeback *wb,
> if (work->for_background && !over_bground_thresh())
> break;
>
> + /*
> + * Kupdate and background works are special and we want to
> + * include all inodes that need writing. Livelock avoidance is
> + * handled by these works yielding to any other work so we are
> + * safe.
> + */
> if (work->for_kupdate) {
> oldest_jif = jiffies -
> msecs_to_jiffies(dirty_expire_interval * 10);
> - work->older_than_this = &oldest_jif;
> - }
> + } else if (work->for_background)
> + oldest_jif = jiffies;
>
> trace_writeback_start(wb->bdi, work);
> if (list_empty(&wb->b_io))
> --
> 1.7.1
>
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