From: Andrew Morton <akpm@linux-foundation.org>
To: Chris Mason <chris.mason@oracle.com>
Cc: linux-kernel@vger.kernel.org, jens.axboe@oracle.com, jack@suse.cz
Subject: Re: [PATCH] bdi_sync_writeback should WB_SYNC_NONE first
Date: Sun, 27 Sep 2009 01:34:58 -0700 [thread overview]
Message-ID: <20090927013458.53e43459.akpm@linux-foundation.org> (raw)
In-Reply-To: <20090925141014.GB15853@think>
On Fri, 25 Sep 2009 10:10:14 -0400 Chris Mason <chris.mason@oracle.com> wrote:
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 8e1e5e1..27f8e0e 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -225,7 +225,7 @@ static void bdi_sync_writeback(struct backing_dev_info *bdi,
> {
> struct wb_writeback_args args = {
> .sb = sb,
> - .sync_mode = WB_SYNC_ALL,
> + .sync_mode = WB_SYNC_NONE,
> .nr_pages = LONG_MAX,
> .range_cyclic = 0,
> };
> @@ -236,6 +236,13 @@ static void bdi_sync_writeback(struct backing_dev_info *bdi,
>
> bdi_queue_work(bdi, &work);
> bdi_wait_on_work_clear(&work);
> +
> + args.sync_mode = WB_SYNC_ALL;
> + args.nr_pages = LONG_MAX;
> +
> + work.state = WS_USED | WS_ONSTACK;
> + bdi_queue_work(bdi, &work);
> + bdi_wait_on_work_clear(&work);
> }
Those LONG_MAX's are a worry. What prevents a very long
almost-livelock from occurring if userspace is concurrently dirtying
pagecache at a high rate?
next prev parent reply other threads:[~2009-09-27 8:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-25 14:10 [PATCH] bdi_sync_writeback should WB_SYNC_NONE first Chris Mason
2009-09-27 8:34 ` Andrew Morton [this message]
2009-09-27 16:44 ` Jens Axboe
2009-09-27 16:52 ` Andrew Morton
2009-09-27 16:55 ` Jens Axboe
2009-09-27 17:10 ` Andrew Morton
2009-09-29 16:13 ` Jan Kara
2009-09-28 13:32 ` Chris Mason
2009-09-29 20:47 ` Chris Mason
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