Re: [PATCH v2 06/17] mm: doc comment for scary spot in write_one_page
From: Jeff Layton
Date: Wed Apr 12 2017 - 09:01:43 EST
On Wed, 2017-04-12 at 08:06 -0400, Jeff Layton wrote:
> Not sure what to do here just yet.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> mm/page-writeback.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index de0dbf12e2c1..3ac8399dc984 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2388,6 +2388,12 @@ int write_one_page(struct page *page)
> ret = mapping->a_ops->writepage(page, &wbc);
> if (ret == 0) {
> wait_on_page_writeback(page);
> + /*
> + * FIXME: is this racy? What guarantees that PG_error
> + * will still be set once we get around to checking it?
> + * What if writeback fails, but then a read is issued
> + * before we check this, and that calls ClearPageError?
> + */
> if (PageError(page))
> ret = -EIO;
> }
Ahh, we are always under the page lock here, and this is generally used
for writing out directory pages anyway. I'm fine with dropping this
patch unless someone else sees a problem here.
--
Jeff Layton <jlayton@xxxxxxxxxx>