Message-ID: <1492002094.2937.4.camel@redhat.com>
Subject: Re: [PATCH v2 06/17] mm: doc comment for scary spot in
 write_one_page
From: Jeff Layton <jlayton@redhat.com>
To: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, tytso@mit.edu,
        jack@suse.cz, willy@infradead.org, neilb@suse.com,
        viro@zeniv.linux.org.uk
Date: Wed, 12 Apr 2017 09:01:34 -0400
In-Reply-To: <20170412120614.6111-7-jlayton@redhat.com>
References: <20170412120614.6111-1-jlayton@redhat.com>
         <20170412120614.6111-7-jlayton@redhat.com>
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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@redhat.com>
> ---
>  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@redhat.com>