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Date: Wed, 26 Jul 2017 13:12:28 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: axboe@fb.com, Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
	Ross Zwisler <ross.zwisler@linux.intel.com>,
	Matthew Wilcox <mawilcox@microsoft.com>
Subject: Re: [PATCH] brd: fix brd_rw_page() vs copy_to_brd_setup errors
Message-ID: <20170726201228.GA28444@infradead.org>
References: <150103091559.7874.16803761117298861951.stgit@dwillia2-desk3.amr.corp.intel.com>
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On Tue, Jul 25, 2017 at 06:02:29PM -0700, Dan Williams wrote:
> As is done in zram_rw_page, pmem_rw_page, and btt_rw_page, don't
> call page_endio in the error case since do_mpage_readpage and
> __mpage_writepage will resubmit on error. Calling page_endio in the
> error case leads to double completion.
> 
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: Matthew Wilcox <mawilcox@microsoft.com>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> Noticed this while looking at unrelated brd code...

And the real question would be:  where would we see any real life impact
of just removing brd_rw_page?