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From: Avi Kivity <avi@scylladb.com>
To: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: linux-kernel <linux-kernel@vger.kernel.org>, linux-aio@kvack.org
Subject: Re: Spurious EIO on AIO+DIO+RWF_NOWAIT
Date: Mon, 10 Dec 2018 14:49:44 +0200	[thread overview]
Message-ID: <53c17661-4914-5266-2034-9fc447e59383@scylladb.com> (raw)
In-Reply-To: <20181210124823.iw4mxmdqpsdfeap4@merlin>


On 10/12/2018 14.48, Goldwyn Rodrigues wrote:
> On 13:19 09/12, Avi Kivity wrote:
>> I have an application that receives spurious EIO when running with
>> RWF_NOWAIT enabled. Removing RWF_NOWAIT causes those EIOs to disappear. The
>> application uses AIO+DIO, and errors were seen on both xfs and ext4.
>>
>>
>> I suspect the following code:
>>
>>
>> /*
>>   * Process one completed BIO.  No locks are held.
>>   */
>> static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio)
>> {
>>          struct bio_vec *bvec;
>>          unsigned i;
>>          blk_status_t err = bio->bi_status;
>>
>>          if (err) {
>>                  if (err == BLK_STS_AGAIN && (bio->bi_opf & REQ_NOWAIT))
>>                          dio->io_error = -EAGAIN;
>>                  else
>>                          dio->io_error = -EIO;
>>          }
>>
>> Could it be that REQ_NOWAIT was dropped from bio->bi_opf? or that
>> bio->bi_status got changed along the way?
>>
> I don't think REQ_NOWAIT is dropped. I am assuming bio->bi_status error
> is set differently. Is the blk queue being stopped?


Not that I know of.


> Is it possible to
> instrument the kernel in your testcase?
>

I'm happy to apply patches, or run systemtap (or similar) scripts.



  reply	other threads:[~2018-12-10 12:49 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-09 11:19 Spurious EIO on AIO+DIO+RWF_NOWAIT Avi Kivity
2018-12-10 12:48 ` Goldwyn Rodrigues
2018-12-10 12:49   ` Avi Kivity [this message]
2018-12-12 12:05   ` Avi Kivity
2018-12-12 14:41     ` Goldwyn Rodrigues

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