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: Wed, 12 Dec 2018 14:05:40 +0200 [thread overview]
Message-ID: <8fb27ba4-c100-5d08-71b6-ef393d7bcae1@scylladb.com> (raw)
In-Reply-To: <20181210124823.iw4mxmdqpsdfeap4@merlin>
On 12/10/18 2:48 PM, 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? Is it possible to
> instrument the kernel in your testcase?
>
I traced the function, and I see bio->bi_status == BLK_STS_NOTSUPP and
bio->bi_opf == REQ_OP_WRITE|REQ_SYNC|REQ_NOMERGE|REQ_FUA|REQ_NOWAIT.
Presumably the NOTSUPP is the result of NOWAIT not being supported down
the stack, but shouldn't it be detected earlier? And not converted to EIO?
next prev parent reply other threads:[~2018-12-12 12:05 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
2018-12-12 12:05 ` Avi Kivity [this message]
2018-12-12 14:41 ` Goldwyn Rodrigues
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=8fb27ba4-c100-5d08-71b6-ef393d7bcae1@scylladb.com \
--to=avi@scylladb.com \
--cc=linux-aio@kvack.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rgoldwyn@suse.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).