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From: Avi Kivity <avi@scylladb.com>
To: linux-kernel <linux-kernel@vger.kernel.org>,
	linux-aio@kvack.org, Goldwyn Rodrigues <rgoldwyn@suse.de>
Subject: Spurious EIO on AIO+DIO+RWF_NOWAIT
Date: Sun, 9 Dec 2018 13:19:51 +0200
Message-ID: <9bab0f40-5748-f147-efeb-5aac4fd44533@scylladb.com> (raw)

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?


Reducing the test case may be a lot of work, but I can package a binary 
using docker if a reproducer is needed. Seen on 4.18.19 and 4.19.something.


             reply index

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

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