Messages in this thread | | | Subject | Re: Spurious EIO on AIO+DIO+RWF_NOWAIT | From | Avi Kivity <> | Date | Wed, 12 Dec 2018 14:05:40 +0200 |
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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?
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