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?
