Re: [PATCH 1/1] block: end bio with BLK_STS_AGAIN in case of non-mq devs and REQ_NOWAIT

[Jens Axboe <axboe@xxxxxxxxx>]

On 12/17/19 8:54 AM, Roman Penyaev wrote:
> Non-mq devs do not honor REQ_NOWAIT so give a chance to the caller to repeat
> request gracefully on -EAGAIN error.
> 
> The problem is well reproduced using io_uring:
> 
>    mkfs.ext4 /dev/ram0
>    mount /dev/ram0 /mnt
> 
>    # Preallocate a file
>    dd if=/dev/zero of=/mnt/file bs=1M count=1
> 
>    # Start fio with io_uring and get -EIO
>    fio --rw=write --ioengine=io_uring --size=1M --direct=1 --name=job --filename=/mnt/file

Thanks, this makes a lot of sense, doing -EIO for that case is wrong. Applied
for 5.5.

-- 
Jens Axboe