Re: Block device direct read EIO handling broken?

Jens Axboe
2019-08-05T21:28:52Z

On 8/5/19 2:27 PM, Damien Le Moal wrote:
> On 2019/08/06 6:26, Jens Axboe wrote:
>>> In any case, looking again at this code, it looks like there is a
>>> problem with dio->size being incremented early, even for fragments
>>> that get BLK_QC_T_EAGAIN, because dio->size is being used in
>>> blkdev_bio_end_io(). So an incorrect size can be reported to user
>>> space in that case on completion (e.g. large asynchronous no-wait dio
>>> that cannot be issued in one go).
>>>
>>> So maybe something like this ? (completely untested)
>>
>> I think that looks pretty good, I like not double accounting with
>> this_size and dio->size, and we retain the old style ordering for the
>> ret value.
>
> Do you want a proper patch with real testing backup ? I can send that
> later today.

Yeah that'd be great, I like your approach better.

--
Jens Axboe