Re: [PATCHSET 0/2] io_uring: handle short reads internally

[Jeff Moyer <jmoyer@redhat.com>]

Jens Axboe <axboe@kernel.dk> writes:

> On 8/13/20 2:37 PM, Jens Axboe wrote:
>> On 8/13/20 2:33 PM, Jens Axboe wrote:
>>> On 8/13/20 2:25 PM, Jeff Moyer wrote:
>>>> Jens Axboe <axboe@kernel.dk> writes:
>>>>
>>>>> Since we've had a few cases of applications not dealing with this
>>>>> appopriately, I believe the safest course of action is to ensure that
>>>>> we don't return short reads when we really don't have to.
>>>>>
>>>>> The first patch is just a prep patch that retains iov_iter state over
>>>>> retries, while the second one actually enables just doing retries if
>>>>> we get a short read back.
>>>>
>>>> Have you run this through the liburing regression tests?
>>>>
>>>> Tests  <eeed8b54e0df-test> <timeout-overflow> <read-write> failed
>>>>
>>>> I'll take a look at the failures, but wanted to bring it to your
>>>> attention sooner rather than later.  I was using your io_uring-5.9
>>>> branch.
>>>
>>> The eed8b54e0df-test failure is known with this one, pretty sure it
>>> was always racy, but I'm looking into it.
>>>
>>> The timeout-overflow test needs fixing, it's just an ordering thing
>>> with the batched completions done through submit. Not new with these
>>> patches.

OK.

>>> The read-write one I'm interested in, what did you run it on? And
>>> what was the failure?
>> 
>> BTW, what git sha did you run?
>
> I do see a failure with dm on that, I'll take a look.

I ran it on a file system atop nvme with 8 poll queues.

liburing head: 9e1d69e078ee51f253a829ff421b17cfc996d158
linux-block head: ff1353802d86a9d8e40ef1377efb12a1d3000a20

The error I saw was:

Running test read-write:
Non-vectored IO not supported, skipping
cqe res -22, wanted 2048
test_buf_select_short vec failed
Test read-write failed with ret 1

But I don't think it was due to these two commits.

Thanks,
Jeff