Re: [PATCH for-6.0? 0/3] job: Add job_wait_unpaused() for block-job-complete

[John Snow]

On 4/8/21 12:20 PM, Max Reitz wrote:
> Hi,
>
> See patch 1 for a detailed explanation of the problem.
>
> The gist is: Draining a READY job makes it transition to STANDBY, and
> jobs on STANDBY cannot be completed.  Ending the drained section will
> schedule the job (so it is then resumed), but not wait until it is
> actually running again.
>
> Therefore, it can happen that issuing block-job-complete fails when you
> issue it right after some draining operation.
>
> I tried to come up with an iotest reproducer, but in the end I only got
> something that reproduced the issue like 2/10 times, and it required
> heavy I/O, so it is nothing I would like to have as part of the iotests.
> Instead, I opted for a unit test, which allows me to cheat a bit
> (specifically, locking the job IO thread before ending the drained
> section).
>
>
> Max Reitz (3):
>    job: Add job_wait_unpaused() for block-job-complete
>    test-blockjob: Test job_wait_unpaused()
>    iotests/041: block-job-complete on user-paused job
>
>   include/qemu/job.h         |  15 ++++
>   blockdev.c                 |   3 +
>   job.c                      |  42 +++++++++++
>   tests/unit/test-blockjob.c | 140 +++++++++++++++++++++++++++++++++++++
>   tests/qemu-iotests/041     |  13 +++-
>   5 files changed, 212 insertions(+), 1 deletion(-)

Left comments and review on #1, skimmed 2/3. Not sure if it's 
appropriate for 6.0 yet, that might depend on the responses to my 
comments and other reviewers and so on.

Acked-by: John Snow <jsnow@redhat.com>