Re: [PATCH for-6.2 v3 05/12] job: @force parameter for job_cancel_sync{, _all}()

[Eric Blake]

On Fri, Aug 06, 2021 at 11:38:52AM +0200, Max Reitz wrote:
> Callers should be able to specify whether they want job_cancel_sync() to
> force-cancel the job or not.
> 
> In fact, almost all invocations do not care about consistency of the
> result and just want the job to terminate as soon as possible, so they
> should pass force=true.  The replication block driver is the exception.
> 
> This changes some iotest outputs, because quitting qemu while a mirror
> job is active will now lead to it being cancelled instead of completed,
> which is what we want.  (Cancelling a READY mirror job with force=false
> may take an indefinite amount of time, which we do not want when
> quitting.  If users want consistent results, they must have all jobs be
> done before they quit qemu.)

Feels somewhat like a bug fix, but I also understand why you'd prefer
to delay this to 6.2 (it is not a fresh regression, but a longstanding
issue).

> 
> Buglink: https://gitlab.com/qemu-project/qemu/-/issues/462
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---

> +++ b/job.c
> @@ -982,12 +982,24 @@ static void job_cancel_err(Job *job, Error **errp)
>      job_cancel(job, false);
>  }
>  
> -int job_cancel_sync(Job *job)
> +/**
> + * Same as job_cancel_err(), but force-cancel.
> + */
> +static void job_force_cancel_err(Job *job, Error **errp)
>  {
> -    return job_finish_sync(job, &job_cancel_err, NULL);
> +    job_cancel(job, true);
> +}

In isolation, it looks odd that errp is passed but not used.  But
looking further, it's because this is a callback that must have a
given signature, so it's okay.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org