Re: [Qemu-devel] [PATCH v2 31/45] mirror: add support for on-source-error/on-target-error

[Paolo Bonzini]

Il 18/10/2012 15:07, Kevin Wolf ha scritto:
>> > +    s->synced = false;
>> > +    if (read) {
>> > +        return block_job_error_action(&s->common, s->common.bs,
>> > +                                      s->on_source_error, true, error);
>> > +    } else {
>> > +        return block_job_error_action(&s->common, s->target,
>> > +                                      s->on_target_error, false, error);
> Here we produce an event that reports an error on s->bs, i.e. on the
> source, even though the error was on the target.

More precisely, this is an event that reports an error on s->bs's job.
In principle there is no reason why asynchronous long-running operations
are tied to a block device (in fact migration fits the definition quite
well, with the only twist that the VM is stopped at the end), but that's
the API we're stuck with.

> This makes some sense
> today that the target doesn't have a name, but once it has, we would
> better use the target name here.
> 
> Can we change this later on? If not, what's the way forward?

Yes, we can change it to one of these:

1) produce both a BLOCK_JOB_ERROR event on the source and a
BLOCK_IO_ERROR event on the target;

2) add a "device" argument to the BLOCK_JOB_ERROR and fill it.

I think I prefer the latter, but it can be discussed separately.

Paolo