Re: [PATCH v3 1/5] block-copy: streamline choice of copy_range vs. read/write

[Paolo Bonzini]

On 09/06/21 10:51, Vladimir Sementsov-Ogievskiy wrote:
> > +    default:
> > [...]
> > +        bounce_buffer = qemu_blockalign(s->source->bs, nbytes);
> > +        ret = bdrv_co_pread(s->source, offset, nbytes, bounce_buffer, 
> > 0);
> > +        if (ret < 0) {
> > +            trace_block_copy_read_fail(s, offset, ret);
> > +            *error_is_read = true;
> > +            goto out;
> > +        }
> > +        ret = bdrv_co_pwrite(s->target, offset, nbytes, bounce_buffer,
> > +                            s->write_flags);
> > +        if (ret < 0) {
> > +            trace_block_copy_write_fail(s, offset, ret);
> > +            *error_is_read = false;
> > +            goto out;
> > +        }
> > +out:
> > +        qemu_vfree(bounce_buffer);
>
> label inside switch operator? Rather unusual. Please, let's avoid it and 
> just keep out: after switch operator.

Agreed with all comments except this one, the bounce_buffer doesn't 
exist in the other cases.

> > +    ret = block_copy_do_copy(s, t->offset, t->bytes, &method, &error_is_read);
> > +    if (s->method == t->method) {
> > +        s->method = method;
>
> you leave another t->s occurrences in the function untouched. It's somehow inconsistent. Could we just use t->s in this patch, and refactor with a follow-up patch (or as preparing patch)? 

Maybe as a first patch, yes.

Paolo