[alsa-devel] snd_pcm_ioplug_avail_update() confusion

I'm working on an external IO plugin based on ioplug and I'm confused about the behavior of snd_pcm_ioplug_avail_update(). Specifically this call (src/pcm/pcm_ioplug.c:657):

result = io->data->callback->transfer(io->data, areas, offset, size);

Why isn't there a subsequent call to snd_pcm_mmap_appl_forward() like there is in ioplug_priv_transfer_areas()? It seems that without such a call the captured data will be lost, or have I missed something?

Thanks,

Rob.