dispatch_bios
ms->rh = dm_region_hash_create(ms, dispatch_bios, wakeup_mirrord,
void *context, void (*dispatch_bios)(void *context,
rh->dispatch_bios = dispatch_bios;
rh->dispatch_bios(rh->context, ®->delayed_bios);
void (*dispatch_bios)(void *context, struct bio_list *bios);
void *context, void (*dispatch_bios)(void *context,