assert(((size_t)b >> REGION_SCALE) < ((1 << HEADER_REGION_SCALE) / sizeof(header_t)));
header_t *h = region_header_ + ((size_t)b >> REGION_SCALE);
TRACE("m0", "nbd_free(): block %p scale %llu", x, h->scale);
assert(((size_t)b >> REGION_SCALE) < ((1 << HEADER_REGION_SCALE) / sizeof(header_t)));
header_t *h = region_header_ + ((size_t)b >> REGION_SCALE);
TRACE("m0", "nbd_free(): block %p scale %llu", x, h->scale);