pfn_to_block_id
const unsigned long block_id = pfn_to_block_id(pfn);
const unsigned long block_id = pfn_to_block_id(pfn);
const unsigned long start_block_id = pfn_to_block_id(PFN_DOWN(start));
unsigned long end_block_id = pfn_to_block_id(PFN_DOWN(start + size));
const unsigned long start_block_id = pfn_to_block_id(PFN_DOWN(start));
const unsigned long end_block_id = pfn_to_block_id(PFN_DOWN(start + size));
return pfn_to_block_id(PFN_DOWN(phys));