>> - bio = iomap_dio_alloc_bio(iter, dio, 1, REQ_OP_WRITE | REQ_SYNC | REQ_IDLE);
>> + if (len > PAGE_SIZE) {
>> + page = mm_get_huge_zero_page(current->mm);
>> + if (likely(page))
>> + huge_page = true;
>> + }
>> +
>> + if (!huge_page)
>> + page = ZERO_PAGE(0);
>> +
>> + fallback = ((len > PAGE_SIZE) && !huge_page);
>> +
> That is pointless.
> Bios can handle pages larger than PAGE_SIZE.
Yes, I know BIOs can handle large pages. But the point here is if we fail
to allocate a huge zero page that can cover the complete large FSB ( > page size),
then we need to use the statically allocated ZERO_PAGE (see the original patch)
for multiple offsets covering the range.
Unless we have an API that can return a zero folio with arbitrary order(see also the
reply from Willy), we can't use a bio with one vec for LBS support.
--
Pankaj
