On 27/10/2023 07:18, Christoph Hellwig wrote:
>>
>> - __bio_add_page(bio, page, len, 0);
>> + while (len) {
>> + unsigned int io_len = min_t(unsigned int, len, PAGE_SIZE);
>> +
>> + __bio_add_page(bio, page, io_len, 0);
>> + len -= io_len;
>> + }
>
> Maybe out of self-interest, but shouldn't we replace ZERO_PAGE with a
> sufficiently larger ZERO_FOLIO? Right now I have a case where I have
> to have a zero padding of up to MAX_PAGECACHE_ORDER minus block size,
> so having a MAX_PAGECACHE_ORDER folio would have been really helpful
> for me, but I suspect there are many other such cases as well.
I think that would definitely be useful.
I also noticed this pattern in fscrypt_zeroout_range_inline_crypt().
Probably there are more places which could use a ZERO_FOLIO directly
instead of iterating with ZERO_PAGE.
Chinner also had a similar comment. It would be nice if we can reserve
a zero huge page that is the size of MAX_PAGECACHE_ORDER and add it as
one folio to the bio.
