On Wed, May 19, 2021 at 11:22:47PM -0700, Chaitanya Kulkarni wrote: > The helper functions bio_add_XXX_page() returns the length which is > unsigned int but the return type of those functions is defined > as int instead of unsigned int. I've been thinking about this for a few weeks as part of the folio patches: https://lore.kernel.org/linux-fsdevel/20210505150628.111735-72-willy@xxxxxxxxxxxxx/ - len and off are measured in bytes - neither are permitted to be negative - for efficiency we only permit them to be up to 4GB I therefore believe the correct type for these parameters to be size_t, and we should range-check them if they're too large. they should actually always fit within the page that they're associated with, but people do allocate non-compound pages and i'm not trying to break that today. using size_t makes it clear that these are byte counts, not (eg) sector counts. i do think it's good to make the return value unsigned so we don't have people expecting a negative errno on failure.
