On 8/23/20 12:25 AM, Christoph Hellwig wrote: > On Fri, Aug 21, 2020 at 09:20:58PM -0700, John Hubbard wrote: >> Add a new BIO_FOLL_PIN flag to struct bio, whose "short int" flags field >> was full, thuse triggering an expansion of the field from 16, to 32 >> bits. This allows for a nice assertion in bio_release_pages(), that the >> bio page release mechanism matches the page acquisition mechanism. >> >> Set BIO_FOLL_PIN whenever pin_user_pages_fast() is used, and check for >> BIO_FOLL_PIN before using unpin_user_page(). > > When would the flag not be set when BIO_NO_PAGE_REF is not set? > > Also I don't think we can't just expand the flags field, but I can send > a series to kill off two flags. (not relevant to this series as this patch has thankfully already been dropped, just in general - but yes, definitely need a *strong* justification to bump the bio size). Would actually be nice to kill off a few flags, if possible, so the flags space isn't totally full. -- Jens Axboe
