On Tue, Sep 06, 2022 at 12:44:28AM -0700, John Hubbard wrote: > OK, that part is clear. > > > - for the pin case don't use the existing bvec helper at all, but > > copy the logic for the block layer for not pinning. > > I'm almost, but not quite sure I get the idea above. Overall, what > happens to bvec pages? Leave the get_page() pin in place for FOLL_GET > (or USE_FOLL_GET), I suppose, but do...what, for FOLL_PIN callers? Do not change anyhing for FOLL_GET callers, as they are on the way out anyway. For FOLL_PIN callers, never pin bvec and kvec pages: For file systems not acquiring a reference is obviously safe, and the other callers will need an audit, but I can't think of why it woul ever be unsafe.
