On venerdì 25 novembre 2022 23:50:56 CET Al Viro wrote: > On Fri, Nov 25, 2022 at 10:17:28PM +0000, Al Viro wrote: > > The bottom line: > > * teach your ufs_put_page() to accept any address within the page > > * flip the ways you return page and address in ufs_get_page() > > * use offset_in_page(addr) instead of these addr - page_address(page) > > > > and you'll get a much smaller patch, with a lot less noise in it. > > What's more, offset_in_page() part can be carved out into a separate > > commit - it's valid on its own, and it makes both halves easier to > > follow. > > > > AFAICS, similar observations apply in your sysvfs patch; the point about > > calling conventions for ufs_get_page() definitely applies there, and > > stronger than for ufs - those casts are eye-watering... > > As the matter of fact, I'd probably split it into 3 steps: > 1) switch the calling conventions of ufs_get_page() - callers follow > it with something like kaddr = page_address(page); and that change makes > sense on its own. Isolated and easy to follow. > 2) offset_in_page() changes. Again, separate, stands on its own and > is easy to follow. > 3) kmap_local() switch itself - pass address to ufs_put_page(), etc. > Considerably smaller and less cluttered than your current variant. Al, thanks for taking the time to answer in such detail although I can believe that, to spot the mistakes in my patch and then write your email, it probably took you 10 minutes or so :-) Instead I had to read two or three times to make sense of it all. I will do my best to first rewrite these kmap_local_page() conversions in fs/ufs by separating the work into three patches, as you recommended. I'm pretty sure that the next attempt won't be applicable yet, because I might not fully understand your suggestions or I might not be able to implement them correctly. I'm afraid I addressed something that, as it stands, is a little beyond my knowledge and experience, so I hope you'll want to chime in and comment on the next version as well. When the changes to fs/ufs will be done I will also rewrite the patch for fs/ sysv which (as you pointed out) needs to be worked out according to the same requirements. I am sincerely grateful to you also because it seemed to me that I would never get any feedback regarding these two old patches. Regards, Fabio
