On 3/3/26 8:32 PM, Yury Norov wrote:

My motivation is that it helps to simplify constructions like this:

-               loff_t cmp_len = min(PAGE_SIZE - offset_in_page(srcoff),
-                                    PAGE_SIZE - offset_in_page(dstoff));
+               loff_t cmp_len = min(rest_of_page(srcoff), rest_of_page(dstoff));

Or this:

-               if (folio_test_highmem(dst_folio) &&
-                   chunk > PAGE_SIZE - offset_in_page(dst_off))
-                       chunk = PAGE_SIZE - offset_in_page(dst_off);
-               if (folio_test_highmem(src_folio) &&
-                   chunk > PAGE_SIZE - offset_in_page(src_off))
-                       chunk = PAGE_SIZE - offset_in_page(src_off);
+               if (folio_test_highmem(dst_folio) && chunk > rest_of_page(dst_off))
+                       chunk = rest_of_page(dst_off);
+               if (folio_test_highmem(src_folio) && chunk > rest_of_page(src_off))
+                       chunk = rest_of_page(src_off);

To a point where I don't have to use my brains to decode them. I agree
it's an easy math. It's just too bulky to my (and 9p guys too) taste.

The thing is, now I have to go lookup what on earth rest_of_page() does,
whereas PAGE_SIZE - offset_in_page(page) is immediately obvious. It's a
classic case of "oh let's add this helper to simplify things" which
really just makes it worse, because now you have to jump to the
definition of rest_of_page().

IOW, just no.

-- 
Jens Axboe