On Mon, Mar 29, 2021 at 11:39:32AM -0400, Zi Yan wrote:
> + for (off_cur = off_start; off_cur < off_end;) {
> + struct page *fpage = pagecache_get_page(mapping, off_cur,
> + FGP_ENTRY | FGP_HEAD, 0);
> +
> + if (xa_is_value(fpage) || !fpage) {
> + off_cur += PAGE_SIZE;
> + continue;
> + }
> +
> + if (!is_transparent_hugepage(fpage)) {
> + off_cur += PAGE_SIZE;
> + goto next;
> + }
> + total++;
> + off_cur = fpage->index + thp_size(fpage);
That can't be right. fpage->index is in units of pages and thp_size is
in units of bytes. I wish C had a better type system.
I think you meant:
off_cur = fpage->index + thp_nr_pages(fpage);
Also, I think this loop would read better as ...
for (index = off_start; index < off_end; index += nr_pages) {
struct page *fpage = pagecache_get_page(mapping, index,
FGP_ENTRY | FGP_HEAD, 0);
nr_pages = 1;
if (xa_is_value(fpage) || !fpage)
continue;
if (!is_transparent_hugepage(fpage))
goto next;
total++;
nr_pages = thp_nr_pages(fpage);
...
