include/linux/pagemap.h: optimise find_subpage for !THP

If THP is disabled, find_subpage() can become a no-op by using hpage_nr_pages() instead of compound_nr(). hpage_nr_pages() embeds a check for PageTail, so we can drop the check here.

Matthew Wilcox (Oracle) committed 6 years ago

Commit a0650601 parent 85b9f461 file · +1 −3Browse files

Showing the changes to include/linux (1 of 1 file). Show all

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include/linux/pagemap.h+1−3

@@ -341,9 +341,7 @@ static inline struct page find_subpage(struct page head, pgoff_t index) · 340 unmodified lines
341	341	if (PageHuge(head))
342	342	return head;
343	343
344		− VM_BUG_ON_PAGE(PageTail(head), head);
345		−
346		− return head + (index & (compound_nr(head) - 1));
	344	+ return head + (index & (hpage_nr_pages(head) - 1));
347	345	}
348	346
349	347	struct page find_get_entry(struct address_space mapping, pgoff_t offset);