There is a READ_ONCE() in the macro of compound_head(), which will
prevent compiler from optimizing the code when there are more than
once calling of it in a function. Remove the redundant calling of
compound_head() from page_to_index() and page_add_file_rmap() for
better code generation.
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
include/linux/pagemap.h | 7 +++----
mm/rmap.c | 6 ++++--
2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 79ec90e97e94..03b9a957ef10 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -608,18 +608,17 @@ static inline struct page *read_mapping_page(struct address_space *mapping,
*/
static inline pgoff_t page_to_index(struct page *page)
{
- pgoff_t pgoff;
+ struct page *head;
if (likely(!PageTransTail(page)))
return page->index;
+ head = compound_head(page);
/*
* We don't initialize ->index for tail pages: calculate based on
* head page
*/
- pgoff = compound_head(page)->index;
- pgoff += page - compound_head(page);
- return pgoff;
+ return head->index + page - head;
}
extern pgoff_t hugetlb_basepage_index(struct page *page);
diff --git a/mm/rmap.c b/mm/rmap.c
index 232494888628..2e216835f07c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1231,11 +1231,13 @@ void page_add_file_rmap(struct page *page, bool compound)
nr_pages);
} else {
if (PageTransCompound(page) && page_mapping(page)) {
+ struct page *head = compound_head(page);
+
VM_WARN_ON_ONCE(!PageLocked(page));
- SetPageDoubleMap(compound_head(page));
+ SetPageDoubleMap(head);
if (PageMlocked(page))
- clear_page_mlock(compound_head(page));
+ clear_page_mlock(head);
}
if (!atomic_inc_and_test(&page->_mapcount))
goto out;
--
2.11.0
