[PATCH 8/8] mm: Hoist find_subpage call further up in pagecache_get_page

Matthew Wilcox (Oracle)
2020-08-19T18:48:50Z

This avoids a call to compound_head().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
mm/filemap.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 6594baae7cd2..8c354277108d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1667,7 +1667,6 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
page = NULL;
if (!page)
goto no_page;
- page = find_subpage(page, index);

if (fgp_flags & FGP_LOCK) {
if (fgp_flags & FGP_NOWAIT) {
@@ -1680,12 +1679,12 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
}

/* Has the page been truncated? */
- if (unlikely(compound_head(page)->mapping != mapping)) {
+ if (unlikely(page->mapping != mapping)) {
unlock_page(page);
put_page(page);
goto repeat;
}
- VM_BUG_ON_PAGE(page->index != index, page);
+ VM_BUG_ON_PAGE(!thp_valid_index(page, index), page);
}

if (fgp_flags & FGP_ACCESSED)
@@ -1695,6 +1694,7 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
if (page_is_idle(page))
clear_page_idle(page);
}
+ page = find_subpage(page, index);

no_page:
if (!page && (fgp_flags & FGP_CREAT)) {
--
2.28.0