From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: mm/swap: optimise get_shadow_from_swap_cache

There's no need to get a reference to the page, just load the entry and
see if it's a shadow entry.

Link: https://lkml.kernel.org/r/20201112212641.27837-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <redacted>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <redacted>
Cc: William Kucharski <redacted>
Cc: Yang Shi <redacted>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/swap_state.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/mm/swap_state.c~mm-swap-optimise-get_shadow_from_swap_cache
+++ a/mm/swap_state.c

@@ -87,11 +87,9 @@ void *get_shadow_from_swap_cache(swp_ent
 	pgoff_t idx = swp_offset(entry);
 	struct page *page;
 
-	page = find_get_entry(address_space, idx);
+	page = xa_load(&address_space->i_pages, idx);
 	if (xa_is_value(page))
 		return page;
-	if (page)
-		put_page(page);
 	return NULL;
 }
 

_