[PATCH 5.11 031/210] nds32: flush_dcache_page: use page_mapping_file to avoid races with swapoff

[Greg Kroah-Hartman]

From: Mike Rapoport <rppt@xxxxxxxxxxxxx>

commit a3a8833dffb7e7329c2586b8bfc531adb503f123 upstream.

Commit cb9f753a3731 ("mm: fix races between swapoff and flush dcache")
updated flush_dcache_page implementations on several architectures to
use page_mapping_file() in order to avoid races between page_mapping()
and swapoff().

This update missed arch/nds32 and there is a possibility of a race
there.

Replace page_mapping() with page_mapping_file() in nds32 implementation
of flush_dcache_page().

Link: https://lkml.kernel.org/r/20210330175126.26500-1-rppt@xxxxxxxxxx
Fixes: cb9f753a3731 ("mm: fix races between swapoff and flush dcache")
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Acked-by: Greentime Hu <green.hu@xxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Nick Hu <nickhu@xxxxxxxxxxxxx>
Cc: Vincent Chen <deanbo422@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/nds32/mm/cacheflush.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/nds32/mm/cacheflush.c
+++ b/arch/nds32/mm/cacheflush.c
@@ -238,7 +238,7 @@ void flush_dcache_page(struct page *page
 {
 	struct address_space *mapping;
 
-	mapping = page_mapping(page);
+	mapping = page_mapping_file(page);
 	if (mapping && !mapping_mapped(mapping))
 		set_bit(PG_dcache_dirty, &page->flags);
 	else {