[RFC 1/6] mm: clean up PAGE_MAPPING_FLAGS

[Minchan Kim]

It's preparation to squeeze a new flag PAGE_MAPPING_LZFREE so
functions to get a anon_vma from mapping shouldn't assume that
+/- PAGE_MAPPING_ANON is enough.

Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
 mm/rmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index d9d42316a99a..76069afa6b81 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -412,7 +412,7 @@ struct anon_vma *page_get_anon_vma(struct page *page)
 	if (!page_mapped(page))
 		goto out;
 
-	anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
+	anon_vma = page_rmapping(page);
 	if (!atomic_inc_not_zero(&anon_vma->refcount)) {
 		anon_vma = NULL;
 		goto out;
@@ -455,7 +455,7 @@ struct anon_vma *page_lock_anon_vma_read(struct page *page)
 	if (!page_mapped(page))
 		goto out;
 
-	anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
+	anon_vma = page_rmapping(page);
 	root_anon_vma = ACCESS_ONCE(anon_vma->root);
 	if (down_read_trylock(&root_anon_vma->rwsem)) {
 		/*
-- 
1.9.0

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