[PATCH v13 052/137] mm: Add folio_raw_mapping()

Matthew Wilcox (Oracle)
2021-07-12T03:35:59Z

Convert __page_rmapping to folio_raw_mapping and move it to mm/internal.h.
It's only a couple of instructions (load and mask), so it's definitely
going to be cheaper to inline it than call it. Leave page_rmapping
out of line.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
mm/internal.h | 7 +++++++
mm/util.c | 20 ++++----------------
2 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 1a8851b73031..fa31a7f0ed79 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -34,6 +34,13 @@

void page_writeback_init(void);

+static inline void *folio_raw_mapping(struct folio *folio)
+{
+ unsigned long mapping = (unsigned long)folio->mapping;
+
+ return (void *)(mapping & ~PAGE_MAPPING_FLAGS);
+}
+
vm_fault_t do_swap_page(struct vm_fault *vmf);
void folio_rotate_reclaimable(struct folio *folio);

diff --git a/mm/util.c b/mm/util.c
index 0c65b260cded..48d843165a1a 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -635,21 +635,10 @@ void kvfree_sensitive(const void *addr, size_t len)
}
EXPORT_SYMBOL(kvfree_sensitive);

-static inline void *__page_rmapping(struct page *page)
-{
- unsigned long mapping;
-
- mapping = (unsigned long)page->mapping;
- mapping &= ~PAGE_MAPPING_FLAGS;
-
- return (void *)mapping;
-}
-
/* Neutral page->mapping pointer to address_space or anon_vma or other */
void *page_rmapping(struct page *page)
{
- page = compound_head(page);
- return __page_rmapping(page);
+ return folio_raw_mapping(page_folio(page));
}

/**
@@ -680,13 +669,12 @@ EXPORT_SYMBOL(folio_mapped);

struct anon_vma *page_anon_vma(struct page *page)
{
- unsigned long mapping;
+ struct folio *folio = page_folio(page);
+ unsigned long mapping = (unsigned long)folio->mapping;

- page = compound_head(page);
- mapping = (unsigned long)page->mapping;
if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
return NULL;
- return __page_rmapping(page);
+ return (void *)(mapping - PAGE_MAPPING_ANON);
}

/**
--
2.30.2