[PATCH v6 04/38] mm: Add folio_flush_mapping()
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Date: 2023-08-02 15:16:18
Also in:
linux-mm, lkml
Subsystem:
page cache, the rest · Maintainers:
Matthew Wilcox, Jan Kara, Linus Torvalds
This is the folio equivalent of page_mapping_file(), but rename it to make it clear that it's very different from page_file_mapping(). Theoretically, there's nothing flush-only about it, but there are no other users today, and I doubt there will be; it's almost always more useful to know the swapfile's mapping or the swapcache's mapping. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Reviewed-by: Anshuman Khandual <redacted> --- include/linux/pagemap.h | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 04c0fc6f81b3..bd522a64b714 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h@@ -389,6 +389,26 @@ static inline struct address_space *folio_file_mapping(struct folio *folio) return folio->mapping; } +/** + * folio_flush_mapping - Find the file mapping this folio belongs to. + * @folio: The folio. + * + * For folios which are in the page cache, return the mapping that this + * page belongs to. Anonymous folios return NULL, even if they're in + * the swap cache. Other kinds of folio also return NULL. + * + * This is ONLY used by architecture cache flushing code. If you aren't + * writing cache flushing code, you want either folio_mapping() or + * folio_file_mapping(). + */ +static inline struct address_space *folio_flush_mapping(struct folio *folio) +{ + if (unlikely(folio_test_swapcache(folio))) + return NULL; + + return folio_mapping(folio); +} + static inline struct address_space *page_file_mapping(struct page *page) { return folio_file_mapping(page_folio(page));
@@ -399,11 +419,7 @@ static inline struct address_space *page_file_mapping(struct page *page) */ static inline struct address_space *page_mapping_file(struct page *page) { - struct folio *folio = page_folio(page); - - if (unlikely(folio_test_swapcache(folio))) - return NULL; - return folio_mapping(folio); + return folio_flush_mapping(page_folio(page)); } /**
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2.40.1