From e880034cf7182aa35962bd30dfc9fa60476d56a4 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Wed, 21 Aug 2024 18:39:10 +0100 Subject: [PATCH] mm: introduce page_mapcount_is_type() Resolve the awkward "and add one to this opaque constant" test into a self-documenting inline function. Link: https://lkml.kernel.org/r/20240821173914.2270383-3-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Acked-by: David Hildenbrand Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Kent Overstreet Signed-off-by: Andrew Morton --- fs/proc/internal.h | 3 +-- include/linux/mm.h | 3 +-- include/linux/page-flags.h | 12 +++++++++--- 3 files changed, 11 insertions(+), 7 deletions(-) diff --git a/fs/proc/internal.h b/fs/proc/internal.h index a8a8576d8592e..cc520168f8b69 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -166,8 +166,7 @@ static inline int folio_precise_page_mapcount(struct folio *folio, { int mapcount = atomic_read(&page->_mapcount) + 1; - /* Handle page_has_type() pages */ - if (mapcount < PAGE_MAPCOUNT_RESERVE + 1) + if (page_mapcount_is_type(mapcount)) mapcount = 0; if (folio_test_large(folio)) mapcount += folio_entire_mapcount(folio); diff --git a/include/linux/mm.h b/include/linux/mm.h index 0fde51c0532f2..6f6053d7ea6f5 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1228,8 +1228,7 @@ static inline int folio_mapcount(const struct folio *folio) if (likely(!folio_test_large(folio))) { mapcount = atomic_read(&folio->_mapcount) + 1; - /* Handle page_has_type() pages */ - if (mapcount < PAGE_MAPCOUNT_RESERVE + 1) + if (page_mapcount_is_type(mapcount)) mapcount = 0; return mapcount; } diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 2515ae85f191b..0b5484fdbca1a 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -956,12 +956,18 @@ enum pagetype { #define folio_test_type(folio, flag) \ ((READ_ONCE(folio->page.page_type) & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE) -static inline int page_type_has_type(unsigned int page_type) +static inline bool page_type_has_type(int page_type) { - return (int)page_type < PAGE_MAPCOUNT_RESERVE; + return page_type < PAGE_MAPCOUNT_RESERVE; } -static inline int page_has_type(const struct page *page) +/* This takes a mapcount which is one more than page->_mapcount */ +static inline bool page_mapcount_is_type(unsigned int mapcount) +{ + return page_type_has_type(mapcount - 1); +} + +static inline bool page_has_type(const struct page *page) { return page_type_has_type(READ_ONCE(page->page_type)); } -- 2.49.0