From 4ba1119cd53166d853050ff1a9d76079cd8f8e06 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Mon, 17 Jan 2022 16:33:26 -0500 Subject: mm: Add folio_mapcount() This implements the same algorithm as total_mapcount(), which is transformed into a wrapper function. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig --- mm/huge_memory.c | 24 ------------------------ mm/util.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+), 24 deletions(-) (limited to 'mm') diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 9afca0122723..beebe4105659 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2465,30 +2465,6 @@ static void __split_huge_page(struct page *page, struct list_head *list, } } -int total_mapcount(struct page *page) -{ - int i, compound, nr, ret; - - VM_BUG_ON_PAGE(PageTail(page), page); - - if (likely(!PageCompound(page))) - return atomic_read(&page->_mapcount) + 1; - - compound = compound_mapcount(page); - nr = compound_nr(page); - if (PageHuge(page)) - return compound; - ret = compound; - for (i = 0; i < nr; i++) - ret += atomic_read(&page[i]._mapcount) + 1; - /* File pages has compound_mapcount included in _mapcount */ - if (!PageAnon(page)) - return ret - compound * nr; - if (PageDoubleMap(page)) - ret -= nr; - return ret; -} - /* * This calculates accurately how many mappings a transparent hugepage * has (unlike page_mapcount() which isn't fully accurate). This full diff --git a/mm/util.c b/mm/util.c index 7e43369064c8..b614f423aaa4 100644 --- a/mm/util.c +++ b/mm/util.c @@ -740,6 +740,39 @@ int __page_mapcount(struct page *page) } EXPORT_SYMBOL_GPL(__page_mapcount); +/** + * folio_mapcount() - Calculate the number of mappings of this folio. + * @folio: The folio. + * + * A large folio tracks both how many times the entire folio is mapped, + * and how many times each individual page in the folio is mapped. + * This function calculates the total number of times the folio is + * mapped. + * + * Return: The number of times this folio is mapped. + */ +int folio_mapcount(struct folio *folio) +{ + int i, compound, nr, ret; + + if (likely(!folio_test_large(folio))) + return atomic_read(&folio->_mapcount) + 1; + + compound = folio_entire_mapcount(folio); + nr = folio_nr_pages(folio); + if (folio_test_hugetlb(folio)) + return compound; + ret = compound; + for (i = 0; i < nr; i++) + ret += atomic_read(&folio_page(folio, i)->_mapcount) + 1; + /* File pages has compound_mapcount included in _mapcount */ + if (!folio_test_anon(folio)) + return ret - compound * nr; + if (folio_test_double_map(folio)) + ret -= nr; + return ret; +} + /** * folio_copy - Copy the contents of one folio to another. * @dst: Folio to copy to. -- cgit