mm: Add folio_mapped()

This function is the equivalent of page_mapped().  It is slightly
shorter as we do not need to handle the PageTail() case.  Reimplement
page_mapped() as a wrapper around folio_mapped().  folio_mapped()
is 13 bytes smaller than page_mapped(), but the page_mapped() wrapper
is 30 bytes, for a net increase of 17 bytes of text.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index bc5c38e..95e36d0 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1769,6 +1769,7 @@ static inline pgoff_t page_index(struct page *page)
 }
 
 bool page_mapped(struct page *page);
+bool folio_mapped(struct folio *folio);
 
 /*
  * Return true only if the page has been allocated with

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 5ebcb86..82dab23 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -299,6 +299,12 @@ FOLIO_MATCH(memcg_data, memcg_data);
 #endif
 #undef FOLIO_MATCH
 
+static inline atomic_t *folio_mapcount_ptr(struct folio *folio)
+{
+       struct page *tail = &folio->page + 1;
+       return &tail->compound_mapcount;
+}
+
 static inline atomic_t *compound_mapcount_ptr(struct page *page)
 {
        return &page[1].compound_mapcount;

diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index 3c83f03..7044fcc 100644 (file)
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -35,3 +35,9 @@ void wait_for_stable_page(struct page *page)
        return folio_wait_stable(page_folio(page));
 }
 EXPORT_SYMBOL_GPL(wait_for_stable_page);
+
+bool page_mapped(struct page *page)
+{
+       return folio_mapped(page_folio(page));
+}
+EXPORT_SYMBOL(page_mapped);

diff --git a/mm/util.c b/mm/util.c
index 6c1fe9b..e322a42 100644 (file)
--- a/mm/util.c
+++ b/mm/util.c
@@ -671,28 +671,31 @@ void *page_rmapping(struct page *page)
        return __page_rmapping(page);
 }
 
-/*
- * Return true if this page is mapped into pagetables.
- * For compound page it returns true if any subpage of compound page is mapped.
+/**
+ * folio_mapped - Is this folio mapped into userspace?
+ * @folio: The folio.
+ *
+ * Return: True if any page in this folio is referenced by user page tables.
  */
-bool page_mapped(struct page *page)
+bool folio_mapped(struct folio *folio)
 {
-       int i;
+       long i, nr;
 
-       if (likely(!PageCompound(page)))
-               return atomic_read(&page->_mapcount) >= 0;
-       page = compound_head(page);
-       if (atomic_read(compound_mapcount_ptr(page)) >= 0)
+       if (folio_test_single(folio))
+               return atomic_read(&folio->_mapcount) >= 0;
+       if (atomic_read(folio_mapcount_ptr(folio)) >= 0)
                return true;
-       if (PageHuge(page))
+       if (folio_test_hugetlb(folio))
                return false;
-       for (i = 0; i < compound_nr(page); i++) {
-               if (atomic_read(&page[i]._mapcount) >= 0)
+
+       nr = folio_nr_pages(folio);
+       for (i = 0; i < nr; i++) {
+               if (atomic_read(&folio_page(folio, i)->_mapcount) >= 0)
                        return true;
        }
        return false;
 }
-EXPORT_SYMBOL(page_mapped);
+EXPORT_SYMBOL(folio_mapped);
 
 struct anon_vma *page_anon_vma(struct page *page)
 {