diff mbox series

[v6,14/27] mm: Add folio_mapcount

Message ID 20210331184728.1188084-15-willy@infradead.org (mailing list archive)
State New, archived
Headers show
Series Memory Folios | expand

Commit Message

Matthew Wilcox March 31, 2021, 6:47 p.m. UTC 
This is the folio equivalent of page_mapcount().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/mm.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Comments

Christoph Hellwig April 6, 2021, 1:46 p.m. UTC | #1 
On Wed, Mar 31, 2021 at 07:47:15PM +0100, Matthew Wilcox (Oracle) wrote:
> This is the folio equivalent of page_mapcount().
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox series

Patch

diff --git a/include/linux/mm.h b/include/linux/mm.h
index a4f2818aeb1d..fc15a256e686 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -869,6 +869,22 @@  static inline int page_mapcount(struct page *page)
 	return atomic_read(&page->_mapcount) + 1;
 }
 
+/**
+ * folio_mapcount - The number of mappings of this folio.
+ * @folio: The folio.
+ *
+ * The result includes the number of times any of the pages in the
+ * folio are mapped to userspace.
+ *
+ * Return: The number of page table entries which refer to this folio.
+ */
+static inline int folio_mapcount(struct folio *folio)
+{
+	if (unlikely(FolioMulti(folio)))
+		return __page_mapcount(&folio->page);
+	return atomic_read(&folio->_mapcount) + 1;
+}
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 int total_mapcount(struct page *page);
 int page_trans_huge_mapcount(struct page *page, int *total_mapcount);