Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   "Matthew Wilcox (Oracle)" <willy@infradead.org>
To:     linux-mm@kvack.org
Cc:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-cachefs@redhat.com, linux-afs@lists.infradead.org,
        Christoph Hellwig <hch@lst.de>,
        Jeff Layton <jlayton@kernel.org>
Subject: [PATCH v7 15/28] mm: Add folio_mapcount
Date:   Fri,  9 Apr 2021 19:50:52 +0100
Message-Id: <20210409185105.188284-16-willy@infradead.org>
In-Reply-To: <20210409185105.188284-1-willy@infradead.org>
References: <20210409185105.188284-1-willy@infradead.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

This is the folio equivalent of page_mapcount().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Layton <jlayton@kernel.org>
---
 include/linux/mm.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 143b354c3f4a..7bd2ce197e2f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -883,6 +883,22 @@ 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);
-- 
2.30.2