linux-kernel - [PATCH v13 15/32] mm/filemap: Add folio_pos() and folio_file

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Message-Id: <20210712190204.80979-16-willy@infradead.org>
Date:   Mon, 12 Jul 2021 20:01:47 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     akpm@...ux-foundation.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, Christoph Hellwig <hch@....de>,
        Jeff Layton <jlayton@...nel.org>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        William Kucharski <william.kucharski@...cle.com>,
        David Howells <dhowells@...hat.com>
Subject: [PATCH v13 15/32] mm/filemap: Add folio_pos() and folio_file_pos()

These are just wrappers around page_offset() and page_file_offset()
respectively.  No change to generated code.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Reviewed-by: Christoph Hellwig <hch@....de>
Acked-by: Jeff Layton <jlayton@...nel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Acked-by: Vlastimil Babka <vbabka@...e.cz>
Reviewed-by: William Kucharski <william.kucharski@...cle.com>
Reviewed-by: David Howells <dhowells@...hat.com>
---
 include/linux/pagemap.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index aac447fbaddd..89bfc92714bf 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -562,6 +562,27 @@ static inline loff_t page_file_offset(struct page *page)
 	return ((loff_t)page_index(page)) << PAGE_SHIFT;
 }
 
+/**
+ * folio_pos - Returns the byte position of this folio in its file.
+ * @folio: The folio.
+ */
+static inline loff_t folio_pos(struct folio *folio)
+{
+	return page_offset(&folio->page);
+}
+
+/**
+ * folio_file_pos - Returns the byte position of this folio in its file.
+ * @folio: The folio.
+ *
+ * This differs from folio_pos() for folios which belong to a swap file.
+ * NFS is the only filesystem today which needs to use folio_file_pos().
+ */
+static inline loff_t folio_file_pos(struct folio *folio)
+{
+	return page_file_offset(&folio->page);
+}
+
 extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
 				     unsigned long address);
 
-- 
2.30.2