iomap: use attach/detach_page_private

Since the new pair function is introduced, we can call them to clean the
code in iomap.
Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Link: http://lkml.kernel.org/r/20200517214718.468-7-guoqing.jiang@cloud.ionos.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/iomap/buffered-io.c

@@ -59,24 +59,19 @@ iomap_page_create(struct inode *inode, struct page *page)
 	 * migrate_page_move_mapping() assumes that pages with private data have
 	 * their count elevated by 1.
 	 */
-	get_page(page);
-	set_page_private(page, (unsigned long)iop);
-	SetPagePrivate(page);
+	attach_page_private(page, iop);
 	return iop;
 }
 
 static void
 iomap_page_release(struct page *page)
 {
-	struct iomap_page *iop = to_iomap_page(page);
+	struct iomap_page *iop = detach_page_private(page);
 
 	if (!iop)
 		return;
 	WARN_ON_ONCE(atomic_read(&iop->read_count));
 	WARN_ON_ONCE(atomic_read(&iop->write_count));
-	ClearPagePrivate(page);
-	set_page_private(page, 0);
-	put_page(page);
 	kfree(iop);
 }
 
@@ -526,14 +521,8 @@ iomap_migrate_page(struct address_space *mapping, struct page *newpage,
 	if (ret != MIGRATEPAGE_SUCCESS)
 		return ret;
 
-	if (page_has_private(page)) {
-		ClearPagePrivate(page);
-		get_page(newpage);
-		set_page_private(newpage, page_private(page));
-		set_page_private(page, 0);
-		put_page(page);
-		SetPagePrivate(newpage);
-	}
+	if (page_has_private(page))
+		attach_page_private(newpage, detach_page_private(page));
 
 	if (mode != MIGRATE_SYNC_NO_COPY)
 		migrate_page_copy(newpage, page);