linuxkpi: Add pagemap.h

Add release_pages needed by drm which simply calls put_page for
all the pages provided

Reviewed by:	bz
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D26680

sys/compat/linuxkpi/common/include/linux/pagemap.h

@@ -0,0 +1,45 @@
+/*-
+ * Copyright (c) 2020 The FreeBSD Foundation
+ *
+ * This software was developed by Emmanuel Vadot under sponsorship
+ * from the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _LINUX_PAGEMAP_H_
+#define _LINUX_PAGEMAP_H_
+
+#include <linux/mm.h>
+
+static inline void
+release_pages(struct page **pages, int nr)
+{
+	int i;
+
+	for (i = 0; i < nr; i++)
+		put_page(pages[i]);
+}
+
+#endif