Linux 6.11: add compat macro for page_mapping()

Since the change to folios it has just been a wrapper anyway. Linux has
removed their wrapper, so we add one.

Reviewed-by: Tony Hutter <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Rob Norris <[email protected]>
Sponsored-by: https://despairlabs.com/sponsor/
Closes #16400

Author: robn

config/kernel-mm-page-size.m4

@@ -0,0 +1,36 @@
+AC_DEFUN([ZFS_AC_KERNEL_SRC_MM_PAGE_SIZE], [
+	ZFS_LINUX_TEST_SRC([page_size], [
+		#include <linux/mm.h>
+	],[
+		unsigned long s;
+		s = page_size(NULL);
+	])
+])
+AC_DEFUN([ZFS_AC_KERNEL_MM_PAGE_SIZE], [
+	AC_MSG_CHECKING([whether page_size() is available])
+	ZFS_LINUX_TEST_RESULT([page_size], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_MM_PAGE_SIZE, 1, [page_size() is available])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+
+AC_DEFUN([ZFS_AC_KERNEL_SRC_MM_PAGE_MAPPING], [
+	ZFS_LINUX_TEST_SRC([page_mapping], [
+		#include <linux/pagemap.h>
+	],[
+		struct page *p = NULL;
+		struct address_space *m = page_mapping(NULL);
+	])
+])
+AC_DEFUN([ZFS_AC_KERNEL_MM_PAGE_MAPPING], [
+	AC_MSG_CHECKING([whether page_mapping() is available])
+	ZFS_LINUX_TEST_RESULT([page_mapping], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_MM_PAGE_MAPPING, 1, [page_mapping() is available])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])

config/kernel-mm-pagemap.m4

@@ -171,6 +171,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
 	ZFS_AC_KERNEL_SRC_COPY_SPLICE_READ
 	ZFS_AC_KERNEL_SRC_SYNC_BDEV
 	ZFS_AC_KERNEL_SRC_MM_PAGE_SIZE
+	ZFS_AC_KERNEL_SRC_MM_PAGE_MAPPING
 	case "$host_cpu" in
 		powerpc*)
 			ZFS_AC_KERNEL_SRC_CPU_HAS_FEATURE
@@ -324,6 +325,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
 	ZFS_AC_KERNEL_COPY_SPLICE_READ
 	ZFS_AC_KERNEL_SYNC_BDEV
 	ZFS_AC_KERNEL_MM_PAGE_SIZE
+	ZFS_AC_KERNEL_MM_PAGE_MAPPING
 	case "$host_cpu" in
 		powerpc*)
 			ZFS_AC_KERNEL_CPU_HAS_FEATURE

config/kernel.m4

@@ -21,16 +21,23 @@
 
 /*
  * Copyright (c) 2023, 2024, Klara Inc.
+ * Copyright (c) 2024, Rob Norris <[email protected]>
  */
 
 #ifndef _ZFS_MM_COMPAT_H
 #define	_ZFS_MM_COMPAT_H
 
 #include <linux/mm.h>
+#include <linux/pagemap.h>
 
 /* 5.4 introduced page_size(). Older kernels can use a trivial macro instead */
 #ifndef HAVE_MM_PAGE_SIZE
 #define	page_size(p) ((unsigned long)(PAGE_SIZE << compound_order(p)))
 #endif
 
+/* 6.11 removed page_mapping(). A simple wrapper around folio_mapping() works */
+#ifndef HAVE_MM_PAGE_MAPPING
+#define	page_mapping(p) folio_mapping(page_folio(p))
+#endif
+
 #endif /* _ZFS_MM_COMPAT_H */

include/os/linux/kernel/linux/mm_compat.h

@@ -69,6 +69,7 @@
 #include <sys/zpl.h>
 #include <sys/zil.h>
 #include <sys/sa_impl.h>
+#include <linux/mm_compat.h>
 
 /*
  * Programming rules.