From ef661d455012608cc172c0804230f10b0e60179f Mon Sep 17 00:00:00 2001
From: Rob Norris <robn@despairlabs.com>
Date: Wed, 31 Jul 2024 18:43:39 +1000
Subject: [PATCH] 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.

Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://despairlabs.com/sponsor/
---
 config/kernel-mm-page-size.m4             | 17 -----------
 config/kernel-mm-pagemap.m4               | 36 +++++++++++++++++++++++
 config/kernel.m4                          |  2 ++
 include/os/linux/kernel/linux/mm_compat.h |  7 +++++
 module/os/linux/zfs/zfs_vnops_os.c        |  1 +
 5 files changed, 46 insertions(+), 17 deletions(-)
 delete mode 100644 config/kernel-mm-page-size.m4
 create mode 100644 config/kernel-mm-pagemap.m4

diff --git a/config/kernel-mm-page-size.m4 b/config/kernel-mm-page-size.m4
deleted file mode 100644
index d5ebd926986a..000000000000
--- a/config/kernel-mm-page-size.m4
+++ /dev/null
@@ -1,17 +0,0 @@
-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)
-	])
-])
diff --git a/config/kernel-mm-pagemap.m4 b/config/kernel-mm-pagemap.m4
new file mode 100644
index 000000000000..466b6fa07d9a
--- /dev/null
+++ b/config/kernel-mm-pagemap.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)
+	])
+])
diff --git a/config/kernel.m4 b/config/kernel.m4
index 6194c119cca6..d6ea3453292a 100644
--- a/config/kernel.m4
+++ b/config/kernel.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
diff --git a/include/os/linux/kernel/linux/mm_compat.h b/include/os/linux/kernel/linux/mm_compat.h
index 40056c68d6dd..817f6df422de 100644
--- a/include/os/linux/kernel/linux/mm_compat.h
+++ b/include/os/linux/kernel/linux/mm_compat.h
@@ -21,16 +21,23 @@
 
 /*
  * Copyright (c) 2023, 2024, Klara Inc.
+ * Copyright (c) 2024, Rob Norris <robn@despairlabs.com>
  */
 
 #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 */
diff --git a/module/os/linux/zfs/zfs_vnops_os.c b/module/os/linux/zfs/zfs_vnops_os.c
index 1cecad9f7755..8061169c3293 100644
--- a/module/os/linux/zfs/zfs_vnops_os.c
+++ b/module/os/linux/zfs/zfs_vnops_os.c
@@ -69,6 +69,7 @@
 #include <sys/zpl.h>
 #include <sys/zil.h>
 #include <sys/sa_impl.h>
+#include <linux/mm_compat.h>
 
 /*
  * Programming rules.