Linux 6.0 compat: Check for migratepage VFS (#17217)

The 6.0 kernel removes the 'migratepage' VFS op. Check for
migratepage.

Signed-off-by: Tony Hutter <[email protected]>
Reviewed-by: Rob Norris <[email protected]>
Reviewed-by: Alexander Motin <[email protected]

Author: tonyhutter

config/kernel-vfs-migratepage.m4

@@ -0,0 +1,27 @@
+dnl #
+dnl # Linux 6.0 gets rid of address_space_operations.migratepage
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_VFS_MIGRATEPAGE], [
+	ZFS_LINUX_TEST_SRC([vfs_has_migratepage], [
+		#include <linux/fs.h>
+		#include <linux/migrate.h>
+
+		static const struct address_space_operations
+		    aops __attribute__ ((unused)) = {
+			.migratepage	= migrate_page,
+		};
+	],[])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_VFS_MIGRATEPAGE], [
+	dnl #
+	dnl # Linux 6.0 gets rid of address_space_operations.migratepage
+	dnl #
+	AC_MSG_CHECKING([whether migratepage exists])
+	ZFS_LINUX_TEST_RESULT([vfs_has_migratepage], [
+		AC_MSG_RESULT([yes])
+		AC_DEFINE(HAVE_VFS_MIGRATEPAGE, 1, [migratepage exists])
+	],[
+		AC_MSG_RESULT([no])
+	])
+])

config/kernel.m4

@@ -79,6 +79,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
 	ZFS_AC_KERNEL_SRC_VFS_FILEMAP_DIRTY_FOLIO
 	ZFS_AC_KERNEL_SRC_VFS_READ_FOLIO
 	ZFS_AC_KERNEL_SRC_VFS_MIGRATE_FOLIO
+	ZFS_AC_KERNEL_SRC_VFS_MIGRATEPAGE
 	ZFS_AC_KERNEL_SRC_VFS_FSYNC_2ARGS
 	ZFS_AC_KERNEL_SRC_VFS_READPAGES
 	ZFS_AC_KERNEL_SRC_VFS_SET_PAGE_DIRTY_NOBUFFERS
@@ -191,6 +192,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
 	ZFS_AC_KERNEL_VFS_FILEMAP_DIRTY_FOLIO
 	ZFS_AC_KERNEL_VFS_READ_FOLIO
 	ZFS_AC_KERNEL_VFS_MIGRATE_FOLIO
+	ZFS_AC_KERNEL_VFS_MIGRATEPAGE
 	ZFS_AC_KERNEL_VFS_FSYNC_2ARGS
 	ZFS_AC_KERNEL_VFS_READPAGES
 	ZFS_AC_KERNEL_VFS_SET_PAGE_DIRTY_NOBUFFERS

module/os/linux/zfs/zpl_file.c

@@ -1058,7 +1058,7 @@ const struct address_space_operations zpl_address_space_operations = {
 #endif
 #ifdef HAVE_VFS_MIGRATE_FOLIO
 	.migrate_folio	= migrate_folio,
-#else
+#elif defined(HAVE_VFS_MIGRATEPAGE)
 	.migratepage	= migrate_page,
 #endif
 };