[Ocfs2-devel] [PATCH 05/30] ocfs2: Handle macro zero_user_page()

[Sunil Mushran]

Commit 01f2705daf5a36208e69d7cf95db9c330f843af6 in mainline introduced
macro zero_user_page(). This patch allows one to build ocfs2 with
kernels having/not having that change.

Signed-off-by: Sunil Mushran <sunil.mushran at oracle.com>
Signed-off-by: Joel Becker <joel.becker at oracle.com>
---
 Makefile                      |    3 ++-
 configure.in                  |    5 +++++
 kapi-compat/include/highmem.h |   22 ++++++++++++++++++++++
 3 files changed, 29 insertions(+), 1 deletions(-)
 create mode 100644 kapi-compat/include/highmem.h

diff --git a/Makefile b/Makefile
index 21ff590..b7b86db 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,8 @@ LINUX_INCLUDE_FILES =
 
 KAPI_COMPAT_FILES = \
 	kapi-compat/include/workqueue.h \
-	kapi-compat/include/compiler.h
+	kapi-compat/include/compiler.h \
+	kapi-compat/include/highmem.h
 
 PATCH_FILES =
 
diff --git a/configure.in b/configure.in
index 70c4041..0108f99 100644
--- a/configure.in
+++ b/configure.in
@@ -167,6 +167,11 @@ OCFS2_CHECK_KERNEL([uninitialized_var() in compiler-gcc4.h], compiler-gcc4.h,
   , compiler_compat_header="compiler.h", [uninitialized_var])
 KAPI_COMPAT_HEADERS="$KAPI_COMPAT_HEADERS $compiler_compat_header"
 
+highmem_compat_header=""
+OCFS2_CHECK_KERNEL([zero_user_page() in highmem.h], highmem.h,
+  , highmem_compat_header="highmem.h", [zero_user_page])
+KAPI_COMPAT_HEADERS="$KAPI_COMPAT_HEADERS $highmem_compat_header"
+
 # using -include has two advantages:
 #  the source doesn't need to know to include compat headers
 #  the compat header file names don't go through the search path
diff --git a/kapi-compat/include/highmem.h b/kapi-compat/include/highmem.h
new file mode 100644
index 0000000..a8c7e11
--- /dev/null
+++ b/kapi-compat/include/highmem.h
@@ -0,0 +1,22 @@
+#ifndef KAPI_HIGHMEM_H
+#define KAPI_HIGHMEM_H
+
+/*
+ * Same but also flushes aliased cache contents to RAM.
+ *
+ * This must be a macro because KM_USER0 and friends aren't defined if
+ * !CONFIG_HIGHMEM
+ */
+#define zero_user_page(page, offset, size, km_type)		\
+	do {							\
+		void *kaddr;					\
+								\
+		BUG_ON((offset) + (size) > PAGE_SIZE);		\
+								\
+		kaddr = kmap_atomic(page, km_type);		\
+		memset((char *)kaddr + (offset), 0, (size));	\
+		flush_dcache_page(page);			\
+		kunmap_atomic(kaddr, (km_type));		\
+	} while (0)
+
+#endif
-- 
1.5.3.4