Create version-4 bitmaps if kernel supports it.

Version-3 bitmaps are host-endian.  Version-4 are little-endian
and so more portable.

Signed-off-by: Neil Brown <neilb@suse.de>

1 files changed, 9 insertions, 1 deletions

diff --git a/Build.c b/Build.c
index 689aad0e..2fcc47e1 100644
--- a/Build.c
+++ b/Build.c
@@ -202,13 +202,21 @@ int Build(char *mddev, int mdfd, int chunk, int level, int layout,
 		if (bitmap_file) {
 			bitmap_fd = open(bitmap_file, O_RDWR);
 			if (bitmap_fd < 0) {
+				int major = BITMAP_MAJOR_HI;
 				if (bitmap_chunk == UnSet) {
 					fprintf(stderr, Name ": %s cannot be openned.",
 						bitmap_file);
 					return 1;
 				}
+				if (vers < 9003) {
+					major = BITMAP_MAJOR_HOSTENDIAN;
+#ifdef __BIG_ENDIAN
+					fprintf(stderr, Name ": Warning - bitmaps created on this kernel are not portable\n"
+						"  between different architectured.  Consider upgrading the Linux kernel.\n");
+#endif
+				}
 				if (CreateBitmap(bitmap_file, 1, NULL, bitmap_chunk,
-						 delay, write_behind, size>>9)) {
+						 delay, write_behind, size>>9, major)) {
 					return 1;
 				}
 				bitmap_fd = open(bitmap_file, O_RDWR);