[PATCH] md: make md on-disk bitmaps not host-endian

Current bitmaps use set_bit et.al and so are host-endian, which means
not-portable.  Oops.

Define a new version number (4) for which bitmaps are little-endian.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 12 insertions, 3 deletions

diff --git a/include/linux/raid/bitmap.h b/include/linux/raid/bitmap.h
index 9de99198caf1..899437802aea 100644
--- a/include/linux/raid/bitmap.h
+++ b/include/linux/raid/bitmap.h
@@ -6,7 +6,13 @@
 #ifndef BITMAP_H
 #define BITMAP_H 1
 
-#define BITMAP_MAJOR 3
+#define BITMAP_MAJOR_LO 3
+/* version 4 insists the bitmap is in little-endian order
+ * with version 3, it is host-endian which is non-portable
+ */
+#define BITMAP_MAJOR_HI 4
+#define BITMAP_MAJOR_HOSTENDIAN 3
+
 #define BITMAP_MINOR 39
 
 /*
@@ -133,7 +139,8 @@ typedef __u16 bitmap_counter_t;
 /* use these for bitmap->flags and bitmap->sb->state bit-fields */
 enum bitmap_state {
         BITMAP_ACTIVE = 0x001, /* the bitmap is in use */
-        BITMAP_STALE  = 0x002  /* the bitmap file is out of date or had -EIO */
+        BITMAP_STALE  = 0x002,  /* the bitmap file is out of date or had -EIO */
+        BITMAP_HOSTENDIAN = 0x8000,
 };
 
 /* the superblock at the front of the bitmap file -- little endian */
diff --git a/include/linux/raid/md.h b/include/linux/raid/md.h
index ffa316ce4dc8..91467a3c4a52 100644
--- a/include/linux/raid/md.h
+++ b/include/linux/raid/md.h
@@ -66,8 +66,10 @@
  *     and major_version/minor_version accordingly
  * >=2 means that Internal bitmaps are supported by setting MD_SB_BITMAP_PRESENT
  *     in the super status byte
+ * >=3 means that bitmap superblock version 4 is supported, which uses
+ *     little-ending representation rather than host-endian
  */
-#define MD_PATCHLEVEL_VERSION           2
+#define MD_PATCHLEVEL_VERSION           3
 
 extern int register_md_personality (int p_num, mdk_personality_t *p);
 extern int unregister_md_personality (int p_num);