[PATCH] md: allow checkpoint of recovery with version-1 superblock

For a while we have had checkpointing of resync.  The version-1 superblock
allows recovery to be checkpointed as well, and this patch implements that.

Due to early carelessness we need to add a feature flag to signal that the
recovery_offset field is in use, otherwise older kernels would assume that a
partially recovered array is in fact fully recovered.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/raid/md_p.h b/include/linux/raid/md_p.h
index f1fbae7..b6ebc69 100644
--- a/include/linux/raid/md_p.h
+++ b/include/linux/raid/md_p.h
@@ -265,9 +265,12 @@
 
 /* feature_map bits */
 #define MD_FEATURE_BITMAP_OFFSET	1
+#define	MD_FEATURE_RECOVERY_OFFSET	2 /* recovery_offset is present and
+					   * must be honoured
+					   */
 #define	MD_FEATURE_RESHAPE_ACTIVE	4
 
-#define	MD_FEATURE_ALL			5
+#define	MD_FEATURE_ALL			(1|2|4)
 
 #endif