[PATCH] md: Split reshape handler in check_reshape and start_reshape

check_reshape checks validity and does things that can be done instantly -
like adding devices to raid1.  start_reshape initiates a restriping process to
convert the whole array.

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_k.h b/include/linux/raid/md_k.h
index 1a6f9f2..002ee63 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -261,7 +261,8 @@
 	int (*spare_active) (mddev_t *mddev);
 	sector_t (*sync_request)(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster);
 	int (*resize) (mddev_t *mddev, sector_t sectors);
-	int (*reshape) (mddev_t *mddev, int raid_disks);
+	int (*check_reshape) (mddev_t *mddev);
+	int (*start_reshape) (mddev_t *mddev);
 	int (*reconfig) (mddev_t *mddev, int layout, int chunk_size);
 	/* quiesce moves between quiescence states
 	 * 0 - fully active