[PATCH] md: handle hot-add for arrays with non-persistent superblocks

If the superblock isn't persistent, we shouldn't allow room for it.

From: Paul Clements <Paul.Clements@SteelEye.com>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/md.c

@@ -2251,7 +2251,12 @@ static int hot_add_disk(mddev_t * mddev, dev_t dev)
 		return -EINVAL;
 	}
 
-	rdev->sb_offset = calc_dev_sboffset(rdev->bdev);
+	if (mddev->persistent)
+		rdev->sb_offset = calc_dev_sboffset(rdev->bdev);
+	else
+		rdev->sb_offset =
+			rdev->bdev->bd_inode->i_size >> BLOCK_SIZE_BITS;
+
 	size = calc_dev_size(rdev, mddev->chunk_size);
 	rdev->size = size;