[PATCH] md: Always allow a half-built md array to be stopped.

When starting an array fails, we have to tear it down, but
in some circumstances (particularly autostart_array) the
reference count will be 3, so do_md_stop will fail.

With this patch we only worry about the number of users
is the array has been fully started.

drivers/md/md.c

@@ -1669,13 +1669,12 @@ static int do_md_stop(mddev_t * mddev, int ro)
 	int err = 0;
 	struct gendisk *disk = disks[mdidx(mddev)];
 
+	if (mddev->pers) {
 		if (atomic_read(&mddev->active)>2) {
 			printk("md: md%d still in use.\n",mdidx(mddev));
-		err = -EBUSY;
-		goto out;
+			return -EBUSY;
 		}
 
-	if (mddev->pers) {
 		if (mddev->sync_thread) {
 			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
 			md_unregister_thread(mddev->sync_thread);