ocfs2: Return -EINVAL when a device is not ocfs2.

In case of non-modular kernels the root filesystem is mounted by trying
several filesystems. If ocfs2 was tried before the actual filesystem
type, the mount would fail because ocfs2_sb_probe() returns -EAGAIN
instead of -EINVAL.  ocfs2 will now return -EINVAL properly.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Reported-by: Laszlo Attila Toth <panther@balabit.hu>

fs/ocfs2/super.c

@@ -773,19 +773,21 @@ static int ocfs2_sb_probe(struct super_block *sb,
 		if (tmpstat < 0) {
 			status = tmpstat;
 			mlog_errno(status);
-			goto bail;
+			break;
 		}
 		di = (struct ocfs2_dinode *) (*bh)->b_data;
 		memset(stats, 0, sizeof(struct ocfs2_blockcheck_stats));
 		spin_lock_init(&stats->b_lock);
-		status = ocfs2_verify_volume(di, *bh, blksize, stats);
-		if (status >= 0)
-			goto bail;
+		tmpstat = ocfs2_verify_volume(di, *bh, blksize, stats);
+		if (tmpstat < 0) {
 			brelse(*bh);
 			*bh = NULL;
-		if (status != -EAGAIN)
+		}
+		if (tmpstat != -EAGAIN) {
+			status = tmpstat;
 			break;
 		}
+	}
 
 bail:
 	return status;