ext4: prevent memory leaks from ext4_mb_init_backend() on error path

In ext4_mb_init(), if the s_locality_group allocation fails it will
currently cause the allocations made in ext4_mb_init_backend() to
be leaked.  Moving the ext4_mb_init_backend() allocation after the
s_locality_group allocation avoids that problem.
Signed-off-by: Yu Jian <yujian@whamcloud.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/mballoc.c

@@ -2465,12 +2465,6 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
 		i++;
 	} while (i <= sb->s_blocksize_bits + 1);
 
-	/* init file for buddy data */
-	ret = ext4_mb_init_backend(sb);
-	if (ret != 0) {
-		goto out;
-	}
-
 	spin_lock_init(&sbi->s_md_lock);
 	spin_lock_init(&sbi->s_bal_lock);
 
@@ -2507,6 +2501,12 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
 		spin_lock_init(&lg->lg_prealloc_lock);
 	}
 
+	/* init file for buddy data */
+	ret = ext4_mb_init_backend(sb);
+	if (ret != 0) {
+		goto out;
+	}
+
 	if (sbi->s_proc)
 		proc_create_data("mb_groups", S_IRUGO, sbi->s_proc,
 				 &ext4_mb_seq_groups_fops, sb);