Btrfs: add missing error checks to add_data_references

The function relocation.c:add_data_references() was not checking
if all calls to __add_tree_block() and find_data_references() were
succeeding or not.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/relocation.c

@@ -3628,7 +3628,7 @@ int add_data_references(struct reloc_control *rc,
 	unsigned long ptr;
 	unsigned long end;
 	u32 blocksize = btrfs_level_size(rc->extent_root, 0);
-	int ret;
+	int ret = 0;
 	int err = 0;
 
 	eb = path->nodes[0];
@@ -3655,6 +3655,10 @@ int add_data_references(struct reloc_control *rc,
 		} else {
 			BUG();
 		}
+		if (ret) {
+			err = ret;
+			goto out;
+		}
 		ptr += btrfs_extent_inline_ref_size(key.type);
 	}
 	WARN_ON(ptr > end);
@@ -3700,6 +3704,7 @@ int add_data_references(struct reloc_control *rc,
 		}
 		path->slots[0]++;
 	}
+out:
 	btrfs_release_path(path);
 	if (err)
 		free_block_list(blocks);