Btrfs: improve error handling for btrfs_insert_dir_item callers

This allows us to gracefully continue if we aren't able to insert
directory items, both for normal files/dirs and snapshots.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/inode.c

@@ -4585,7 +4585,8 @@ int btrfs_add_link(struct btrfs_trans_handle *trans,
 		ret = btrfs_insert_dir_item(trans, root, name, name_len,
 					    parent_inode, &key,
 					    btrfs_inode_type(inode), index);
-		BUG_ON(ret);
+		if (ret)
+			goto fail_dir_item;
 
 		btrfs_i_size_write(parent_inode, parent_inode->i_size +
 				   name_len * 2);
@@ -4593,6 +4594,23 @@ int btrfs_add_link(struct btrfs_trans_handle *trans,
 		ret = btrfs_update_inode(trans, root, parent_inode);
 	}
 	return ret;
+
+fail_dir_item:
+	if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
+		u64 local_index;
+		int err;
+		err = btrfs_del_root_ref(trans, root->fs_info->tree_root,
+				 key.objectid, root->root_key.objectid,
+				 parent_ino, &local_index, name, name_len);
+
+	} else if (add_backref) {
+		u64 local_index;
+		int err;
+
+		err = btrfs_del_inode_ref(trans, root, name, name_len,
+					  ino, parent_ino, &local_index);
+	}
+	return ret;
 }
 
 static int btrfs_add_nondir(struct btrfs_trans_handle *trans,

fs/btrfs/transaction.c

@@ -915,7 +915,11 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 				dentry->d_name.name, dentry->d_name.len,
 				parent_inode, &key,
 				BTRFS_FT_DIR, index);
-	BUG_ON(ret);
+	if (ret) {
+		pending->error = -EEXIST;
+		dput(parent);
+		goto fail;
+	}
 
 	btrfs_i_size_write(parent_inode, parent_inode->i_size +
 					 dentry->d_name.len * 2);
@@ -993,12 +997,9 @@ static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
 {
 	struct btrfs_pending_snapshot *pending;
 	struct list_head *head = &trans->transaction->pending_snapshots;
-	int ret;
 
-	list_for_each_entry(pending, head, list) {
-		ret = create_pending_snapshot(trans, fs_info, pending);
-		BUG_ON(ret);
-	}
+	list_for_each_entry(pending, head, list)
+		create_pending_snapshot(trans, fs_info, pending);
 	return 0;
 }