diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index c6d257fb40af..a97dfc72a80a 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1618,7 +1618,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
 		clear_bits |= EXTENT_CLEAR_DATA_RESV;
 		extent_clear_unlock_delalloc(inode, start, end, locked_folio,
 					     &cached, clear_bits, page_ops);
-		btrfs_qgroup_free_data(inode, NULL, start, cur_alloc_size, NULL);
+		btrfs_qgroup_free_data(inode, NULL, start, end - start + 1, NULL);
 	}
 	return ret;
 }