diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index d92462fe66c8..f64aad613727 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1016,19 +1016,21 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 		parent_start = parent->start;
 
 	/*
-	 * If we are COWing a node/leaf from the extent, chunk or device trees,
-	 * make sure that we do not finish block group creation of pending block
-	 * groups. We do this to avoid a deadlock.
+	 * If we are COWing a node/leaf from the extent, chunk, device or free
+	 * space trees, make sure that we do not finish block group creation of
+	 * pending block groups. We do this to avoid a deadlock.
 	 * COWing can result in allocation of a new chunk, and flushing pending
 	 * block groups (btrfs_create_pending_block_groups()) can be triggered
 	 * when finishing allocation of a new chunk. Creation of a pending block
-	 * group modifies the extent, chunk and device trees, therefore we could
-	 * deadlock with ourselves since we are holding a lock on an extent
-	 * buffer that btrfs_create_pending_block_groups() may try to COW later.
+	 * group modifies the extent, chunk, device and free space trees,
+	 * therefore we could deadlock with ourselves since we are holding a
+	 * lock on an extent buffer that btrfs_create_pending_block_groups() may
+	 * try to COW later.
 	 */
 	if (root == fs_info->extent_root ||
 	    root == fs_info->chunk_root ||
-	    root == fs_info->dev_root)
+	    root == fs_info->dev_root ||
+	    root == fs_info->free_space_root)
 		trans->can_flush_pending_bgs = false;
 
 	cow = btrfs_alloc_tree_block(trans, root, parent_start,