+enum flush_state {
+ FLUSH_DELALLOC = 1,
+ FLUSH_DELALLOC_WAIT = 2,
+ FLUSH_DELAYED_ITEMS_NR = 3,
+ FLUSH_DELAYED_ITEMS = 4,
+ COMMIT_TRANS = 5,
+};
+
+static int flush_space(struct btrfs_root *root,
+ struct btrfs_space_info *space_info, u64 num_bytes,
+ u64 orig_bytes, int state)
+{
+ struct btrfs_trans_handle *trans;
+ int nr;
+ int ret = 0;
+
+ switch (state) {
+ case FLUSH_DELALLOC:
+ case FLUSH_DELALLOC_WAIT:
+ shrink_delalloc(root, num_bytes, orig_bytes,
+ state == FLUSH_DELALLOC_WAIT);
+ break;
+ case FLUSH_DELAYED_ITEMS_NR:
+ case FLUSH_DELAYED_ITEMS:
+ if (state == FLUSH_DELAYED_ITEMS_NR) {
+ u64 bytes = btrfs_calc_trans_metadata_size(root, 1);
+
+ nr = (int)div64_u64(num_bytes, bytes);
+ if (!nr)
+ nr = 1;
+ nr *= 2;
+ } else {
+ nr = -1;
+ }
+ trans = btrfs_join_transaction(root);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ break;
+ }
+ ret = btrfs_run_delayed_items_nr(trans, root, nr);
+ btrfs_end_transaction(trans, root);
+ break;
+ case COMMIT_TRANS:
+ ret = may_commit_transaction(root, space_info, orig_bytes, 0);
+ break;
+ default:
+ ret = -ENOSPC;
+ break;
+ }
+
+ return ret;
+}