+static inline u64 heads_to_leaves(struct btrfs_root *root, u64 heads)
+{
+ u64 num_bytes;
+
+ num_bytes = heads * (sizeof(struct btrfs_extent_item) +
+ sizeof(struct btrfs_extent_inline_ref));
+ if (!btrfs_fs_incompat(root->fs_info, SKINNY_METADATA))
+ num_bytes += heads * sizeof(struct btrfs_tree_block_info);
+
+ /*
+ * We don't ever fill up leaves all the way so multiply by 2 just to be
+ * closer to what we're really going to want to ouse.
+ */
+ return div64_u64(num_bytes, BTRFS_LEAF_DATA_SIZE(root));
+}
+
+int btrfs_should_throttle_delayed_refs(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ struct btrfs_block_rsv *global_rsv;
+ u64 num_heads = trans->transaction->delayed_refs.num_heads_ready;
+ u64 num_bytes;
+ int ret = 0;
+
+ num_bytes = btrfs_calc_trans_metadata_size(root, 1);
+ num_heads = heads_to_leaves(root, num_heads);
+ if (num_heads > 1)
+ num_bytes += (num_heads - 1) * root->leafsize;
+ num_bytes <<= 1;
+ global_rsv = &root->fs_info->global_block_rsv;
+
+ /*
+ * If we can't allocate any more chunks lets make sure we have _lots_ of
+ * wiggle room since running delayed refs can create more delayed refs.
+ */
+ if (global_rsv->space_info->full)
+ num_bytes <<= 1;
+
+ spin_lock(&global_rsv->lock);
+ if (global_rsv->reserved <= num_bytes)
+ ret = 1;
+ spin_unlock(&global_rsv->lock);
+ return ret;
+}
+