+ size = orig->end - orig->start + 1;
+ if (size > BTRFS_MAX_EXTENT_SIZE) {
+ u64 num_extents;
+ u64 new_size;
+
+ /*
+ * We need the largest size of the remaining extent to see if we
+ * need to add a new outstanding extent. Think of the following
+ * case
+ *
+ * [MEAX_EXTENT_SIZEx2 - 4k][4k]
+ *
+ * The new_size would just be 4k and we'd think we had enough
+ * outstanding extents for this if we only took one side of the
+ * split, same goes for the other direction. We need to see if
+ * the larger size still is the same amount of extents as the
+ * original size, because if it is we need to add a new
+ * outstanding extent. But if we split up and the larger size
+ * is less than the original then we are good to go since we've
+ * already accounted for the extra extent in our original
+ * accounting.
+ */
+ new_size = orig->end - split + 1;
+ if ((split - orig->start) > new_size)
+ new_size = split - orig->start;
+
+ num_extents = div64_u64(size + BTRFS_MAX_EXTENT_SIZE - 1,
+ BTRFS_MAX_EXTENT_SIZE);
+ if (div64_u64(new_size + BTRFS_MAX_EXTENT_SIZE - 1,
+ BTRFS_MAX_EXTENT_SIZE) < num_extents)
+ return;
+ }
+