+/*
+ * This is for space we already have accounted in space_info->bytes_may_use, so
+ * basically when we're returning space from block_rsv's.
+ */
+static void space_info_add_old_bytes(struct btrfs_fs_info *fs_info,
+ struct btrfs_space_info *space_info,
+ u64 num_bytes)
+{
+ struct reserve_ticket *ticket;
+ struct list_head *head;
+ u64 used;
+ enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH;
+ bool check_overcommit = false;
+
+ spin_lock(&space_info->lock);
+ head = &space_info->priority_tickets;
+
+ /*
+ * If we are over our limit then we need to check and see if we can
+ * overcommit, and if we can't then we just need to free up our space
+ * and not satisfy any requests.
+ */
+ used = space_info->bytes_used + space_info->bytes_reserved +
+ space_info->bytes_pinned + space_info->bytes_readonly +
+ space_info->bytes_may_use;
+ if (used - num_bytes >= space_info->total_bytes)
+ check_overcommit = true;
+again:
+ while (!list_empty(head) && num_bytes) {
+ ticket = list_first_entry(head, struct reserve_ticket,
+ list);
+ /*
+ * We use 0 bytes because this space is already reserved, so
+ * adding the ticket space would be a double count.
+ */
+ if (check_overcommit &&
+ !can_overcommit(fs_info->extent_root, space_info, 0,
+ flush))
+ break;
+ if (num_bytes >= ticket->bytes) {
+ list_del_init(&ticket->list);
+ num_bytes -= ticket->bytes;
+ ticket->bytes = 0;
+ wake_up(&ticket->wait);
+ } else {
+ ticket->bytes -= num_bytes;
+ num_bytes = 0;
+ }
+ }
+
+ if (num_bytes && head == &space_info->priority_tickets) {
+ head = &space_info->tickets;
+ flush = BTRFS_RESERVE_FLUSH_ALL;
+ goto again;
+ }
+ space_info->bytes_may_use -= num_bytes;
+ trace_btrfs_space_reservation(fs_info, "space_info",
+ space_info->flags, num_bytes, 0);
+ spin_unlock(&space_info->lock);
+}
+
+/*
+ * This is for newly allocated space that isn't accounted in
+ * space_info->bytes_may_use yet. So if we allocate a chunk or unpin an extent
+ * we use this helper.
+ */
+static void space_info_add_new_bytes(struct btrfs_fs_info *fs_info,
+ struct btrfs_space_info *space_info,
+ u64 num_bytes)
+{
+ struct reserve_ticket *ticket;
+ struct list_head *head = &space_info->priority_tickets;
+
+again:
+ while (!list_empty(head) && num_bytes) {
+ ticket = list_first_entry(head, struct reserve_ticket,
+ list);
+ if (num_bytes >= ticket->bytes) {
+ trace_btrfs_space_reservation(fs_info, "space_info",
+ space_info->flags,
+ ticket->bytes, 1);
+ list_del_init(&ticket->list);
+ num_bytes -= ticket->bytes;
+ space_info->bytes_may_use += ticket->bytes;
+ ticket->bytes = 0;
+ wake_up(&ticket->wait);
+ } else {
+ trace_btrfs_space_reservation(fs_info, "space_info",
+ space_info->flags,
+ num_bytes, 1);
+ space_info->bytes_may_use += num_bytes;
+ ticket->bytes -= num_bytes;
+ num_bytes = 0;
+ }
+ }
+
+ if (num_bytes && head == &space_info->priority_tickets) {
+ head = &space_info->tickets;
+ goto again;
+ }
+}
+