We saw a case where the recovery stats reported `recovered_bytes` greater than `length_in_bytes` for one file:

```
GET /_recovery?detailed

200 OK
...
{
  "name": "_buk.fdt",
  "length_in_bytes": 26891307173,
  "reused": false,
  "recovered_in_bytes": 35324928266,
  "recovered_from_snapshot_in_bytes": 8433621093
}
...
```

NB `35324928266 == 26891307173 + 8433621093`

This causes Elasticsearch to compute a negative value for the reserved space on the target node of this recovery, which prevents stats APIs from working. This appears to be caused by a network-level failure which triggers a retry without first cancelling an ongoing download of a different file with the same name from the snapshot repository.

---

### Workaround

Restart the target node to clear these stats.
server/src/main/java/org/elasticsearch/index/shard/IndexShard.java
if (getOperationPrimaryTerm() < newPrimaryTerm) {
                        replicationTracker.setOperationPrimaryTerm(newPrimaryTerm);
                        onBlocked.run();
                    }
                } catch (final Exception e) {
                    if (combineWithAction == null) {
                        
                        releaseOnce.close();
                    }
                    innerFail(e);
                } finally {
                    if (combineWithAction != null) {
                        combineWithAction.onResponse(releasable);
                    } else {
                        releaseOnce.close();
                    }
                }
            }
        }, 30, TimeUnit.MINUTES);
        pendingPrimaryTerm = newPrimaryTerm;
        termUpdated.countDown();
    }
    /**
     * Acquire a replica operation permit whenever the shard is ready for indexing (see
     * {@link #acquirePrimaryOperationPermit(ActionListener, String, Object)}). If the given primary term is lower than then one in
     * {@link #shardRouting}, the {@link ActionListener#onFailure(Exception)} method of the provided listener is invoked with an
     * {@link IllegalStateException}. If permit acquisition is delayed, the listener will be invoked on the executor with the specified
     * name.
     *
     * @param opPrimaryTerm              the operation primary term