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
throw new IOException("index check failure");
            }
            if (logger.isDebugEnabled()) {
                logger.debug("check index [success]\n{}", os.bytes().utf8ToString());
            }
        }
        recoveryState.getVerifyIndex().checkIndexTime(Math.max(0, TimeValue.nsecToMSec(System.nanoTime() - timeNS)));
    }
    Engine getEngine() {
        Engine engine = getEngineOrNull();
        if (engine == null) {
            throw new AlreadyClosedException("engine is closed");
        }
        return engine;
    }
    /**
     * NOTE: returns null if engine is not yet started (e.g. recovery phase 1, copying over index files, is still running), or if engine is
     * closed.
     */
    protected Engine getEngineOrNull() {
        return this.currentEngineReference.get();
    }
    public void startRecovery(
        RecoveryState recoveryState,
        PeerRecoveryTargetService recoveryTargetService,
        PeerRecoveryTargetService.RecoveryListener recoveryListener,
        RepositoriesService repositoriesService,
        Consumer<MappingMetadata> mappingUpdateConsumer,
        IndicesService indicesService
    ) {