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/indices/recovery/RecoveryTarget.java
boolean resetRecovery(CancellableThreads newTargetCancellableThreads) throws IOException {
        if (finished.compareAndSet(false, true)) {
            try {
                logger.debug("reset of recovery with shard {} and id [{}]", shardId, recoveryId);
            } finally {
                
                decRef();
            }
            try {
                newTargetCancellableThreads.execute(closedLatch::await);
            } catch (CancellableThreads.ExecutionCancelledException e) {
                logger.trace(
                    "new recovery target cancelled for shard {} while waiting on old recovery target with id [{}] to close",
                    shardId,
                    recoveryId
                );
                return false;
            }
            RecoveryState.Stage stage = indexShard.recoveryState().getStage();
            if (indexShard.recoveryState().getPrimary() && (stage == RecoveryState.Stage.FINALIZE || stage == RecoveryState.Stage.DONE)) {
                
                
                
                
                assert stage != RecoveryState.Stage.DONE : "recovery should not have completed when it's being reset";
                throw new IllegalStateException("cannot reset recovery as previous attempt made it past finalization step");
            }
            indexShard.performRecoveryRestart();
            return true;
        }