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/RecoveryState.java
builder.humanReadableField(Fields.TOTAL_TIME_IN_MILLIS, Fields.TOTAL_TIME, new TimeValue(timer.time()));
        if (recoverySource.getType() == RecoverySource.Type.PEER) {
            toXContentNode(Fields.SOURCE, builder, sourceNode);
        } else {
            builder.startObject(Fields.SOURCE);
            recoverySource.addAdditionalFields(builder, params);
            builder.endObject();
        }
        toXContentNode(Fields.TARGET, builder, targetNode);
        builder.startObject(Fields.INDEX);
        index.toXContent(builder, params);
        builder.endObject();
        builder.startObject(Fields.TRANSLOG);
        translog.toXContent(builder, params);
        builder.endObject();
        builder.startObject(Fields.VERIFY_INDEX);
        verifyIndex.toXContent(builder, params);
        builder.endObject();
        return builder;
    }
    private static void toXContentNode(String fieldName, XContentBuilder builder, DiscoveryNode node) throws IOException {
        builder.startObject(fieldName);
        builder.field(Fields.ID, node.getId());
        builder.field(Fields.HOST, node.getHostName());
        builder.field(Fields.TRANSPORT_ADDRESS, node.getAddress().toString());
        builder.field(Fields.IP, node.getHostAddress());
        builder.field(Fields.NAME, node.getName());
        builder.endObject();
    }
    static final class Fields {