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
private Engine.DeleteResult delete(Engine engine, Engine.Delete delete) throws IOException {
        active.set(true);
        final Engine.DeleteResult result;
        delete = indexingOperationListeners.preDelete(shardId, delete);
        try {
            if (logger.isTraceEnabled()) {
                logger.trace("delete [{}] (seq no [{}])", delete.uid().text(), delete.seqNo());
            }
            result = engine.delete(delete);
        } catch (Exception e) {
            indexingOperationListeners.postDelete(shardId, delete, e);
            throw e;
        }
        indexingOperationListeners.postDelete(shardId, delete, result);
        return result;
    }
    public Engine.GetResult get(Engine.Get get) {
        readAllowed();
        MappingLookup mappingLookup = mapperService.mappingLookup();
        if (mappingLookup.hasMappings() == false) {
            return GetResult.NOT_EXISTS;
        }
        if (indexSettings.getIndexVersionCreated().isLegacyIndexVersion()) {
            throw new IllegalStateException("get operations not allowed on a legacy index");
        }
        return getEngine().get(get, mappingLookup, mapperService.documentParser(), this::wrapSearcher);
    }
    /**
     * Writes all indexing changes to disk and opens a new searcher reflecting all changes.  This can throw {@link AlreadyClosedException}.
     */