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.
x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/recovery/SearchableSnapshotRecoveryState.java
FileDetail fileDetail = fileDetails.computeIfAbsent(name, n -> new FileDetail(name, length, reused));
            assert fileDetail == null || fileDetail.name().equals(name) && fileDetail.length() == length
                : "The file "
                    + name
                    + " was reported multiple times with different lengths: ["
                    + fileDetail.length()
                    + "] and ["
                    + length
                    + "]";
        }
        void markFileAsReused(String name) {
            final FileDetail fileDetail = fileDetails.get(name);
            assert fileDetail != null;
            fileDetails.put(name, new FileDetail(fileDetail.name(), fileDetail.length(), true));
        }
        @Override
        public void clear() {
            
            
            complete = false;
        }
    }
}