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/snapshot-based-recoveries/src/internalClusterTest/java/org/elasticsearch/xpack/snapshotbasedrecoveries/recovery/SnapshotBasedIndexRecoveryIT.java
NodesStatsResponse statsResponse = client().admin()
                .cluster()
                .prepareNodesStats()
                .clear()
                .setIndices(new CommonStatsFlags(CommonStatsFlags.Flag.Recovery))
                .get();
            for (NodeStats nodeStats : statsResponse.getNodes()) {
                RecoveryStats recoveryStats = nodeStats.getIndices().getRecoveryStats();
                String nodeName = nodeStats.getNode().getName();
                if (nodeName.equals(sourceNode)) {
                    assertThat(recoveryStats.throttleTime().getMillis(), is(equalTo(0L)));
                }
                if (nodeName.equals(targetNode)) {
                    assertThat(recoveryStats.throttleTime().getMillis(), is(greaterThan(0L)));
                }
            }
        } finally {
            updateSetting(INDICES_RECOVERY_MAX_BYTES_PER_SEC_SETTING.getKey(), null);
        }
    }
    public void testPeerRecoveryTriesToUseMostOfTheDataFromAnAvailableSnapshot() throws Exception {
        String sourceNode = internalCluster().startDataOnlyNode();
        String indexName = randomAlphaOfLength(10).toLowerCase(Locale.ROOT);
        createIndex(
            indexName,
            Settings.builder()
                .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, 1)
                .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 0)
                .put(MergePolicyConfig.INDEX_MERGE_ENABLED, false)
                .put(IndexService.GLOBAL_CHECKPOINT_SYNC_INTERVAL_SETTING.getKey(), "1s")