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
public void testDisabledSnapshotBasedRecoveryUsesSourceFiles() throws Exception {
        updateSetting(RecoverySettings.INDICES_RECOVERY_USE_SNAPSHOTS_SETTING.getKey(), "false");
        try {
            checkRecoveryIsPerformedFromSourceNode();
        } finally {
            updateSetting(RecoverySettings.INDICES_RECOVERY_USE_SNAPSHOTS_SETTING.getKey(), null);
        }
    }
    public void testRecoveryConcurrentlyWithIndexing() throws Exception {
        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")
                .build()
        );
        AtomicInteger numDocs = new AtomicInteger(randomIntBetween(1, 1000));
        indexDocs(indexName, 0, numDocs.get());
        String repoName = "repo";
        createRepo(repoName, TestRepositoryPlugin.INSTRUMENTED_TYPE);
        createSnapshot(repoName, "snap", Collections.singletonList(indexName));
        long snapshotSizeForIndex = getSnapshotSizeForIndex(repoName, "snap", indexName);
        assertAcked(
            client().admin()
                .indices()
                .prepareUpdateSettings(indexName)