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
}
    /**
     * Should be called for each no-op update operation to increment relevant statistics.
     */
    public void noopUpdate() {
        internalIndexingStats.noopUpdate();
    }
    public void maybeCheckIndex() {
        recoveryState.setStage(RecoveryState.Stage.VERIFY_INDEX);
        if (Booleans.isTrue(checkIndexOnStartup) || "checksum".equals(checkIndexOnStartup)) {
            logger.warn(
                "performing expensive diagnostic checks during shard startup [{}={}]; "
                    + "these checks should only be enabled temporarily, you must remove this index setting as soon as possible",
                IndexSettings.INDEX_CHECK_ON_STARTUP.getKey(),
                checkIndexOnStartup
            );
            try {
                checkIndex();
            } catch (IOException ex) {
                throw new RecoveryFailedException(recoveryState, "check index failed", ex);
            }
        }
    }
    void checkIndex() throws IOException {
        if (store.tryIncRef()) {
            try {
                doCheckIndex();
            } catch (IOException e) {
                store.markStoreCorrupted(e);
                throw e;