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
} finally {
                store.decRef();
            }
        }
    }
    private void doCheckIndex() throws IOException {
        long timeNS = System.nanoTime();
        if (Lucene.indexExists(store.directory()) == false) {
            return;
        }
        if ("checksum".equals(checkIndexOnStartup)) {
            
            IOException corrupt = null;
            final MetadataSnapshot metadata;
            try {
                metadata = snapshotStoreMetadata();
            } catch (IOException e) {
                logger.warn("check index [failure]", e);
                throw e;
            }
            final List<String> checkedFiles = new ArrayList<>(metadata.size());
            for (Map.Entry<String, StoreFileMetadata> entry : metadata.fileMetadataMap().entrySet()) {
                try {
                    Store.checkIntegrity(entry.getValue(), store.directory());
                    if (corrupt == null) {
                        checkedFiles.add(entry.getKey());
                    } else {
                        logger.info("check index [ok]: checksum check passed on [{}]", entry.getKey());
                    }
                } catch (IOException ioException) {