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
for (final String checkedFile : checkedFiles) {
                        logger.info("check index [ok]: checksum check passed on [{}]", checkedFile);
                    }
                    checkedFiles.clear();
                    logger.warn(() -> "check index [failure]: checksum failed on [" + entry.getKey() + "]", ioException);
                    corrupt = ioException;
                }
            }
            if (corrupt != null) {
                throw corrupt;
            }
            if (logger.isDebugEnabled()) {
                for (final String checkedFile : checkedFiles) {
                    logger.debug("check index [ok]: checksum check passed on [{}]", checkedFile);
                }
            }
        } else {
            
            final BytesStreamOutput os = new BytesStreamOutput();
            final PrintStream out = new PrintStream(os, false, StandardCharsets.UTF_8.name());
            final CheckIndex.Status status = store.checkIndex(out);
            out.flush();
            if (status.clean == false) {
                if (state == IndexShardState.CLOSED) {
                    
                    return;
                }
                logger.warn("check index [failure]");
                
                logger.warn("{}", os.bytes().utf8ToString());