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
* @return a sequence number that an operation-based peer recovery can start with.
     * This is the first operation after the local checkpoint of the safe commit if exists.
     */
    public long recoverLocallyUpToGlobalCheckpoint() {
        assert Thread.holdsLock(mutex) == false : "recover locally under mutex";
        if (state != IndexShardState.RECOVERING) {
            throw new IndexShardNotRecoveringException(shardId, state);
        }
        recoveryState.validateCurrentStage(RecoveryState.Stage.INDEX);
        assert routingEntry().recoverySource().getType() == RecoverySource.Type.PEER : "not a peer recovery [" + routingEntry() + "]";
        final Optional<SequenceNumbers.CommitInfo> safeCommit;
        final long globalCheckpoint;
        try {
            final String translogUUID = store.readLastCommittedSegmentsInfo().getUserData().get(Translog.TRANSLOG_UUID_KEY);
            globalCheckpoint = Translog.readGlobalCheckpoint(translogConfig.getTranslogPath(), translogUUID);
            safeCommit = store.findSafeIndexCommit(globalCheckpoint);
        } catch (org.apache.lucene.index.IndexNotFoundException e) {
            logger.trace("skip local recovery as no index commit found");
            return UNASSIGNED_SEQ_NO;
        } catch (Exception e) {
            logger.debug("skip local recovery as failed to find the safe commit", e);
            return UNASSIGNED_SEQ_NO;
        }
        try {
            maybeCheckIndex(); 
            recoveryState.setLocalTranslogStage();
            if (safeCommit.isPresent() == false) {
                logger.trace("skip local recovery as no safe commit found");
                return UNASSIGNED_SEQ_NO;
            }