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
state,
                "operations only allowed when shard state is one of " + readAllowedStates.toString()
            );
        }
    }
    
    public boolean isReadAllowed() {
        return readAllowedStates.contains(state);
    }
    private void ensureWriteAllowed(Engine.Operation.Origin origin) throws IllegalIndexShardStateException {
        IndexShardState state = this.state; 
        if (origin.isRecovery()) {
            if (state != IndexShardState.RECOVERING) {
                throw new IllegalIndexShardStateException(
                    shardId,
                    state,
                    "operation only allowed when recovering, origin [" + origin + "]"
                );
            }
        } else {
            if (origin == Engine.Operation.Origin.PRIMARY) {
                assert assertPrimaryMode();
            } else if (origin == Engine.Operation.Origin.REPLICA) {
                assert assertReplicationTarget();
            } else {
                assert origin == Engine.Operation.Origin.LOCAL_RESET;
                assert getActiveOperationsCount() == OPERATIONS_BLOCKED
                    : "locally resetting without blocking operations, active operations are [" + getActiveOperations() + "]";
            }
            if (writeAllowedStates.contains(state) == false) {