Ceph » rgw

Is there any legitimate use-case for an olh entry with key.name == "" ? If not, let's trim them, e.g. during reshard, because...

#46456 had the effect of leaving several olh entries in shard 0 with an empty name.
Historically, these polluted buckets with versioning / lc expiration, and it's difficult or impossible for an operator to clean those from existing cli tooling.

For detail, here's the sort of entry we are trying to remove from a bucket index:

(The idx prefix is 0x80, the "ugly namespace")

{
  "type": "olh",
  "idx": "�1001_tmp/uploads/1544726371-28197-0001-2685-9890cb8c67e31032c7660031601b8dcc",
  "entry": {
    "key": {
      "name": "",
      "instance": "" 
    },
    "delete_marker": "false",
    "epoch": 7,
    "pending_log": [],
    "tag": "uemrg479c5wg78kcrq7ezeb4mhc616vg",
    "exists": "false",
    "pending_removal": "true" 
  }
}