rgw: RGWMetaSyncShardControlCR retries with backoff on all error codes

RGWBackoffControlCR only treats EBUSY and EAGAIN as 'temporary' error
codes, with all other errors being fatal when exit_on_error is set

to RGWMetaSyncShardControlCR, a 'fatal' error means that no further sync
is possible on that shard until the gateway restarts

this changes RGWMetaSyncShardControlCR to set exit_on_error to false, so
that it will continue to retry with backoff no matter what error code it
gets

Fixes: http://tracker.ceph.com/issues/19019

Signed-off-by: Casey Bodley <cbodley@redhat.com>

src/rgw/rgw_sync.cc

@@ -1657,12 +1657,13 @@ class RGWMetaSyncShardControlCR : public RGWBackoffControlCR
   rgw_meta_sync_marker sync_marker;
   const std::string period_marker;
 
+  static constexpr bool exit_on_error = false; // retry on all errors
 public:
   RGWMetaSyncShardControlCR(RGWMetaSyncEnv *_sync_env, const rgw_bucket& _pool,
                             const std::string& period, RGWMetadataLog* mdlog,
                             uint32_t _shard_id, const rgw_meta_sync_marker& _marker,
                             std::string&& period_marker)
-    : RGWBackoffControlCR(_sync_env->cct, true), sync_env(_sync_env),
+    : RGWBackoffControlCR(_sync_env->cct, exit_on_error), sync_env(_sync_env),
       pool(_pool), period(period), mdlog(mdlog), shard_id(_shard_id),
       sync_marker(_marker), period_marker(std::move(period_marker)) {}