From: Matt Benjamin <mbenjamin@redhat.com>
Date: Fri, 18 Feb 2022 14:31:06 +0000 (-0500)
Subject: rgwlc: avoid front() on empty lc entry vector
X-Git-Tag: v18.0.0~1240^2~3
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=d83540235e315be4c12ced8cbccd79f81e10b7bd;p=ceph.git

rgwlc: avoid front() on empty lc entry vector

Conveniently, this arose after removing all lifecycle shards from
RADOS, proving it could be done safely.

A restart is currently needed to recognize new lifecycle shards,
if rgw_gc_max_objs also changed.

Signed-off-by: Matt Benjamin <mbenjamin@redhat.com>
---

diff --git a/src/rgw/rgw_lc.cc b/src/rgw/rgw_lc.cc
index e1fbe374e8fb..620576a9a496 100644
--- a/src/rgw/rgw_lc.cc
+++ b/src/rgw/rgw_lc.cc
@@ -2155,9 +2155,11 @@ int RGWLC::process(int index, int max_lock_secs, LCWorker* worker,
 			   << "entries) returned error ret==" << ret << dendl;
 	goto exit;
       }
-      entry = entries.front();
-      head.marker = entry.bucket;
-      head.start_date = now;
+      if (entries.size() > 0) {
+	entry = entries.front();
+	head.marker = entry.bucket;
+	head.start_date = now;
+      }
     } else {
       ldpp_dout(this, 0) << "RGWLC::process() head.marker !empty() at START for shard=="
 			 << lc_shard << " head last stored at "