rgw: make sure max_objs_per_shard is appropriate in debugging scenarios

When we have a versioned bucket, we reduce max_objs_per_shard by a
factor of 3 to account for the extra bucket index entries required in
such buckets. And during debugging, we may want to induce early
resharding by setting max_objs_per_shard to an artificially low
value. Combined, that math could result in max_objs_per_shard with a
value of 0 that would cause a division by zero crash. This fixes that.

Signed-off-by: J. Eric Ivancich <[email protected]>

Author: ivancich

src/rgw/driver/rados/rgw_rados.cc

@@ -11151,6 +11151,10 @@ void RGWRados::calculate_preferred_shards(const DoutPrefixProvider* dpp,
     max_objs_per_shard /= 3;
   }
 
+  // make sure it's at least 1, as in some testing scenarios it's artificially low
+  constexpr uint64_t min_max_objs_per_shard = 1;
+  max_objs_per_shard = std::max(min_max_objs_per_shard, max_objs_per_shard);
+
   const bool is_multisite = svc.zone->need_to_log_data();
 
   RGWBucketReshard::calculate_preferred_shards(dpp,