SERVER-30060 Do not gather shard disk usage statistics unless 'maxSize' is set

(cherry picked from commit e0136739285c097a7da59ba54d6bcd109bb184b5)

3 files changed, 16 insertions, 4 deletions

diff --git a/src/mongo/db/s/balancer/cluster_statistics.h b/src/mongo/db/s/balancer/cluster_statistics.h
index a8e433062e8..9feb8a4a8f4 100644
--- a/src/mongo/db/s/balancer/cluster_statistics.h
+++ b/src/mongo/db/s/balancer/cluster_statistics.h
@@ -78,10 +78,10 @@ public:
         // The id of the shard for which this statistic applies
         ShardId shardId;
 
-        // The maximum size allowed for the shard
+        // The maximum storage size allowed for the shard. Zero means no maximum specified.
         uint64_t maxSizeMB{0};
 
-        // The current size of the shard
+        // The current storage size of the shard.
         uint64_t currSizeMB{0};
 
         // Whether the shard is in draining mode
diff --git a/src/mongo/db/s/balancer/cluster_statistics_impl.cpp b/src/mongo/db/s/balancer/cluster_statistics_impl.cpp
index 6ae4d9c223f..3bde0866770 100644
--- a/src/mongo/db/s/balancer/cluster_statistics_impl.cpp
+++ b/src/mongo/db/s/balancer/cluster_statistics_impl.cpp
@@ -117,9 +117,16 @@ StatusWith<vector<ShardStatistics>> ClusterStatisticsImpl::getStats(OperationCon
     vector<ShardStatistics> stats;
 
     for (const auto& shard : shards) {
-        auto shardSizeStatus = shardutil::retrieveTotalShardSize(txn, shard.getName());
+        const auto shardSizeStatus = [&]() -> StatusWith<long long> {
+            if (!shard.getMaxSizeMB()) {
+                return 0;
+            }
+
+            return shardutil::retrieveTotalShardSize(txn, shard.getName());
+        }();
+
         if (!shardSizeStatus.isOK()) {
-            const Status& status = shardSizeStatus.getStatus();
+            const auto& status = shardSizeStatus.getStatus();
 
             return {status.code(),
                     str::stream() << "Unable to obtain shard utilization information for "
diff --git a/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp b/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
index d503e3aeaa0..a11d74ef587 100644
--- a/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
+++ b/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
@@ -592,6 +592,11 @@ Status MigrationChunkClonerSourceLegacy::_storeCurrentLocs(OperationContext* txn
     RecordId recordId;
     PlanExecutor::ExecState state;
     while (PlanExecutor::ADVANCED == (state = exec->getNext(&obj, &recordId))) {
+        Status interruptStatus = txn->checkForInterruptNoAssert();
+        if (!interruptStatus.isOK()) {
+            return interruptStatus;
+        }
+
         if (!isLargeChunk) {
             stdx::lock_guard<stdx::mutex> lk(_mutex);
             _cloneLocs.insert(recordId);