net_processing: move CNode data access out of lock

CNode::m_relays_tx and CNode::m_bloom_filter_loaded access don't require
the Peer::TxRelay::m_bloom_filter_mutex lock, so move them out of the
lock scope.

See bitcoin/bitcoin#21160 (comment)
and bitcoin/bitcoin#21160 (comment).

Author: jnewbery

src/net_processing.cpp

@@ -2715,8 +2715,10 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
         pfrom.m_limited_node = (!(nServices & NODE_NETWORK) && (nServices & NODE_NETWORK_LIMITED));
 
         if (peer->m_tx_relay != nullptr) {
-            LOCK(peer->m_tx_relay->m_bloom_filter_mutex);
-            peer->m_tx_relay->m_relay_txs = fRelay; // set to true after we get the first filter* message
+            {
+                LOCK(peer->m_tx_relay->m_bloom_filter_mutex);
+                peer->m_tx_relay->m_relay_txs = fRelay; // set to true after we get the first filter* message
+            }
             if (fRelay) pfrom.m_relays_txs = true;
         }
 
@@ -4030,10 +4032,12 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
         }
         else if (peer->m_tx_relay != nullptr)
         {
-            LOCK(peer->m_tx_relay->m_bloom_filter_mutex);
-            peer->m_tx_relay->m_bloom_filter.reset(new CBloomFilter(filter));
+            {
+                LOCK(peer->m_tx_relay->m_bloom_filter_mutex);
+                peer->m_tx_relay->m_bloom_filter.reset(new CBloomFilter(filter));
+                peer->m_tx_relay->m_relay_txs = true;
+            }
             pfrom.m_bloom_filter_loaded = true;
-            peer->m_tx_relay->m_relay_txs = true;
             pfrom.m_relays_txs = true;
         }
         return;
@@ -4076,10 +4080,13 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
         if (peer->m_tx_relay == nullptr) {
             return;
         }
-        LOCK(peer->m_tx_relay->m_bloom_filter_mutex);
-        peer->m_tx_relay->m_bloom_filter = nullptr;
+
+        {
+            LOCK(peer->m_tx_relay->m_bloom_filter_mutex);
+            peer->m_tx_relay->m_bloom_filter = nullptr;
+            peer->m_tx_relay->m_relay_txs = true;
+        }
         pfrom.m_bloom_filter_loaded = false;
-        peer->m_tx_relay->m_relay_txs = true;
         pfrom.m_relays_txs = true;
         return;
     }