More security: don't delete stuff too easily

src/model/block.rs

@@ -305,6 +305,9 @@ impl BlockManager {
 			let ring = self.system.ring.borrow().clone();
 
 			let mut who = self.replication.replication_nodes(&hash, &ring);
+			if who.len() < self.replication.write_quorum(&self.system) {
+				return Err(Error::Message(format!("Not trying to offload block because we don't have a quorum of nodes to write to")));
+			}
 			who.retain(|id| *id != self.system.id);
 
 			let msg = Arc::new(Message::NeedBlockQuery(*hash));

src/table/replication/fullcopy.rs

@@ -41,7 +41,12 @@ impl TableReplication for TableFullReplication {
 		self.replication_nodes(hash, system.ring.borrow().as_ref())
 	}
 	fn write_quorum(&self, system: &System) -> usize {
-		system.ring.borrow().config.members.len() - self.max_faults
+		let nmembers = system.ring.borrow().config.members.len();
+		if nmembers > self.max_faults {
+			nmembers - self.max_faults
+		} else {
+			1
+		}
 	}
 	fn max_write_errors(&self) -> usize {
 		self.max_faults

src/table/sync.rs

@@ -277,6 +277,9 @@ where
 					warn!("Interrupting offload as partitions seem to have changed");
 					break;
 				}
+				if nodes.len() < self.aux.replication.write_quorum(&self.aux.system) {
+					return Err(Error::Message(format!("Not offloading as we don't have a quorum of nodes to write to.")));
+				}
 
 				counter += 1;
 				debug!(