layout: move block_read_nodes_of to rpc_helper to avoid double-locking

(in theory, this could have caused a deadlock)

src/rpc/layout/helper.rs

@@ -8,7 +8,6 @@ use garage_util::data::*;
 
 use super::schema::*;
 use crate::replication_mode::ReplicationMode;
-use crate::rpc_helper::RpcHelper;
 
 #[derive(Debug, Clone, Serialize, Deserialize, Default, PartialEq, Eq)]
 pub struct LayoutDigest {
@@ -155,6 +154,10 @@ impl LayoutHelper {
 		self.ack_map_min
 	}
 
+	pub fn all_sync(&self) -> u64 {
+		self.sync_map_min
+	}
+
 	pub fn sync_versions(&self) -> (u64, u64, u64) {
 		(
 			self.layout().current().version,
@@ -177,28 +180,6 @@ impl LayoutHelper {
 			.collect()
 	}
 
-	pub fn block_read_nodes_of(&self, position: &Hash, rpc_helper: &RpcHelper) -> Vec<Uuid> {
-		let mut ret = Vec::with_capacity(12);
-		let ver_iter = self
-			.layout()
-			.versions
-			.iter()
-			.rev()
-			.chain(self.layout().old_versions.iter().rev());
-		for ver in ver_iter {
-			if ver.version > self.sync_map_min {
-				continue;
-			}
-			let nodes = ver.nodes_of(position, ver.replication_factor);
-			for node in rpc_helper.request_order(nodes) {
-				if !ret.contains(&node) {
-					ret.push(node);
-				}
-			}
-		}
-		ret
-	}
-
 	pub fn storage_sets_of(&self, position: &Hash) -> Vec<Vec<Uuid>> {
 		self.layout()
 			.versions