fixup "replication/driver: enforce ordering during initial replication in order to support encrypted send": correctly propagate non-inital parent failures

replication/driver/replication_driver.go

@@ -505,30 +505,49 @@ func (f *fs) do(ctx context.Context, pq *stepQueue, prev *fs) {
 	f.debug("wait for parents %s", parents)
 	for {
 		var initialReplicatingParentsWithErrors []string
-		allParentsDidInitialReplication := true
+		allParentsPresentOnReceiver := true
 		f.l.DropWhile(func() {
 			for _, p := range f.initialRepOrd.parents {
-				p.l.Lock()
-
-				parentDidInitialReplication :=
+				p.l.HoldWhile(func() {
 					// (get the preconditions that allow us to inspect p.planned)
-					p.planning.done && p.planning.err == nil &&
-						// if there are no steps to be done, the filesystem must exist on the receiving side
-						// (otherwise we'd replicate it, and there would be a step for that)
-						(len(p.planned.steps) == 0 ||
-							// OR if it has completed at least one step
-							// (remember that .step points to the next step to be done)
-							// (TODO technically, we could make this step ready in the moment the recv-side
-							//  dataset exists, but we'd have to ask the receiver for that -> pool ListFilesystems RPC)
-							(p.planned.step >= 1))
+					parentHasPlanningDone := p.planning.done && p.planning.err == nil
+					if !parentHasPlanningDone {
+						// if the parent couldn't be planned, we cannot know whether it needs initial replication
+						// or incremental replication => be conservative and assume it was initial replication
+						allParentsPresentOnReceiver = false
+						if p.planning.err != nil {
+							initialReplicatingParentsWithErrors = append(initialReplicatingParentsWithErrors, p.fs.ReportInfo().Name)
+						}
+						return
+					}
+					// now allowed to inspect p.planned
 
-				allParentsDidInitialReplication = allParentsDidInitialReplication && parentDidInitialReplication
+					// if there are no steps to be done, the filesystem must exist on the receiving side
+					// (otherwise we'd replicate it, and there would be a step for that)
+					// (FIXME hardcoded initial replication policy, assuming the policy will always do _some_ initial replication)
+					parentHasNoSteps := len(p.planned.steps) == 0
 
-				if parentDidInitialReplication && (p.planning.err != nil || p.planned.stepErr != nil) {
-					initialReplicatingParentsWithErrors = append(initialReplicatingParentsWithErrors, p.fs.ReportInfo().Name)
-				}
+					// OR if it has completed at least one step
+					// (remember that .step points to the next step to be done)
+					// (TODO technically, we could make this step ready in the moment the recv-side
+					//  dataset exists, i.e. after the first few megabytes of transferred data, but we'd have to ask the receiver for that -> poll ListFilesystems RPC)
+					parentHasTakenAtLeastOneSuccessfulStep := !parentHasNoSteps && p.planned.step >= 1
 
-				p.l.Unlock()
+					parentFirstStepIsIncremental := // no need to lock for .report() because step.l == it's fs.l
+						len(p.planned.steps) > 0 && p.planned.steps[0].report().IsIncremental()
+
+					f.debug("parentHasNoSteps=%v parentFirstStepIsIncremental=%v parentHasTakenAtLeastOneSuccessfulStep=%v",
+						parentHasNoSteps, parentFirstStepIsIncremental, parentHasTakenAtLeastOneSuccessfulStep)
+
+					parentPresentOnReceiver := parentHasNoSteps || parentFirstStepIsIncremental || parentHasTakenAtLeastOneSuccessfulStep
+
+					allParentsPresentOnReceiver = allParentsPresentOnReceiver && parentPresentOnReceiver // no shadow
+
+					if !parentPresentOnReceiver && p.planned.stepErr != nil {
+						initialReplicatingParentsWithErrors = append(initialReplicatingParentsWithErrors, p.fs.ReportInfo().Name)
+					}
+
+				})
 			}
 		})
 
@@ -537,7 +556,7 @@ func (f *fs) do(ctx context.Context, pq *stepQueue, prev *fs) {
 			return
 		}
 
-		if allParentsDidInitialReplication {
+		if allParentsPresentOnReceiver {
 			break // good to go
 		}
 

util/chainlock/chainlock.go

@@ -40,3 +40,8 @@ func (l *L) DropWhile(f func()) {
 	defer l.Unlock().Lock()
 	f()
 }
+
+func (l *L) HoldWhile(f func()) {
+	defer l.Lock().Unlock()
+	f()
+}