only enable rcmgr by default in full nodes

opt-in with envvar for other nodes, as there are still some issues
with markets related protocols

node/modules/lp2p/rcmgr.go

@@ -27,9 +27,10 @@ import (
 
 func ResourceManager(connMgrHi uint) func(lc fx.Lifecycle, repo repo.LockedRepo) (network.ResourceManager, error) {
 	return func(lc fx.Lifecycle, repo repo.LockedRepo) (network.ResourceManager, error) {
+		isFullNode := repo.RepoType().Type() == "FullNode"
 		envvar := os.Getenv("LOTUS_RCMGR")
-		if envvar == "0" {
-			// this is enabled by default; specify LOTUS_RCMGR=0 to disable
+		if (isFullNode && envvar == "0") || // only set NullResourceManager if envvar is explicitly "0"
+			(!isFullNode && envvar != "1") { // set NullResourceManager *unless* envvar is explicitly "1"
 			log.Info("libp2p resource manager is disabled")
 			return network.NullResourceManager, nil
 		}

node/repo/fsrepo.go

@@ -417,6 +417,10 @@ type fsLockedRepo struct {
 	configLk  sync.Mutex
 }
 
+func (fsr *fsLockedRepo) RepoType() RepoType {
+	return fsr.repoType
+}
+
 func (fsr *fsLockedRepo) Readonly() bool {
 	return fsr.readonly
 }

node/repo/interface.go

@@ -52,6 +52,9 @@ type LockedRepo interface {
 	// Close closes repo and removes lock.
 	Close() error
 
+	// returns the type of this repo
+	RepoType() RepoType
+
 	// Returns datastore defined in this repo.
 	// The supplied context must only be used to initialize the datastore.
 	// The implementation should not retain the context for usage throughout

node/repo/memrepo.go

@@ -55,6 +55,10 @@ type lockedMemRepo struct {
 	token *byte
 }
 
+func (lmem *lockedMemRepo) RepoType() RepoType {
+	return lmem.t
+}
+
 func (lmem *lockedMemRepo) GetStorage() (stores.StorageConfig, error) {
 	if err := lmem.checkToken(); err != nil {
 		return stores.StorageConfig{}, err