feat: stmgr: add env to disable premigrations

Setting the environment variable `LOTUS_DISABLE_PRE_MIGRATIONS=1` will
discard premigrations for all upgrade.

chain/stmgr/forks.go

@@ -173,7 +173,7 @@ func (sm *StateManager) HandleStateForks(ctx context.Context, root cid.Cid, heig
 	u := sm.stateMigrations[height]
 	if u != nil && u.upgrade != nil {
 		if migCid, ok := u.migratedStateroots[root]; ok {
-			log.Warnw("SKIP migration", "height", height, "from", root, "to", migCid)
+			log.Warnw("CACHED migration", "height", height, "from", root, "to", migCid)
 			return migCid, nil
 		}
 

chain/stmgr/stmgr.go

@@ -2,6 +2,7 @@ package stmgr
 
 import (
 	"context"
+	"os"
 	"sync"
 
 	"github.com/ipfs/go-cid"
@@ -35,6 +36,8 @@ import (
 const LookbackNoLimit = api.LookbackNoLimit
 const ReceiptAmtBitwidth = 3
 
+const EnvDisablePreMigrations = "LOTUS_DISABLE_PRE_MIGRATIONS"
+
 var log = logging.Logger("statemgr")
 
 type StateManagerAPI interface {
@@ -114,6 +117,12 @@ func NewStateManager(cs *store.ChainStore, exec Executor, sys vm.SyscallBuilder,
 	expensiveUpgrades := make(map[abi.ChainEpoch]struct{}, len(us))
 	var networkVersions []versionSpec
 	lastVersion := build.GenesisNetworkVersion
+
+	disablePreMigrations := false
+	if disabled := os.Getenv(EnvDisablePreMigrations); disabled == "1" {
+		disablePreMigrations = true
+	}
+
 	if len(us) > 0 {
 		// If we have any upgrades, process them and create a version
 		// schedule.
@@ -125,6 +134,11 @@ func NewStateManager(cs *store.ChainStore, exec Executor, sys vm.SyscallBuilder,
 					cache:              nv16.NewMemMigrationCache(),
 					migratedStateroots: make(map[cid.Cid]cid.Cid),
 				}
+
+				if disablePreMigrations {
+					migration.preMigrations = []PreMigration{}
+				}
+
 				stateMigrations[upgrade.Height] = migration
 			}
 			if upgrade.Expensive {