Migrate MaxValidatorsCount from storage to dynamic param + fixes

polkadot/runtime/test-runtime/src/lib.rs

@@ -400,6 +400,7 @@ impl pallet_staking::Config for Runtime {
 	type DisablingStrategy = pallet_staking::UpToLimitWithReEnablingDisablingStrategy;
 	type MaxInvulnerables = ConstU32<20>;
 	type MaxRewardPagesPerValidator = ConstU32<20>;
+	type MaxValidatorsCount = ConstU32<300>;
 }
 
 parameter_types! {

polkadot/runtime/westend/src/genesis_config_presets.rs

@@ -33,7 +33,7 @@ use sp_consensus_grandpa::AuthorityId as GrandpaId;
 use sp_core::{crypto::get_public_from_string_or_panic, sr25519};
 use sp_genesis_builder::PresetId;
 use sp_keyring::Sr25519Keyring;
-use sp_runtime::Perbill;
+use sp_runtime::{BoundedVec, Perbill};
 use westend_runtime_constants::currency::UNITS as WND;
 
 /// Helper function to generate stash, controller and session key from seed
@@ -201,7 +201,10 @@ fn westend_testnet_genesis(
 				.iter()
 				.map(|x| (x.0.clone(), x.0.clone(), STASH, StakerStatus::<AccountId>::Validator))
 				.collect::<Vec<_>>(),
-			invulnerables: initial_authorities.iter().map(|x| x.0.clone()).collect::<Vec<_>>(),
+			invulnerables: BoundedVec::try_from(
+				initial_authorities.iter().map(|x| x.0.clone()).collect::<Vec<_>>()
+			)
+			.unwrap(),
 			force_era: Forcing::NotForcing,
 			slash_reward_fraction: Perbill::from_percent(10),
 		},
@@ -372,7 +375,10 @@ fn westend_staging_testnet_config_genesis() -> serde_json::Value {
 				.iter()
 				.map(|x| (x.0.clone(), x.0.clone(), STASH, StakerStatus::<AccountId>::Validator))
 				.collect::<Vec<_>>(),
-			invulnerables: initial_authorities.iter().map(|x| x.0.clone()).collect::<Vec<_>>(),
+			invulnerables: BoundedVec::try_from(
+				initial_authorities.iter().map(|x| x.0.clone()).collect::<Vec<_>>()
+			)
+			.unwrap(),
 			force_era: Forcing::ForceNone,
 			slash_reward_fraction: Perbill::from_percent(10),
 		},

polkadot/runtime/westend/src/lib.rs

@@ -287,6 +287,14 @@ pub mod dynamic_params {
 		#[codec(index = 4)]
 		pub static UseAuctionSlots: bool = false;
 	}
+
+	#[dynamic_pallet_params]
+	#[codec(index = 1)]
+	pub mod staking {
+		/// Maximum number of validators allowed.
+		#[codec(index = 0)]
+		pub static MaxValidatorsCount: u32 = 300;
+	}
 }
 
 #[cfg(feature = "runtime-benchmarks")]
@@ -319,6 +327,7 @@ impl EnsureOriginWithArg<RuntimeOrigin, RuntimeParametersKey> for DynamicParamet
 
 		match key {
 			Inflation(_) => frame_system::ensure_root(origin.clone()),
+			Staking(_) => frame_system::ensure_root(origin.clone()),
 		}
 		.map_err(|_| origin)
 	}
@@ -760,6 +769,7 @@ impl pallet_staking::Config for Runtime {
 	type DisablingStrategy = pallet_staking::UpToLimitWithReEnablingDisablingStrategy;
 	type MaxInvulnerables = frame_support::traits::ConstU32<20>;
 	type MaxRewardPagesPerValidator = frame_support::traits::ConstU32<20>;
+	type MaxValidatorsCount = dynamic_params::staking::MaxValidatorsCount;
 }
 
 impl pallet_fast_unstake::Config for Runtime {

substrate/bin/node/runtime/src/lib.rs

@@ -749,6 +749,7 @@ impl pallet_staking::Config for Runtime {
 	type DisablingStrategy = pallet_staking::UpToLimitWithReEnablingDisablingStrategy;
 	type MaxInvulnerables = ConstU32<20>;
 	type MaxRewardPagesPerValidator = ConstU32<20>;
+	type MaxValidatorsCount = ConstU32<300>;
 }
 
 impl pallet_fast_unstake::Config for Runtime {

substrate/frame/babe/src/mock.rs

@@ -39,7 +39,7 @@ use sp_runtime::{
 	impl_opaque_keys,
 	testing::{Digest, DigestItem, Header, TestXt},
 	traits::{Header as _, OpaqueKeys},
-	BuildStorage, Perbill,
+	BoundedVec, BuildStorage, Perbill,
 };
 use sp_staking::{EraIndex, SessionIndex};
 
@@ -342,7 +342,7 @@ pub fn new_test_ext_raw_authorities(authorities: Vec<AuthorityId>) -> sp_io::Tes
 		validator_count: 8,
 		force_era: pallet_staking::Forcing::ForceNew,
 		minimum_validator_count: 0,
-		invulnerables: vec![],
+		invulnerables: BoundedVec::new(),
 		..Default::default()
 	};
 

substrate/frame/beefy/src/mock.rs

@@ -36,7 +36,7 @@ use sp_runtime::{
 	impl_opaque_keys,
 	testing::TestXt,
 	traits::{Header as HeaderT, OpaqueKeys},
-	BuildStorage, Perbill,
+	BoundedVec, BuildStorage, Perbill,
 };
 use sp_staking::{EraIndex, SessionIndex};
 use sp_state_machine::BasicExternalities;
@@ -303,7 +303,7 @@ impl ExtBuilder {
 			validator_count: 2,
 			force_era: pallet_staking::Forcing::ForceNew,
 			minimum_validator_count: 0,
-			invulnerables: vec![],
+			invulnerables: BoundedVec::new(),
 			..Default::default()
 		};
 

substrate/frame/delegated-staking/src/mock.rs

@@ -24,7 +24,7 @@ use frame_support::{
 	PalletId,
 };
 
-use sp_runtime::{traits::IdentityLookup, BuildStorage, Perbill};
+use sp_runtime::{traits::IdentityLookup, BoundedVec, BuildStorage, Perbill};
 
 use frame_election_provider_support::{
 	bounds::{ElectionBounds, ElectionBoundsBuilder},
@@ -217,7 +217,7 @@ impl ExtBuilder {
 			// ideal validator count
 			validator_count: 2,
 			minimum_validator_count: 1,
-			invulnerables: vec![],
+			invulnerables: BoundedVec::new(),
 			slash_reward_fraction: Perbill::from_percent(10),
 			min_nominator_bond: ExistentialDeposit::get(),
 			min_validator_bond: ExistentialDeposit::get(),

substrate/frame/grandpa/src/mock.rs

@@ -39,7 +39,7 @@ use sp_runtime::{
 	impl_opaque_keys,
 	testing::{TestXt, UintAuthorityId},
 	traits::OpaqueKeys,
-	BuildStorage, DigestItem, Perbill,
+	BoundedVec, BuildStorage, DigestItem, Perbill,
 };
 use sp_staking::{EraIndex, SessionIndex};
 
@@ -258,7 +258,7 @@ pub fn new_test_ext_raw_authorities(authorities: AuthorityList) -> sp_io::TestEx
 		validator_count: 8,
 		force_era: pallet_staking::Forcing::ForceNew,
 		minimum_validator_count: 0,
-		invulnerables: vec![],
+		invulnerables: BoundedVec::new(),
 		..Default::default()
 	};
 

substrate/frame/root-offences/src/mock.rs

@@ -188,7 +188,7 @@ impl Default for ExtBuilder {
 		Self {
 			validator_count: 2,
 			minimum_validator_count: 0,
-			invulnerables: vec![],
+			invulnerables: BoundedVec::new(),
 			balance_factor: 1,
 		}
 	}
@@ -235,7 +235,7 @@ impl ExtBuilder {
 			stakers: stakers.clone(),
 			validator_count: self.validator_count,
 			minimum_validator_count: self.minimum_validator_count,
-			invulnerables: self.invulnerables,
+			invulnerables: BoundedVec::force_from(self.invulnerables),
 			slash_reward_fraction: Perbill::from_percent(10),
 			..Default::default()
 		}

substrate/frame/staking/src/benchmarking.rs

@@ -1021,7 +1021,6 @@ mod benchmarks {
 			ConfigOp::Set(BalanceOf::<T>::max_value()),
 			ConfigOp::Set(BalanceOf::<T>::max_value()),
 			ConfigOp::Set(u32::MAX),
-			ConfigOp::Set(u32::MAX),
 			ConfigOp::Set(Percent::max_value()),
 			ConfigOp::Set(Perbill::max_value()),
 			ConfigOp::Set(Percent::max_value()),
@@ -1030,7 +1029,6 @@ mod benchmarks {
 		assert_eq!(MinNominatorBond::<T>::get(), BalanceOf::<T>::max_value());
 		assert_eq!(MinValidatorBond::<T>::get(), BalanceOf::<T>::max_value());
 		assert_eq!(MaxNominatorsCount::<T>::get(), Some(u32::MAX));
-		assert_eq!(MaxValidatorsCount::<T>::get(), Some(u32::MAX));
 		assert_eq!(ChillThreshold::<T>::get(), Some(Percent::from_percent(100)));
 		assert_eq!(MinCommission::<T>::get(), Perbill::from_percent(100));
 		assert_eq!(MaxStakedRewards::<T>::get(), Some(Percent::from_percent(100)));
@@ -1047,13 +1045,11 @@ mod benchmarks {
 			ConfigOp::Remove,
 			ConfigOp::Remove,
 			ConfigOp::Remove,
-			ConfigOp::Remove,
 		);
 
 		assert!(!MinNominatorBond::<T>::exists());
 		assert!(!MinValidatorBond::<T>::exists());
 		assert!(!MaxNominatorsCount::<T>::exists());
-		assert!(!MaxValidatorsCount::<T>::exists());
 		assert!(!ChillThreshold::<T>::exists());
 		assert!(!MinCommission::<T>::exists());
 		assert!(!MaxStakedRewards::<T>::exists());
@@ -1077,7 +1073,6 @@ mod benchmarks {
 			ConfigOp::Set(BalanceOf::<T>::max_value()),
 			ConfigOp::Set(BalanceOf::<T>::max_value()),
 			ConfigOp::Set(0),
-			ConfigOp::Set(0),
 			ConfigOp::Set(Percent::from_percent(0)),
 			ConfigOp::Set(Zero::zero()),
 			ConfigOp::Noop,

substrate/frame/staking/src/migrations.rs

@@ -70,6 +70,8 @@ pub mod v17 {
 		fn on_runtime_upgrade() -> Weight {
 			let mut migration_errors = false;
 
+			v16::MaxValidatorsCount::<T>::kill();
+
 			let old_disabled_validators = v16::DisabledValidators::<T>::get();
 			// BoundedVec with MaxWinners limit, this should always work
 			let disabled_validators_maybe = WeakBoundedVec::try_from(old_disabled_validators);
@@ -249,6 +251,9 @@ pub mod v16 {
 		OptionQuery,
 	>;
 
+	#[frame_support::storage_alias]
+	pub(crate) type MaxValidatorsCount<T: Config> = StorageValue<Pallet<T>, u32, OptionQuery>;
+
 	pub struct VersionUncheckedMigrateV15ToV16<T>(core::marker::PhantomData<T>);
 	impl<T: Config> UncheckedOnRuntimeUpgrade for VersionUncheckedMigrateV15ToV16<T> {
 		#[cfg(feature = "try-runtime")]

substrate/frame/staking/src/mock.rs

@@ -290,6 +290,7 @@ impl crate::pallet::pallet::Config for Test {
 		pallet_staking::UpToLimitWithReEnablingDisablingStrategy<DISABLING_LIMIT_FACTOR>;
 	type MaxInvulnerables = ConstU32<20>;
 	type MaxRewardPagesPerValidator = ConstU32<20>;
+	type MaxValidatorsCount = ConstU32<300>;
 }
 
 pub struct WeightedNominationsQuota<const MAX: u32>;

substrate/frame/staking/src/pallet/mod.rs

@@ -143,6 +143,12 @@ pub mod pallet {
 		#[pallet::no_default_bounds]
 		type NominationsQuota: NominationsQuota<BalanceOf<Self>>;
 
+		/// The maximum validator count before we stop allowing new validators to join.
+		///
+		/// This is a dynamic runtime parameters, so updates do not require storage migrations.
+		#[pallet::constant]
+		type MaxValidatorsCount: Get<u32>;
+
 		/// Number of eras to keep in history.
 		///
 		/// Following information is kept for eras in `[current_era -
@@ -361,6 +367,7 @@ pub mod pallet {
 			type DisablingStrategy = crate::UpToLimitDisablingStrategy;
 			type MaxInvulnerables = ConstU32<20>;
 			type MaxRewardPagesPerValidator = ConstU32<20>;
+			type MaxValidatorsCount = ConstU32<300>;
 			#[cfg(feature = "std")]
 			type BenchmarkingConfig = crate::TestBenchmarkingConfig;
 			type WeightInfo = ();
@@ -427,12 +434,6 @@ pub mod pallet {
 	pub type Validators<T: Config> =
 		CountedStorageMap<_, Twox64Concat, T::AccountId, ValidatorPrefs, ValueQuery>;
 
-	/// The maximum validator count before we stop allowing new validators to join.
-	///
-	/// When this value is not set, no limits are enforced.
-	#[pallet::storage]
-	pub type MaxValidatorsCount<T> = StorageValue<_, u32, OptionQuery>;
-
 	/// The map from nominator stash key to their nomination preferences, namely the validators that
 	/// they wish to support.
 	///
@@ -710,7 +711,6 @@ pub mod pallet {
 			Vec<(T::AccountId, T::AccountId, BalanceOf<T>, crate::StakerStatus<T::AccountId>)>,
 		pub min_nominator_bond: BalanceOf<T>,
 		pub min_validator_bond: BalanceOf<T>,
-		pub max_validator_count: Option<u32>,
 		pub max_nominator_count: Option<u32>,
 	}
 
@@ -729,9 +729,6 @@ pub mod pallet {
 			SlashRewardFraction::<T>::put(self.slash_reward_fraction);
 			MinNominatorBond::<T>::put(self.min_nominator_bond);
 			MinValidatorBond::<T>::put(self.min_validator_bond);
-			if let Some(x) = self.max_validator_count {
-				MaxValidatorsCount::<T>::put(x);
-			}
 			if let Some(x) = self.max_nominator_count {
 				MaxNominatorsCount::<T>::put(x);
 			}
@@ -1347,12 +1344,10 @@ pub mod pallet {
 				// If this error is reached, we need to adjust the `MinValidatorBond` and start
 				// calling `chill_other`. Until then, we explicitly block new validators to protect
 				// the runtime.
-				if let Some(max_validators) = MaxValidatorsCount::<T>::get() {
-					ensure!(
-						Validators::<T>::count() < max_validators,
-						Error::<T>::TooManyValidators
-					);
-				}
+				ensure!(
+					Validators::<T>::count() < T::MaxValidatorsCount::get(),
+					Error::<T>::TooManyValidators,
+				);
 			}
 
 			Self::do_remove_nominator(stash);
@@ -1911,7 +1906,6 @@ pub mod pallet {
 			min_nominator_bond: ConfigOp<BalanceOf<T>>,
 			min_validator_bond: ConfigOp<BalanceOf<T>>,
 			max_nominator_count: ConfigOp<u32>,
-			max_validator_count: ConfigOp<u32>,
 			chill_threshold: ConfigOp<Percent>,
 			min_commission: ConfigOp<Perbill>,
 			max_staked_rewards: ConfigOp<Percent>,
@@ -1931,7 +1925,6 @@ pub mod pallet {
 			config_op_exp!(MinNominatorBond<T>, min_nominator_bond);
 			config_op_exp!(MinValidatorBond<T>, min_validator_bond);
 			config_op_exp!(MaxNominatorsCount<T>, max_nominator_count);
-			config_op_exp!(MaxValidatorsCount<T>, max_validator_count);
 			config_op_exp!(ChillThreshold<T>, chill_threshold);
 			config_op_exp!(MinCommission<T>, min_commission);
 			config_op_exp!(MaxStakedRewards<T>, max_staked_rewards);
@@ -1955,8 +1948,8 @@ pub mod pallet {
 		///
 		/// * A `ChillThreshold` must be set and checked which defines how close to the max
 		///   nominators or validators we must reach before users can start chilling one-another.
-		/// * A `MaxNominatorCount` and `MaxValidatorCount` must be set which is used to determine
-		///   how close we are to the threshold.
+		/// * A `MaxNominatorCount` must be set which is used to determine how close we are to the
+		///   threshold.
 		/// * A `MinNominatorBond` and `MinValidatorBond` must be set and checked, which determines
 		///   if this is a person that should be chilled because they have not met the threshold
 		///   bond required.
@@ -1984,7 +1977,7 @@ pub mod pallet {
 			//
 			// * A `ChillThreshold` is set which defines how close to the max nominators or
 			//   validators we must reach before users can start chilling one-another.
-			// * A `MaxNominatorCount` and `MaxValidatorCount` which is used to determine how close
+			// * A `MaxNominatorCount` and `MaxValidatorsCount` which is used to determine how close
 			//   we are to the threshold.
 			// * A `MinNominatorBond` and `MinValidatorBond` which is the final condition checked to
 			//   determine this is a person that should be chilled because they have not met the
@@ -2009,8 +2002,7 @@ pub mod pallet {
 					);
 					MinNominatorBond::<T>::get()
 				} else if Validators::<T>::contains_key(&stash) {
-					let max_validator_count =
-						MaxValidatorsCount::<T>::get().ok_or(Error::<T>::CannotChillOther)?;
+					let max_validator_count = T::MaxValidatorsCount::get();
 					let current_validator_count = Validators::<T>::count();
 					ensure!(
 						threshold * max_validator_count < current_validator_count,