Unable to bond extra

[xlc]

Address: 14DsLzVyTUTDMm2eP3czwPbH53KgqnQRp3CJJZS9GR7yxGDP
This tx failed: https://polkadot.subscan.io/extrinsic/23965894-2
It is trying to bond extra 1 dot and I have 30+ transferable DOT and the bond failed
And I am able to transfer 1 DOT out of this account: https://polkadot.subscan.io/extrinsic/23966216-2

[xlc]

It is this line failed

polkadot-sdk/substrate/frame/staking/src/pallet/impls.rs

Lines 167 to 169 in 88d900a

	asset::stakeable_balance::<T>(stash)
	.checked_sub(&ledger.total)
	.ok_or(ArithmeticError::Overflow)?,

Relevant state at block 23965893

staking.ledger: Option<PalletStakingStakingLedger>
{
  stash: 14DsLzVyTUTDMm2eP3czwPbH53KgqnQRp3CJJZS9GR7yxGDP
  total: 12,929,164,149,143
  active: 12,929,164,149,143
  unlocking: []
  legacyClaimedRewards: []
}

system.account: FrameSystemAccountInfo
{
  nonce: 515
  consumers: 2
  providers: 1
  sufficients: 0
  data: {
    free: 11,929,004,994,238
    reserved: 1,302,990,000,000
    frozen: 12,929,164,149,143
    flags: 170,141,183,460,469,231,731,687,309,715,884,105,728
  }
}

So it failed because free is less than ledger.total
But the transferable amount suppose to be free - froze + reserved and I see no reason to not use it for max staking amount calculation?

[bkchr]

CC @Ank4n @kianenigma

[gui1117]

The same logic is implemented when calling bond. In both case the maximum stakeable amount is Currency::free_balance, and doesn't include the reserved amount. Maybe we should change like this:

diff --git a/substrate/frame/staking/src/asset.rs b/substrate/frame/staking/src/asset.rs
index 23368b1f8fc..b939987ae72 100644
--- a/substrate/frame/staking/src/asset.rs
+++ b/substrate/frame/staking/src/asset.rs
@@ -41,7 +41,7 @@ pub fn total_balance<T: Config>(who: &T::AccountId) -> BalanceOf<T> {
 ///
 /// This includes balance free to stake along with any balance that is already staked.
 pub fn stakeable_balance<T: Config>(who: &T::AccountId) -> BalanceOf<T> {
-       T::Currency::free_balance(who)
+       T::Currency::total_balance(who)
 }
 
 /// Balance of `who` that is currently at stake.

[xlc]

I would like to confirm, reserved tokens can be used for staking right?
This is a test that's currently passing:

#[test]
fn can_stake_reserve_balances() {
	use frame_support::traits::tokens::Fortitude::Polite;
	use frame_support::traits::fungible::Inspect;
	use frame_support::traits::tokens::Preservation::Expendable;
	use frame_support::traits::ExistenceRequirement::AllowDeath;

	ExtBuilder::default().build_and_execute(|| {
		// account 1 have 10 tokens

		// reserve 5
		let _ = Balances::reserve(&1, 5);

		// check transferable balance = 10 - 5 - ED = 4
		assert_eq!(Balances::reducible_balance(&1, Expendable, Polite), 4);

		// stake all tokens
		assert_ok!(Staking::bond(RuntimeOrigin::signed(1), 10, RewardDestination::Staked));

		// only 5 is staked
		assert_eq!(Staking::ledger(1.into()).unwrap().active, 5);

		// transfer 4 tokens from account 1 to account 2
		assert_ok!(Balances::transfer(&1, &2, 4, AllowDeath));

		// check transferable balance
		assert_eq!(Balances::reducible_balance(&1, Expendable, Polite), 0);
	});
}

So resrved token cannot be used for staking, but can be transferred out, and obviously can be used for staking on another account.

I agree change stakeable_balance to use total_balance make the most sense.

Another small thing is that I made such patch locally, and all existing pallet-staking tests are passing. So test coverage on that needs improvement.

[kianenigma]

closing as per #7047 (comment)