testnet fixup: only update rent_epoch on load until feature (#28543)

* feature 28541 no-op

* Revert "manual backport of #28422 (#28532)"

This reverts commit 5571aca.

* only update rent_epoch on load until feature

runtime/src/accounts_db.rs

@@ -45,6 +45,7 @@ use {
         bank::Rewrites,
         cache_hash_data::CacheHashData,
         contains::Contains,
+        expected_rent_collection::{ExpectedRentCollection, SlotInfoInEpoch},
         pubkey_bins::PubkeyBinCalculator24,
         read_only_accounts_cache::ReadOnlyAccountsCache,
         rent_collector::RentCollector,
@@ -1792,22 +1793,26 @@ trait AppendVecScan: Send + Sync + Clone {
 /// These would have been captured in a fn from within the scan function.
 /// Some of these are constant across all pubkeys, some are constant across a slot.
 /// Some could be unique per pubkey.
-struct ScanState<'a> {
+struct ScanState<'a, T: Fn(Slot) -> Option<Slot> + Sync + Send + Clone> {
     /// slot we're currently scanning
     current_slot: Slot,
     /// accumulated results
     accum: BinnedHashData,
+    /// max slot (inclusive) that we're calculating accounts hash on
+    max_slot_info: SlotInfoInEpoch,
     bin_calculator: &'a PubkeyBinCalculator24,
     bin_range: &'a Range<usize>,
     config: &'a CalcAccountsHashConfig<'a>,
     mismatch_found: Arc<AtomicU64>,
+    stats: &'a crate::accounts_hash::HashStats,
+    find_unskipped_slot: &'a T,
     filler_account_suffix: Option<&'a Pubkey>,
     range: usize,
     sort_time: Arc<AtomicU64>,
     pubkey_to_bin_index: usize,
 }
 
-impl<'a> AppendVecScan for ScanState<'a> {
+impl<'a, T: Fn(Slot) -> Option<Slot> + Sync + Send + Clone> AppendVecScan for ScanState<'a, T> {
     fn set_slot(&mut self, slot: Slot) {
         self.current_slot = slot;
     }
@@ -1836,6 +1841,20 @@ impl<'a> AppendVecScan for ScanState<'a> {
         };
 
         let loaded_hash = loaded_account.loaded_hash();
+        let new_hash = ExpectedRentCollection::maybe_rehash_skipped_rewrite(
+            loaded_account,
+            &loaded_hash,
+            pubkey,
+            self.current_slot,
+            self.config.epoch_schedule,
+            self.config.rent_collector,
+            self.stats,
+            &self.max_slot_info,
+            self.find_unskipped_slot,
+            self.filler_account_suffix,
+        );
+        let loaded_hash = new_hash.unwrap_or(loaded_hash);
+
         let source_item = CalculateHashIntermediate::new(loaded_hash, balance, *pubkey);
 
         if self.config.check_hash
@@ -6236,6 +6255,8 @@ impl AccountsDb {
         let total_lamports = Mutex::<u64>::new(0);
         let stats = HashStats::default();
 
+        let max_slot_info = SlotInfoInEpoch::new(max_slot, config.epoch_schedule);
+
         let get_hashes = || {
             keys.par_chunks(chunks)
                 .map(|pubkeys| {
@@ -6268,7 +6289,23 @@ impl AccountsDb {
                                     .get_loaded_account()
                                     .and_then(
                                         |loaded_account| {
+                                            let find_unskipped_slot = |slot: Slot| {
+                                                self.find_unskipped_slot(slot, config.ancestors)
+                                            };
                                             let loaded_hash = loaded_account.loaded_hash();
+                                            let new_hash = ExpectedRentCollection::maybe_rehash_skipped_rewrite(
+                                                &loaded_account,
+                                                &loaded_hash,
+                                                pubkey,
+                                                *slot,
+                                                config.epoch_schedule,
+                                                config.rent_collector,
+                                                &stats,
+                                                &max_slot_info,
+                                                find_unskipped_slot,
+                                                self.filler_account_suffix.as_ref(),
+                                            );
+                                            let loaded_hash = new_hash.unwrap_or(loaded_hash);
                                             let balance = loaded_account.lamports();
                                             if config.check_hash && !self.is_filler_account(pubkey) {  // this will not be supported anymore
                                                 let computed_hash =
@@ -6853,15 +6890,22 @@ impl AccountsDb {
         let range = bin_range.end - bin_range.start;
         let sort_time = Arc::new(AtomicU64::new(0));
 
+        let find_unskipped_slot = |slot: Slot| self.find_unskipped_slot(slot, config.ancestors);
+
+        let max_slot_info =
+            SlotInfoInEpoch::new(storage.max_slot_inclusive(), config.epoch_schedule);
         let scanner = ScanState {
             current_slot: Slot::default(),
             accum: BinnedHashData::default(),
             bin_calculator: &bin_calculator,
             config,
             mismatch_found: mismatch_found.clone(),
+            max_slot_info,
+            find_unskipped_slot: &find_unskipped_slot,
             filler_account_suffix,
             range,
             bin_range,
+            stats,
             sort_time: sort_time.clone(),
             pubkey_to_bin_index: 0,
         };

runtime/src/bank.rs

@@ -54,6 +54,7 @@ use {
         builtins::{self, BuiltinAction, BuiltinFeatureTransition, Builtins},
         cost_tracker::CostTracker,
         epoch_stakes::{EpochStakes, NodeVoteAccounts},
+        expected_rent_collection::{ExpectedRentCollection, SlotInfoInEpoch},
         inline_spl_associated_token_account, inline_spl_token,
         message_processor::MessageProcessor,
         rent_collector::{CollectedInfo, RentCollector},
@@ -6380,7 +6381,33 @@ impl Bank {
         ancestors: &Ancestors,
         pubkey: &Pubkey,
     ) -> Option<(AccountSharedData, Slot)> {
-        self.rc.accounts.load_with_fixed_root(ancestors, pubkey)
+        match self.rc.accounts.load_with_fixed_root(ancestors, pubkey) {
+            Some((mut account, storage_slot)) => {
+                if !self.feature_set.is_active(
+                    &solana_sdk::feature_set::on_load_preserve_rent_epoch_for_rent_exempt_accounts::id(),
+                ) {
+                    // this was a bug in 1.14+. This code should not have run once this feature was activated:
+                    //  preserve rent epoch for rent exempt accounts #26479
+                    // But, it did run. On mnb, this caused bank mismatches.
+                    // On testnet, where ALL validators were running this code incorrectly, the rent_epoch was updated here.
+                    // The network was happy, but the behavior was wrong. So, correctly removing this code disagreed with
+                    // what the network agreed was 'correct'. So, we have to preserve the previous erroneous behavior on testnet
+                    // until we can activate this feature to switch the network's understanding of 'correct'.
+                    ExpectedRentCollection::maybe_update_rent_epoch_on_load(
+                        &mut account,
+                        &SlotInfoInEpoch::new_small(storage_slot),
+                        &SlotInfoInEpoch::new_small(self.slot()),
+                        self.epoch_schedule(),
+                        self.rent_collector(),
+                        pubkey,
+                        &self.rewrites_skipped_this_slot,
+                    );
+                }
+
+                Some((account, storage_slot))
+            }
+            None => None,
+        }
     }
 
     pub fn get_program_accounts(