v1.18: blockstore: relax backwards chained merkle root check for upgrades (backport of #1163) (#1196)

blockstore: relax backwards chained merkle root check for upgrades (#1163)

* blockstore: relax backwards chained merkle root check for upgrades

* s/v1.18.12/v1.18.13

Co-authored-by: Trent Nelson <490004+t-nelson@users.noreply.github.com>

---------

Co-authored-by: Trent Nelson <490004+t-nelson@users.noreply.github.com>
(cherry picked from commit a645d07)

Co-authored-by: Ashwin Sekar <ashwin@anza.xyz>

Author: 2 people

ledger/src/blockstore.rs

@@ -1930,7 +1930,7 @@ impl Blockstore {
             return true;
         };
 
-        let prev_merkle_root_meta = merkle_root_metas
+        let Some(prev_merkle_root_meta) = merkle_root_metas
             .get(&prev_erasure_set)
             .map(WorkingEntry::as_ref)
             .map(Cow::Borrowed)
@@ -1939,7 +1939,14 @@ impl Blockstore {
                     .unwrap()
                     .map(Cow::Owned)
             })
-            .expect("merkle root meta must exist for erasure meta");
+        else {
+            warn!(
+                "The merkle root meta for the previous erasure set {prev_erasure_set:?} does not exist.
+                This should only happen if you have recently upgraded from a version < v1.18.13.
+                Skipping the backwards chained merkle root for {erasure_set:?}"
+            );
+            return true;
+        };
         let prev_shred_id = ShredId::new(
             slot,
             prev_merkle_root_meta.first_received_shred_index(),
@@ -11641,4 +11648,108 @@ pub mod tests {
             )
         );
     }
+
+    #[test]
+    fn test_chained_merkle_root_upgrade_inconsistency_backwards() {
+        // Insert a coding shred (without a merkle meta) then inconsistent shreds from the next FEC set
+        let ledger_path = get_tmp_ledger_path_auto_delete!();
+        let blockstore = Blockstore::open(ledger_path.path()).unwrap();
+
+        let parent_slot = 0;
+        let slot = 1;
+        let fec_set_index = 0;
+        let (data_shreds, coding_shreds, leader_schedule) =
+            setup_erasure_shreds_with_index(slot, parent_slot, 10, fec_set_index);
+        let coding_shred_previous = coding_shreds[0].clone();
+        let next_fec_set_index = fec_set_index + data_shreds.len() as u32;
+
+        assert!(blockstore
+            .insert_shred_return_duplicate(coding_shred_previous.clone(), &leader_schedule,)
+            .is_empty());
+
+        // Remove the merkle root meta in order to simulate this blockstore originating from
+        // an older version.
+        let mut write_batch = blockstore.db.batch().unwrap();
+        blockstore
+            .db
+            .delete_range_cf::<cf::MerkleRootMeta>(&mut write_batch, slot, slot)
+            .unwrap();
+        blockstore.db.write(write_batch).unwrap();
+        assert!(blockstore
+            .merkle_root_meta(coding_shred_previous.erasure_set())
+            .unwrap()
+            .is_none());
+
+        // Add an incorrectly chained merkle from the next set. Although incorrectly chained
+        // we skip the duplicate check as the merkle root meta is missing.
+        let merkle_root = Hash::new_unique();
+        assert!(merkle_root != coding_shred_previous.merkle_root().unwrap());
+        let (data_shreds, coding_shreds, leader_schedule) =
+            setup_erasure_shreds_with_index_and_chained_merkle(
+                slot,
+                parent_slot,
+                10,
+                next_fec_set_index,
+                Some(merkle_root),
+            );
+        let data_shred = data_shreds[0].clone();
+        let coding_shred = coding_shreds[0].clone();
+        assert!(blockstore
+            .insert_shred_return_duplicate(coding_shred, &leader_schedule)
+            .is_empty());
+        assert!(blockstore
+            .insert_shred_return_duplicate(data_shred, &leader_schedule,)
+            .is_empty());
+    }
+
+    #[test]
+    fn test_chained_merkle_root_upgrade_inconsistency_forwards() {
+        // Insert a data shred (without a merkle root), then an inconsistent coding shred from the previous FEC set.
+        let ledger_path = get_tmp_ledger_path_auto_delete!();
+        let blockstore = Blockstore::open(ledger_path.path()).unwrap();
+
+        let parent_slot = 0;
+        let slot = 1;
+        let fec_set_index = 0;
+        let (data_shreds, coding_shreds, leader_schedule) =
+            setup_erasure_shreds_with_index(slot, parent_slot, 10, fec_set_index);
+        let coding_shred = coding_shreds[0].clone();
+        let next_fec_set_index = fec_set_index + data_shreds.len() as u32;
+
+        // Incorrectly chained merkle
+        let merkle_root = Hash::new_unique();
+        assert!(merkle_root != coding_shred.merkle_root().unwrap());
+        let (next_data_shreds, next_coding_shreds, leader_schedule_next) =
+            setup_erasure_shreds_with_index_and_chained_merkle(
+                slot,
+                parent_slot,
+                10,
+                next_fec_set_index,
+                Some(merkle_root),
+            );
+        let next_data_shred = next_data_shreds[0].clone();
+
+        assert!(blockstore
+            .insert_shred_return_duplicate(next_data_shred, &leader_schedule_next,)
+            .is_empty());
+
+        // Remove the merkle root meta in order to simulate this blockstore originating from
+        // an older version.
+        let mut write_batch = blockstore.db.batch().unwrap();
+        blockstore
+            .db
+            .delete_range_cf::<cf::MerkleRootMeta>(&mut write_batch, slot, slot)
+            .unwrap();
+        blockstore.db.write(write_batch).unwrap();
+        assert!(blockstore
+            .merkle_root_meta(next_coding_shreds[0].erasure_set())
+            .unwrap()
+            .is_none());
+
+        // Insert previous FEC set, although incorrectly chained we skip the duplicate check
+        // as the merkle root meta is missing.
+        assert!(blockstore
+            .insert_shred_return_duplicate(coding_shred, &leader_schedule)
+            .is_empty());
+    }
 }