Fixes

server/src/main/java/org/opensearch/action/support/replication/TransportReplicationAction.java

@@ -1072,15 +1072,10 @@ protected void doRun() {
 
                 ShardRouting primary = null;
                 if (indexMetadata.getSplitShardsMetadata().isEmptyParentShard(request.shardId().id())) {
-                    if (state.version() < request.routedBasedOnClusterVersion()) {
-                        // This will get retried on coordinator. Entire request will be re-driven on respective child shards.
-                        // Since, we are throwing a custom exception, coordinator will re-drive it explicitly on child shards
-                        // even if it is also stale and yet to receive update from cluster manager.
-                        throw new PrimaryShardSplitException("Primary shard is already split. Cannot perform replication operation on parent primary.");
-                    } else {
-                        finishAsFailed(new IndexNotFoundException(request.shardId().getIndex()));
-                        return;
-                    }
+                    // This will get retried on coordinator. Entire request will be re-driven on respective child shards.
+                    // Since, we are throwing a custom exception, coordinator will re-drive it explicitly on child shards
+                    // even if coordinator is also stale and yet to receive update from cluster manager.
+                    throw new PrimaryShardSplitException("Primary shard is already split. Cannot perform replication operation on parent primary.");
                 } else {
                     IndexRoutingTable indexRoutingTable = state.getRoutingTable().index(request.shardId().getIndex());
                     IndexShardRoutingTable shardRoutingTable = indexRoutingTable.shard(request.shardId().id());

server/src/main/java/org/opensearch/index/translog/RemoteFsTranslog.java

@@ -537,18 +537,6 @@ protected Releasable drainSync() {
         }
     }
 
-    @Override
-    protected void copyTranslogToTarget(Translog translog) {
-        assert translog instanceof RemoteFsTranslog;
-        RemoteFsTranslog targetTranslog = (RemoteFsTranslog) translog;
-        translogTransferManager.copyTranslogToTarget(targetTranslog.translogTransferManager);
-    }
-
-    public Releasable acquireRemoteDeletionPermits() throws InterruptedException {
-        remoteGenerationDeletionPermits.acquire(REMOTE_DELETION_PERMITS);
-        return Releasables.releaseOnce(() -> remoteGenerationDeletionPermits.release(REMOTE_DELETION_PERMITS));
-    }
-
     @Override
     public void trimUnreferencedReaders() throws IOException {
         // clean up local translog files and updates readers

server/src/main/java/org/opensearch/index/translog/Translog.java

@@ -739,6 +739,7 @@ public GatedCloseable<Long> acquireRetentionLockWithMinGen() {
         try (ReleasableLock lock = readLock.acquire()) {
             ensureOpen();
             final long viewGen = getMinFileGeneration();
+            logger.info("Minimum translog with gen " + viewGen + " seq number " + current.getCheckpoint().minSeqNo);
             Closeable closeable = acquireTranslogGenFromDeletionPolicy(viewGen);
             return new GatedCloseable<>(viewGen, closeable::close);
         }
@@ -1832,12 +1833,6 @@ protected void setMinSeqNoToKeep(long seqNo) {}
 
     protected void onDelete() {}
 
-    protected void copyTranslogToTarget(Translog translog) {}
-
-    protected Releasable acquireRemoteDeletionPermits() throws InterruptedException {
-        return Releasables.releaseOnce(() -> {});
-    }
-
     /**
      * Drains ongoing syncs to the underlying store. It returns a releasable which can be closed to resume the syncs back.
      */

server/src/main/java/org/opensearch/indices/recovery/inplacesplit/InPlaceShardSplitRecoverySourceHandler.java

@@ -164,6 +164,9 @@ protected void innerRecoveryToTarget(ActionListener<RecoveryResponse> listener,
             initiateTracking();
 
             final long endingSeqNo = sourceShard.seqNoStats().getMaxSeqNo();
+            // Syncing here because sequence number can be greater than local checkpoint and operations may not yet be
+            // present in translog.
+            sourceShard.sync();
             final Translog.Snapshot phase2Snapshot;
             if (startingSeqNo > endingSeqNo) {
                 phase2Snapshot = new EmptySnapshot();