Don't call into the old LFC when using the new communicator

This fixes errors like `index "pg_class_relname_nsp_index" contains
unexpected zero page at block 2` when running the python tests

smgrzeroextend() still called into the old LFC's lfc_write() function,
even when using the new communicator, which zeroed some arbitrary
pages in the LFC file, overwriting pages managed by the new LFC
implementation managed by `integrated_cache.rs`

pgxn/neon/file_cache.c

@@ -693,6 +693,7 @@ lfc_prewarm(FileCacheState* fcs, uint32 n_workers)
 	dsm_segment *seg;
 	BackgroundWorkerHandle* bgw_handle[MAX_PREWARM_WORKERS];
 
+	Assert(!neon_enable_new_communicator);
 
 	if (!lfc_ensure_opened())
 		return;
@@ -847,6 +848,8 @@ lfc_prewarm_main(Datum main_arg)
 	PrewarmWorkerState* ws;
 	uint32 worker_id = DatumGetInt32(main_arg);
 
+	Assert(!neon_enable_new_communicator);
+
 	AmPrewarmWorker = true;
 
 	pqsignal(SIGTERM, die);
@@ -947,6 +950,8 @@ lfc_invalidate(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber nblocks)
 	FileCacheEntry *entry;
 	uint32		hash;
 
+	Assert(!neon_enable_new_communicator);
+
 	if (lfc_maybe_disabled())	/* fast exit if file cache is disabled */
 		return;
 
@@ -992,6 +997,8 @@ lfc_cache_contains(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno)
 	bool		found = false;
 	uint32		hash;
 
+	Assert(!neon_enable_new_communicator);
+
 	if (lfc_maybe_disabled())	/* fast exit if file cache is disabled */
 		return false;
 
@@ -1027,6 +1034,8 @@ lfc_cache_containsv(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
 	uint32		hash;
 	int			i = 0;
 
+	Assert(!neon_enable_new_communicator);
+
 	if (lfc_maybe_disabled())	/* fast exit if file cache is disabled */
 		return 0;
 
@@ -1134,6 +1143,8 @@ lfc_readv_select(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
 	int			blocks_read = 0;
 	int			buf_offset = 0;
 
+	Assert(!neon_enable_new_communicator);
+
 	if (lfc_maybe_disabled())	/* fast exit if file cache is disabled */
 		return -1;
 
@@ -1500,6 +1511,8 @@ lfc_prefetch(NRelFileInfo rinfo, ForkNumber forknum, BlockNumber blkno,
 
 	int		chunk_offs = BLOCK_TO_CHUNK_OFF(blkno);
 
+	Assert(!neon_enable_new_communicator);
+
 	if (lfc_maybe_disabled())	/* fast exit if file cache is disabled */
 		return false;
 
@@ -1645,6 +1658,8 @@ lfc_writev(NRelFileInfo rinfo, ForkNumber forkNum, BlockNumber blkno,
 	uint32		entry_offset;
 	int			buf_offset = 0;
 
+	Assert(!neon_enable_new_communicator);
+
 	if (lfc_maybe_disabled())	/* fast exit if file cache is disabled */
 		return;
 

pgxn/neon/pagestore_smgr.c

@@ -1104,11 +1104,14 @@ neon_zeroextend(SMgrRelation reln, ForkNumber forkNum, BlockNumber start_block,
 
 		lsn = XLogInsert(RM_XLOG_ID, XLOG_FPI);
 
-		for (int i = 0; i < count; i++)
+		if (!neon_enable_new_communicator)
 		{
-			lfc_write(InfoFromSMgrRel(reln), forkNum, blocknum + i, buffer.data);
-			neon_set_lwlsn_block(lsn, InfoFromSMgrRel(reln), forkNum,
-									  blocknum + i);
+			for (int i = 0; i < count; i++)
+			{
+				lfc_write(InfoFromSMgrRel(reln), forkNum, blocknum + i, buffer.data);
+				neon_set_lwlsn_block(lsn, InfoFromSMgrRel(reln), forkNum,
+									 blocknum + i);
+			}
 		}
 
 		blocknum += count;