BRIN: mask BRIN_EVACUATE_PAGE for WAL consistency checking

That bit is unlogged and therefore it's wrong to consider it in WAL page
comparison.

Add a test that tickles the case, as branch testing technology allows.

This has been a problem ever since wal consistency checking was
introduced (commit a507b86 for pg10), so backpatch to all supported
branches.

Author: 王海洋 (Haiyang Wang) <wanghaiyang.001@bytedance.com>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/CACciXAD2UvLMOhc4jX9VvOKt7DtYLr3OYRBhvOZ-jRxtzc_7Jg@mail.gmail.com
Discussion: https://postgr.es/m/CACciXADOfErX9Bx0nzE_SkdfXr6Bbpo5R=v_B6MUTEYW4ya+cg@mail.gmail.com

Author: alvherre

src/backend/access/brin/brin_pageops.c

@@ -541,7 +541,12 @@ brin_start_evacuating_page(Relation idxRel, Buffer buf)
 		lp = PageGetItemId(page, off);
 		if (ItemIdIsUsed(lp))
 		{
-			/* prevent other backends from adding more stuff to this page */
+			/*
+			 * Prevent other backends from adding more stuff to this page:
+			 * BRIN_EVACUATE_PAGE informs br_page_get_freespace that this page
+			 * can no longer be used to add new tuples.  Note that this flag
+			 * is not WAL-logged, except accidentally.
+			 */
 			BrinPageFlags(page) |= BRIN_EVACUATE_PAGE;
 			MarkBufferDirtyHint(buf, true);
 

src/backend/access/brin/brin_xlog.c

@@ -358,4 +358,10 @@ brin_mask(char *pagedata, BlockNumber blkno)
 	{
 		mask_unused_space(page);
 	}
+
+	/*
+	 * BRIN_EVACUATE_PAGE is not WAL-logged, since it's of no use in recovery.
+	 * Mask it.  See brin_start_evacuating_page() for details.
+	 */
+	BrinPageFlags(page) &= ~BRIN_EVACUATE_PAGE;
 }

src/test/modules/brin/t/02_wal_consistency.pl

@@ -0,0 +1,64 @@
+# Copyright (c) 2021-2022, PostgreSQL Global Development Group
+
+# Verify WAL consistency
+
+use strict;
+use warnings;
+
+use PostgreSQL::Test::Utils;
+use Test::More;
+use PostgreSQL::Test::Cluster;
+
+# Set up primary
+my $whiskey = PostgreSQL::Test::Cluster->new('whiskey');
+$whiskey->init(allows_streaming => 1);
+$whiskey->append_conf('postgresql.conf', 'wal_consistency_checking = brin');
+$whiskey->start;
+$whiskey->safe_psql('postgres', 'create extension pageinspect');
+is( $whiskey->psql(
+		'postgres',
+		qq[SELECT pg_create_physical_replication_slot('standby_1');]),
+	0,
+	'physical slot created on primary');
+
+# Take backup
+my $backup_name = 'brinbkp';
+$whiskey->backup($backup_name);
+
+# Create streaming standby linking to primary
+my $charlie = PostgreSQL::Test::Cluster->new('charlie');
+$charlie->init_from_backup($whiskey, $backup_name, has_streaming => 1);
+$charlie->append_conf('postgresql.conf', 'primary_slot_name = standby_1');
+$charlie->start;
+
+# Now write some WAL in the primary
+
+$whiskey->safe_psql(
+	'postgres', qq{
+create table tbl_timestamp0 (d1 timestamp(0) without time zone) with (fillfactor=10);
+create index on tbl_timestamp0 using brin (d1) with (pages_per_range = 1, autosummarize=false);
+});
+# Run a loop that will end when the second revmap page is created
+$whiskey->safe_psql(
+	'postgres', q{
+do
+$$
+declare
+  current timestamp with time zone := '2019-03-27 08:14:01.123456789 America/Punta_Arenas';
+begin
+  loop
+    insert into tbl_timestamp0 select i from
+      generate_series(current, current + interval '1 day', '28 seconds') i;
+    perform brin_summarize_new_values('tbl_timestamp0_d1_idx');
+    if (brin_metapage_info(get_raw_page('tbl_timestamp0_d1_idx', 0))).lastrevmappage > 1 then
+      exit;
+    end if;
+    current := current + interval '1 day';
+  end loop;
+end
+$$;
+});
+
+$whiskey->wait_for_catchup($charlie, 'replay', $whiskey->lsn('insert'));
+
+done_testing();