From e092f00d061ede6faffe17638b4a1dc9f71bc47d Mon Sep 17 00:00:00 2001
From: Noah Misch <noah@leadboat.com>
Date: Wed, 26 Jan 2022 18:06:19 -0800
Subject: [PATCH] On sparc64+ext4, suppress test failures from known WAL read
 failure.

Buildfarm members kittiwake, tadarida and snapper began to fail
frequently when commits 3cd9c3b921977272e6650a5efbeade4203c4bca2 and
f47ed79cc8a0cfa154dc7f01faaf59822552363f added tests of concurrency, but
the problem was reachable before those commits.  Back-patch to v10 (all
supported versions).

Discussion: https://postgr.es/m/20220116210241.GC756210@rfd.leadboat.com
---
 src/bin/pgbench/t/023_cic_2pc.pl |  2 ++
 src/test/perl/TestLib.pm         | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/bin/pgbench/t/023_cic_2pc.pl b/src/bin/pgbench/t/023_cic_2pc.pl
index e29c2564b77..707f28c34e8 100644
--- a/src/bin/pgbench/t/023_cic_2pc.pl
+++ b/src/bin/pgbench/t/023_cic_2pc.pl
@@ -11,6 +11,8 @@ use TestLib;
 
 use Test::More tests => 6;
 
+local $TODO = 'filesystem bug' if TestLib::has_wal_read_bug;
+
 my ($node, $result);
 
 #
diff --git a/src/test/perl/TestLib.pm b/src/test/perl/TestLib.pm
index 1231c10fc3c..0c561565e3b 100644
--- a/src/test/perl/TestLib.pm
+++ b/src/test/perl/TestLib.pm
@@ -223,6 +223,29 @@ sub real_dir
 	return perl2host(@_);
 }
 
+=pod
+
+=item has_wal_read_bug()
+
+Returns true if $tmp_check is subject to a sparc64+ext4 bug that causes WAL
+readers to see zeros if another process simultaneously wrote the same offsets.
+Consult this in tests that fail frequently on affected configurations.  The
+bug has made streaming standbys fail to advance, reporting corrupt WAL.  It
+has made COMMIT PREPARED fail with "could not read two-phase state from WAL".
+Non-WAL PostgreSQL reads haven't been affected, likely because those readers
+and writers have buffering systems in common.  See
+https://postgr.es/m/20220116210241.GC756210@rfd.leadboat.com for details.
+
+=cut
+
+sub has_wal_read_bug
+{
+	return
+	     $Config{osname} eq 'linux'
+	  && $Config{archname} =~ /^sparc/
+	  && !run_log([ qw(df -x ext4), $tmp_check ], '>', '/dev/null', '2>&1');
+}
+
 sub system_log
 {
 	print("# Running: " . join(" ", @_) . "\n");