[PATCH v3] generic: test for seeing unseen fsync errors on newly open files

[Jeff Layton <jlayton@kernel.org>]

From: Jeff Layton <jlayton@redhat.com>

This adds a regression test for the following kernel patch:

    errseq: Always report a writeback error once

This is motivated by some rather odd behavior done by the PostgreSQL
project. The main database writers will offload the fsync calls to a
separate process, which can open files after a writeback error has
already occurred.

This used to work with older kernels that reported the error to only
one fd, but with the errseq_t changes we lost the ability to see
errors that occurred before the open. The above patch restores that
behavior.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
---
 tests/generic/999     | 95 +++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/generic/999.out |  5 +++
 tests/generic/group   |  1 +
 3 files changed, 101 insertions(+)
 create mode 100755 tests/generic/999
 create mode 100644 tests/generic/999.out

diff --git a/tests/generic/999 b/tests/generic/999
new file mode 100755
index 000000000000..b816fd3bb423
--- /dev/null
+++ b/tests/generic/999
@@ -0,0 +1,95 @@
+#! /bin/bash
+# FS QA Test No. XXX
+#
+# Open a file several times, write to it, fsync on all fds and make sure that
+# they all return 0. Change the device to start throwing errors. Write again
+# on all fds and fsync on all fds. Ensure that we get errors on all of them.
+# Then fsync on all one last time and verify that all return 0.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2018, Jeff Layton <jlayton@redhat.com>
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1    # failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -rf $tmp.* $testdir
+	_dmerror_cleanup
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/dmerror
+
+# real QA test starts here
+_supported_os Linux
+_require_scratch_nocheck
+# This test uses "dm" without taking into account the data could be on
+# realtime subvolume, thus the test will fail with rtinherit=1
+_require_no_rtinherit
+
+_require_dm_target error
+
+rm -f $seqres.full
+
+echo "Format and mount"
+_scratch_mkfs > $seqres.full 2>&1
+_dmerror_init
+_dmerror_mount
+
+datalen=65536
+_require_fs_space $SCRATCH_MNT $datalen
+
+# use fd 5 to hold file open
+testfile=$SCRATCH_MNT/fsync-open-after-err
+exec 5>$testfile
+
+# write some data to file and fsync it out
+$XFS_IO_PROG -c "pwrite -q 0 $datalen" -c fsync $testfile
+
+# flip device to non-working mode
+_dmerror_load_error_table
+
+# rewrite the data, call sync to ensure it's written back w/o scraping error
+$XFS_IO_PROG -c "pwrite -q 0 $datalen" -c sync $testfile
+
+# heal the device error
+_dmerror_load_working_table
+
+# open again and call fsync
+echo "The following fsync should fail with EIO:"
+$XFS_IO_PROG -c fsync $testfile
+echo "done"
+
+# close file
+exec 5>&-
+
+# success, all done
+_dmerror_unmount
+_dmerror_cleanup
+
+status=0
+exit
diff --git a/tests/generic/999.out b/tests/generic/999.out
new file mode 100644
index 000000000000..38d2d7f6495f
--- /dev/null
+++ b/tests/generic/999.out
@@ -0,0 +1,5 @@
+QA output created by 999
+Format and mount
+The following fsync should fail with EIO:
+fsync: Input/output error
+done
diff --git a/tests/generic/group b/tests/generic/group
index ea8e51b35e79..48f491a5c32b 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -486,3 +486,4 @@
 481 auto quick log metadata
 482 auto metadata replay
 483 auto quick log metadata
+999 auto quick
-- 
2.14.3