[PATCH] generic: test mapped write after shutdown and failed writeback

[Brian Foster <bfoster@redhat.com>]

XFS has a regression where it failed to check shutdown status in the
write fault path. This produced an iomap warning if the page
happened to recently fail a writeback attempt because writeback
failure can clear Uptodate status on the page. Add a test for this
scenario to help ensure mapped write failures are handled as
expected in the event of filesystem shutdown.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---

Note that this test currently fails on XFS. The fix is posted for review
on linux-xfs:

https://lore.kernel.org/linux-xfs/20210210170112.172734-1-bfoster@redhat.com/

Brian

 tests/generic/999     | 45 +++++++++++++++++++++++++++++++++++++++++++
 tests/generic/999.out |  4 ++++
 tests/generic/group   |  1 +
 3 files changed, 50 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 00000000..5e5408e7
--- /dev/null
+++ b/tests/generic/999
@@ -0,0 +1,45 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0-only
+# Copyright 2021 Red Hat, Inc.
+#
+# FS QA Test No. 999
+#
+# Test a write fault scenario on a shutdown fs.
+#
+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()
+{
+	rm -f $tmp.*
+}
+
+. ./common/rc
+. ./common/filter
+
+rm -f $seqres.full
+
+_supported_fs generic
+_require_scratch_nocheck
+_require_scratch_shutdown
+
+_scratch_mkfs &>> $seqres.full
+_scratch_mount
+
+# XFS had a regression where it failed to check shutdown status in the fault
+# path. This produced an iomap warning because writeback failure clears Uptodate
+# status on the page.
+file=$SCRATCH_MNT/file
+$XFS_IO_PROG -fc "pwrite 0 4k" -c fsync $file | _filter_xfs_io
+$XFS_IO_PROG -x -c "mmap 0 4k" -c "mwrite 0 4k" -c shutdown -c fsync \
+	-c "mwrite 0 4k" $file | _filter_xfs_io
+
+# success, all done
+status=0
+exit
diff --git a/tests/generic/999.out b/tests/generic/999.out
new file mode 100644
index 00000000..f55569ff
--- /dev/null
+++ b/tests/generic/999.out
@@ -0,0 +1,4 @@
+QA output created by 999
+wrote 4096/4096 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+fsync: Input/output error
diff --git a/tests/generic/group b/tests/generic/group
index b10fdea4..edd54ce5 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -625,3 +625,4 @@
 620 auto mount quick
 621 auto quick encrypt
 622 auto shutdown metadata atime
+999 auto quick shutdown
-- 
2.26.2