[PATCH] xfs: test a race between dio reads and mapped writes

[Xiao Yang <yangx.jy@cn.fujitsu.com>]

This regression test reproduces a race between a direct
I/O read and a mapped write to a hole in a file.  If the
race occurs, it will trigger a BUG_ON().  This XFS bug
has been fixed by:

04197b3 (xfs: don't BUG() on mixed direct and mapped I/O)

Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
---
 tests/xfs/422     | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/xfs/422.out |  2 ++
 tests/xfs/group   |  1 +
 3 files changed, 89 insertions(+)
 create mode 100755 tests/xfs/422
 create mode 100644 tests/xfs/422.out

diff --git a/tests/xfs/422 b/tests/xfs/422
new file mode 100755
index 0000000..a57ffab
--- /dev/null
+++ b/tests/xfs/422
@@ -0,0 +1,86 @@
+#! /bin/bash
+# FS QA Test No. 422
+#
+# Regression test for commit:
+# 04197b3 ("xfs: don't BUG() on mixed direct and mapped I/O)
+#
+# This case tests a race between a direct I/O read and a
+# mapped write to a hole in a file.  If the race occurs,
+# it will trigger a BUG_ON().
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2017 Fujitsu.  All Rights Reserved.
+# Author: Xiao Yang <yangx.jy@cn.fujitsu.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()
+{
+	rm -rf $tmp.*
+}
+
+# get standard environment and checks
+. ./common/rc
+
+# real QA test starts here
+_supported_os Linux
+_supported_fs xfs
+_require_scratch
+_disable_dmesg_check
+_require_xfs_io_command "truncate"
+_require_xfs_io_command "fpunch"
+
+rm -f $seqres.full
+
+# format and mount
+_scratch_mkfs > $seqres.full 2>&1
+_scratch_mount >> $seqres.full 2>&1
+
+filesz=$((65536 * 2))
+
+# create a test file with a hole
+$XFS_IO_PROG -f -c "truncate $((filesz * 2))" $SCRATCH_MNT/file >> $seqres.full
+
+# run a background dio read to a hole in a loop
+while true; do
+	$XFS_IO_PROG -d -c "pread 0 $filesz" $SCRATCH_MNT/file > /dev/null 2>&1
+done &
+
+dread_pid=$!
+
+# run mapped write to the same hole as dio read
+for i in `seq 0 999`; do
+	$XFS_IO_PROG -c "mmap 0 $filesz" -c "mwrite 0 $filesz" $SCRATCH_MNT/file \
+		> /dev/null
+	$XFS_IO_PROG -c "fpunch 0 $filesz" $SCRATCH_MNT/file > /dev/null
+done
+
+kill -9 $dread_pid > /dev/null 2>&1
+wait $dread_pid > /dev/null 2>&1
+
+echo "Silence is golden"
+
+# success, all done
+status=0
+exit
diff --git a/tests/xfs/422.out b/tests/xfs/422.out
new file mode 100644
index 0000000..f70693f
--- /dev/null
+++ b/tests/xfs/422.out
@@ -0,0 +1,2 @@
+QA output created by 422
+Silence is golden
diff --git a/tests/xfs/group b/tests/xfs/group
index 2a3b950..f43ffcf 100644
--- a/tests/xfs/group
+++ b/tests/xfs/group
@@ -419,3 +419,4 @@
 419 auto quick
 420 auto quick clone dedupe
 421 auto quick clone dedupe
+422 auto quick dangerous
-- 
1.8.3.1