generic: Test races between processes doing mmap writes

Add test which spawns two processes both writing one file via mmap.
Then to the test when processes first prefault the file by reading it
via mmap. This is mainly interesting to uncover races in DAX fault
handling.

Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/generic/345

@@ -0,0 +1,59 @@
+#! /bin/bash
+# FSQA Test No. 345
+#
+# Test races between mmap from racing processes with and without prefaulting.
+#
+#-----------------------------------------------------------------------
+#
+# Copyright (C) 2016 SUSE Linux Products GmbH. All Rights Reserved.
+# Author: Jan Kara <jack@suse.cz>
+#
+# 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"
+tmp=/tmp/$$
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -f $tmp.*
+}
+
+# get standard environment and checks
+. ./common/rc
+
+# real QA test starts here
+_supported_fs generic
+_supported_os Linux
+_require_scratch
+_require_test_program "holetest"
+
+rm -f $seqres.full
+
+_scratch_mkfs >>$seqres.full 2>&1
+_scratch_mount
+
+src/holetest -f -F $SCRATCH_MNT/testfile 16
+src/holetest -f -F $SCRATCH_MNT/testfile 256
+src/holetest -f -F -r $SCRATCH_MNT/testfile 16
+src/holetest -f -F -r $SCRATCH_MNT/testfile 256
+
+status=0
+exit

tests/generic/345.out

@@ -0,0 +1,73 @@
+QA output created by 345
+
+INFO: zero-filled test...
+INFO: sz = 16777216
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected
+
+INFO: posix_fallocate test...
+INFO: sz = 16777216
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected
+
+INFO: ftruncate test...
+INFO: sz = 16777216
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected
+
+INFO: zero-filled test...
+INFO: sz = 268435456
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected
+
+INFO: posix_fallocate test...
+INFO: sz = 268435456
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected
+
+INFO: ftruncate test...
+INFO: sz = 268435456
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected
+
+INFO: zero-filled test...
+INFO: sz = 16777216
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected
+
+INFO: posix_fallocate test...
+INFO: sz = 16777216
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected
+
+INFO: ftruncate test...
+INFO: sz = 16777216
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected
+
+INFO: zero-filled test...
+INFO: sz = 268435456
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected
+
+INFO: posix_fallocate test...
+INFO: sz = 268435456
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected
+
+INFO: ftruncate test...
+INFO: sz = 268435456
+INFO: process 0 created
+INFO: process 1 created
+INFO: 0 error(s) detected

tests/generic/group

@@ -347,6 +347,7 @@
 342 auto quick metadata
 343 auto quick metadata
 344 auto
+345 auto
 346 auto
 705 blockdev quick rw
 706 blockdev quick rw