generic: new case to test getcwd(2)

The following kernel commit introduced a race condition that causes
getcwd(2) to return "/" instead of correct path

232d2d6 dcache: Translating dentry into pathname without taking rename_lock

Jan Stancek hit it once when building ltp and Mikulas Patocka could
hit it by running lvm2 test suite. Please refer to this thread

https://www.mail-archive.com/ltp-list@lists.sourceforge.net/msg17896.html

These commits fixed the bug
ede4ceb prepend_path() needs to reinitialize dentry/vfsmount/mnt on restarts
f650080 __dentry_path() fixes

Cc: Artem Savkov <asavkov@redhat.com>
Cc: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/generic/028

@@ -0,0 +1,58 @@
+#! /bin/bash
+# FS QA Test No. generic/028
+#
+# The following commit introduced a race condition that causes getcwd(2)
+# to return "/" instead of correct path
+#
+# 232d2d6 dcache: Translating dentry into pathname without taking rename_lock
+#
+# These commits fixed the bug
+# ede4ceb prepend_path() needs to reinitialize dentry/vfsmount/mnt on restarts
+# f650080 __dentry_path() fixes
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2014 Red Hat Inc.  All Rights Reserved.
+#
+# 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 -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+_supported_fs generic
+_supported_os Linux
+
+echo "Silence is golden"
+
+$here/src/t_getcwd $TEST_DIR
+status=$?
+exit

tests/generic/028.out

@@ -0,0 +1,2 @@
+QA output created by 028
+Silence is golden

tests/generic/group

@@ -30,6 +30,7 @@
 025 auto quick
 026 acl quick auto
 027 auto enospc
+028 auto quick
 053 acl repair auto quick
 062 attr udf auto quick
 068 other auto freeze dangerous stress