[PATCH v2] fstests: test regression of -EEXIST on creating new file after log replay

[Liu Bo <bo.li.liu@oracle.com>]

The regression is introduced to btrfs in linux v4.4 and it refuses to create
new files after log replay by returning -EEXIST.

Although the problem is on btrfs only, there is no btrfs stuff in terms of
test, so this makes it generic.

The kernel fix is
  Btrfs: fix unexpected -EEXIST when creating new inode

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
---
v2: - Remove failed message from 481.out
    - Drop the unnecessary write in creating a file

 tests/generic/481     | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/generic/481.out |  2 ++
 tests/generic/group   |  1 +
 3 files changed, 78 insertions(+)
 create mode 100755 tests/generic/481
 create mode 100644 tests/generic/481.out

diff --git a/tests/generic/481 b/tests/generic/481
new file mode 100755
index 0000000..6a7e9dd
--- /dev/null
+++ b/tests/generic/481
@@ -0,0 +1,75 @@
+#! /bin/bash
+# FSQA Test No. 481
+#
+# Reproduce a regression of btrfs that leads to -EEXIST on creating new files
+# after log replay.
+#
+# The kernel fix is
+#   Btrfs: fix unexpected -EEXIST when creating new inode
+#
+#-----------------------------------------------------------------------
+#
+# Copyright (C) 2018 Oracle. All Rights Reserved.
+# Author: Bo Liu <bo.li.liu@oracle.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"
+tmp=/tmp/$$
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	_cleanup_flakey
+	cd /
+	rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/dmflakey
+
+# real QA test starts here
+_supported_fs generic
+_supported_os Linux
+_require_scratch
+_require_dm_target flakey
+
+rm -f $seqres.full
+
+_scratch_mkfs >>$seqres.full 2>&1
+_init_flakey
+_mount_flakey
+
+# create a file and keep it in write ahead log
+$XFS_IO_PROG -f -c "fsync" $SCRATCH_MNT/foo
+
+# fail this filesystem so that remount can replay the write ahead log
+_flakey_drop_and_remount
+
+# see if we can create a new file successfully
+touch $SCRATCH_MNT/bar
+
+_unmount_flakey
+
+echo "Silence is golden"
+
+status=0
+exit
diff --git a/tests/generic/481.out b/tests/generic/481.out
new file mode 100644
index 0000000..206e116
--- /dev/null
+++ b/tests/generic/481.out
@@ -0,0 +1,2 @@
+QA output created by 481
+Silence is golden
diff --git a/tests/generic/group b/tests/generic/group
index ea2056b..05f60f2 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -483,3 +483,4 @@
 478 auto quick
 479 auto quick metadata
 480 auto quick metadata
+481 auto quick
-- 
2.5.0