[PATCH] fstests: generic test for fsync after adding hard links

[fdmanana@kernel.org]

From: Filipe Manana <fdmanana@suse.com>

Test that if we add hard links (in the same directory) to two files and
then fsync only one of the files, after the fsync log/journal is replayed
all the links exist and the filesystem metadata (directory and file
inodes) is in a consistent state.

This test is motivated by a bug found in btrfs that is fixed by linux
kernel patch titled:

  "Btrfs: fix stale directory entries after fsync log replay"

Verified against ext3/4, xfs, f2fs and reiserfs on a 4.1 linux kernel.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 tests/generic/096     | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/generic/096.out |  3 ++
 tests/generic/group   |  1 +
 3 files changed, 103 insertions(+)
 create mode 100755 tests/generic/096
 create mode 100644 tests/generic/096.out

diff --git a/tests/generic/096 b/tests/generic/096
new file mode 100755
index 0000000..877ea95
--- /dev/null
+++ b/tests/generic/096
@@ -0,0 +1,99 @@
+#! /bin/bash
+# FSQA Test No. 096
+#
+# Test that if we add hard links (in the same directory) to two files and then
+# fsync only one of the files, after the fsync log/journal is replayed all the
+# links exist and the filesystem metadata (directory and file inodes) is in a
+# consistent state.
+#
+#-----------------------------------------------------------------------
+#
+# Copyright (C) 2015 SUSE Linux Products GmbH. All Rights Reserved.
+# Author: Filipe Manana <fdmanana@suse.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
+	rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/dmflakey
+
+# real QA test starts here
+_need_to_be_root
+_supported_fs generic
+_supported_os Linux
+_require_scratch
+_require_dm_flakey
+_require_metadata_journaling $SCRATCH_DEV
+
+rm -f $seqres.full
+
+_scratch_mkfs >>$seqres.full 2>&1
+_init_flakey
+_mount_flakey
+
+# Create our test directory and files.
+mkdir $SCRATCH_MNT/testdir
+touch $SCRATCH_MNT/testdir/foo
+touch $SCRATCH_MNT/testdir/bar
+
+# Make sure everything done so far is durably persisted.
+sync
+
+# Create one hard link for file foo and another one for file bar. After that
+# fsync only the file bar.
+ln $SCRATCH_MNT/testdir/bar $SCRATCH_MNT/testdir/bar_link
+ln $SCRATCH_MNT/testdir/foo $SCRATCH_MNT/testdir/foo_link
+$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/testdir/bar
+
+# Silently drop all writes on our scratch device to simulate a power failure.
+_load_flakey_table $FLAKEY_DROP_WRITES
+_unmount_flakey
+
+# Allow writes again and mount the fs to trigger log/journal replay.
+_load_flakey_table $FLAKEY_ALLOW_WRITES
+_mount_flakey
+
+# Now verify both our files have a link count of 2.
+echo "Link count for file foo: $(stat --format=%h $SCRATCH_MNT/testdir/foo)"
+echo "Link count for file bar: $(stat --format=%h $SCRATCH_MNT/testdir/bar)"
+
+# We should be able to remove all the links of our files in testdir, and after
+# that the parent directory should become empty and therefore possible to
+# remove it.
+rm -f $SCRATCH_MNT/testdir/*
+rmdir $SCRATCH_MNT/testdir
+
+_unmount_flakey
+
+# The fstests framework will call fsck against our filesystem which will verify
+# that all metadata is in a consistent state.
+
+status=0
+exit
diff --git a/tests/generic/096.out b/tests/generic/096.out
new file mode 100644
index 0000000..09544ad
--- /dev/null
+++ b/tests/generic/096.out
@@ -0,0 +1,3 @@
+QA output created by 096
+Link count for file foo: 2
+Link count for file bar: 2
diff --git a/tests/generic/group b/tests/generic/group
index 1f1a0b0..1e21d17 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -98,6 +98,7 @@
 093 attr cap udf auto
 094 auto quick metadata
 095 auto quick metadata
+096 auto quick metadata
 097 udf auto
 099 udf auto
 100 udf auto
-- 
2.1.3