generic: add dir fsync test

This test is motivated by a bug found in btrfs when replaying a
directory from the fsync log. The issue was that if a directory
entry is both found in the persisted metadata and in the fsync
log, at log replay time the directory got set with a wrong i_size.
This had the consequence of not being able to rmdir empty
directories (failed with errno ENOTEMPTY).
This was fixed in btrfs with the following linux kernel patch:

     Btrfs: fix directory recovery from fsync log

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/generic/034

@@ -0,0 +1,105 @@
+#! /bin/bash
+# FS QA Test No. 034
+#
+# This test is motivated by a bug found in btrfs when replaying a directory
+# from the fsync log. The issue was that if a directory entry is both found
+# in the persisted metadata and in the fsync log, at log replay time the
+# directory got set with a wrong i_size. This had the consequence of not being
+# able to rmdir empty directories (failed with errno ENOTEMPTY).
+# This was fixed in btrfs with the following linux kernel patch:
+#
+#     Btrfs: fix directory recovery from fsync log
+#
+#-----------------------------------------------------------------------
+# Copyright (C) 2014 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"
+
+here=`pwd`
+status=1	# failure is the default!
+
+_cleanup()
+{
+	_cleanup_flakey
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/dmflakey
+
+# real QA test starts here
+_supported_fs generic
+_supported_os Linux
+_need_to_be_root
+_require_scratch
+_require_dm_flakey
+
+rm -f $seqres.full
+
+_scratch_mkfs >> $seqres.full 2>&1
+
+_init_flakey
+_mount_flakey
+
+mkdir $SCRATCH_MNT/test_dir
+touch $SCRATCH_MNT/test_dir/foo
+
+# Invoke sync here because it's necessary to trigger the original bug in btrfs.
+# The intention is that at log recovery time we have a dir entry for 'foo' both
+# in the fs/subvol tree and in the log tree - this is necessary to trigger the
+# bug on btrfs.
+sync
+
+touch $SCRATCH_MNT/test_dir/bar
+$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/test_dir
+$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/test_dir/bar
+
+_load_flakey_table $FLAKEY_DROP_WRITES
+_unmount_flakey
+
+_load_flakey_table $FLAKEY_ALLOW_WRITES
+# In the original btrfs bug, log replay would update the directory's inode
+# i_size incorrectly - it would sum again the size of dentry 'foo' (3) to
+# the inode's i_size, which is incorrect because the dentry was already
+# persisted before (in the fs/subvol tree).
+_mount_flakey
+
+[ -f $SCRATCH_MNT/test_dir/foo ] || echo "file foo is missing"
+[ -f $SCRATCH_MNT/test_dir/bar ] || echo "file bar is missing"
+
+rm -f $SCRATCH_MNT/test_dir/foo
+rm -f $SCRATCH_MNT/test_dir/bar
+
+# In btrfs removing all entries from a directory should set the directory's
+# inode i_size to 0, but with this bug that didn't happen and this made
+# an rmdir fail with errno ENOTEMPTY (even though the directory had no more
+# entries in it).
+rmdir $SCRATCH_MNT/test_dir
+[ -d $SCRATCH_MNT/test_dir ] && echo "rmdir didn't succeed"
+
+_unmount_flakey
+
+echo "Silence is golden"
+
+status=0
+exit

tests/generic/034.out

@@ -0,0 +1,2 @@
+QA output created by 034
+Silence is golden

tests/generic/group

@@ -36,6 +36,7 @@
 031 auto quick prealloc rw
 032 auto quick rw
 033 auto quick rw
+034 auto quick metadata log
 053 acl repair auto quick
 062 attr udf auto quick
 068 other auto freeze dangerous stress