fstests: generic test for directory fsync after adding hard links

This test is motivated by an fsync issue discovered in btrfs.
The issue was that after adding a new hard link to an existing file
(one that was created in a past transaction) and fsync'ing the parent
directory of the new hard link, after the fsync log replay the file's
inode link count did not get its link count incremented, while the new
directory entry was visible.
Also, unlike xfs and ext4, new files under the directory we fsync were
not being written to the fsync log, nor were any child directories and
new files and links under the children directories. So this test verifies
too that btrfs has the same behaviour as xfs and ext4.

The btrfs issue was fixed by the following linux kernel patch:

  Btrfs: fix metadata inconsistencies after directory fsync

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

tests/generic/065

@@ -0,0 +1,172 @@
+#! /bin/bash
+# FS QA Test No. 065
+#
+# Test fsync on directories that got new hardlinks added to them and that point
+# to existing inodes. The goal is to verify that after the fsync log is replayed
+# the new hardlinks exist and the inodes have a correct link count.
+# Also test that new hardlinks pointing to new inodes are logged and exist as
+# well after the fsync log is replayed.
+#
+# This test is motivated by an issue discovered in btrfs, where the inode link
+# counts were incorrect after the fsync log was replayed and the hardlinks for
+# new inodes were not logged.
+#
+#-----------------------------------------------------------------------
+# 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"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1	# failure is the default!
+
+_cleanup()
+{
+	_cleanup_flakey
+	rm -f $tmp.*
+}
+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
+_require_metadata_journaling $SCRATCH_DEV
+
+rm -f $seqres.full
+
+_scratch_mkfs >> $seqres.full 2>&1
+_init_flakey
+_mount_flakey
+
+# Create our main test file and directory.
+$XFS_IO_PROG -f -c "pwrite -S 0xaa 0 8K" $SCRATCH_MNT/foo | _filter_xfs_io
+mkdir $SCRATCH_MNT/mydir
+
+# Make sure all metadata and data are durably persisted.
+sync
+
+# Add a hard link to 'foo' inside our test directory and fsync only the
+# directory. The btrfs fsync implementation had a bug that caused the new
+# directory entry to be visible after the fsync log replay but, the inode
+# of our file remained with a link count of 1.
+ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/foo_2
+
+# Add a few more links and new files.
+# This is just to verify nothing breaks or gives incorrect results after the
+# fsync log is replayed.
+ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/foo_3
+$XFS_IO_PROG -f -c "pwrite -S 0xff 0 64K" $SCRATCH_MNT/hello | _filter_xfs_io
+ln $SCRATCH_MNT/hello $SCRATCH_MNT/mydir/hello_2
+
+# Add some subdirectories and new files and links to them. This is to verify
+# that after fsyncing our top level directory 'mydir', all the subdirectories
+# and their files/links are registered in the fsync log and exist after the
+# fsync log is replayed.
+mkdir -p $SCRATCH_MNT/mydir/x/y/z
+ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/x/y/foo_y_link
+ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/x/y/z/foo_z_link
+touch $SCRATCH_MNT/mydir/x/y/z/qwerty
+
+# Now fsync only our top directory.
+$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/mydir
+
+# Simulate a crash/power loss.
+_load_flakey_table $FLAKEY_DROP_WRITES
+_unmount_flakey
+
+_load_flakey_table $FLAKEY_ALLOW_WRITES
+_mount_flakey
+
+# Verify the content of our file 'foo' remains the same as before, 8192 bytes,
+# all with the value 0xaa.
+echo "File 'foo' content after log replay:"
+od -t x1 $SCRATCH_MNT/foo
+
+# Remove the first name of our inode. Because of the directory fsync bug, the
+# inode's link count was 1 instead of 5, so removing the 'foo' name ended up
+# deleting the inode and the other names became stale directory entries (still
+# visible to applications). Attempting to remove or access the remaining
+# dentries pointing to that inode resulted in stale file handle errors and
+# made it impossible to remove the parent directories since it was impossible
+# for them to become empty.
+echo "file 'foo' link count after log replay: $(stat -c %h $SCRATCH_MNT/foo)"
+rm -f $SCRATCH_MNT/foo
+
+# Now verify that all files, links and directories created before fsyncing our
+# directory exist after the fsync log was replayed.
+[ -f $SCRATCH_MNT/mydir/foo_2 ] || echo "Link mydir/foo_2 is missing"
+[ -f $SCRATCH_MNT/mydir/foo_3 ] || echo "Link mydir/foo_3 is missing"
+[ -f $SCRATCH_MNT/hello ] || echo "File hello is missing"
+[ -f $SCRATCH_MNT/mydir/hello_2 ] || echo "Link mydir/hello_2 is missing"
+[ -f $SCRATCH_MNT/mydir/x/y/foo_y_link ] || \
+	echo "Link mydir/x/y/foo_y_link is missing"
+[ -f $SCRATCH_MNT/mydir/x/y/z/foo_z_link ] || \
+	echo "Link mydir/x/y/z/foo_z_link is missing"
+[ -f $SCRATCH_MNT/mydir/x/y/z/qwerty ] || \
+	echo "File mydir/x/y/z/qwerty is missing"
+
+digest_ok=no
+hello_digest=$(md5sum $SCRATCH_MNT/hello | cut -d ' ' -f 1)
+
+case "$FSTYP" in
+ext3)
+	# a 64Kb file, with all bytes having the value 0xff
+	[ $hello_digest == "ecb99e6ffea7be1e5419350f725da86b" ] && digest_ok=yes
+	;;
+*)
+	# an empty file
+	[ $hello_digest == "d41d8cd98f00b204e9800998ecf8427e" ] && digest_ok=yes
+	;;
+esac
+
+if [ $digest_ok == "yes" ]; then
+	echo "file 'hello' has expected size and content"
+else
+	echo "file 'hello' has unexpected size or content"
+fi
+
+# Now remove all files/links, under our test directory 'mydir', and verify we
+# can remove all the directories.
+rm -f $SCRATCH_MNT/mydir/x/y/z/*
+rmdir $SCRATCH_MNT/mydir/x/y/z
+rm -f $SCRATCH_MNT/mydir/x/y/*
+rmdir $SCRATCH_MNT/mydir/x/y
+rmdir $SCRATCH_MNT/mydir/x
+rm -f $SCRATCH_MNT/mydir/*
+rmdir $SCRATCH_MNT/mydir
+
+# An fsck, run by the fstests framework everytime a test finishes, also detected
+# the inconsistency and printed the following error message:
+#
+# root 5 inode 257 errors 2001, no inode item, link count wrong
+#    unresolved ref dir 258 index 2 namelen 5 name foo_2 filetype 1 errors 4, no inode ref
+#    unresolved ref dir 258 index 3 namelen 5 name foo_3 filetype 1 errors 4, no inode ref
+
+status=0
+exit

tests/generic/065.out

@@ -0,0 +1,11 @@
+QA output created by 065
+wrote 8192/8192 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+File 'foo' content after log replay:
+0000000 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
+*
+0020000
+file 'foo' link count after log replay: 5
+file 'hello' has expected size and content

tests/generic/group

@@ -67,6 +67,7 @@
 062 attr udf auto quick
 063 auto quick prealloc
 064 auto quick prealloc
+065 metadata auto quick
 068 other auto freeze dangerous stress
 069 rw udf auto quick
 070 attr udf auto quick stress