[PATCH] fstests: generic test for fsync of file with multiple links

[fdmanana@kernel.org]

From: Filipe Manana <fdmanana@suse.com>

Test that when we have a file with multiple hard links belonging to
different parent directories, if we remove one of those links, fsync the
file using one of its other links (that has a parent directory different
from the one we removed a link from), power fail and then replay the
fsync log/journal, the hard link we removed is not available anymore and
all the filesystem metadata is in a consistent state.

This test is motivated by an issue found in btrfs, where the test fails
with:

  generic/107 2s ... - output mismatch (see .../results/generic/107.out.bad)
    --- tests/generic/107.out	2015-08-04 09:47:46.922131256 +0100
    +++ /home/fdmanana/git/hub/xfstests/results//generic/107.out.bad
    @@ -1,3 +1,5 @@
     QA output created by 107
     Entries in testdir:
     foo2
    +foo3
    +rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/testdir': Directory not empty
    ...
    (Run 'diff -u tests/generic/107.out .../generic/107.out.bad'  to see the entire diff)
  _check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent (see .../generic/107.full)
  _check_dmesg: something found in dmesg (see .../generic/107.dmesg)

  $ cat /home/fdmanana/git/hub/xfstests/results//generic/107.full
  _check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent
  *** fsck.btrfs output ***
  checking extents
  checking free space cache
  checking fs roots
  root 5 inode 257 errors 200, dir isize wrong
	unresolved ref dir 257 index 3 namelen 4 name foo3 filetype 1 \
          errors 5, no dir item, no inode ref

  $ cat /home/fdmanana/git/hub/xfstests/results//generic/107.dmesg
  (...)
  [188897.707311] BTRFS info (device dm-0): failed to delete reference to \
    foo3, inode 258 parent 257
  [188897.711345] ------------[ cut here ]------------
  [188897.713369] WARNING: CPU: 10 PID: 19452 at fs/btrfs/inode.c:3956 \
    __btrfs_unlink_inode+0x182/0x35a [btrfs]()
  [188897.717661] BTRFS: Transaction aborted (error -2)
  (...)
  [188897.747898] Call Trace:
  [188897.748519]  [<ffffffff8145f077>] dump_stack+0x4f/0x7b
  [188897.749602]  [<ffffffff81095de5>] ? console_unlock+0x356/0x3a2
  [188897.750682]  [<ffffffff8104b3b0>] warn_slowpath_common+0xa1/0xbb
  [188897.751936]  [<ffffffffa04c5d09>] ? __btrfs_unlink_inode+0x182/0x35a [btrfs]
  [188897.753485]  [<ffffffff8104b410>] warn_slowpath_fmt+0x46/0x48
  [188897.754781]  [<ffffffffa04c5d09>] __btrfs_unlink_inode+0x182/0x35a [btrfs]
  [188897.756295]  [<ffffffffa04c6e8f>] btrfs_unlink_inode+0x1e/0x40 [btrfs]
  [188897.757692]  [<ffffffffa04c6f11>] btrfs_unlink+0x60/0x9b [btrfs]
  [188897.758978]  [<ffffffff8116fb48>] vfs_unlink+0x9c/0xed
  [188897.760151]  [<ffffffff81173481>] do_unlinkat+0x12b/0x1fb
  [188897.761354]  [<ffffffff81253855>] ? lockdep_sys_exit_thunk+0x12/0x14
  [188897.762692]  [<ffffffff81174056>] SyS_unlinkat+0x29/0x2b
  [188897.763741]  [<ffffffff81465197>] system_call_fastpath+0x12/0x6f
  [188897.764894] ---[ end trace bbfddacb7aaada8c ]---
  [188897.765801] BTRFS warning (device dm-0): __btrfs_unlink_inode:3956: \
    Aborting unused transaction(No such entry).

Tested against ext3/4, xfs, reiserfs and f2fs too, and all these
filesystems currently pass this test (on a 4.1 linux kernel at least).

The btrfs issue is fixed by the linux kernel patch titled:
"Btrfs: fix stale dir entries after removing a link and fsync".

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 tests/generic/107     | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/generic/107.out |  3 ++
 tests/generic/group   |  1 +
 3 files changed, 103 insertions(+)
 create mode 100755 tests/generic/107
 create mode 100644 tests/generic/107.out

diff --git a/tests/generic/107 b/tests/generic/107
new file mode 100755
index 0000000..7d107d7
--- /dev/null
+++ b/tests/generic/107
@@ -0,0 +1,99 @@
+#! /bin/bash
+# FSQA Test No. 107
+#
+# Test that when we have a file with multiple hard links belonging to different
+# parent directories, if we remove one of those links, fsync the file using one
+# of its other links (that has a parent directory different from the one we
+# removed a link from), power fail and then replay the fsync log/journal, the
+# hard link we removed is not available anymore and all the filesystem metadata
+# 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 file.
+mkdir $SCRATCH_MNT/testdir
+touch $SCRATCH_MNT/foo
+ln $SCRATCH_MNT/foo $SCRATCH_MNT/testdir/foo2
+ln $SCRATCH_MNT/foo $SCRATCH_MNT/testdir/foo3
+
+# Make sure everything done so far is durably persisted.
+sync
+
+# Now we remove one of our file's hardlinks in the directory testdir.
+unlink $SCRATCH_MNT/testdir/foo3
+
+# We now fsync our file using the "foo" link, which has a parent that
+# is not the directory "testdir".
+$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo
+
+# Silently drop all writes and unmount to simulate a crash/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
+
+# After the journal/log is replayed we expect to not see the "foo3" link anymore
+# and we should be able to remove all names in the directory "testdir" and then
+# remove it (no stale directory entries left after the journal/log replay).
+echo "Entries in testdir:"
+ls -1 $SCRATCH_MNT/testdir
+
+rm -f $SCRATCH_MNT/testdir/*
+rmdir $SCRATCH_MNT/testdir
+
+_unmount_flakey
+
+status=0
+exit
diff --git a/tests/generic/107.out b/tests/generic/107.out
new file mode 100644
index 0000000..5bb36ee
--- /dev/null
+++ b/tests/generic/107.out
@@ -0,0 +1,3 @@
+QA output created by 107
+Entries in testdir:
+foo2
diff --git a/tests/generic/group b/tests/generic/group
index a33536e..bc5150d 100644
--- a/tests/generic/group
+++ b/tests/generic/group
@@ -109,6 +109,7 @@
 104 auto quick metadata
 105 acl auto quick
 106 auto quick metadata
+107 auto quick metadata
 112 rw aio auto quick
 113 rw aio auto quick
 117 attr auto quick
-- 
2.1.3