tests/generic/073

#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2015 SUSE Linux Products GmbH. All Rights Reserved.
#
# FS QA Test No. 073
#
# Test file A fsync after moving one other unrelated file B between directories
# and fsyncing B's old parent directory before fsyncing the file A. Check that
# after a crash all the file A data we fsynced is available.
#
# This test is motivated by an issue discovered in btrfs which caused the file
# data to be lost (despite fsync returning success to user space). That btrfs
# bug was fixed by the following linux kernel patch:
#
#   Btrfs: fix data loss in the fast fsync path
#
. ./common/preamble
_begin_fstest metadata auto quick log

# Override the default cleanup function.
_cleanup()
{
	_cleanup_flakey
	rm -f $tmp.*
}

# Import common functions.
. ./common/filter
. ./common/dmflakey

# real QA test starts here
_supported_fs generic
_require_scratch
_require_dm_target flakey

_scratch_mkfs >> $seqres.full 2>&1
_require_metadata_journaling $SCRATCH_DEV
_init_flakey
_mount_flakey

# Create our main test file 'foo', the one we check for data loss.
# By doing an fsync against our file, it makes btrfs clear the 'needs_full_sync'
# bit from its flags (btrfs inode specific flags).
$XFS_IO_PROG -f -c "pwrite -S 0xaa 0 8K" \
		-c "fsync" $SCRATCH_MNT/foo | _filter_xfs_io

# Now create one other file and 2 directories. We will move this second file
# from one directory to the other later because it forces btrfs to commit its
# currently open transaction if we fsync the old parent directory. This is
# necessary to trigger the data loss bug that affected btrfs.
mkdir $SCRATCH_MNT/testdir_1
touch $SCRATCH_MNT/testdir_1/bar
mkdir $SCRATCH_MNT/testdir_2

# Make sure everything is durably persisted.
sync

# Write more 8Kb of data to our file.
$XFS_IO_PROG -c "pwrite -S 0xbb 8K 8K" $SCRATCH_MNT/foo | _filter_xfs_io

# Move our 'bar' file into a new directory.
mv $SCRATCH_MNT/testdir_1/bar $SCRATCH_MNT/testdir_2/bar

# Fsync our first directory. Because it had a file moved into some other
# directory, this made btrfs commit the currently open transaction. This is
# a condition necessary to trigger the data loss bug.
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/testdir_1

# Now fsync our main test file. If the fsync succeeds, we expect the 8Kb of
# data we wrote previously to be persisted and available if a crash happens.
# This did not happen with btrfs, because of the transaction commit that
# happened when we fsynced the parent directory.
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo

_flakey_drop_and_remount

# Now check that all data we wrote before are available.
echo "File content after log replay:"
od -t x1 $SCRATCH_MNT/foo

status=0
exit