tests/generic/469

#! /bin/bash
# FS QA Test 469
#
# Test that mmap read doesn't see non-zero data past EOF on truncate down.
#
# This is inspired by an XFS bug that truncate down fails to zero page cache
# beyond new EOF and causes stale data written to disk unexpectedly and a
# subsequent mmap reads and sees non-zeros post EOF.
#
# Patch "xfs: truncate pagecache before writeback in xfs_setattr_size()" fixed
# the bug on XFS.
#
#-----------------------------------------------------------------------
# Copyright (c) 2017 Red Hat Inc., All Rights Reserved.
#
# 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/$$
file=$TEST_DIR/$seq.fsx
status=1	# failure is the default!
trap "_cleanup; exit \$status" 0 1 2 3 15

_cleanup()
{
	cd /
	rm -f $file $tmp.*
}

# get standard environment, filters and checks
. ./common/rc
. ./common/filter

# remove previous $seqres.full before test
rm -f $seqres.full

# real QA test starts here
_supported_fs generic
_supported_os Linux
_require_test

run_fsx()
{
	$here/ltp/fsx $2 --replay-ops $1 $file 2>&1 | tee -a $seqres.full >$tmp.fsx
	if [ ${PIPESTATUS[0]} -ne 0 ]; then
		cat $tmp.fsx
		exit 1
	fi
}

# run fsx with and without fsync(2) after write to get more coverage
test_fsx()
{
	echo "fsx --replay-ops ${1#*.}" | tee -a $seqres.full
	run_fsx $1

	echo "fsx -y --replay-ops ${1#*.}" | tee -a $seqres.full
	run_fsx $1 -y
}

# simplified fsx operations that work on small & not blocksize-aligned offsets,
# so filesystems with small block size could reproduce too
cat >$tmp.fsxops.0 <<EOF
# create file with unwritten extent, KEEP_SIZE flag is required, otherwise page
# straddles new i_size in the writeback triggered by truncate, range [i_size,
# page_boundary] will be zeroed there, and bug won't be reproduced
fallocate 0x0 0x1000 0x0 keep_size

# overwrite the unwritten extents with non-zeros, but extent will stay in
# unwritten till I/O completion
write 0x0 0x1000 0x0

# truncate down the file, which should zero page cache beyong new EOF but a
# buggy kernel won't
truncate 0x0 0x10 0x1000

# unmap the file and invalidate the pagecache of the block
punch_hole 0x0 0x10 0x10

# mmap reads the whole block from disk, and fsx will check page range beyond
# EOF to make sure we only see zeros there
mapread 0x0 0x10 0x10
EOF

# to get a bit more test coverage, try other operation combinations too
# same as fsxops.0, but skip punch_hole to keep the pagecache before mapread
cat >$tmp.fsxops.1 <<EOF
fallocate 0x0 0x1000 0x0 keep_size
write 0x0 0x1000 0x0
truncate 0x0 0x10 0x1000
mapread 0x0 0x10 0x10
EOF

# same as fsxops.0, but fallocate without KEEP_SIZE flag
cat >$tmp.fsxops.2 <<EOF
fallocate 0x0 0x1000 0x0
write 0x0 0x1000 0x0
truncate 0x0 0x10 0x1000
punch_hole 0x0 0x10 0x10
mapread 0x0 0x10 0x10
EOF

# this is from the original fsxops when bug was first hit
cat >$tmp.fsxops.3 <<EOF
fallocate 0x35870 0xa790 0x0 keep_size
write 0x2aa50 0xc37f 0x0
truncate 0x0 0x36dcd 0x36dcf
zero_range 0x35849 0x1584 0x36dcd
mapread 0x361c8 0xc05 0x36dcd
EOF

for i in 0 1 2 3; do
	test_fsx $tmp.fsxops.$i
done

# success, all done
status=0
exit