#! /bin/bash
# FS QA Test No. 306
#
# Regression test for an XFS multi-block buffer logging bug.
#
# The XFS bug results in a panic when a non-contiguous multi-block buffer is
# mapped and logged in a particular manner, such that only regions beyond the
# first fsb-sized mapping are logged. The crash occurs asynchronous to
# transaction submission, when the associated buffer log item is pushed from the
# CIL (i.e., when the log is subsequently flushed).
#
#-----------------------------------------------------------------------
# Copyright (c) 2016 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/$$
status=1	# failure is the default!
trap "_cleanup; exit \$status" 0 1 2 3 15

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

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

# Modify as appropriate.
_supported_fs xfs
_supported_os Linux

_require_scratch_nocheck	# check complains about single AG fs
_require_xfs_io_command "fpunch"
_require_command $UUIDGEN_PROG uuidgen

rm -f $seqres.full

# Create a small fs with a large directory block size. We want to fill up the fs
# quickly and then create multi-fsb dirblocks over fragmented free space.
_scratch_mkfs_xfs -d size=20m -n size=64k >> $seqres.full 2>&1
_scratch_mount

# Fill a source directory with many largish-named files. 1k uuid-named entries
# sufficiently populates a 64k directory block.
mkdir $SCRATCH_MNT/src
for i in $(seq 0 1023); do
	touch $SCRATCH_MNT/src/`$UUIDGEN_PROG`
done

# precreate target dirs while we still have free space for inodes
for i in $(seq 0 3); do
	mkdir $SCRATCH_MNT/$i
done

# consume and fragment free space
$XFS_IO_PROG -xc "resblks 16" $SCRATCH_MNT >> $seqres.full 2>&1
dd if=/dev/zero of=$SCRATCH_MNT/file bs=4k >> $seqres.full 2>&1
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/file >> $seqres.full 2>&1
size=`stat -c %s $SCRATCH_MNT/file`
for i in $(seq 0 8192 $size); do
	$XFS_IO_PROG -c "fpunch $i 4k" $SCRATCH_MNT/file >> $seqres.full 2>&1
done

# Replicate the src dir several times into fragmented free space. After one or
# two dirs, we should have nothing but non-contiguous directory blocks.
for d in $(seq 0 3); do
	for f in `ls -1 $SCRATCH_MNT/src`; do
		ln $SCRATCH_MNT/src/$f $SCRATCH_MNT/$d/$f
	done
done

# Fragment the target dirs a bit. Remove a handful of entries from each to
# populate the best free space regions in the directory block headers. We want
# to populate these now so the subsequent unlinks have no reason to log the
# first block of the directory.
for d in $(seq 0 3); do
	i=0
	for f in `ls -U $SCRATCH_MNT/$d`; do
		if [ $i == 0 ]; then
			unlink $SCRATCH_MNT/$d/$f
		fi
		i=$(((i + 1) % 128))
	done
done

# remount to flush and ensure subsequent operations allocate a new log item
_scratch_cycle_mount

# Unlink an entry towards the end of each dir and fsync. The unlink should only
# need to log the latter mappings of the 64k directory block. If the logging bug
# is present, this will crash!
for d in $(seq 0 3); do
	f=`ls -U $SCRATCH_MNT/$d | tail -10 | head -n 1`
	unlink $SCRATCH_MNT/$d/$f
	$XFS_IO_PROG -c fsync $SCRATCH_MNT/$d
done

echo Silence is golden.

# success, all done
status=0
exit
