tests/btrfs/156

#! /bin/bash
# FS QA Test 156
#
# Check if btrfs can correctly trim free space in block groups
#
# An ancient regression prevent btrfs from trimming free space inside
# existing block groups, if bytenr of block group starts beyond
# btrfs_super_block->total_bytes.
# However all bytenr in btrfs is in btrfs logical address space,
# where any bytenr in range [0, U64_MAX] is valid.
#
# Fixed by patch named "btrfs: Ensure btrfs_trim_fs can trim the whole fs".
#
#-----------------------------------------------------------------------
# Copyright (c) 2017 SUSE Linux Products GmbH.  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
. ./common/filter

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

# real QA test starts here

# Modify as appropriate.
_supported_fs btrfs
_supported_os Linux
_require_scratch
_require_fstrim

# 1024fs size
fs_size=$((1024 * 1024 * 1024))

# Use small files to fill half of the fs
file_size=$(( 1024 * 1024 ))
nr_files=$(( $fs_size / $file_size / 2))

# Force to use single data and meta profile.
# Since the test relies on fstrim output, which will differ for different
# profiles
_scratch_mkfs -b $fs_size -m single -d single > /dev/null
_scratch_mount

_require_batched_discard "$SCRATCH_MNT"

for n in $(seq -w 0 $(( $nr_files - 1))); do
	$XFS_IO_PROG -f -c "pwrite 0 $file_size" "$SCRATCH_MNT/file_$n" \
		> /dev/null
done

# Flush all buffer data into disk, to trigger chunk allocation
sync

# Now we have take at least 50% of the filesystem, relocate all chunks twice
# so all chunks will start after 1G in logical space.
# (Btrfs chunk allocation will not rewind to reuse lower space)
_run_btrfs_util_prog balance start --full-balance "$SCRATCH_MNT"

# To avoid possible false ENOSPC alert on v4.15-rc1, seems to be a
# reserved space related bug (maybe related to outstanding space rework?),
# but that's another story.
sync

_run_btrfs_util_prog balance start --full-balance "$SCRATCH_MNT"

# Now remove half of the files to make some holes for later trim.
# While still keep the chunk space fragmented, so no chunk will be freed
rm $SCRATCH_MNT/file_*[13579] -f

# Make sure space is freed
sync

trimmed=$($FSTRIM_PROG -v "$SCRATCH_MNT" | _filter_fstrim)
echo "Trimmed=$trimmed total_size=$fs_size ratio=$(($trimmed * 100 / $fs_size))%" \
	>> $seqres.full

# For correct full fs trim, both unallocated space (less than 50%)
# and free space in existing block groups (about 25%) should be trimmed.
# If less than 50% is trimmed, then only unallocated space is trimmed.
# BTW, without fix only 31% can be trimmed, while after fix it's 64%.
if [ $trimmed -lt $(( $fs_size / 2)) ]; then
	echo "Free space in block groups not trimmed"
	echo "Trimmed=$trimmed total_size=$fs_size ratio=$(($trimmed * 100 / $fs_size))%"
fi

echo "Silence is golden"
# success, all done
status=0
exit