tests/qemu-iotests/108

#!/usr/bin/env bash
# group: rw auto quick
#
# Test case for repairing qcow2 images which cannot be repaired using
# the on-disk refcount structures
#
# Copyright (C) 2014 Red Hat, Inc.
#
# 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; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will 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, see <http://www.gnu.org/licenses/>.
#

# creator
owner=hreitz@redhat.com

seq="$(basename $0)"
echo "QA output created by $seq"

status=1	# failure is the default!

_cleanup()
{
    _cleanup_test_img
    if [ -f "$TEST_DIR/qsd.pid" ]; then
        qsd_pid=$(cat "$TEST_DIR/qsd.pid")
        kill -KILL "$qsd_pid"
        fusermount -u "$TEST_DIR/fuse-export" &>/dev/null
    fi
    rm -f "$TEST_DIR/fuse-export"
}
trap "_cleanup; exit \$status" 0 1 2 3 15

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

# This tests qcow2-specific low-level functionality
_supported_fmt qcow2
_supported_proto file fuse
_supported_os Linux
# This test directly modifies a refblock so it relies on refcount_bits being 16;
# and the low-level modification it performs are not tuned for external data
# files
_unsupported_imgopts 'refcount_bits=\([^1]\|.\([^6]\|$\)\)' data_file

# This test either needs sudo -n losetup or FUSE exports to work
if sudo -n losetup &>/dev/null; then
    loopdev=true
else
    loopdev=false

    # Check for usable FUSE in the host environment:
    if test ! -c "/dev/fuse"; then
        _notrun 'No passwordless sudo nor usable /dev/fuse'
    fi

    # QSD --export fuse will either yield "Parameter 'id' is missing"
    # or "Invalid parameter 'fuse'", depending on whether there is
    # FUSE support or not.
    error=$($QSD --export fuse 2>&1)
    if [[ $error = *"'fuse'"* ]]; then
        _notrun 'Passwordless sudo for losetup or FUSE support required, but' \
                'neither is available'
    fi
fi

echo
echo '=== Repairing an image without any refcount table ==='
echo

_make_test_img 64M
# just write some data
$QEMU_IO -c 'write -P 42 0 64k' "$TEST_IMG" | _filter_qemu_io

# refcount_table_offset
poke_file "$TEST_IMG" $((0x30)) "\x00\x00\x00\x00\x00\x00\x00\x00"
# refcount_table_clusters
poke_file "$TEST_IMG" $((0x38)) "\x00\x00\x00\x00"

_check_test_img -r all

$QEMU_IO -c 'read -P 42 0 64k' "$TEST_IMG" | _filter_qemu_io

echo
echo '=== Repairing unreferenced data cluster in new refblock area ==='
echo

_make_test_img -o 'cluster_size=512' 64M
# Allocate the first 128 kB in the image (first refblock)
$QEMU_IO -c 'write 0 0x1b200' "$TEST_IMG" | _filter_qemu_io
# should be 131072 == 0x20000
stat -c '%s' "$TEST_IMG"

# Enter a cluster at 128 kB (0x20000)
# XXX: This should be the first free entry in the last L2 table, but we cannot
# be certain
poke_file "$TEST_IMG" $((0x1ccc8)) "\x80\x00\x00\x00\x00\x02\x00\x00"

# Fill the cluster
truncate -s $((0x20200)) "$TEST_IMG"
$QEMU_IO -c "open -o driver=raw $TEST_IMG" -c 'write -P 42 128k 512' \
    | _filter_qemu_io

# The data should now appear at this guest offset
$QEMU_IO -c 'read -P 42 0x1b200 512' "$TEST_IMG" | _filter_qemu_io

# This cluster is unallocated; fix it
_check_test_img -r all

# This repair operation must have allocated a new refblock; and that refblock
# should not overlap with the unallocated data cluster. If it does, the data
# will be damaged, so check it.
$QEMU_IO -c 'read -P 42 0x1b200 512' "$TEST_IMG" | _filter_qemu_io

echo
echo '=== Repairing refblock beyond the image end ==='
echo

echo
echo '--- Otherwise clean ---'
echo

_make_test_img 64M
# Normally, qemu doesn't create empty refblocks, so we just have to do it by
# hand
# XXX: This should be the entry for the second refblock
poke_file "$TEST_IMG" $((0x10008)) "\x00\x00\x00\x00\x00\x10\x00\x00"
# Mark that refblock as used
# XXX: This should be the 17th entry (cluster 16) of the first
# refblock
poke_file "$TEST_IMG" $((0x20020)) "\x00\x01"
_check_test_img -r all

echo
echo '--- Refblock is unallocated ---'
echo

_make_test_img 64M
poke_file "$TEST_IMG" $((0x10008)) "\x00\x00\x00\x00\x00\x10\x00\x00"
_check_test_img -r all

echo
echo '--- Signed overflow after the refblock ---'
echo

_make_test_img 64M
poke_file "$TEST_IMG" $((0x10008)) "\x7f\xff\xff\xff\xff\xff\x00\x00"
_check_test_img -r all

echo
echo '--- Unsigned overflow after the refblock ---'
echo

_make_test_img 64M
poke_file "$TEST_IMG" $((0x10008)) "\xff\xff\xff\xff\xff\xff\x00\x00"
_check_test_img -r all

echo
echo '=== Check rebuilt reftable location ==='

# In an earlier version of the refcount rebuild algorithm, the
# reftable was generally placed at the image end (unless something was
# allocated in the area covered by the refblock right before the image
# file end, then we would try to place the reftable in that refblock).
# This was later changed so the reftable would be placed in the
# earliest possible location.  Test this.

echo
echo '--- Does the image size increase? ---'
echo

# First test: Just create some image, write some data to it, and
# resize it so there is free space at the end of the image (enough
# that it spans at least one full refblock, which for cluster_size=512
# images, spans 128k).  With the old algorithm, the reftable would
# have then been placed at the end of the image file, but with the new
# one, it will be put in that free space.
# We want to check whether the size of the image file increases due to
# rebuilding the refcount structures (it should not).

_make_test_img -o 'cluster_size=512' 1M
# Write something
$QEMU_IO -c 'write 0 64k' "$TEST_IMG" | _filter_qemu_io

# Add free space
file_len=$(stat -c '%s' "$TEST_IMG")
truncate -s $((file_len + 256 * 1024)) "$TEST_IMG"

# Corrupt the image by saying the image header was not allocated
rt_offset=$(peek_file_be "$TEST_IMG" 48 8)
rb_offset=$(peek_file_be "$TEST_IMG" $rt_offset 8)
poke_file "$TEST_IMG" $rb_offset "\x00\x00"

# Check whether rebuilding the refcount structures increases the image
# file size
file_len=$(stat -c '%s' "$TEST_IMG")
echo
# The only leaks there can be are the old refcount structures that are
# leaked during rebuilding, no need to clutter the output with them
_check_test_img -r all | grep -v '^Repairing cluster.*refcount=1 reference=0'
echo
post_repair_file_len=$(stat -c '%s' "$TEST_IMG")

if [[ $file_len -eq $post_repair_file_len ]]; then
    echo 'OK: Image size did not change'
else
    echo 'ERROR: Image size differs' \
        "($file_len before, $post_repair_file_len after)"
fi

echo
echo '--- Will the reftable occupy a hole specifically left for it?  ---'
echo

# Note: With cluster_size=512, every refblock covers 128k.
# The reftable covers 8M per reftable cluster.

# Create an image that requires two reftable clusters (just because
# this is more interesting than a single-clustered reftable).
_make_test_img -o 'cluster_size=512' 9M
$QEMU_IO -c 'write 0 8M' "$TEST_IMG" | _filter_qemu_io

# Writing 8M will have resized the reftable.  Unfortunately, doing so
# will leave holes in the file, so we need to fill them up so we can
# be sure the whole file is allocated.  Do that by writing
# consecutively smaller chunks starting from 8 MB, until the file
# length increases even with a chunk size of 512.  Then we must have
# filled all holes.
ofs=$((8 * 1024 * 1024))
block_len=$((16 * 1024))
while [[ $block_len -ge 512 ]]; do
    file_len=$(stat -c '%s' "$TEST_IMG")
    while [[ $(stat -c '%s' "$TEST_IMG") -eq $file_len ]]; do
        # Do not include this in the reference output, it does not
        # really matter which qemu-io calls we do here exactly
        $QEMU_IO -c "write $ofs $block_len" "$TEST_IMG" >/dev/null
        ofs=$((ofs + block_len))
    done
    block_len=$((block_len / 2))
done

# Fill up to 9M (do not include this in the reference output either,
# $ofs is random for all we know)
$QEMU_IO -c "write $ofs $((9 * 1024 * 1024 - ofs))" "$TEST_IMG" >/dev/null

# Make space as follows:
# - For the first refblock: Right at the beginning of the image (this
#   refblock is placed in the first place possible),
# - For the reftable somewhere soon afterwards, still near the
#   beginning of the image (i.e. covered by the first refblock); the
#   reftable too is placed in the first place possible, but only after
#   all refblocks have been placed)
# No space is needed for the other refblocks, because no refblock is
# put before the space it covers.  In this test case, we do not mind
# if they are placed at the image file's end.

# Before we make that space, we have to find out the host offset of
# the area that belonged to the two data clusters at guest offset 4k,
# because we expect the reftable to be placed there, and we will have
# to verify that it is.

l1_offset=$(peek_file_be "$TEST_IMG" 40 8)
l2_offset=$(peek_file_be "$TEST_IMG" $l1_offset 8)
l2_offset=$((l2_offset & 0x00fffffffffffe00))
data_4k_offset=$(peek_file_be "$TEST_IMG" \
                 $((l2_offset + 4096 / 512 * 8)) 8)
data_4k_offset=$((data_4k_offset & 0x00fffffffffffe00))

$QEMU_IO -c "discard 0 512" -c "discard 4k 1k" "$TEST_IMG" | _filter_qemu_io

# Corrupt the image by saying the image header was not allocated
rt_offset=$(peek_file_be "$TEST_IMG" 48 8)
rb_offset=$(peek_file_be "$TEST_IMG" $rt_offset 8)
poke_file "$TEST_IMG" $rb_offset "\x00\x00"

echo
# The only leaks there can be are the old refcount structures that are
# leaked during rebuilding, no need to clutter the output with them
_check_test_img -r all | grep -v '^Repairing cluster.*refcount=1 reference=0'
echo

# Check whether the reftable was put where we expected
rt_offset=$(peek_file_be "$TEST_IMG" 48 8)
if [[ $rt_offset -eq $data_4k_offset ]]; then
    echo 'OK: Reftable is where we expect it'
else
    echo "ERROR: Reftable is at $rt_offset, but was expected at $data_4k_offset"
fi

echo
echo '--- Rebuilding refcount structures on block devices ---'
echo

# A block device cannot really grow, at least not during qemu-img
# check.  As mentioned in the above cases, rebuilding the refcount
# structure may lead to new refcount structures being written after
# the end of the image, and in the past that happened even if there
# was more than sufficient space in the image.  Such post-EOF writes
# will not work on block devices, so test that the new algorithm
# avoids it.

# If we have passwordless sudo and losetup, we can use those to create
# a block device.  Otherwise, we can resort to qemu's FUSE export to
# create a file that isn't growable, which effectively tests the same
# thing.

_cleanup_test_img
truncate -s $((64 * 1024 * 1024)) "$TEST_IMG"

if $loopdev; then
    export_mp=$(sudo -n losetup --show -f "$TEST_IMG")
    export_mp_driver=host_device
    sudo -n chmod go+rw "$export_mp"
else
    # Create non-growable FUSE export that is a bit like an empty
    # block device
    export_mp="$TEST_DIR/fuse-export"
    export_mp_driver=file
    touch "$export_mp"

    $QSD \
        --blockdev file,node-name=export-node,filename="$TEST_IMG" \
        --export fuse,id=fuse-export,node-name=export-node,mountpoint="$export_mp",writable=on,growable=off,allow-other=off \
        --pidfile "$TEST_DIR/qsd.pid" \
        --daemonize
fi

# Now create a qcow2 image on the device -- unfortunately, qemu-img
# create force-creates the file, so we have to resort to the
# blockdev-create job.
_launch_qemu \
    --blockdev $export_mp_driver,node-name=file,filename="$export_mp"

_send_qemu_cmd \
    $QEMU_HANDLE \
    '{ "execute": "qmp_capabilities" }' \
    'return'

# Small cluster size again, so the image needs multiple refblocks
_send_qemu_cmd \
    $QEMU_HANDLE \
    '{ "execute": "blockdev-create",
       "arguments": {
           "job-id": "create",
           "options": {
               "driver": "qcow2",
               "file": "file",
               "size": '$((64 * 1024 * 1024))',
               "cluster-size": 512
           } } }' \
    '"concluded"'

_send_qemu_cmd \
    $QEMU_HANDLE \
    '{ "execute": "job-dismiss", "arguments": { "id": "create" } }' \
    'return'

_send_qemu_cmd \
    $QEMU_HANDLE \
    '{ "execute": "quit" }' \
    'return'

wait=y _cleanup_qemu
echo

# Write some data
$QEMU_IO -c 'write 0 64k' "$export_mp" | _filter_qemu_io

# Corrupt the image by saying the image header was not allocated
rt_offset=$(peek_file_be "$export_mp" 48 8)
rb_offset=$(peek_file_be "$export_mp" $rt_offset 8)
poke_file "$export_mp" $rb_offset "\x00\x00"

# Repairing such a simple case should just work
# (We used to put the reftable at the end of the image file, which can
# never work for non-growable devices.)
echo
TEST_IMG="$export_mp" _check_test_img -r all \
    | grep -v '^Repairing cluster.*refcount=1 reference=0'

if $loopdev; then
    sudo -n losetup -d "$export_mp"
else
    qsd_pid=$(cat "$TEST_DIR/qsd.pid")
    kill -TERM "$qsd_pid"
    # Wait for process to exit (cannot `wait` because the QSD is daemonized)
    while [ -f "$TEST_DIR/qsd.pid" ]; do
        true
    done
fi

# success, all done
echo '*** done'
rm -f $seq.full
status=0