qemu/tests/qemu-iotests/223
Eric Blake a1532a225a iotests: New test 223 for exporting dirty bitmap over NBD
Although this test is NOT a full test of image fleecing (as it
intentionally uses just a single block device directly exported
over NBD, rather than trying to set up a blockdev-backup job with
multiple BDS involved), it DOES prove that qemu as a server is
able to properly expose a dirty bitmap over NBD.

When coupled with image fleecing, it is then possible for a
third-party client to do an incremental backup by using
qemu-img map with the x-dirty-bitmap option to learn which parts
of the file are dirty (perhaps confusingly, they are the portions
mapped as "data":false - which is part of the reason this is
still in the x- experimental namespace), along with another
normal client (perhaps 'qemu-nbd -c' to expose the server over
/dev/nbd0 and then just use normal I/O on that block device) to
read the dirty sections.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180702191458.28741-3-eblake@redhat.com>
Tested-by: John Snow <jsnow@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
2018-07-02 19:50:37 -05:00

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#!/bin/bash
#
# Test reading dirty bitmap over NBD
#
# Copyright (C) 2018 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/>.
#
seq="$(basename $0)"
echo "QA output created by $seq"
here="$PWD"
status=1 # failure is the default!
_cleanup()
{
_cleanup_test_img
_cleanup_qemu
rm -f "$TEST_DIR/nbd"
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common.rc
. ./common.filter
. ./common.qemu
_supported_fmt qcow2
_supported_proto file # uses NBD as well
_supported_os Linux
function do_run_qemu()
{
echo Testing: "$@"
$QEMU -nographic -qmp stdio -serial none "$@"
echo
}
function run_qemu()
{
do_run_qemu "$@" 2>&1 | _filter_testdir | _filter_qmp \
| _filter_qemu | _filter_imgfmt \
| _filter_actual_image_size
}
echo
echo "=== Create partially sparse image, then add dirty bitmap ==="
echo
_make_test_img 4M
$QEMU_IO -c 'w -P 0x11 1M 2M' "$TEST_IMG" | _filter_qemu_io
run_qemu <<EOF
{ "execute": "qmp_capabilities" }
{ "execute": "blockdev-add",
"arguments": {
"driver": "$IMGFMT",
"node-name": "n",
"file": {
"driver": "file",
"filename": "$TEST_IMG"
}
}
}
{ "execute": "block-dirty-bitmap-add",
"arguments": {
"node": "n",
"name": "b",
"persistent": true
}
}
{ "execute": "quit" }
EOF
echo
echo "=== Write part of the file under active bitmap ==="
echo
$QEMU_IO -c 'w -P 0x22 2M 2M' "$TEST_IMG" | _filter_qemu_io
echo
echo "=== End dirty bitmap, and start serving image over NBD ==="
echo
_launch_qemu 2> >(_filter_nbd)
silent=
_send_qemu_cmd $QEMU_HANDLE '{"execute":"qmp_capabilities"}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"blockdev-add",
"arguments":{"driver":"qcow2", "node-name":"n",
"file":{"driver":"file", "filename":"'"$TEST_IMG"'"}}}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"x-block-dirty-bitmap-disable",
"arguments":{"node":"n", "name":"b"}}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-start",
"arguments":{"addr":{"type":"unix",
"data":{"path":"'"$TEST_DIR/nbd"'"}}}}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
"arguments":{"device":"n"}}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"x-nbd-server-add-bitmap",
"arguments":{"name":"n", "bitmap":"b"}}' "return"
echo
echo "=== Contrast normal status with dirty-bitmap status ==="
echo
QEMU_IO_OPTIONS=$QEMU_IO_OPTIONS_NO_FMT
IMG="driver=nbd,export=n,server.type=unix,server.path=$TEST_DIR/nbd"
$QEMU_IO -r -c 'r -P 0 0 1m' -c 'r -P 0x11 1m 1m' \
-c 'r -P 0x22 2m 2m' --image-opts "$IMG" | _filter_qemu_io
$QEMU_IMG map --output=json --image-opts \
"$IMG" | _filter_qemu_img_map
$QEMU_IMG map --output=json --image-opts \
"$IMG,x-dirty-bitmap=qemu:dirty-bitmap:b" | _filter_qemu_img_map
echo
echo "=== End NBD server ==="
echo
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-remove",
"arguments":{"name":"n"}}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-stop"}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"quit"}' "return"
# success, all done
echo '*** done'
rm -f $seq.full
status=0