xemu/tests/qemu-iotests/223
Eric Blake 5fcbeb0681 nbd: Allow bitmap export during QMP nbd-server-add
With the experimental x-nbd-server-add-bitmap command, there was
a window of time where an NBD client could see the export but not
the associated dirty bitmap, which can cause a client that planned
on using the dirty bitmap to be forced to treat the entire image
as dirty as a safety fallback.  Furthermore, if the QMP client
successfully exports a disk but then fails to add the bitmap, it
has to take on the burden of removing the export.  Since we don't
allow changing the exposed dirty bitmap (whether to a different
bitmap, or removing advertisement of the bitmap), it is nicer to
make the bitmap tied to the export at the time the export is
created, with automatic failure to export if the bitmap is not
available.

The experimental command included an optional 'bitmap-export-name'
field for remapping the name exposed over NBD to be different from
the bitmap name stored on disk.  However, my libvirt demo code
for implementing differential backups on top of persistent bitmaps
did not need to take advantage of that feature (it is instead
possible to create a new temporary bitmap with the desired name,
use block-dirty-bitmap-merge to merge one or more persistent
bitmaps into the temporary, then associate the temporary with the
NBD export, if control is needed over the exported bitmap name).
Hence, I'm not copying that part of the experiment over to the
stable addition. For more details on the libvirt demo, see
https://www.redhat.com/archives/libvir-list/2018-October/msg01254.html,
https://kvmforum2018.sched.com/event/FzuB/facilitating-incremental-backup-eric-blake-red-hat

This patch focuses on the user interface, and reduces (but does
not completely eliminate) the window where an NBD client can see
the export but not the dirty bitmap, with less work to clean up
after errors.  Later patches will add further cleanups now that
this interface is declared stable via a single QMP command,
including removing the race window.

Update test 223 to use the new interface.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20190111194720.15671-6-eblake@redhat.com>
2019-01-14 10:09:46 -06:00

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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 $seq"
status=1 # failure is the default!
_cleanup()
{
_cleanup_test_img
_cleanup_qemu
rm -f "$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
# Persistent dirty bitmaps require compat=1.1
_unsupported_imgopts 'compat=0.10'
do_run_qemu()
{
echo Testing: "$@"
$QEMU -nographic -qmp stdio -serial none "$@"
echo
}
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 bitmaps ==="
echo
# Two bitmaps, to contrast granularity issues
# Also note that b will be disabled, while b2 is left enabled, to
# check for read-only interactions
_make_test_img -o cluster_size=4k 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,
"granularity": 65536
}
}
{ "execute": "block-dirty-bitmap-add",
"arguments": {
"node": "n",
"name": "b2",
"persistent": true,
"granularity": 512
}
}
{ "execute": "quit" }
EOF
echo
echo "=== Write part of the file under active bitmap ==="
echo
$QEMU_IO -c 'w -P 0x22 512 512' -c 'w -P 0x33 2M 2M' "$TEST_IMG" \
| _filter_qemu_io
echo
echo "=== End dirty bitmaps, and start serving image over NBD ==="
echo
_launch_qemu 2> >(_filter_nbd)
# Intentionally provoke some errors as well, to check error handling
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":"block-dirty-bitmap-disable",
"arguments":{"node":"n", "name":"b"}}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
"arguments":{"device":"n"}}' "error" # Attempt add without server
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-start",
"arguments":{"addr":{"type":"unix",
"data":{"path":"'"$TEST_DIR/nbd"'"}}}}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-start",
"arguments":{"addr":{"type":"unix",
"data":{"path":"'"$TEST_DIR/nbd"1'"}}}}' "error" # Attempt second server
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
"arguments":{"device":"n", "bitmap":"b"}}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
"arguments":{"device":"nosuch"}}' "error" # Attempt to export missing node
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
"arguments":{"device":"n"}}' "error" # Attempt to export same name twice
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
"arguments":{"device":"n", "name":"n2",
"bitmap":"b2"}}' "error" # enabled vs. read-only
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
"arguments":{"device":"n", "name":"n2",
"bitmap":"b3"}}' "error" # Missing bitmap
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",
"arguments":{"device":"n", "name":"n2", "writable":true,
"bitmap":"b2"}}' "return"
echo
echo "=== Contrast normal status to large granularity dirty-bitmap ==="
echo
QEMU_IO_OPTIONS=$QEMU_IO_OPTIONS_NO_FMT
IMG="driver=nbd,export=n,server.type=unix,server.path=$TEST_DIR/nbd"
$QEMU_IO -r -c 'r -P 0x22 512 512' -c 'r -P 0 512k 512k' -c 'r -P 0x11 1m 1m' \
-c 'r -P 0x33 2m 2m' --image-opts "$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 "=== Contrast to small granularity dirty-bitmap ==="
echo
IMG="driver=nbd,export=n2,server.type=unix,server.path=$TEST_DIR/nbd"
$QEMU_IMG map --output=json --image-opts \
"$IMG,x-dirty-bitmap=qemu:dirty-bitmap:b2" | _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-remove",
"arguments":{"name":"n2"}}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-remove",
"arguments":{"name":"n2"}}' "error" # Attempt duplicate clean
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-stop"}' "return"
_send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-stop"}' "error" # Again
_send_qemu_cmd $QEMU_HANDLE '{"execute":"quit"}' "return"
# success, all done
echo '*** done'
rm -f $seq.full
status=0