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1104d83c72
The NBD spec says that clients should not try to write/trim to an export advertised as read-only by the server. But we failed to check that, and would allow the block layer to use NBD with BDRV_O_RDWR even when the server is read-only, which meant we were depending on the server sending a proper EPERM failure for various commands, and also exposes a leaky abstraction: using qemu-io in read-write mode would succeed on 'w -z 0 0' because of local short-circuiting logic, but 'w 0 0' would send a request over the wire (where it then depends on the server, and fails at least for qemu-nbd but might pass for other NBD implementations). With this patch, a client MUST request read-only mode to access a server that is doing a read-only export, or else it will get a message like: can't open device nbd://localhost:10809/foo: request for write access conflicts with read-only export It is no longer possible to even attempt writes over the wire (including the corner case of 0-length writes), because the block layer enforces the explicit read-only request; this matches the behavior of qcow2 when backed by a read-only POSIX file. Fix several iotests to comply with the new behavior (since qemu-nbd of an internal snapshot, as well as nbd-server-add over QMP, default to a read-only export, we must tell blockdev-add/qemu-io to set up a read-only client). CC: qemu-stable@nongnu.org Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20171108215703.9295-3-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
104 lines
2.6 KiB
Bash
Executable File
104 lines
2.6 KiB
Bash
Executable File
#!/bin/bash
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#
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# Test case for ejecting a BlockBackend with an NBD server attached to it
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#
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# Verify that the NBD server stops offering the drive when ejecting a
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# BlockDriverState tree from a BlockBackend (that is, a medium from a
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# drive) exposed via an NBD server.
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#
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# Copyright (C) 2016 Red Hat, Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# creator
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owner=mreitz@redhat.com
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seq="$(basename $0)"
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echo "QA output created by $seq"
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here="$PWD"
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status=1 # failure is the default!
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_cleanup()
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{
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_cleanup_qemu
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_cleanup_test_img
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rm -f "$TEST_DIR/nbd"
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}
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trap "_cleanup; exit \$status" 0 1 2 3 15
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# get standard environment, filters and checks
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. ./common.rc
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. ./common.filter
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. ./common.qemu
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_supported_fmt generic
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_supported_proto file
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_supported_os Linux
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_make_test_img 64k
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$QEMU_IO -c 'write -P 42 0 64k' "$TEST_IMG" | _filter_qemu_io
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if test "$IMGOPTSSYNTAX" = "true"
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then
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SYSEMU_DRIVE_ARG=if=none,media=cdrom,id=drv,"$TEST_IMG"
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else
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SYSEMU_DRIVE_ARG=if=none,media=cdrom,id=drv,file="$TEST_IMG",driver=$IMGFMT
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fi
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keep_stderr=y \
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_launch_qemu -drive $SYSEMU_DRIVE_ARG \
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2> >(_filter_nbd)
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_send_qemu_cmd $QEMU_HANDLE \
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"{ 'execute': 'qmp_capabilities' }" \
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'return'
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_send_qemu_cmd $QEMU_HANDLE \
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"{ 'execute': 'nbd-server-start',
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'arguments': { 'addr': { 'type': 'unix',
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'data': { 'path': '$TEST_DIR/nbd' }}}}" \
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'return'
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_send_qemu_cmd $QEMU_HANDLE \
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"{ 'execute': 'nbd-server-add',
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'arguments': { 'device': 'drv' }}" \
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'return'
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$QEMU_IO_PROG -f raw -r -c 'read -P 42 0 64k' \
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"nbd+unix:///drv?socket=$TEST_DIR/nbd" 2>&1 \
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| _filter_qemu_io | _filter_nbd
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_send_qemu_cmd $QEMU_HANDLE \
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"{ 'execute': 'eject',
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'arguments': { 'device': 'drv' }}" \
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'return'
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$QEMU_IO_PROG -f raw -r -c close \
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"nbd+unix:///drv?socket=$TEST_DIR/nbd" 2>&1 \
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| _filter_qemu_io | _filter_nbd
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_send_qemu_cmd $QEMU_HANDLE \
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"{ 'execute': 'quit' }" \
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'return'
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wait=1 _cleanup_qemu
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# success, all done
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echo '*** done'
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rm -f $seq.full
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status=0
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