8417e1378c
The recently-added NBD context qemu:allocation-depth is able to
distinguish between locally-present data (even when that data is
sparse) [shown as depth 1 over NBD], and data that could not be found
anywhere in the backing chain [shown as depth 0]; and the libnbd
project was recently patched to give the human-readable name "absent"
to an allocation-depth of 0. But qemu-img map --output=json predates
that addition, and has the unfortunate behavior that all portions of
the backing chain that resolve without finding a hit in any backing
layer report the same depth as the final backing layer. This makes it
harder to reconstruct a qcow2 backing chain using just 'qemu-img map'
output, especially when using "backing":null to artificially limit a
backing chain, because it is impossible to distinguish between a
QCOW2_CLUSTER_UNALLOCATED (which defers to a [missing] backing file)
and a QCOW2_CLUSTER_ZERO_PLAIN cluster (which would override any
backing file), since both types of clusters otherwise show as
"data":false,"zero":true" (but note that we can distinguish a
QCOW2_CLUSTER_ZERO_ALLOCATED, which would also have an "offset":
listing).
The task of reconstructing a qcow2 chain was made harder in commit
0da9856851 (nbd: server: Report holes for raw images), because prior
to that point, it was possible to abuse NBD's block status command to
see which portions of a qcow2 file resulted in BDRV_BLOCK_ALLOCATED
(showing up as NBD_STATE_ZERO in isolation) vs. missing from the chain
(showing up as NBD_STATE_ZERO|NBD_STATE_HOLE); but now qemu reports
more accurate sparseness information over NBD.
An obvious solution is to make 'qemu-img map --output=json' add an
additional "present":false designation to any cluster lacking an
allocation anywhere in the chain, without any change to the "depth"
parameter to avoid breaking existing clients. The iotests have
several examples where this distinction demonstrates the additional
accuracy.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210701190655.2131223-3-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[eblake: fix more iotest fallout]
Signed-off-by: Eric Blake <eblake@redhat.com>
250 lines
10 KiB
Plaintext
250 lines
10 KiB
Plaintext
QA output created by 223
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=== Create partially sparse image, then add dirty bitmaps ===
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=4194304
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wrote 2097152/2097152 bytes at offset 1048576
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2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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Testing:
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QMP_VERSION
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{"return": {}}
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{"return": {}}
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{"return": {}}
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{"return": {}}
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{"return": {}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false, "reason": "host-qmp-quit"}}
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=== Write part of the file under active bitmap ===
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wrote 512/512 bytes at offset 512
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512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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wrote 2097152/2097152 bytes at offset 2097152
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2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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=== End dirty bitmaps, and start serving image over NBD ===
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{"execute":"qmp_capabilities"}
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{"return": {}}
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{"execute":"blockdev-add",
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"arguments":{"driver":"IMGFMT", "node-name":"n",
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"file":{"driver":"file", "filename":"TEST_DIR/t.IMGFMT"}}}
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{"return": {}}
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{"execute":"block-dirty-bitmap-disable",
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"arguments":{"node":"n", "name":"b"}}
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{"return": {}}
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=== Set up NBD with normal access ===
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{"execute":"nbd-server-add",
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"arguments":{"device":"n"}}
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{"error": {"class": "GenericError", "desc": "NBD server not running"}}
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{"execute":"nbd-server-start",
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"arguments":{"addr":{"type":"unix",
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"data":{"path":"SOCK_DIR/nbd"}}}}
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{"return": {}}
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{"execute":"nbd-server-start",
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"arguments":{"addr":{"type":"unix",
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"data":{"path":"SOCK_DIR/nbd1"}}}}
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{"error": {"class": "GenericError", "desc": "NBD server already running"}}
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exports available: 0
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{"execute":"nbd-server-add",
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"arguments":{"device":"n", "bitmap":"b"}}
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{"return": {}}
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{"execute":"nbd-server-add",
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"arguments":{"device":"nosuch"}}
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{"error": {"class": "GenericError", "desc": "Cannot find device='nosuch' nor node-name='nosuch'"}}
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{"execute":"nbd-server-add",
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"arguments":{"device":"n"}}
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{"error": {"class": "GenericError", "desc": "Block export id 'n' is already in use"}}
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{"execute":"nbd-server-add",
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"arguments":{"device":"n", "name":"n2",
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"bitmap":"b2"}}
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{"error": {"class": "GenericError", "desc": "Enabled bitmap 'b2' incompatible with readonly export"}}
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{"execute":"nbd-server-add",
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"arguments":{"device":"n", "name":"n2",
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"bitmap":"b3"}}
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{"error": {"class": "GenericError", "desc": "Bitmap 'b3' is not found"}}
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{"execute":"nbd-server-add",
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"arguments":{"device":"n", "name":"n2", "writable":true,
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"description":"some text", "bitmap":"b2"}}
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{"return": {}}
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exports available: 2
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export: 'n'
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size: 4194304
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flags: 0x58f ( readonly flush fua df multi cache )
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min block: 1
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opt block: 4096
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max block: 33554432
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available meta contexts: 2
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base:allocation
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qemu:dirty-bitmap:b
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export: 'n2'
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description: some text
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size: 4194304
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flags: 0xced ( flush fua trim zeroes df cache fast-zero )
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min block: 1
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opt block: 4096
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max block: 33554432
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available meta contexts: 2
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base:allocation
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qemu:dirty-bitmap:b2
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=== Contrast normal status to large granularity dirty-bitmap ===
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read 512/512 bytes at offset 512
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512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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read 524288/524288 bytes at offset 524288
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512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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read 1048576/1048576 bytes at offset 1048576
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1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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read 2097152/2097152 bytes at offset 2097152
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2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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{ "start": 4096, "length": 1044480, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
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{ "start": 1048576, "length": 3145728, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
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[{ "start": 0, "length": 65536, "depth": 0, "present": false, "zero": false, "data": false},
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{ "start": 65536, "length": 2031616, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
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=== Contrast to small granularity dirty-bitmap ===
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[{ "start": 0, "length": 512, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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{ "start": 512, "length": 512, "depth": 0, "present": false, "zero": false, "data": false},
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{ "start": 1024, "length": 2096128, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
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=== End qemu NBD server ===
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{"execute":"nbd-server-remove",
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"arguments":{"name":"n"}}
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{"return": {}}
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{"execute":"nbd-server-remove",
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"arguments":{"name":"n2"}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_EXPORT_DELETED", "data": {"id": "n"}}
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{"return": {}}
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{"execute":"nbd-server-remove",
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"arguments":{"name":"n2"}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_EXPORT_DELETED", "data": {"id": "n2"}}
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{"error": {"class": "GenericError", "desc": "Export 'n2' is not found"}}
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{"execute":"nbd-server-stop"}
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{"return": {}}
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{"execute":"nbd-server-stop"}
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{"error": {"class": "GenericError", "desc": "NBD server not running"}}
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=== Set up NBD with iothread access ===
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{"execute":"x-blockdev-set-iothread",
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"arguments":{"node-name":"n", "iothread":"io0"}}
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{"return": {}}
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{"execute":"nbd-server-add",
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"arguments":{"device":"n"}}
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{"error": {"class": "GenericError", "desc": "NBD server not running"}}
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{"execute":"nbd-server-start",
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"arguments":{"addr":{"type":"unix",
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"data":{"path":"SOCK_DIR/nbd"}}}}
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{"return": {}}
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{"execute":"nbd-server-start",
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"arguments":{"addr":{"type":"unix",
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"data":{"path":"SOCK_DIR/nbd1"}}}}
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{"error": {"class": "GenericError", "desc": "NBD server already running"}}
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exports available: 0
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{"execute":"nbd-server-add",
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"arguments":{"device":"n", "bitmap":"b"}}
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{"return": {}}
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{"execute":"nbd-server-add",
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"arguments":{"device":"nosuch"}}
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{"error": {"class": "GenericError", "desc": "Cannot find device='nosuch' nor node-name='nosuch'"}}
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{"execute":"nbd-server-add",
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"arguments":{"device":"n"}}
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{"error": {"class": "GenericError", "desc": "Block export id 'n' is already in use"}}
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{"execute":"nbd-server-add",
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"arguments":{"device":"n", "name":"n2",
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"bitmap":"b2"}}
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{"error": {"class": "GenericError", "desc": "Enabled bitmap 'b2' incompatible with readonly export"}}
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{"execute":"nbd-server-add",
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"arguments":{"device":"n", "name":"n2",
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"bitmap":"b3"}}
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{"error": {"class": "GenericError", "desc": "Bitmap 'b3' is not found"}}
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{"execute":"nbd-server-add",
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"arguments":{"device":"n", "name":"n2", "writable":true,
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"description":"some text", "bitmap":"b2"}}
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{"return": {}}
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exports available: 2
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export: 'n'
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size: 4194304
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flags: 0x58f ( readonly flush fua df multi cache )
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min block: 1
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opt block: 4096
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max block: 33554432
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available meta contexts: 2
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base:allocation
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qemu:dirty-bitmap:b
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export: 'n2'
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description: some text
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size: 4194304
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flags: 0xced ( flush fua trim zeroes df cache fast-zero )
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min block: 1
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opt block: 4096
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max block: 33554432
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available meta contexts: 2
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base:allocation
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qemu:dirty-bitmap:b2
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=== Contrast normal status to large granularity dirty-bitmap ===
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read 512/512 bytes at offset 512
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512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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read 524288/524288 bytes at offset 524288
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512 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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read 1048576/1048576 bytes at offset 1048576
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1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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read 2097152/2097152 bytes at offset 2097152
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2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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[{ "start": 0, "length": 4096, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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{ "start": 4096, "length": 1044480, "depth": 0, "present": true, "zero": true, "data": false, "offset": OFFSET},
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{ "start": 1048576, "length": 3145728, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
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[{ "start": 0, "length": 65536, "depth": 0, "present": false, "zero": false, "data": false},
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{ "start": 65536, "length": 2031616, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
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=== Contrast to small granularity dirty-bitmap ===
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[{ "start": 0, "length": 512, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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{ "start": 512, "length": 512, "depth": 0, "present": false, "zero": false, "data": false},
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{ "start": 1024, "length": 2096128, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
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=== End qemu NBD server ===
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{"execute":"nbd-server-remove",
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"arguments":{"name":"n"}}
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{"return": {}}
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{"execute":"nbd-server-remove",
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"arguments":{"name":"n2"}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_EXPORT_DELETED", "data": {"id": "n"}}
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{"return": {}}
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{"execute":"nbd-server-remove",
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"arguments":{"name":"n2"}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "BLOCK_EXPORT_DELETED", "data": {"id": "n2"}}
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{"error": {"class": "GenericError", "desc": "Export 'n2' is not found"}}
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{"execute":"nbd-server-stop"}
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{"return": {}}
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{"execute":"nbd-server-stop"}
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{"error": {"class": "GenericError", "desc": "NBD server not running"}}
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{"execute":"quit"}
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{"return": {}}
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{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false, "reason": "host-qmp-quit"}}
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=== Use qemu-nbd as server ===
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[{ "start": 0, "length": 65536, "depth": 0, "present": false, "zero": false, "data": false},
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{ "start": 65536, "length": 2031616, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
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[{ "start": 0, "length": 512, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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{ "start": 512, "length": 512, "depth": 0, "present": false, "zero": false, "data": false},
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{ "start": 1024, "length": 11321, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
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[{ "start": 12345, "length": 2084807, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
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{ "start": 2097152, "length": 2097152, "depth": 0, "present": false, "zero": false, "data": false}]
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*** done
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